ANALYTICAL CHEMISTRY, VOL. 51, NO. 5, APRIL 1979
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Ferrous Metallurgy W. A. Straub" and J.
K. Hurwitz
United States Steel Corporation, Research Laboratory, 125 Jamison Lane, Monroeville, Pennsylvania 15 146
This review covers the period from November 1976 through October 1978, and is a continuation of previous reviews. The search of Chemical Abstracts was aided by the Knowledge Availability Service Center a t the University of Pittsburgh. Following all citations in the Literature Cited, the Chemical Abstract (Chem. Abstr.) volume, numbers, and year are given. During the past two years, development of methods for the analysis of ores was emphasized because of the need for new sources of raw materials for the steel industry. New instruments offered by manufacturers or developed by research laboratories have as integral parts minicomputers or microprocessors or the capability of being interfaced to these devices for data acquisition and reduction. Consequently, technical papers describing computer hardware and software for analytical chemistry are appearing with increasing frequency.
ALUMINUM Titrimetric. Three variations of a compleximetric titration of aluminum with EDTA have been described for iron ore and sinter ( 3 8 ) ,ferrotitanium (490),and ores and ferroalloys in general (491). Polarographic. An ac polarographic method involving the decrease in the polarographic wave of Chromazurol S by aluminum has been reported (513). Spectrophotometric. An automated method for major blast furnace slag components has been developed on an AutoAnalyzer, with aluminum being determined by using Chromazurol (53). Several manual methods for the determination of alumina in iron ore with Chromazurol S (492), in ores and sinters with Alizarin reds ( 6 0 ) ,and following a preliminary ion-exchange separation from limestone (515)have been reported. Methylthymol blue has been recommended for the determination of aluminum in high-purity iron (452) and in Fe-Mn-Al alloys (1521, while the old standby Aluminon is still being applied to alloyed steels (299),following careful precipitation of several interfering elements. Atomic Absorption. Acid solutions of low-alloy steel samples have been analyzed for aluminum (120,489),as have high-alloy solutions (402) without removal of the major elements. Other work has been reported in which the dissolved steel samples are atomized from graphite furnaces for either atomic absorption analysis (200,376)or atomic emission (365). Ferrovanadium has also been analyzed directly in acid solution for its aluminum content (335). Basic refractories (419) and slags (72, 226) have been assayed by atomic absorption methods following very careful sample preparation using acid and/or alkaline fusions. An extraction-atomic absorption method (232),in which iron is removed by extraction prior to the determination of trace metals by atomic absorption, has been reported. Emission Spectrometry. Optimum conditions have been developed for the determination of aluminum (among other elements) in liquid steel (531, 532), iron and low-alloy steels (2091, in solutions of steel samples (265), by inductively coupled plasma excitation for traces (431),and in medium alloys with a fully automated, computer-controlled spectrometer (47). High-voltage spark excitation was used for profiling aluminized layers on steel (470). X-ray Spectrometry. Fused samples of iron ores and similar materials have been successfully analyzed by X-ray fluorescence techniques (22, 4261, while blast furnace slags have also been subjected to this method for aluminum determination (345). Other Methods. Neutron activation with a 252Cfsource has been reportedly used for ore analyses, with a 5-min irradiation time required for Al as low as 0.01% (24). Secondary ion mass spectrometry (SIMS) has been tried for the determination of trace quantities of aluminum in iron (234). 0003-2700/79/0351-155R$05.00/0
ANTIMONY Atomic Absorption. Antimony has been determined directly in dissolved steel samples with a graphite furnace (200, 273) and following coprecipitation with manganese dioxide with subsequent analysis of the dissolved precipitate (78). Extraction with trioctylamine followed by atomic absorption analysis of the extract has been reported (456). Electrochemical. Inverse voltammetry has been applied to the determination of antimony in ferromanganese after separation either by coprecipitation with manganese dioxide (347) or electrochemical deposition as SbCl,--malachite complex (75). Diantipyrylmethane has been used in extraction polarography for the estimation of antimony in steel (207). Emission and X-ray Spectroscopy. A solution spectrochemical method has been applied to steels (265) while a spectrographic method has been used for to 5 X lo-*% antimony in slags and iron ores (545). High-purity irons, mild and low-alloy steels have been analyzed for trace antimony by X-ray fluorescence methods (177). Auger electron spectroscopy and X-ray photoelectron spectroscopy have been used in studying segregation of antimony in steels during embrittlement (433) and a t intergranular fractures (311).
