TC21钛合金网篮组织特征对力学性能的影响研究

Influence of Basket Microstructure Characteristics on Mechanical Properties of TC21 Titanium Alloy

TC21钛合金是我国自主研发的一种高强高韧损伤容限型钛合金,分别采用准β锻造、准β锻造+(α+β)锻造以及β锻造工艺对TC21钛合金进行锻造,采用金相显微镜和扫描电子显微镜研究了锻造工艺对TC21钛合金显微组织的影响规律,以及显微组织与力学性能之间的关系。结果表明:采用准β锻造(T_(β)+15℃)后,TC21钛合金显微组织特征为破碎的β晶粒和编织程度较好的网篮组织,并且该组织具有良好的强度-塑性-韧性匹配;采用准β锻造后再进行(α+β)相区小变形,显微组织中部分片层α相呈短棒状分布,且网篮编织程度较差,强度与塑性与准β锻造后相当,但断裂韧性较差;在较高温度(T_(β)+25℃)进行锻造,TC21钛合金显微组织中形成粗大平直的晶界α相,材料的强度、塑性和韧性均较低。

TC21 titanium alloy is a kind of titanium alloy with high strength and high toughness damage tolerance developed independently in China.In this paper,quasi-β forging,quasi-β forging+(α+β)forging andβforging process were used to forge TC21 titanium alloy.The influence of forging process on microstructure of TC21 titanium alloy and the relationship between microstructure and mechanical properties were studied by optical microscope(OM)and scanning electron microscope(SEM).The results showed that:after quasi-βforging(T_(β)+15℃),the microstructure of TC21 titanium alloy was characterized by broken β grains and well-woven basket structure,which had good strength-plastic-toughness matching;after small deformation of(α+β)phase region after quasi-β forging,theαphases were distributed in short rod shape,and the weave degree of the basket was poor;the strength and plastic properties of the basket are similar to those of quasi-βforging,but the fracture toughness was poor;after high temperature(T_(β)+25℃)forging,coarse and straight grain boundaryαphase was formed,the strength,plasticity and toughness of the material were low.