FORMING OF TITANIUM AND TITANIUM ALLOYS
For contract manufacturers competing in the aerospace market, Joseph Beal, Rodney Boyer, and Daniel Sanders of Boeing explain how to reduce the effect of springback variation, improve accuracy, and gain the advantage of increased ductility when hot forming or cold forming then hot sizing titanium and its alloys.
Posted: August 1, 2009
Titanium and its alloys can be formed in standard machines to tolerances similar to those obtained in the forming of stainless steel. However, to reduce the effect of springback variation, improve accuracy, and to gain the advantage of increased ductility, the great majority of formed titanium parts are made by hot forming or by cold preforming and then hot sizing.
The following characteristics of titanium and titanium alloy sheet materials must be considered in forming:
? Notch sensitivity, which may cause cracking and tearing, especially in cold forming
? Galling (more severe than with stainless steel)
? Relatively poor ability to shrink (a disadvantage in some flanging operations)
? Potential embrittlement from overheating and from absorption of gases, principally hydrogen and oxygen (scale and the surface layer adversely affected by the slower penetration of oxygen can be removed readily)
? Limited workability?varies with the alloy
? Higher springback than that encountered in ferrous alloys at the same strength level
However, as long as these limitations are recognized and established guidelines for hot and cold forming are followed, titanium and titanium alloys can be successfully formed into complex parts. The mechanical properties, and therefore the formabilities, of titanium and its alloys vary widely.
To continue this article, go to "Forming Of Titanium And Titanium Alloys", a white paper from ASM International, www.asminternational.org.
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