ARSENIC Spectrophotometry. Traces of arsenic in high-purity iron and in steels have been extracted as an arsenic-thionalide complex (484) or as H7[A~(Mo207)jOMo305] (132) and determined by the molybdenum blue method. Evolution of arsine from iron and steels with the subsequent measurement of the absorbed hydride as a red-violet complex with silver diethyldithiocarbamate and 1-ephedrin has been recommended (12). Atomic Absorption and Fluorescence. Three interesting variations of atomic absorption technology for the determination of arsenic in steels and iron have appeared, as follows: nondispersive atomic fluorescence following entrainment of arsine into an argon-H, flame (500),as-dissolved steels in hollow cathode or electrodeless discharge lamps (116), and indirectly after formation of molybdoarsenic acid, with extraction and determination of the coextracted molybdenum with an N20-C2H2 flame. Emission and X-ray Spectrometry. Methods for the direct determination of arsenic in iron ores and slags (545), and in carbon and low-alloy steels (209)have been reported, while evolved arsine was entrained into a UHF-Plasma Spectrascan spectrometer for the determination of as little as 0.01 pg of arsenic (339). Different Fe-alloy reference samples were analyzed as standards to be used to determine trace amounts of arsenic in high-purity irons and steels by X-ray fluorescence methods (177). Polarography. Arsenic at 0.17 to 0.19%, but as low as 0.0015% has been determined by direct polarography (146). BERYLLIUM A comparative study of the use of Chromazurol-S, Eriochrome Cyanine R, and acetylacetone for the determination of beryllium in steel at the 0.01 to 0.1% level has been reported (681, as has the use of Beryllon I1 for alloy steel analysis (461). At the 2- to 200-ppm level in steels and cast irons, atomic absorption has been applied successfully for beryllium analysis in dissolved samples (225). BISMUTH Atomic Absorption. Following dissolution of steels or iron in sulfuric or nitric acid, aliquots have been analyzed comparatively in either a carbon-filament carbon furnace, an air-C2H2 flame (204), or a heated graphite atomizer (200). Direct methods for bismuth in steel and cast iron have also 1979 American Chemical Society
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been described that utilize a graphite induction furnace (13, 140) and have been shown to offer a significant time advantage. An extraction-atomic absorption determination of trace impurities in steel at to 10-5% levels has been reported (456). Anodic stripping voltammetry at a mercury-coated graphite electrode has been used for the determination of trace bismuth in ferroniobium following acid dissolution (344).
B O O K S A N D REVIEWS Books describing standard methods for analysis of ores ( 9 , 10,58, 363), steel ( 9 , 10, 70, 125,505),pig iron (70, 305), and high-temperature alloys (227) have been published during the past two years. Ores. The prospect of using y-activation and nondispersive and dispersive X-ray analyses of ores and ore-processing products has been reviewed (118, 169, 283, 439). Steel, Pig Iron, and Cast Iron. Reviews of the application to steel and iron analyses of atomic absorption (46, 378), atomic emission and atomic fluorescence (46),X-ray spectrometry (258,293,294,309,324,346),emission spectrometry (258,294,309,324),and sampling (450)have been published. Nuclear techniques have been applied to the determination of carbon and nitrogen (149) nonmetallic inclusions (405), and trace elements (294)as well as to surface analysis (123). Other reviews were concerned with the determination of nonmetallic inclusions (34, 35, 111, 189, 318, 473) and gases (oxygen, hydrogen, and nitrogen) (81, 82, 189, 487). Several reviews were published on surface analysis of steels with an ion microanalyzer (236),electron probe microanalyzers (160,247, 298), Auger electron spectrometry (485,530, 540), and X-ray photoelectron spectrometry (191,196,197,361). Methods for the electrochemical determination of oxygen (264, 324, 382) and carbon and sulfur (324), and for mass spectrometric analysis of gases from the blast furnace (324) have been reviewed. Ferroalloys. One review describing methods for the routine analysis of ferrosilicon has been published (533). In addition to the above, four reviews covering analytical chemistry in the steel industry (356, 429, 449, 450) are available. BORON A recently published bibliography contains a section on the chemical analysis of steels for boron for the period covering 1964 to 1977 (449). Stainless steels have been analyzed by an extraction-spectrophotometric method (306). Emission Spectrometry. One publication describes the preheating and quenching of steel samples to disperse boron uniformly before spectral analysis, thus giving rise to high precision analysis (213). Traces of boron in steels (5,526) and cast iron ( I 09) have been determined spectrographically, and with photoelectric means of detection (47, 209, 255). An inductively coupled plasma has been used for determining both major and minor elements, including boron, in ferromanganese (431). Other Methods. Borided layers on steels have been determined with high-voltage spark excitation (471),while Auger techniques have been used to study segregation of boron to steel surfaces following vacuum heating (355). Electrodissolution of steel samples, followed by either infrared analysis of the isolated residue (537) or chemical analysis (1341, has been used to determine the boron nitride phase in steel, or to detect either soluble or insoluble boron compounds in steel. CADMIUM Atomic absorption spectrometry with prior extraction of the cadmium has been reported for iron ores (232),and steels (456), while a solution spectrographic method, with prior extractive removal of iron, has been applied to steels (265). CALCIUM Atomic Absorption. Two studies appeared describing interference effects on alkaline-earth determinations in steel (423), and comparison of AA and spectrometry for the determination of calcium in steel (493). Extraction-atomic absorption methods were described for the determination of calcium in steel (422), high-alloy steel (4021, and iron ores (232),while direct atomic absorption analysis was reported
for slags (72,2261,basic refractories (4191,and ores, slags, and sinters (290). X-ray Fluorescence. Several papers described the use of fluorescence methods for ores (22),moving ore mixtures (260, 261), and ore-flux mixtures (541). On-line X-ray fluorescence has also been used in finished sinter production (179),while errors in on-stream X-ray spectral methods have been discussed (262). Blast-furnace slags (345) and rusted surfaces on steels (295) have also been subjected to X-ray analysis. Other Methods. A combination ion-exchange-titrimetric method for the analysis of limestone has been described (515), while major blast-furnace slag components have been successfully analyzed by AutoAnalyzer techniques (53). Ferrochromium slag has been assayed for calcium by a precipitation separation-EDTA titration procedure (41).
