预热温度对微弧等离子弧单道焊残余应力和性能的影响

Effect of preheating temperature on residual stress and performance of micro-arc plasma single-pass welding

文中通过数值模拟建立了微弧等离子弧焊的模型,研究了不同预热温度对微弧等离子弧单道焊残余应力的影响规律,通过X射线残余应力仪测量了焊后件的残余应力,验证了模型的准确性。结果表明,等离子弧堆焊过程中的预热提高了热输入,使焊接熔池变深,热影响区变宽;焊后最大残余应力发生在热影响区内,最大残余应力在y方向上,最大值为1022 MPa,且为拉应力。随着预热温度的提高,最大残余应力逐步下降,最大残余应力区域逐步向外扩展,趋势与热影响区的一致。最大显微硬度值在热影响区,随着预热温度的提高,硬度逐步在提高。热影响区内产生的马氏体组织是硬度提高的根本原因。

In this paper, the model of micro-arc plasma welding was established by numerical simulation. The effect of different preheating temperature on the residual stress of micro-arc plasma single-pass welding was studied. The residual stress of the welded parts was measured by X-ray residual stress meter to verify the model accuracy. The results showed that the preheating during plasma surfacing increasesd the heat input, making the weld pool deeper and the heat affected zone wider, the maximum residual stress after welding occured in the heat affected zone, and the maximum residual stress was in the y direction. The value was 1 022 MPa, and it was the tensile stress. As the preheating temperature increased, the maximum residual stress gradually decreased, and the area of maximum residual stress gradually expanded outward, the trend was consistent with the heat affected zone. The maximum microhardness value was in the heat-affected zone. As the preheating temperature increased, the hardness gradually increased. The martensite structure generated in the heat affected zone was the root cause of the hardness increase.