热处理工艺对低合金铸钢力学性能的影响

Effect of Heat Treatment Process on Mechanical Properties of Low Alloy Cast Steel

本文研究了初始淬火温度、淬火温度、回火温度对低合金铸钢拉伸强度、硬度、韧性等力学性能的影响。结果表明:随着初始淬火温度的升高,低合金铸钢的抗拉强度逐渐降低,伸长率先升高后降低,并在260℃时出现拐点,伸长率达最大值14.53%。当初始淬火温度为260℃时,低合金铸钢的力学性能最优。低合金铸钢的拉伸强度、硬度冲击韧性、断裂韧性随着淬火温度的升高呈先上升后下降的趋势,当淬火温度为(960±10)℃时,低合金铸钢表现出优异的综合力学性能。低合金铸钢的硬度随回火温度的上升逐渐下降,冲击韧性随回火温度的上升先上升后下降。综合考虑,回火温度的最佳温度为(200±10)℃。低合金铸钢经960℃淬火后,其微观组织结构为单一马氏体结构,且大量纳米级奥氏体薄膜夹杂在马氏体板条间。这种微观组织结构使低合金铸钢具有较高的强度、硬度、韧性及塑性。

The effects of initial quenching temperature, quenching temperature and tempering temperature on the tensile strength,hardness and toughness of low alloy cast steel were studied. The results show that with the increase of initial quenching temperature,the tensile strength of low alloy cast steel gradually decreases, the elongation first increases and then decreases, and there is an inflection point at 260 ℃, and the elongation reaches the maximum value of 14.53%. When the initial quenching temperature is 260 ℃, the mechanical properties of low alloy cast steel are the best. The tensile strength, hardness, impact toughness and fracture toughness of low alloy cast steel first increase and then decrease with the increase of quenching temperature. When the quenching temperature is(960 ± 10) ℃, low alloy cast steel shows excellent comprehensive mechanical properties. The hardness of low alloy cast steel decreases gradually with the increase of tempering temperature. The impact toughness increases first and then decreases with the increase of tempering temperature. The optimum tempering temperature is(200 ± 10) ℃. After quenching at 960 ℃, the microstructure of low alloy cast steel is a single martensite structure, and a large number of nano austenitic films are mixed between martensite laths. This microstructure makes low alloy cast steel have high strength, hardness, toughness and plasticity.