• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2015, Vol. 51 ›› Issue (16): 150-155.doi: 10.3901/JME.2015.16.150

• 材料科学与工程 • 上一篇    下一篇

碳迁移对9%Cr和2.25%Cr异种钢焊接接头高温韧性的影响

李克俭, 蔡志鹏, 李轶非, 孙林根, 何雨晨, 潘际銮   

  1. 清华大学机械工程系 北京 100084
  • 收稿日期:2015-11-09 修回日期:2015-11-09 出版日期:2015-08-20 发布日期:2015-08-20

Influence of Carbon Migration on the Toughness of Heat Affected Zone of 9%Cr+2.25%Cr Dissimilar Welds at High Temperature

LI Kejian, CAI Zhipeng, LI Yifei, SUN Lingen, HE Yuchen, PAN Jiluan   

  1. Department of Mechanical Engineering, Tsinghua University, Beijing 100084
  • Received:2015-11-09 Revised:2015-11-09 Online:2015-08-20 Published:2015-08-20

摘要: 异种钢的焊接连接在发电设备中制造中扮演着重要角色,其中碳迁移是影响异种钢焊接接头服役性能的一个重要因素。研究9%Cr+2.25%Cr异种钢焊接接头的碳迁移现象及其对接头高温韧性的影响,发现该接头在9%Cr母材侧热影响区(Heat affected zone, HAZ)中形成富碳区,在紧邻的2.25%Cr焊缝一侧形成贫碳区,富碳区和贫碳区存在较大的硬度差异。在对接头HAZ的高温(500 ℃)准静态断裂韧度测试中,发现位于焊缝的贫碳区裂纹容易扩展。富碳区断口形貌以准解理为主,贫碳区断口形貌以浅韧窝为主。有限元计算结果表明,在贫碳区中有塑性应变集中现象,导致其损伤加剧,成为裂纹扩展过程中的较弱环节。结合断口形貌以及有限元计算结果,对控制该接头断裂过程的机理进行分析,认为弹性能与塑性能储备能力的不同是导致断口形貌差异的主要原因。

关键词: 高温韧性, 碳迁移, 显微硬度, 异种钢接头, 有限元分析

Abstract: Dissimilar welds are playing important roles in the manufacturing of components in power stations, and carbon migration is an important factor influencing the life of dissimilar welds. The influence of carbon migration on dissimilar welds (9%Cr+2.25%Cr) is studied. A carbon-rich hard zone, adjoining the soft zone (carbon denuded zone) is also detected in the high Cr side of the welds. There is an obvious difference in hardness between the carbon rich and denuded zones. In the quasi-static fracture toughness test of HAZ of the weldment at high temperature (500 ℃), it is found that the crack propagates more easily in the carbon denuded zone. The fracture appearance of carbon-rich zone is quasi-cleavage, and the carbon denuded zone’s presents mainly dimples. Finite element analysis(FEA) indicates that plastic strain concentrates in the carbon denuded zone. The carbon denuded zone is the weaker part of toughness because of the low absorption of elastic & plastic energy.

Key words: carbon migration, dissimilar welds, finite element analysis, high temperature toughness, micro hardness

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