S690Q高强钢对接节点的焊后性能

通过试验研究了S690Q高强钢对接节点的焊后性能.利用手工电弧焊焊接了3个厚度为8 mm的S690Q高强钢对接节点,焊接过程中对3个节点分别采用不同的焊接热量.在微观层面上,用微观结构测试和微观硬度测试研究焊接对于节点的影响;在宏观层面上,通过拉伸试验研究焊接对于节点力学性能的影响.微观结构测试结果表明,S690Q高强...

Post-welding behaviour of S690Q high strength steel butt joints

In this study, we investigated the post-welding behaviour of S690Q high strength steel butt joints experimentally. Three S690Q high strength steel butt joints were welded with 8 mm thickness plate by shield metal arc welding with different welding heat inputs. Microstructure observation and micro-hardness test of heat-affected zone were employed to reveal the welding influence on the joints at the micro level, and tensile test of S690Q high strength steel butt joints showed the welding impact at the macro level. The microstructure test indicated that the main microstructure of the S690Q high strength steel was tempered martensite and was transformed to granular bainite in the coarse-grained heat-affected zone and to ferrite and cementite in the fine-grained heat-affected zone after welding of the joints. In the tempering zone, some of the tempered martensite decomposed to ferrite. Based on the hardness test results, it can be observed there is a soft layer in the heat-affected zone with lower hardness compared with the base material. In addition, the width of the heat-affected zone increased in the joint welded with higher heat input. The subsequent tensile test showed that the formation of a soft layer directly impairs the tensile behaviour of S690Q high strength steel butt joints, and the strength deterioration becomes more serious with the increase of the welding heat input.