CARBON Combustion Methods. Sampling of cast iron by forming a thin iron shell on a cold surface has been used to obtain better accuracy than by drilling or machining (510),while tungsten powder is recommended as a combustion aid for C analysis of steels (539). Several automatic analyzers utilizing a combustion decomposition and an infrared finish (77),a thermal conductivity measurement (353),or an automatic coulometric titration (193, 454) have been evaluated. Several types of apparatus have been described in which the initial decomposition of the steel or iron is by combustion, followed by coulometric titration of the evolved carbon dioxide (78,229,538)in a nonaqueous solvent. Coulometry was also used in a method that employed a carefully controlled arc excitation of the steel prior to analysis of the evolved gases (330). Either oxygen or dry air tube combustion was used prior to gas analysis (364) or gravimetric analysis (113) of the COS generated by oxidation of steel or cast iron. Emission Spectrometry. An argon-hydrogen mixture was recommended during arc excitation for the determination of C in steel (385),while several papers have described the use of photoelectric detectors for spectral analysis of steels (209, 520), of pulsed unipolar spark excitation (410, 411), and of the direct excitation of liquid steel (531, 532) for carbon content. Ferronickel has also been analyzed by emission spectrometric methods (290). Glow discharge lamp excitation was used for surface or gradient analysis of carbon in steels (43, 126) and cast irons (290, 2353, while laser excitation was reported used in the vacuum ultraviolet region for low-carbon steel analysis (20). X-ray Spectrometry. X-ray microanalysis has been applied to the determination of carbon in steel (15), stainless steels (129),and carburized steel (248). Other Methods. Secondary ion emission mass spectrometry (284), ion scattering spectrometry, and Auger electron spectroscopy (59) have been applied to steel and galvanized surfaces for carbon analysis. Isotopic dilution techniques with 14C have been used for the study of surface carbon diffusion in steels and iron powders (5231,while Auger electron spectroscopy was also used to characterize carbon diffusion in a-iron (467). The use of activation techniques with 3He or deuterons was reported for the determination of carbon in steel (249) or iron (332). CHROMIUM Emission Spectrometry. Emission vacuum spectrometry has been used to determine chromium as well as several other elements in cast iron and in carbon and low-alloy steels (209, 255, 520, 531, 532) and ferronickel (290). Apparatus and operating procedures have been described for analyzing liquid alloys, such as low-alloy steel, cast iron, pig iron, and stainless steel (531,532). Spectrographic methods have been published for the determination of chromium in stainless steel (233), high-manganese steel (301), and ores (545). New spectrometric sources have been applied to chromium determinations. such as the inductively coupled plasma in the analysis of ferromanganese (430, 431) and unipolar pulsed discharge in the analysis of carbon and low-alloy steel (409, 410). A portable spectrometer, in which a hand-held directcurrent arc source is connected to the spectrometer by a flexible fiber-optics light guide, has been described for sorting mixed steel (11). Changes in composition within welds in
ANALYTICAL CHEMISTRY, VOL. 51, NO 5, APRIL 1979
Willlam A Straub, Associate Research Consultant, U.S Steel Corporation, Research Laboratory, Monroeville, Pa, has been with U S Steel since obtaining his Ph.D. from Cornell University in 1958 As a Research Chemist, he has been active mainly in the areas of inclusion analyses by thermal methods and in the application of ion-selective electrodes and other electrochemical devices for both laboratory and phnt use, particularly in continwus process monitors. He is a member of the American Chemical Society,has served as the chauman of the Socety fw Analytical Chemists of Pittsburgh, and has worked on the Pittsburgh Conference committee in various capacities
J. K. Hurwltz is an Associate Research Consubnt at the Research Laboratory, United States Steel Corporation in Monroeville, Pa Previousty, he was Senior Scientific Officer at the Mines Branch, Government of Canada in Ottawa. Canada. He received his 6.A Sc in Engineering Physics and M A and Ph D in Physics from the University of Toronto His research interests include method development in emission spectroscopy, spectrochemical applications of computers, development of standard materials for optical and X-ray emission spectrometric analysis, and ionsputtering sources He is the author or coauthor of 27 papers in scientific journals and a book and has contributed papers to two symposia published by the American Society for Testing and Materials. He is an honorary member and a past president of the SpecWoscopy Society of Canada, member and past secretary of the Society for Applied Spectroscopy, and president of the Iron and Steel Chemists Association.
