热输入对Q460钢焊接接头组织及拉伸变形行为的影响

以Q460钢为对象，研究了埋弧焊热输入对其接头组织及其拉伸变形行为的作用规律与机理.结果表明:接头HAZ宽度随热输入增加而增大，同时FZ柱状晶比例也增加，FZ靠近熔合线的组织明显细化，且FZ的软化得到改善.热输入对接头整体强度无明显影响，而断裂延伸率呈增加趋势.19.0kJ/cm下焊接接头FZ与HAZ界面的变形不协调，导致过早发生断裂.随热输入的增加，FZ组织细化，缓解了FZ与HAZ界面硬度差，提高了接头的塑性变形能力，拉伸断裂位置由FZ转移至BM.

Effect of Heat Input on Microstructure and Tensile Deformation Behavior of Q460 Steel Weld Joint

The effect of heat input by submerged arc welding on microstructure and tensile deformation behavior of weld joint in Q460 steel was studied and its mechanism was also discussed. The results showed that with the increase of the heat input， the width of the heat affected zone (HAZ) of the welding joint and the proportion of columnar zone in the fusion zone (FZ) increase， meanwhile the microstructure becomes finer near the weld zone and the welding softening in the FZ is improved. It is also found that the heat input has little effect on the tensile strength of the welding joint， while the fracture elongation of the joint increases with increasing heat input. When the heat input is 19.0kJ/cm， the fracture of the joint occurs very easily due to the mismatch of plastic deformation at the joint interface between the FZ and HAZ. With increasing heat input， the microstructure in the FZ becomes finer and the hardness difference at the interface between the FZ and HAZ can be reduced. Therefore， the plasticity of the overall joint can be improved and the fracture of the joints is located from the FZ to BM.