TMCP钢焊接热影响区局部脆化区断裂韧度测试

Investigation on measurement of fracture toughness for local brittlezone in weld heat-affected zone of TMCP steels

针对强度 (屈服点应力 )级别为 4 2 0～ 4 6 0MPa的三种TMCP钢 ,探讨通常的焊接热影响区局部脆化区断裂韧度测试方法的可行性及存在问题。由于多层焊热影响区组织复杂 ,需进一步研究确认试验中得到的断裂韧度能否代表局部脆化区的韧度。试验结果发现 ,对多层焊热影响区试样 ,试验后必须进行刨面 (Sectioning)分析 ,首先检查疲劳裂纹前沿是否位于所测试的目标区域 ;其次当有延性裂纹扩展时 ,检查延性裂纹扩展是否偏离目标区域。当满足这些条件时 ,所测试的断裂韧度才能代表目标区域的韧度值。同时也试验研究了焊缝强度匹配对热影响区断裂韧度的影响。

The measurement on fracture toughness of the local brittlezone in heat-affected zone (HAZ) was investigated for three kinds of TM-CP steels with yielding strength 420 ~ 460 MPa. It is necessary to analyzeif the testing results can reflect the fracture toughness of the local brittlezone, because of the complexity of multi-pass welding HAZ. It has beenpointed that the section technique should be conducted after the multi-pass welding HAZ fracture toughness tests, the following examinationsshould be taken. First whether the pre-fatigue crack front is in the targetzone is checked. Second whether the ductile crack deviates from the tar-get zone is checked. The fracture toughness gotten from testings could re-flect the target zone property if the above requirements are satisfied. Theeffect of strength mis-matching on fracture toughness for weld HAZ as alsodiscussed by testing results.