(中国船舶重工集团公司 第七二五研究所,洛阳 471039)
摘 要: 对热锻态Ti80合金进行Tβ(30~50 ℃)淬火+(500~750 ℃)、(4~8 h)时效处理,测试了其拉伸和冲击性能,采用XRD、OM和TEM分析时效后的相结构及显微组织特征。结果表明:淬火态Ti80合金显微组织由棒状初生αp相+亚稳βt相+细小针状次生αs相(宽度小于0.1 μm)组成。经500 ℃时效,棒状初生αp相球化,亚稳βt相转变为细小针状次生αs相弥散析出,使强度、塑性和冲击韧性均升高;升高时效温度至550 ℃,细小针状次生αs弥散析出相含量增加,强度、塑性分别呈现小幅度升高和下降趋势,冲击韧性急速下降;继续升高时效温度,初生αp相与细小针状次生αs弥散析出相开始长大,使强度、塑性大幅度下降,冲击韧性显著升高。分析Ti80合金强度、塑性和冲击韧性-次生弥散αs析出相特征-时效处理制度之间的系统关系,指出次生αs弥散析出相含量及形貌特征变化是导致冲击韧性显著升高和下降的主要原因。
关键字: Ti80合金;时效;αs相;显微组织;力学性能
(Luoyang Ship Material Research Institute, Luoyang 471039, China)
Abstract:The (500-750 ℃), (4-8 h) aging treatments and then tensile and Charpy pendulum impact tests for quenched large Ti80 alloy were carried out. The microstructure was studied by XRD, OM and TEM. The results show that quenched metastable β phase transforms to fine acicular α phase and recovery happens in original α phase during aging. As a result, α grain is fine, the distribution of β phase between α grain becomes more uniformly, and the alloy obtains the higher match of strength-plasticity-toughness. However, when aging temperature increases and aging time is prolonged, α grain coarsens, which makes the toughness greatly increase, but the strength contrarily decreases. Finally, the relationship between microstructural evolution and the change of mechanical properties during aging is clarified.
Key words: Ti80 alloy; age; αs precipitates; microstructure; mechanical properties