空冷贝氏体钢的残余应力对屈服强度的影响

Effect of residual stress on yield strength of air-cooled bainitic steel

测量了贝氏体超强精轧螺纹钢筋正火态和低温回火后的屈服强度,结果表明,正火态的屈服强度值较低,经300℃低温回火后屈服强度提高约230MPa。同时用盲孔法测定了该两种状态下的表层残余应力值,正火态高达270MPa左右,低温回火后表层残余应力降至70MPa左右,正火态低的屈服强度可能与试样内部高的残余拉应力有关;低温回火能显著降低残余应力,有效提高贝氏体超强钢筋的屈服强度。

Yield strength（ R0.2 ） of a precision-rolled bainitic screw-thread steel（BSS） normalized and tempered at low temperature was measured, results show that R0.2 of the BSS after normalizing is relatively lower and it can increase by 230MPa tempered at 300℃ . Meanwhile the skin residual stress under the two conditions were measured by blind hole method and the result shows that residual stress is about 270MPa in normalized status but decreases to about 70MPa after tempering. Lower yield strength may result from the high tensile residual stress in the BSS. The residual stress can be significantlv decreased and the R0.2 of the BSS can be imnroved effectivelv after low temperature tempering.