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研究了回火温度对高强度42CrMo 钢应力腐蚀断裂行为的影响。结果表明,在淬火态和低温回火态.均为沿晶断裂.K_(ISCC)很低;当回火温度高于300℃后,K_(ISSCC)随回火温度升高而显著早升,断裂方式从沿晶型过渡为穿晶韧窝和沿晶的混合型。俄歇能谱和电镜分析表明,该钢的应力腐蚀断裂行为主要决定于碳比物的分布。在淬火态和低温回火态,碳化物主要分布于原奥氏体晶界,导致沿晶断裂和 K_(ISCC)值很低。较高温度回火后,晶界上碳化物的聚集粗化和晶粒内部碳化物的大量析出,导致了断裂方式由沿晶型向混合型转化和 K_(ISCC)的明显升高。
The effect of tempering temperature on the stress corrosion cracking behavior of high strength 42CrMo steel was studied. The results show that both the as-quenched and the low-temperature tempered state are intergranular fracture, and the IS value is low. When the tempering temperature is higher than 300 ℃, K ISSCC rises sharply with the increase of tempering temperature, Fracture mode transition from the crystal form to the transgranular dimple and along the crystal mixed type. Auger spectroscopy and electron microscopy analysis showed that the stress corrosion cracking behavior of the steel mainly depends on the distribution of carbon ratio. In the as-quenched and the low-temperature tempered states, the carbides are mainly distributed in the original austenite grain boundaries, resulting in the intergranular fracture and the low K_ (ISCC) values. After tempering at higher temperature, the aggregation and coarsening of carbide on the grain boundaries and the large precipitation of intragranular carbides led to a significant increase of fracture mode from intergranular to mixed type and K_ (ISCC).