高温螺栓恢复热处理的研究

Research on Recovery Heat Treatment Technology of Bolt Under High Temperature

通过对在长期高温下运行的已失效螺栓分析,发现沿晶界有碳化物析出,形成网状晶界,使晶界原子结合力下降,晶界弱化,在工作应力长期作用下,网状晶界会产生裂纹并扩展,使螺栓冲击韧度下降,具有热脆化倾向。通过研究螺栓恢复热处理工艺,结果表明,25Cr2Mo1V钢螺栓的恢复热处理工艺为:980℃二次正火+680℃×6 h回火;25Cr2MoV钢螺栓的恢复热处理工艺为:960℃正火+900℃正火+650℃×6 h回火。

The failure bolts running in the long-term high temperature were analyzed.The results show that there is carbide precipitation along the grain boundary,the network grain boundary forms and grain boundary atomic binding force decreases,grain boundary turns to weakening in the long-term effects of work stress,mesh crystal boundary cracks form and expand.So that the bolt impact toughness decreases,has tendency to thermal embrittlement.The recovery heat treatment process of 25Cr2Mo1V steel bolts is： the second normalizing at 980℃ and then tempering at 680 ℃ for 6 h;recovery heat treatment process of 25Cr2MoV steel bolts is：normalizing at 960℃＋normalizing at 900℃and then tempering at 650℃for 6 h.