考虑损伤影响的TC4钛合金改进型热加工图  

Improved hot processing map of TC4 titanium alloy considering damage effects

作　　者：温东旭 熊萍萍 张猛 高萌 黄亮[1] 李建军[1,4] WEN Dong-xu;XIONG Ping-ping;ZHANG Meng;GAO Meng;HUANG Liang;LI Jian-jun(State Key Laboratory of Materials Processing and Die&Mould Technology,School of Materials Science and Engineering,Huazhong University of Science and Technology,Wuhan 430074,China;Daqi Technology Co.,Ltd.,Mianyang 621000,China;Luoyang Ship Material Research Institute,Luoyang 471039,China;Hubei Huangshi Mold Industrial Technology Research Institute,Huangshi 435007,China)

机构地区：[1]华中科技大学材料科学与工程学院材料成形与模具技术全国重点实验室,湖北武汉430074 [2]绵阳大器科技有限公司,四川绵阳621000 [3]中国船舶集团有限公司第七二五研究所,河南洛阳471039 [4]湖北黄石模具产业技术研究院,湖北黄石435007

出　　处：《塑性工程学报》2025年第4期141-151,共11页Journal of Plasticity Engineering

基　　金：国家自然科学基金资助项目(52075197);湖北省自然科学基金资助项目(2023AFB639)。

摘　　要：在TC4钛合金常见成形工艺参数条件(变形温度780~900°C和应变速率0.001~1 s^(-1))下开展高温拉伸试验,分析了成形工艺参数和应变速率敏感性指数对TC4钛合金高温流变行为的影响,分别建立了经典热加工图和考虑损伤影响的改进型热加工图。结果表明:随着变形温度的降低和应变速率的升高,流变应力逐渐升高。流变应力的降低是由流变软化和塑性损伤的共同作用导致的,主要机制包括β相的动态回复和动态再结晶,α→β相转变和损伤累积导致的空洞萌生。高应变速率敏感性指数(m>0.2)主要集中在低应变速率区间(0.001~0.05 s^(-1)),这是由于在低应变速率条件下,TC4钛合金动态回复和动态再结晶行为发展较为充分,具备较好的颈缩扩散和转移能力,对应的材料断裂伸长率也较高。基于改进型热加工图,获得的流变失稳区对应的成形参数范围为变形温度780~900℃,应变速率0.1~1 s^(-1),流变失稳区范围比经典热加工图模型更大,并与高温高应变速率条件下的塑性损伤现象相吻合,表明改进型热加工图模型确定的变形安全区成形参数范围更为准确。最终,TC4钛合金的最佳成形工艺参数范围:区间I为变形温度780~810℃和应变速率0.001~0.02 s^(-1);区间II为变形温度810~900℃和应变速率0.006~0.1 s^(-1)。High-temperature tensile tests were carried out under common forming process parameters of TC4 titanium alloy(deformation temperature of 780-900℃and strain rate of 0.001-1 s^(-1)).The effects of forming process parameters and strain rate sensitivity index on the high-temperature flow behavior of TC4 titanium alloy were analyzed.The classic hot processing maps and the improved hot processing maps considering the damage effect were established,respectively.The results show that the flow stress increases gradually with the decrease of deformation temperature and the increase of strain rate.The decrease of flow stress is caused by the combined effect of flow softening and plastic damage.The main mechanisms include dynamic recovery and dynamic recrystallization ofβphase,α→βphase transformation and void initiation caused by damage accumulation.The high strain rate sensitivity index(m>0.2)is mainly concentrated in the low strain rate range(0.001-0.05 s^(-1)).This is because that the full dynamic recovery and dynamic recrystallization behaviors of TC4 titanium alloy easily take place under low strain rates,leading to the preferred necking diffusion and transfer capabilities.Meanwhile,the corresponding elongation after fracture is also high.Based on the improved hot processing map,the forming process parameter range of flow instability zone is deformation temperature of 780-900℃and strain rate of 0.1-1 s^(-1),which is larger than that of the classic hot processing map.It is consistent with the plastic damage phenomenon at high temperature and high strain rate,indicating that the forming process parameter range of deformation safety zone determined by the improved hot processing map is precise.Finally,the optimal forming process parameter range of TC4 titanium alloy is:zone I is deformation temperature of 780-810℃and strain rate of 0.001-0.02 s^(-1);zone II is deformation temperature of 810-900℃and strain rate of 0.006-0.1 s^(-1).

关 键 词：TC4钛合金 热加工图 拉伸变形 塑性损伤 

分 类 号：TG301[金属学及工艺—金属压力加工]