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一前言采用预裂纹冲击试样可以测定材料的裂纹扩展力G_(IC)其物理意义与断裂韧性相似,由于G_(IC)试样加工方便,试验方法简单,因此可在优选热处理工艺中,定性地对比材料性能。本试验用钢为25SiMnCrNiMoV低碳马氏体钢,对950℃淬火后的100～550℃范围内的10档回火温度进行了常规力学性能、K_(IC)和G_(IC)试验以,探求其与回火温度的关系,并找出本钢种的最佳热处理温度。二实验方法和结果讨论三点弯曲试样的断面尺寸为20×40mm。预裂纹冲击试样为10×10 x55mm,K_(IC)试验按部颁标准进行。G_(IC)计算公式为:
A foreword The use of pre-cracked specimens can determine the material’s crack propagation force G_ (IC) its physical meaning and fracture toughness similar to the G_ (IC) sample processing convenience, the test method is simple, so the preferred heat treatment process, qualitative Contrast to material properties. The test steel is 25SiMnCrNiMoV low carbon martensitic steel. The conventional mechanical properties, K_ (IC) and G_ (IC) tests were carried out on 10 tempering temperatures in the range of 100 ~ 550 ℃ after quenching at 950 ℃. Its relationship with the tempering temperature, and find the best heat treatment temperature of the steel. Two experimental methods and results to discuss three-point bending specimen cross-sectional size of 20 × 40mm. Pre-cracked impact test specimens 10 × 10 × 55mm, K_ (IC) test according to ministerial standards. G_ (IC) is calculated as: