焊后热处理及长时热暴露对HT700高温合金摩擦焊接接头组织的影响  

Effects of Postweld Heat-treatment and Long-time Thermal Exposure on the Microstructure of HT700 Alloy Friction-welded Joints

作　　者：李博帅 朱明[1] 鲁金涛[2] 徐雅欣 党莹樱[2] 张慧慧[1] LI Boshuai;ZHU Ming;LU Jintao;XU Yaxin;DANG Yingying;ZHANG Huihui(School of Materials Science and Engineering,Xi'an University of Science and Technology.xi'an 710054,China;National Energy R&D Center of Clean and High-Efficiency Fossil-fired Power Generation Technology,Xi'an Thermal Power Research Institute Co.,Ltd.,Xi'an 710032,China;School of Materials Science and Engineering,Northwestern Polytechnic University,Xi'an 710072,China)

机构地区：[1]西安科技大学材料科学与工程学院,西安710054 [2]西安热工研究院有限公司国家能源清洁高效火力发电技术研发中心,西安710032 [3]西北工业大学材料科学与工程学院,西安710072

出　　处：《动力工程学报》2021年第4期337-344,共8页Journal of Chinese Society of Power Engineering

基　　金：陕西省自然科学基础研究计划资助项目(2020JM-716);中国华能集团有限公司科技资助项目(HNKJ18-H12)。

摘　　要：在主轴转速为1500r/min、摩擦压力为300MPa的焊接参数下实现了HT700合金的惯性摩擦焊接,并对焊接接头进行了热处理和长时高温暴露实验,研究了热处理工艺和长时高温暴露对镍铁基高温合金摩擦焊接接头组织的影响,并测试了焊接接头的显微硬度。结果表明:焊接接头的显微组织关于焊缝中心区两侧呈对称分布,热处理态和高温暴露后焊接接头可分为焊缝中心区、热影响区和母材区3个部分,当热处理工艺为1140℃×20min+1020℃×1h(水冷)+650℃×16h+820℃×4h时焊接接头的平均显微硬度最高;750℃长时高温暴露会导致M23C6粗化和γ′相合并长大,从而使焊接接头显微硬度降低,但焊接接头在高温暴露过程中未析出有害相,表明HT700合金摩擦焊接接头的显微组织具有良好的热稳定性。HT700 alloy joints were welded by inertial friction method under the spindle speed of 1 500 r/min and the friction pressure of 300 MPa, following which, heat treatment and long-time thermal exposure tests were conducted on the welded joints, so as to study the effects of heat treatment process and long-time thermal exposure on the microstructure of the nickel-iron-based superalloy friction-welded joints. In addition, the microhardness of the welded joints was tested. Results show that the microstructure is symetrically distributed about the centerline of the welded joint, which, after heat treatment and long-time thermal exposure, can be divided into three regions, i.e. the weld center zone, heat affected zone and base metal zone. The average hardness of weld joints is the highest, which appears when the heat treatment process is 1 140 ℃×20 min + 1 020 ℃×1 h(water quenching) + 650 ℃×16 h + 820 ℃×4 h. Long time aging at 750 ℃ will lead to coarsening of the M23C6 as well as merging and growing of the γ′, resulting in lowered microhardness of the welded joint. However, no harmful phase precipates in the process of high-temperature exposure, indicating good thermal stability of the HT700 alloy friction-welded joints.

关 键 词：热处理 高温时效 摩擦焊 显微硬度 组织演化 

分 类 号：TG115[金属学及工艺—物理冶金]