Effect of welding heat input on welding residual stress in submerged-arc welds of thick plate 20MnNiMo joints

Effect of different welding heat input on welding residual stress in master cylinder of 20MnNiMo steel for 80000 tons forging press were observed and studied. The residual stress of thick plate 20MnNiMo steel joints was measured by the blind hole drilling method. The experimental results show that welding residual stress distribution and magnitude are changed with the increase of heat input. When the welding heat input is reduced from 27.3 J/cm to 24.6 J/cm, the residual stress in the weld zone of welded joints in X-direction decreases by 16%; the residual stress in heat-affected zone of welded joints in X-direction decreases by 33%, and the residual stress in heat-affected zone of welded joints in Y-direction increased by 52%. The effect of welding heat input on residual stress in Y-direction is the greatest. In the same welding efficiency conditions, the smaller the welding heat input, the smaller the welding residual stress.