多重热处理对TC4合金的组织和力学性能的影响

The influence of multi heat-treatment on microstructure and mechanical properties of TC4 alloy

研究了多重热处理对TC4钛合金的显微组织和力学性能的影响.多重热处理温度中第一重处理位于单相区,第二重位于两相区,前两重热处理均采用不同的冷却速率,最后进行时效处理.结果表明:采用不同多重热处理制度可以调节材料的显微组织参数,包括片状α的长度、宽度、长宽比以及次生α片层的数量等,从而可以优化材料力学性能的搭配,特别是显著提高片层组织的塑性.采用适当的多重热处理不仅提高了材料的强度和塑性,而且使材料的断裂韧性有一定程度的提高.

TC4 lamellar microstructure obtained by of lamellar microstructure were discussed in this article multi heat-treatment and mechanical properties The first and secondary step of multi heat- treatment were executed respectively in single β phase region and α＋β phase region, both followed by different cooling rates. Tensile properties, fracture toughness and fatigue crack growth rate of samples under different treated conditions were tested. Results show that multi heat-treatment can modulate morphology of α lamella, including length/thickness ratio of primary α lamella and the quantity of secondary α lamella. Mechanical experiments results show that certain multi heat-treatment can enhance both tensile properties and fracture toughness property. Bi-lamellar microstructure can improve the resistance to crack propagation due to the influence of fine secondary α lamella.