PRODUCTION Needed: Molds for Casting Titanium Biggest factor holding back titanium casting industry is cheap, e x p e n d a b l e molds, say Battelle scientists V^ASTING TITANIUM is not yet
feasible
on a commercial scale, say G. H. Schippereit and J. G. Kura of Battelle Memorial Institute's division of nonferrous metallurgy. But metallurgists are making much progress toward that goal. Already, they have shown a "sound metallurgical basis for the establishment of a titanium casting industry," Schippereit declares. Speaking before the American Foundrymen's Society Castings Congress in Cincinnati last week, Schippereit predicted a titanium castings market near 1 0 % of sponge production by 1960 "if a mature casting industry were developed by that time." Biggest drawback to commercialization of casting is the mold, Schippereit declares. T h e industry needs an inexpensive, inert, and expendable mold material. But so far, t h e best available material is graphite, from w h i c h t h e mold must be machined. This is relatively costly, Schippereit points out. U n d e r the best conditions, graphite molds last for about 5 0 castings - But where casting design and other factors
are not optimum, mold life may be as low as 15 castings. Melting and casting of titanium are complicated by the need to keep air from the melt, as both oxygen and nitrogen dissolve in it readily and cause embrittlement. T h e process is further complicated by titanium's tendency to dissolve or react with refractories. This also hurts its properties. Castings made in graphite molds have the least surface contamination, Schippereit says. Maximum depth of contamination is about 0.010 in. in a 1 in. section. But other mold refractories such as alumina, zirconia, and silica lead to penetrations up to 0.060 in, • Industry I n t e r e s t e d . Oregon Metallurgical Corp., Albany, Ore., is accepting orders for titanium castings from those willing to pay the price that goes along with graphite molds. So far, activity has b e e n extremely limited, with most work still classed as experimental. Other companies are watching the field closely, too. Among those who have expressed interest to Battelle are:
Titanium castings are not available on full commercial scale. This consumable electrode, skull melting furnace belongs to Oregon Metallurgical Corp., which will accept special orders. Furnace capacity is 250 l b . of titanium 84
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• Titanium Casting Corp., Milwaukee, Wis. • National ResearcL· Corp., Newton Falls, Mass. • Crane Co., Chicago, 111. • Wisconsin Centrifugal Foundry, Waukesha, Wis. Biggest potential f o r titanium castings lies in aircraft, intissile, a n d chemical process industries, according to Schippereit. They can b e used for hardware, pipe fittings, valves, p u m p impellers and bodies, and pinions. And, their light weight a n d high strength make them very attractive for use in airborne equipment, Schippereit concludes. •
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More on Welding Hard on the heels of Linde's demon stration of its Unionarc welding process ( C & E X . March 18, p a g e 9 2 ) , National Cylinder Gas h a s announced an i m proved welding process of its own. Called Dual Shield, t h e process " d e posits weld metal t h r e e to 1 2 times faster than manual stick electrode weld i n g and a conservative 3 3 % faster than established semiautomatic methods," according to NCG's N o r m a n S. Strandwitz. Dual Shield welding uses a flux-core electrode, Strandwitz told a meeting of t h e American W e l d i n g Society. K e y t o the process lies in t h e flux, m a d e u p of an ionizer to stabilize the electric arc, a deoxidizer that permits welding millr u n steel without cleaning it first, a n d a slag-forming agent, Strandwitz says. Carbon dioxide shields the weld from air. Oxygen is metered to t h e weld pool where it combines with some of t h e flux components. T h e results, ac cording to Strandwitz: a stable arc at least 1000° hotter t h a n the average 9000° axe; welds up t o 1/2 inch thick in one pass; welds t h a t are stronger b e cause d e p t h penetration is greater t h a n is achieved with manual stick electrode welding; and welds t h a t are dense a n d f^ee of porosity. Initial investment t o set up t h e Dual Shield process is less than $2300 in cluding welder training, Strandwitz de clares. And, h e concludes, in one day, a novice can be taught to weld as well as a m a n who h a s b e e n instructed for a month in manual welding.
Electronic Balances The M. W. Kellogg Co. h a s worked o u t a program for electronic computers with which a computer can calculate a complete mole balance around some processing units. Applied first to the absorber-stripper system of a cat cracker gas recovery unit, t h e program l e d to a savings of 1 2 . 5 % o n cost of materials and utilities, according to the company. The program gives a complete solu tion of material balances for u p to 40 components, Kellogg says. With a computer running time of only 15 m i n u t e s for each solution, the company can u s e the time saved t o evaluate al t e r n a t e flow schemes a n d to find the one best suited to t h e specific job. The engineering firm is now working out programs for mole balances around more complex systems, including cat cracker recovery units, reformers, hydrofiners, and alkylation units. •
