TC17钛合金连续冷却转变曲线研究  

Continuous Cooling Transformation Diagram of TC17 Titanium Alloy

作　　者：蔡馨 雷旻[1] 万明攀[1] 赵飞[1] 黄朝文 温鑫 Cai Xin;Lei Ming;Wan Mingpan;Zhao Fei;Huang Chaowen;Wen Xin(Key Laboratory fur Mechanical Behavior and Microstructure of Materials,College of Materials and Metallurgy,Guizhou University,Guiyang 55QQ25,China)

机构地区：[1]贵州大学材料与冶金学院贵州省材料结构与强度重点实验室

出　　处：《稀有金属》2019年第12期1291-1296,共6页Chinese Journal of Rare Metals

基　　金：贵州省科技支撑计划项目([2017]2313);贵州省科学技术基金项目(20171023);贵州省教育厅青年科技人才成长项目(2016122);贵州大学引进人才科研项目(201633)资助

摘　　要：以TC17钛合金为研究对象,采用高精度差分膨胀仪B?hr DIL805A/D获得了TC17钛合金在不同冷却速度下的膨胀曲线。利用导数法获得TC17钛合金在不同冷却速度下的转变开始点及结束点,建立了TC17钛合金的连续冷却转变曲线(CCT),并结合扫描电镜(SEM)、物相分析(XRD)和显微硬度分析,研究了在连续冷却过程中TC17钛合金组织演变及力学性能。结果表明:在低的冷却速度下TC17钛合金的显微组织为α+β片层组织。当冷却速度小于0.50℃·s-1时,获得全部的片状α相和β相组织,当冷却速度为0.35~3.00℃·s-1时在合金中观察到α+β针状结构及未转变的亚稳β相。当冷却速度为3.50℃·s-1时,合金仅由单一亚稳β相组成。故3.50℃·s-1被认为是合金在连续冷却条件下临界冷却速度。随着冷却速度的增加TC17钛合金的显微硬度呈先增后减的趋势,在冷却速度为0.50℃·s-1时,显微硬度达到最大为HV 436。最后利用Kissinger方程计算得出了加热过程中TC17钛合金β→α+β相变激活能为218.447 kJ·mol-1。The effects of continuous cooling rates on the microstructure and mechanical properties of TC17 titanium alloy were investigated. Dilatometric curves of TC17 titanium alloy under different cooling rates were measured by high differential dilatometry B?hr DIL805 A/D. Using the derivative method to obtain the beginning and end points of TC17 titanium alloy at different cooling rates, to establish a continuous cooling transformation(CCT) diagram of TC17 titanium alloy. The effect of cooling rate on microstructure evolution and mechanical properties of TC17 alloy was studied by scanning electric microscopy(SEM), X-ray diffraction(XRD) and micro-hardness analysis. The results showed that the microstructure of TC17 was the α+β structure at the low cooling rate, When the cooling rate was less than 0.50 ℃·s-1, all the lamellar α phase and β phase structure were obtained, when the cooling rates was from 0.35 to 3.00 ℃·s-1, the β→α+β+βm phase transformation and lamellar structure and untransformed metastable β phase were observed in the alloy, when the cooling rate exceeded 3.50 ℃·s-1, the alloy was only composed of a single metastable β phase. Thus, a rate of 3.50 ℃·s-1 was considered as critical cooling rate of the alloy under continuous cooling condition. The micro-hardness of TC17 alloy initially increased and then decreased with increasing of the cooling rate, and at cooling rate of 0.50 ℃·s-1, the micro-hardness reached a maximum of HV 436. The activation energy for the β→α+β phase transformation in TC17 alloy was evaluated on the basis of Kissinger equation, and the value was 218.447 kJ·mol-1.

关 键 词：TC17钛合金 膨胀曲线 CCT曲线 组织演变 激活能 

分 类 号：TG146[一般工业技术—材料科学与工程]