high-alloy steels have been measured with a laser source (297). High-frequency induction melting and centrifugal casting equipment (360) has been evaluated for preparing high-alloy steel samples. X-ray Spectrometry. Chromium has been determined by X-ray spectrometry in carbon and low-alloy steels (295. 349, 457), stainless steel ( 1 1 5 , 241, 395, 414, 506), high-speed tool steels ( 2 1 4 , ferronickel ( 6 ) , and chromite ore3 ( j 1 8 ) . Procedures for performing interference corrections have been published (241, 357). Atomic Absorption. Chromium has been determined in steel and slag by vaporizing the sample solution in a graphite furnace (200,365), in an oxygen-acetylene flame (120).in an air-acetylene flame (79, 128,226,246).and with a low-pressure ion-sputtering source (310). T o overcome the difficulty of different sputtering rates with the ion-sputtering source, an internal standard element was incorporated into the measuring and calculating technique. T o determine chromium in iron ores, iron must be separated chemically (232) before the determination is completed. T h e interference of iron on chromium determinations in steel was also reported (444). Miscellaneous Methods. Several improved spectrophotometric methods (32, 180, 354, 466, 469,508) have been published for determining chromium in steel, as have volumetric methods for this determination in carbon and low-alloy steels (1651, high-speed tool steels (280),ferrochromium slags (41, 6 6 ) , steelmaking slags (304),and ores (97). Chromium may be determined in steel by dissolving the sample in perchloric acid, adding ascorbic acid, and measuring the temperature change, which is proportional to the concentration (443). A calorimetric method for this determination in high-alloy steels (275) has excellent sensitivity and better precision than potentiometric titration or atomic absorption. Several other techniques have been applied in making this determination in steels, such as X-ray photoelectron spectroscopy (19. 391), electron microprobe (397),secondary ion mass spectrometry (284),ion microprobe (80, 358, 3591, and electron energy loss spectrometry (280').
COBALT for Spectrophotometry. Extraction-photometric the determination of cobalt in steel have heen described, with the use of 2-benzimidazole-carboxanilide oxime (31, 108), 6-nitroquinoxaline-2,3-dithiol in a simultaneous determination
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with nickel (54),thiodibenzoylmethane (201),aminobenzene AE (237),and 2,4-dinitroresorcinol or o-nitrosophenol (377). An ion-exchange separation of cobalt prior to analysis was also reported, with a nitroso-R salt finish (472). Extraction separation with the use of salicylideneamino-2-thiophenolfor color development has been applied to high-speed steels (525) while the tri(carbonato)cobdtate(III)complex has been used directly on partially chemically separated high-speed tool steels (312). The cobalt complex with 4-(2-pyridylazo)resorcinolhas been employed for traces in iron-ore beneficiation products (298). Emission and X-ray Spectrometry. Numerous emission methods have appeared in which the determination of cobalt, among others, in cast irons (89, 520), in steels (89, 209, 255, 498) by using photoelectric-recording emission spectrometers, in steel solutions (265),in high-alloy steels (360),in ferronickel ( B O ) , ferromanganese (431),and in ores and slags (540') is described. Extensive use of X-ray spectrometric analysis has been reported for determining cobalt content of steels (300), stainless steels for reactors ( 4 1 4 , manganese nodules (73,305, 4 5 5 ) , and ferronickel ( 6 ) . Atomic Absorption. Extraction-AA methods with cobalt extraction by sodium diethyldithiocarbamate (3221, or prior iron separation with bis(2-ethylhexy1)phosphate (232)have been reported, while direct solution methods have also heen used for steels (240) and ores (462). Other Methods. Ion microanalyzers have reportedly been used for high-alloy steel analysis (359).and in cobalt diffusion studies (80). Cobalt has been determined by gravimetry with acetothioacetanilide in stainless steels (142), by neutron activation in reactor steels (171),and in high-alloy. high-speed tool steels by a gravimetric method following separation of interferences (280). Paper chromatography with identification of metal zones with rubeanic acid has been used for ore assays (514).
COPPER Spectrophotometry. Various solvent-complexing agent combinations have been successfully explored for the extraction-spectrophotometric determination of copper in steel. Among those reported are the use of N-benzylbenzimidazolaldoxime and 2-benzimidazole carboxanilide oxime (31, 108), picramine-t (307), tri-N-octylamine-n-benzoinoxime ( 3 7 3 , pyridine-isonitrosoacetylacetone (374), and hexamethylene- and piperidine-dithiocarbamate for steels, and Na-diethyldithiocarbamate for cast irons (387). Atomic Absorption. Direct atomic absorption spectrophotometry has been used to certify steel standards (62):to analyze steels (120, 128, 246, 444, 445), in the latter two cases with the aid of spectral buffers; and to analyze sponge iron (125),castings (205), and high-alloy steels (402). An automatic AA method is also described (288). Atomization by cathodic sputtering and subsequent atomic absorption analysis for Cu in various alloys has been reported (310). Extraction with salicylaldoximine ( 2 9 ) , diethyldithiocarbamate (224),and trioctylamine (456) for steels, hexamethylene ammonium-hexamethylene dithiocarbamate (499) for high-purity irons, and bis(2-ethylhexy1)phosphate (232) for iron ores has been used in conjunction with atomic absorption analysis of the extract for copper. Carbon-furnace excitation of the dissolved steel solution for copper determination has been favorably reported (365). Emission Spectrometry. Excitation conditions and sample preparation have been described for the automated determination of copper by quantometric methods in steels (47,209,255) and ferronickel (290). Spectrographic methods have been developed for Cu in ores and slags ( 5 4 5 ) . Inductively coupled plasma spectroscopy has been applied specifically to ferromanganese analysis (4311. X-ray Spectrometry. The determination of copper in low-alloy steels (467),stainless steels (414),on rusted surfaces (295). and in ferronickel (6) bv X-rav fluorescence has been reported. A radioisotopic photon source has been used for the X-ray fluorescence analysis of ores (3961,while a glass-bead technique for iron-ore analysis using traditional X-ray fluorescence equipment was published (426). T h e use of on-board nondispersive and dispersive X-ray eauiament for nodule analvsis (73. ,305) has been described, a s has an X-ray fluorescence study of a large number of
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manganese nodules from the Pacific Ocean (455). O t h e r Methods. A precipitation separation-titrimetric method using EDTA for the determination of Cu in cast iron has appeared (39),while a paper chromatographic assay of iron ores for copper content has been tried (514). The feasibility of on-site neutron activation of manganese nodules for copper has been demonstrated (143).
