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采用Charpy(V型缺口)试样对A508-3钢调质处理试样和双相区热处理试样在-196～20℃温度范围内进行示波冲击试验,用扫描电镜对冲击断口形貌进行观察,研究了冲击温度对两种热处理制度下该钢的冲击性能和断口形貌的影响。调质处理试样随着温度的降低,其冲击功和侧膨胀量急剧降低,断裂方式从韧脆混合断裂变为脆性断裂,断口形貌中纤维区和剪切唇面积不断减少,放射区面积相应增大;双相区热处理试样在-20～-100℃冲击时,其冲击功和侧膨胀量改变甚小,断裂方式为全韧性断裂,断口形貌全部为剪切唇和纤维区组成,随着温度的继续降低,冲击功和侧膨胀量开始急剧下降,断裂方式变为韧脆混合断裂,断口形貌出现放射区,放射区微观特征为准解理。与调质处理相比,该钢经双相区热处理后冲击性能大大提高,韧脆转变温度急剧降低。
The Charpy (V notch) sample was used to test the impact fracture of the A508-3 steel quenched and tempered specimen and the two-phase heat-treated specimen in the temperature range of -196 ~ 20 ℃. The impact fracture morphology was observed by scanning electron microscopy The effects of impact temperature on the impact properties and fracture morphology of the steel under two heat treatment regimes were observed and studied. With the decrease of temperature, the impact energy and lateral expansion of quenched and tempered samples decreased sharply, the fracture mode changed from ductile-brittle fracture to brittle fracture, and the area of the fiber zone and the shear lip in the fracture morphology continued to decrease. The area of the radiation zone Correspondingly increases. When the sample is heated at -20 ~ -100 ℃, the impact energy and lateral expansion of the sample in the two-phase zone change little, the fracture mode is all-ductile fracture, and the fracture morphology is composed of the shear lip and the fiber zone As the temperature continues to decrease, the impact energy and lateral expansion begin to drop sharply, the fracture mode becomes ductile-brittle mixed fracture, the radiation appearance appears in the fracture appearance, and the micro-characteristics in the radiation zone are quasi-cleavage. Compared with the quenched and tempered treatment, the impact properties of the steel after heat treatment in the two-phase region are greatly improved, the ductile-brittle transition temperature is sharply reduced.