650℃超超临界铸造镍基耐热合金焊接接头显微组织和力学性能研究  

Research on the Microstructure and Mechanical Properties of Welded Joints of Cast Nickel-based Heat-resistant Alloy for 650℃Ultra-supercritical Units

作　　者：林绍斌 何韦 孙仁潜 沈林[1,3] 黄建泽 朱杰 李岗 LIN Shaobin;HE Wei;SUN Renqian;SHEN Lin;HUANG Jianze;ZHU Jie;LI Gang

机构地区：[1]大型铸锻件先进制造技术及装备国家工程研究中心,四川德阳618013 [2]四川省先进极限制造技术创新中心,四川德阳618013 [3]二重(德阳)重型装备有限公司,四川德阳618013

出　　处：《大型铸锻件》2025年第2期44-49,共6页Heavy Casting and Forging

基　　金：科学技术部2021年国家重点研发计划项目资助(2021YFB3704103)。

摘　　要：采用钨极氩弧焊(GTAW)+焊条电弧焊(SMAW)方法对50 mm厚650℃超超临界铸造镍基耐热合金试板进行多层多道对接焊,对比研究了焊态和时效态[(670~700℃)×12 h]焊接接头的显微组织和显微硬度,重点对时效态焊接接头开展了力学性能研究。结果表明,焊态和时效态焊接接头均以奥氏体为基体,焊缝区晶粒尺寸均匀细小,母材区晶粒粗大;时效热处理使接头显微硬度整体提升,两种状态下的焊缝与热影响区硬度均高于母材;时效态焊接接头试样在室温拉伸、高温拉伸及高温短时持久试验中,均在母材断裂,焊缝受细晶强化和碳化物析出相的共同影响,其强度相比母材较高;经时效热处理后的焊接接头上下层金属间存在力学性能差异,表现为上层金属拥有较高的强度性能,而下层金属拥有较好的塑性性能;选用GTAW+SMAW方法焊接镍基耐热合金,可获得组织均匀、力学性能优异的焊接接头。The gas tungsten arc welding(GTAW)+shielded metal arc welding(SMAW)processes had been employed to perform multi-layer and multi-pass butt welding on 50 mm-thick nickel-based heat-resistant alloy test plates cast for 650℃ultra-supercritical units.A comparative study had been conducted on the microstructure and microhardness of as-welded and aged(670~700℃×12 h)welded joints,with particular focus on the mechanical properties of aged welded joints.The results indicated that both as-welded and aged welded joints had been composed of austenite matrix.The weld zone had exhibited uniform and fine-grained structure,while the base metal area had presented coarse grains.The aging heat treatment had resulted in an overall increase in the microhardness of the joint,with both weld and heat-affected zone(HAZ)showing higher hardness values than base metal under both conditions.For aged welded joints,specimens had fractured in base metal during room-temperature tensile tests,high-temperature tensile tests,and high-temperature short-term creep rupture tests.The weld strength had been enhanced compared with base metal due to combined effects of fine grain strengthening and precipitated phase of carbide.Mechanical property differences had been observed between upper and lower metal layers of welded joints after aging treatment,where upper layers had demonstrated higher strength while lower layers had shown better ductility.The GTAW+SMAW processes adopted for nickel-based heat-resistant alloy had achieved the welded joints with homogeneous microstructure and excellent mechanical properties.

关 键 词：650℃超超临界 铸造镍基耐热合金 焊接接头 显微组织 力学性能 

分 类 号：TG457.11[金属学及工艺—焊接]