D A T A ACQUISITION A N D REDUCTION T h e costs of large computers, minicomputers, microprocessors and associated or peripheral devices for mass storage of data have been significantly reduced to a point where the benefits of highly sophisticated, rapid, accurate calculations outweigh the additional expense of interfacing these devices to analytical equipment. Because this computing equipment tends to have adequate memory and mass storage devices for use with high-level programming languages such as FORTRAN or BASIC,software preparation is less time-consuming with lower associated labor costs. Most of the computer applications for analytical chemistry in the steel industry have been in emission and X-ray spectrometry where instrumentation, although expensive, is capable of rapid determinations of many elements in one analysis and where hundreds of samples are analyzed each day. X-ray Spectrometry. Three papers (76,112,195)describe the general use of computers in the analysis of carbon and alloy steels and high-temperature alloys. Corrections for interferences in the analysis of stainless steel (192, 357, 414, 511), carbon and low-alloy steel (85, 404, 5 1 I ) , high-temperature alloys a1.d tool steels (214, 357), and cast iron (85) have been covered. Several investigations on interferences occurring in ore analysis and development of the required software to make the necessary corrections have been reported (163, 172,503, 504). Nondispersive X-ray equipment for on-stream slurry analysis using a minicomputer for data reduction is available (323). A new computer program, written in BASIC, is used with a computerized X-ray spectrometer for slag analysis (26). Emission Spectrometry. The general application of computerized emission spectrometers for the analysis of carbon and alloy steels (47, 178) and cast iron and pig iron (314) has been reported. Interfacing of existing emission spectrometers with a computer (124) has produced an improvement in analytical service by shortening the analytical time and reducing the number of analytical errors. Specific interferences in the analysis of steel and cast iron, such as manganese on niobium (480) and carbon and manganese on sulfur (90,234),have been measured and expressed mathematically. Regression analysis was used to determine the coefficients in polynomial equations to express the analyte’s concentration as a function of spectral response and the concentrations of up to two interfering elements (498)for the analysis of steel. A high repetition rate source has been evaluated with emission spectrometers in several laboratories (548). The resultant data were input to a computer to evaluate the performance of this source in the analysis of low- and high-alloy steels and to determine the relationship of precision of the determinations with element concentration. Miscellaneous. A new computerized automatic microprobe (362) has been applied to the accurate analysis of stainless steel. A computer program has been developed for the processing of electron microprobe data obtained during quantitative analysis of oxide inclusions in steel (333). An on-line computer program corrects electron microprobe data for background continuum (156). Two digital devices have been incorporated in an atomic absorption spectrometer. In the first (325),a minicomputer is used for mechanical and electrical control of the spectrometer and data acquisition and reduction. In the second (296), the device measures both peak height and peak area from a transient absorbance signal. This transient signal was obtained by direct atomization of lead from stainless steel wire. I t was determined in this investigation that precision and the dynamic range were greater with the peak area measurement than with the peak height measurement. Photometric delerminations (256) were significantly improved both with respect to precision and analytical time when the equipment was computerized. Considerable savings in time and labor costs were obtained when an off-line computer (264) was used to statistically
evaluate analytical results and to calibrate analytical apparatus.
