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对碳的质量分数为0.54%高速车轮钢轮辋进行了不同奥氏体化温度和冷却速率热处理,得到具有不同晶粒尺寸和珠光体片间距的显微组织,在20~-120℃下对具有不同显微组织的紧凑拉伸(CT)试样进行断裂韧性测试。结果表明:在实验温度范围内,不同显微组织车轮钢断裂韧性均随温度的降低而降低,温度对不同显微组织车轮钢材料断裂韧性的影响主要是由于温度对材料流变应力的改变以及CT试样断裂模式的变化。温度较高时,解理断裂的模式为扩展控制,晶粒尺寸和珠光体片间距越小断裂韧性越高;温度较低时,解理断裂的模式为形核控制,显微组织对断裂韧性的影响不明显。
The high-speed steel wheel rim with 0.54% carbon mass fraction was heat-treated at different austenitizing temperatures and cooling rates to obtain microstructures with different grain sizes and pearlite sheet spacing. Fracture toughness tests were performed on compact tensile (CT) specimens of different microstructures. The results show that the fracture toughness of the wheel steel with different microstructure decreases with the decrease of temperature in the experimental temperature range. The effect of temperature on the fracture toughness of wheel steel with different microstructures is mainly attributed to the change of the flow stress, CT specimen fracture mode changes. When the temperature is high, the mode of cleavage fracture is extended control, the smaller the grain size and the pearlite sheet spacing, the higher the fracture toughness; when the temperature is lower, the cleavage fracture mode is nucleation control, The effect is not obvious.