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本文讨论了用X射线应力分析法研究调质大轴中的残余应力与回火冷却制度的关系,并测定了40Cr钢在回火冷却中的弹塑性温度。实验结果表明,40Cr钢的弹、塑性温度在400～450℃之间,调质大轴中的残余应力主要取决于回火后在高于弹、塑性温度时高温阶段的冷却速度,低温阶段冷速的影响甚小。瞬时弹性应力计算表明,对φ800mm以下的40Cr钢调质大轴,当心部温度降至400℃出炉空冷时,其瞬时弹性应力不致超过12.7kgf/mm~2,估计不会构成开裂的危险。
In this paper, the relationship between residual stress in quenched and tempered large shaft and tempering cooling system by X-ray stress analysis is discussed. The elastoplastic temperature of 40Cr steel in tempering cooling is measured. The experimental results show that the elastic and plastic temperature of 40Cr steel is between 400 and 450 ℃. The residual stress in the quenched and tempered large shaft mainly depends on the cooling rate in high temperature stage after tempering and in the cold stage at low temperature Speed has little effect. The calculation of instantaneous elastic stress shows that the instantaneous elastic stress of 40Cr steel quenched and tempered large shaft below 800mm does not exceed 12.7kgf / mm ~ 2 when the temperature of the heart is reduced to 400 ℃ and air-cooled at 400 ℃. It is estimated that it will not form the danger of cracking.