DZ125合金钎焊接头窄钎缝区高温循环应力应变分析方法

Research method of cyclic stress-strain analysis of narrow brazing seam zone of DZ125 alloy brazed joints at high temperature

针对钎焊接头窄钎缝区(大约150μm)在高温环境下的循环应力应变测量困难问题,提出一种基于反推法的新思想,依据以下两类数据进行计算和分析:第一类是采用有限元软件ABAQUS的用户材料子程序(UMAT)嵌入Chaboche热黏塑性本构模型计算得到的DZ125母材合金高温循环应力应变数据;第二类是经高温循环试验得到的钎焊接头的相应数据,最后经过数据处理和MATLAB软件编程获得窄钎缝区的应力应变.研究结果表明,钎焊接头在高温环境下的变形具有明显的不均匀性和局部性,并指出较之母材合金其钎缝区相对较"软",而且它也是整个钎焊接头的薄弱环节,应给予足够的重视.推而广之,反推法的提出为研究普通焊接接头窄焊缝的力学行为提供了一条新的途径.

A back-calculating method for solving difficult measurement of cyclic stress-strain of the narrow brazing seam zone（less than 150 μm） at high temperature was presented based on following two types of data： the first one was cyclic stress-strain data of DZ125 alloy base metal at high temperature,which was obtained by the finite element software ABAQUS coupling user material subroutine（UMAT） embedded into Chaboche viscoplastic model;the second one was cyclic stress-strain data of brazed joints obtained by the high-temperature cycle test;after data processing and MATLAB programming,the cyclic stress-strain of the brazing seam zone at high temperature was obtained concisely.The results show that the deformation of the brazed joints at high temperature has obvious heterogeneous and localized properties,and as compared to the base alloy metal,the brazing seam zone is relatively ＇soft＇,and also a weak link in brazed joints which should be given adequate attention.By extension,the proposed back-calculating method provides a new way for studying the general mechanical behavior of narrow seam of the welded joint.