GASES Oxygen i n Liquid Steel. Several electrochemical probes have been investigated for monitoring the concentration of free oxygen in liquid steel. Most of the probes used zirconium oxide stabilized with calcium oxide (4, 40, 94, 188, 220, 221, 267, 268, 371, 382, 392, 486, 527, 528, 544). In two probes, magnesium oxide (4)and beryllium oxide-stabilized zirconium oxide (220)were also investigated as the electrolyte. Several materials such as pure oxygen ( 4 0 ) , molybdenum-molybdenum oxide or chromium-chromium oxide (188, 392) and nickel-nickel oxide or cobalt-cobalt oxide (528)were used as reference electrodes. An apparatus for oxygen determination, temperature measurement, and sampling (186, 187) was also described. These devices are important for determining the amount of deoxidation in liquid steel and the amount of aluminum to be added to accomplish deoxidation. N u c l e a r Methods. Oxygen was determined in steel by neutron activation (91, 408, 517 ) . triton induced reactions (403),and proton activation ( 8 , 332, 350). T o evaluate the deoxidation of steel (420),radioactive silicon was added to the liquid steel sample and the radioactivity of the inclusions extracted from the sample was measured. Nitrogen was determined in steel by proton and deuteron activation (149, 3.32) and by isotope dilution (161). Concentration profiles of oxygen, nitrogen, and hydrogen in thick corrosion films on steel were determined by activation with nuclear microbeams at Harwell (8). Electrochemical Methods. Two papers (100, 198) describe the potentiometric determination of nitrogen combined as ammonia with an ammonia gas sensing electrode. In one application (198), this technique was used to monitor the evolved nitrogen from silicon steel annealed in hydrogen. In a third paper (496),the evolved ammonia was absorbed in a solution containing bromine and oxidized to nitrogen with hypobromite ions electrolytically generated from this bromine. The current consumed was a measure of the nitrogen concentration. Two coulometric methods for the determination of hydrogen in steel (110) and oxygen in stainless steels containing high concentrations of manganese or aluminum (475) have been published. M a s s Spectrometric. Several mass spectrometric applications have appeared in the literature. The hydrogen distribution in chromium-plated steel was determined by the local fusion of a focused laser beam and the analysis of the extracted gases (547). An automated apparatus was developed for the rapid determination of oxygen and nitrogen in steel (259) by melting the sample in an argon atmosphere with a direct current arc and analyzing the extracted gases. A solids mass spectrometer (284)was used to analyze steel for oxygen as well as several other elements. Volumetric. Three variations of the Kjeldahl method for determining nitrogen in steel have been introduced (253,394, 495). In one variation (394),atmospheric contributions to the blank were thoroughly studied and minimized. The determination of nitrogen as ammonia was completed spectrophotometrically instead of by titration. Spectroscopic Methods. A combined X-ray diffraction-Mossbauer investigation of nitrided surfaces of iron (535) concluded that the nitrogen compounds on the surface were mixtures of Fe4N and Fe3N. Oxide films were stripped from the surface of low-carbon steel with a solution of iodine in methyl alcohol, and the oxide forms were determined with Mossbauer spectroscopy (516). A direct-current arc chamber was constructed to determine nitrogen in steel (145). The limit of detection was 4 parts per million. Several investigations were published describing the determination of nitrogen on steel surfaces by ESCA and emission spectroscopy with a glow discharge source (44)and by Auger electron spectroscopy (31I ) and of oxygen on pure iron, alloy steels, and stainless steels by X-ray photoelectron spectroscopy (19,84,183), ultraviolet photoelectron spectroscopy @4),ion microprobe mass analysis (436),ESCA (117),Auger electron spectroscopy (59, I 1 7 ) , ion scattering spectroscopy (59),and secondary ion mass spectroscopy (I 17). I n e r t - G a s a n d V a c u u m Fusion. Several methods and types of equipment employing vacuum or inert-gas fusion have
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been described ( 1 6 , 4 8 , 4 9 ,158, 174,287.400,488). T o reduce errors from adsorbed water and hydrogen, samples were preheated before analysis (248). Finally, three sampling devices have been described for the determination of oxygen in steel (233,366) and hydrogen in steel (.533).
HALOGENS Fluoride-selective electrodes have been applied to the potentiometric determination of F- in iron ores and slags (2281, as well as fluorspar and mold dressings (67). At high F levels, titration with thorium nitrate has also been used for mold additives and slags (263) while, at low levels in ores, extraction-spectrophotometry (437) has been used. Neutron activation methods, in one case with a mobile activation unit, have been applied to ore analysis for fluoride (242)or chloride (2). Blast furnace slag has also been analyzed for fluoride by X-ray spectrometry (345). Electron spectroscopy (468),ion scattering spectrometry and Auger spectrometry (59) have been applied, respectively, for the determination of chloride in passive layers on iron and on galvanized surfaces. X-ray fluorescence spectrometry has been adapted for analysis of rusts on steels for chloride (295). Finally, a swab test has been developed for the examination of stainless steel components for surface chlorides and fluorides (465). INCLUSIONS Nonmetallic inclusions were investigated with an electron probe in rail steels through each stage of melting, pouring, and rolling (121, 138). Several oxide and sulfide phases of manganese, silicon, aluminum, and magnesium were identified. T h e electron probe was also used to identify carbides in cast steel rolls and stainless steels (135),to determine nitrogen as aluminum nitride precipitates in steel foil (144)and sulfides in free-machining steels (252),to identify inclusions imbedded in fractures (321),and to determine iron and iron sulfide in fine manganese iron sulfide inclusions (393). X-ray microanalysis (240) was used to determine the composition of iron-manganese-chromium inclusions extracted from austenitic steel. This composition depended on heat-treatment temperature. Electrochemical isolation techniques were used to isolate several vanadium carbides, vanadium nitrides, and vanadium carbonitrides (415), cementite and manganese and other sulfides (37, 428, 476), and oxide inclusions and aluminum nitride inclusions from stainless steels (451. 