焊接工艺对30mm厚Q690钢板焊接残余应力的影响

Effect of welding technology on welding residual stress in welding joints of Q690 steel heavy plate

为了得到焊接工艺对30 mm厚Q690钢板焊后残余应力分布及大小的影响,实施了不同工艺条件下的焊接试验,并通过盲孔法对试板焊后应力进行测定,得到了不同工艺条件下的焊接残余应力。结果表明,在焊缝区,横向应力为压应力,最大为569 MPa,纵向应力为拉应力,最大为57 MPa;在热影响区,横向应力为拉应力,最大为143 MPa,纵向应力由压应力逐步变为拉应力,最大拉应力为75 MPa。焊材和焊接热输入对接头残余应力有一定影响,其中,焊接热输入增加,残余应力也逐步变大。采用"X"形坡口可以改善焊接接头残余应力分布,残余应力多为压应力,但残余压应力的存在会降低接头的局部稳定性,需进行焊后热处理,以减小其不利影响。在实际生产中优选药芯焊材和热输入为20.8 k J/cm的焊接工艺。

In order to get the effect of welding technology on welding residual stress in 30 mm thick plate weld joints of Q690 steel,welding experiment under different conditions was implemented,and residual stress in the weld joints was determined by blind hole method. The results show that in the weld zone,transverse stress is compressive stress with the maximum value of 569 MPa,the longitudinal stress is tensile stress and the maximum value is 57 MPa. In the heat-affected zone,the transverse stress is tensile stress and the maximum value is 143 MPa,the longitudinal stress gradually changes from compression stress into tensile stress with the maximum value of 75 MPa.Welding wires and welding heat input mildly influence the welding residual stresses,and the residual stress gradually becomes larger as welding heat input increases. Residual stress distribution can be improved using X-shaped groove,and compressive stress prevails in the joints. The stability of structures may be influenced by the compressive residual stress in joints,and therefore the post weld heat treatment must be implemented to reduce its effects. The cored welding wire and 20. 8 k J / cm heat input welding parameters are recommended for the heavy plate welding in industrial production based on the experiments.