CLAM钢搅拌摩擦焊接头高温蠕变行为  

High temperature creep behavior of friction stir welding joints for CLAM steel

作　　者：田超博 杨新岐[1] 李胜利[1] 唐文珅 李会军[1] TIAN Chaobo;YANG Xinqi;LI Shengli;TANG Wenshen;LI Huijun(Tianjin Key Laboratory of Advanced Joining Technology,Tianjin University,Tianjin 300350,China)

机构地区：[1]天津大学,天津市现代连接技术重点实验室,天津300350

出　　处：《焊接学报》2021年第2期38-45,I0003,I0004,共10页Transactions of The China Welding Institution

基　　金：国际热核聚变实验堆(ITER)计划专项(2015GB119001)。

摘　　要：针对核聚变堆用CLAM钢,对焊后热处理的搅拌摩擦焊接头在823 K条件和180~300 MPa应力水平下的单轴拉伸蠕变性能、断口形貌、显微组织进行了研究.结果表明,当蠕变应力由300,260及220 MPa降低到180 MPa时,CLAM钢搅拌摩擦焊接头的蠕变寿命分别由1.5,19.2及883 h增加到6769 h以上.临界热影响区是接头蠕变断裂的最薄弱区域,主要呈现位错控制的蠕变变形机制和穿晶韧性断裂模式.在蠕变过程中临界热影响区组织发生回复并形成亚晶,导致位错强化作用降低;M23C6碳化物发生不同程度的粗化或周围生成Laves相,导致析出和固溶强化作用减弱;这些因素是CLAM钢FSW接头蠕变性能恶化的主要原因.采用Monkman-Grant方程预测FSW接头在1×10^(5) h蠕变寿命下的蠕变断裂强度估计为156 MPa,达到母材强度的88%.The uniaxial creep tensile strength,fracture features and microstructures of friction stir welded joint with postweld heat treatment for CLAM steel have been investigated in the range of the creep applied stress from 180 MPa to 300 MPa at 823 K condition.It is found that the creep life of the FSW joints of CLAM steel increase from 1.5 h,19.2 h and 883 h to above 6769 h respectively,when the creep stresses decrease from 300 MPa,260 MPa and 220 MPa to 180 MPa.The inter critical heat affected zone is the weakest zone of creep rupture resistance for the FSW joint of CLAM steel,the joints mainly exhibit dislocation-controlled creep deformation mechanism and the transgranular ductile fracture mode.The microstructures of inter critical heat affected zone produce recovery and subgrain boundaries are formed in here during creep process,which result in the decrease of dislocation strengthening action;the coarser M23C6 carbides is produced or the coarser Laves phase around the M23C6 carbides is formed,which result in the reduction of precipitation and solution strengthening action,these issues are the main reasons for the deterioration of the creep performance of FSW joints.The creep fracture strength of FSW joint is estimated to be 156 MPa in the condition of 1×10^(5) h creep life according to the Monkman-Grant equation,which reaches 88%of the strength of base metal.

关 键 词：低活化钢 搅拌摩擦焊 蠕变性能 显微组织 寿命预测 

分 类 号：TG453.9[金属学及工艺—焊接]