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利用逐层钻孔法测试了直接淬火和水淬+空冷+水淬2种冷却工艺下的残余应力,分析了2种工艺下残余应力对裂纹产生和扩展的影响。结果表明:直接淬火工艺下,切向残余拉应力为229~281 MPa,轴向残余拉应力为191~237 MPa;水淬+空冷+水淬工艺下,切向残余应力为压应力,范围为-422~-185 MPa,轴向残余应力为拉应力,范围为90~190 MPa。与直接淬火工艺相比,优化冷却工艺使钢管切向应力变为压应力,轴向残余应力仍为拉应力但数值上减小,随孔深增加,轴向应力减小幅度趋于平缓,进而降低和缓解了钢管内微裂纹产生和扩展趋势。
The residual stress under direct cooling and water quenching + air cooling + water quenching was tested by layer-by-hole drilling method. The effect of residual stress on the generation and propagation of cracks was analyzed. The results show that the residual tensile stress in tangential direction is 229-281 MPa and the axial residual tensile stress is 191-237 MPa in the direct quenching process. The residual stress in the direction of water quenching + air-cooling + water quenching is compressive stress in the range of -422 ~ -185 MPa, the axial residual stress is tensile stress, the range is 90 ~ 190 MPa. Compared with the direct quenching process, the optimization of the cooling process makes the steel pipe tangential stress into compressive stress, axial residual stress is still tensile stress but decreases in value, with the increase of hole depth, axial stress decreases gently, and thus Reduce and ease the micro-cracks in steel pipe production and expansion trend.