Arc melting and powder metallurgy are common methods to prepare TZM alloy. Smelting method is to melt pure molybdenum and a certain amount of Ti, Zr and other elements under the protection of vacuum or H2, and then the bar or green body is obtained by casting or machining. But at present, powder metallurgy is basically used in China.
Powder metallurgy process flow:
1.The alloy powder is obtained by mixing high purity molybdenum powder with TiH2 powder, ZrH2 powder and graphite powder in proportion;
2.Cold isostatic pressing of alloy powder;
3.The blank is sintered under protective atmosphere;
4.The finished product is obtained by high temperature forging, high temperature annealing, medium temperature forging, medium temperature annealing, stress relief and warm forging.
In order to improve the formability and machinability of TZM alloy, extrusion, forging or rolling are needed. However, the residual stress will be produced after extrusion, forging or rolling, so the alloy should be annealed. Annealing is usually carried out under vacuum or H2 protection.
