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研究了经形变热处理和常规热处理后NHS15高强度钢的微观组织结构和高周疲劳性能。结果表明,经形变热处理后,实验钢的屈服强度提高,试样的原奥氏体晶粒被细化,晶粒在轧制方向上被轻微拉长,且晶界被扭曲成锯齿状;形变热处理试样的马氏体束变细,回火后析出的碳化物更加细小、弥散;在107循环周次内,与常规热处理相比,形变热处理提高了试样的疲劳断裂抗力和疲劳寿命;常规热处理试样的疲劳断裂多起源于表面和内部基体,而形变热处理试样的断裂多源于内部夹杂物;疲劳断口裂纹源GBF处的应力场强度因子幅ΔK_(GBF)不随疲劳寿命N_f变化而变化。
The microstructure and high cycle fatigue properties of NHS15 high strength steel after deformation heat treatment and conventional heat treatment were studied. The results show that after the heat treatment, the yield strength of the experimental steel increases, the original austenite grains of the sample are refined, the grains are slightly elongated in the rolling direction, and the grain boundaries are twisted into jaggies; Compared with the conventional heat treatment, the deformation heat treatment increased the fatigue fracture resistance and the fatigue life of the sample after the heat treatment. The martensite beam of the heat-treated sample became thinner and the carbide precipitated after tempering was finer and dispersed. The fatigue fracture of the conventional heat-treated specimens mostly originated from the surface and the inner matrix. The fractures of the heat-treated specimens were mostly from internal inclusions. The stress field strength factor ΔK_ (GBF) at the fatigue fracture source GBF did not change with the fatigue life N_f And change.