502). Boron nitrides and oxides have heen isolated as well (134,537)and determined by infrared absorption spectroscopy. Chloramine T (251)was used to decompose carbides from oxide inclusions. Before separation of nonmetallic inclusions, a thin collodion film is formed on the inside wall of a test tube to collect nonmetallic inclusions (383). Differential thermal analysis combined with effluent gas analysis was used for the determination of carbides and nitrides in steel (36,292, 494) as well as sulfides in maraging steel (412). Radioisotopes were used as tracers to determine oxide inclusions in steel (406--408),and neutron activation methods were used to determine the concentrations of oxygen, aluminum, silicon, and barium in inclusions separated from steel (543). Emission spectrographic methods were applied to determine the compositions of nonmetallic inclusions isolated from steel by spark excitation (497) and inclusions exposed in polished sections of iron ores and steels by laser excitation (257). After separating oxide inclusions, calcium and magnesium (370)may be determined by removing silica with hydrofluoric acid, fusing with sodium tetraborate, dissolving the button in hydrochloric acid, precipitating iron, aluminum, and manganese, and titrating with EDTA in the presence of calmagite as m indicator to detect the photometric end point. IRON X-ray S p e c t r o m e t r y , Iron ores were analyzed for iron in the form of powder or buttons after fusion with sodium tetraborate (22,23,426). Most accurate results were obtained with fused buttons and after corrections were made for absorption effects caused by the presence of titania, lime, silica,
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and oxygen. Iron-ore slurries were also analyzed with similar results after absorption-effect corrections were made (208). Improved precision in iron determinations in iron ore was obtained when potassium iodide was used as the X-ray target (266). An iron ore-flux mixture was analyzed on a conveyor belt (541) for iron and calcium. Iron in manganese nodules has been determined by both dispersive and nondispersive X-ray spectrometry (73, 305, 4 3 5 ) . Radioisotopic X-ray spectrometry has been used to determine iron in ores (396, 482) irradiated with a '09Cd photon source. An on-line automatic X-ray spectrometer has been used to monitor iron content of sinter (179). The presence of about 0.8% nitrogen, carbon, and silicon interferes with the determination of iron in chromium-manganese steels (241). A combined wetchemical/X-ray spectrometric method (27) was developed for determining iron and tungsten in ferrotungsten. Volumetric. Iron has been determined by titration with EDTA in ferrochromium slag (41)and in ores (185,390,442). This element has also been determined as metallic iron in ores after treatment with iodine in hydrochloric acid and titration of the free iodine with sodium thiosulfate (88,269). Instead of using the co. 'ventional reagent, mercuric chloride, 4,4'bis(dimethy1an ino)diphenylamine was used in the titration of iron in ores ~ i t ascorbic h acid (326). The new reagent is reported to be highly sensitive at the end point. Salicylic acid, sulfosalicylic acid, and salicylamide were used as indicators in the determination of iron(II1) when titrated with Nhydroxy-ethylethylenediaminetriacetic acid (129). Iron and ferrous oxide were determined (87, 203) by titration with potassium dichromate and sodium diphenylaminesulfonate as an indicator in ores, and by potentiometric titration with titanium trichloride (66) in ferrochromium slags. Miscellaneous Methods. Iron has been determined in iron ores ( I 01. 231, 291, 303, 41 6 ) and manganese nodules (143, 313) by activation with neutrons and ?-ray spectrometry. Atomic absorption methods have been developed for the determination of iron in slags (72, 2261, ores (173,281), and steel (310). Spectrophotometric methods were used for this determination in ferroalloys (379),steel (372),and ores (130,389,515). Mossbauer spectroscopy has been used to determine iron-containing phases in ores ( 1 3 1 , 139, 286), corrosion products (1761, and coals ( 4 4 8 ,and iron concentrations in iron sponge (331). Ion microanalyzers and X-ray photoelectron spectrometers have been used to determine iron in high-temperature alloys (359),and decorative films and passive oxide layers on stainless steel 119, 358).
LANTHANIDES Spectrophotometry. Total rare earths have been determined in steel with Arsenazo 111, following extractive removal of iron (3361, or after masking interferents (99). Yttrium in steels can be extracted into Bu3POj with subsequent measurement as the Y-quinalizarin complex (157). Extraction liquid chromatography was used to isolate scandium from iron prior to its spectrophotometric determination with xylenol orange (438). Cerium has been determined in both steels (92) and slags (166) by oxalate precipitation and subsequent photometric development of the yellow o-toluidine complex. An ion-exchange separation of cerium from cast iron and steel with color development with 8-quinolinol has been reported (168), while the direct determination of cerium in high-temperature steel with appropriate chemical masking prior to reaction with Arsenazo I11 has also appeared (4.5). Spectrofluorescence of Ce(II1) (86) and a differential spectrophotometric method based on the difference in absorbance between Ce(II1) and Ce(1V) in steel (401) have appeared for the analysis of steels. An oxidative reaction between Ce(1V) and oxine-5-sulfonic acid has been used to develop a fluorometric method for cerium in alloys and ores (368). Emission a n d X - r a y S p e c t r o m e t r y . Yttrium has been separated by a 3-phase extraction method prior to excitation of one of the phases spectrographically (238),while Ce, La, Nd, and Y were measured spectrographically on a separated residue following extraction of the bulk of the iron (21). In another development, a dissolved steel sample was slurried with anion-exchange resin and the separated resin analyzed
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by X-ray fluorescence spectrometry for cerium (11 4 ) . ‘The preparation of cast iron samples for cerium analysis by emission spectrometry is described in another report (380). Other Methods. Neutron activation for the determination of lanthanum, cerium, and praseodymium in steels (40’9) has been demonstrated. An amperometric titration with hlohr’s salt following an extensive chemical separation of cerium from steels, slags, and cast iron has been used in the range 0.1 to 0.005% cerium (65).
LEAD Atomic Absorption. Following dissolution, lead has been determined directly in steels by flameless AA (2729,and by a flame method in high-alloy steels (217). Extraction AA has been applied t o high-purity iron with hexamethylene ammonium hexamethylene dithiocarbamate (499), to steels with trioctylamine (456),to high-alloy steels (402), and to iron ores with bis(2-ethylhexy1)phosphate (232). Direct excitation in a graphite furnace has been reported for the determination of lead in iron-base alloys (140) and in a stainless-steel \\ire (296).
Titrimetric and Polarographic. Lead in iron ore pellets has been determined by a n ion-exchange Complexon 111 separation-titration method ( 6 1 ) , and in steel by an amperometric titration with sodium piperidine thiocarbamate (107). Anodic stripping voltammetry was used for the measurement of lead in steel and cast iron (2.?9), and in ferroniobium at the level ( 3 4 4 ) . Emission and X-ray Spectrometry. Spectrochemical methods have been applied to the trace determination of lead in steel (255, 265), and in iron ores, calcite and slags ( 5 4 5 ) . X-ray fluorescence was also used for trace lead in high-purity iron and low-alloy steels (177). MAGNESIUM Atomic Absorption. Interferences have been studied in the determination of magnesium in steels (423),while the preparation of standard samples of cast iron for magnesium determinations was described (380). A multipurpose niethod for magnesium in cast iron has also appeared (63). Extraction-atomic absorption with bis(2-ethylhexy1)phosphate to measure trace magnesium in ores was described (232),while fused and dissolved slag samples have been analyzed directly (226). A study has appeared on the effect of the method of disintegration of slags on their subsequent atomic ahsorption analysis (72). Automatic AA has been applied to ores, slags, and sinters for their magnesium content (288). X-ray Spectrometry. Fused ore samples h a \ e been successfully analyzed by X-ray spectrometry 122,4261, a? have finished sinter samples ( I 79), and blast-furnace slags 1345). Emission Spectrometry. Laser spectral micrnana!q sis of phases in nodular iron for their magnesium segregation has been reported (571, while a bulk magnesium deterniination in cast iron with a vacuum Quantometer has been descrihed (271).
Other Methods. Magnesium was determined spectrophotometrically with Eriochrome Black ‘r in dissolved cast iron samples (99), and in slags with ‘Titan Yellow, the latter by an automated method (53). Neutron activation has been applied t o magnesium determinations on stainless-steel surfaces (403), whereas a mass spectrometric method waq described for traces (to 10 at. 70) of magnesium in iron samples. MANGANESE As in the previous two reviews of this series, it appears that almost any description of a method of ferrous analysis nr an evaluation of an analytical instrument is not complete unless it includes an application to the determination of manganese in steel or a related ferrous material. This is still the case, as will he discussed below. Titrimetric Methods. Titrants such as thiourea ( 3 1 ) and thiosalicylic acid (51) have been used for the amperometric determination of Mn in ores, while thiomalic acid (97) has been used in a spectrophotometric titration also for ores and alloys. A simultaneous titration of Fe and M n has been described for ores and steels (249), and in another paper the use of thiopiperidone was suggested for the titration of Mn(VI1) in steels and ferrous clinkers (425).Trace manganese in cast iron has also been measured by a coulometric iodonietric method
(103). Fe AI hln alloys have reportedly been analyzed without separation (752) after dissolution. High-temperature steels were assayed for manganese by titration with coulometrically generated ColII) in the presence of low-molecular-weight amines (270); ferromanganese with >70% manganese has heeii aiialyzetl directly by titration with 1,243aminocyclohexane-Ar,N,”’-tetraacetic acid in the presence of appropriate Fe(IT1) masking agents (24g). A thermometric method was described for the determination of Mn in low-alloy and carbon steels ( 4 4 3 ) . Atomic Absorption. Various atomic absorption procedures and sources hace been used for manganese analysis in cast irons (62)and steels (62, 120, 128, 246, 444, 4 4 5 ) directly in solution in a flame and in a carbon furnace (365) following evaporation of an aliquot of sample solution in the furnace. A dual flame-spectral device has been demonstrated to be useful for steel analysis (524). Ores and slags in solution were analyzed directly in the flame (72, 226) or following removal of the hulk of the iron hy extraction (232). Emission Spectrometry. Experiences with a number of similar photoelectrically recording spectrometers for the determination of manganese in iron and steel continue to be published (47,209, 3P5.464, 498, 520,531, 532). Of particular interest is the description of the use of a portable, hand-held arc excitation source with fibre optics for on-Gite steel grading ( I I ) . In other work, new sources or methods of excitation such as glow discharge lamps (89, ,522) or pulsed unipolar sparks (409 411) for steel analysis, inductively coupled plasmas for ferromanganese analysis (431),and laser microspectral analyzers (297) for high-allov steel analysis have been covered. X-ray Fluorescence Spectrometry and Related Methods. X-ray spectrometry has been used for quality control of pig iron production ( 1 6 4 , and for analysis of steels and alloys (,?49,457, ,5061, stainless steels (395, 4 I 4 ) , rusted surfaces (2951, ferroalloys (,55),ores (22,305, 426,482), cements based on slags (641, and manganese nodules (7
