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研究了奥氏体化工艺参数对在国产NM500低合金高强度耐磨钢化学成分的基础上添加微合金元素Nb的试验钢的奥氏体晶粒长大趋势和组织硬度的影响,从而优化淬火工艺参数,使试验钢获得细小的晶粒和组织,在保证试验钢硬度的前提下,提高其冲击韧性。结果表明,含Nb量为0.043%的试验钢的奥氏体粗化温度为950℃,在950℃以下水淬获得的奥氏体晶粒尺寸细小,能使试验钢获得更好的冲击韧性。在850℃保温后水淬,随淬火保温时间的增加,试验钢组织硬度先增加后降低。为使试验钢到达NM500的硬度指标要求,淬火保温时间不能过长,控制在40 min以下为宜。
The effects of austenitizing process parameters on austenite grain growth and microstructure hardness of test steels with addition of microalloyed elements Nb based on the chemical composition of domestic NM500 low-alloy high-strength wear-resistant steel were studied in order to optimize quenching Process parameters, the test steel to obtain small grains and organizations, to ensure the hardness of the test steel under the premise of improving its impact toughness. The results show that austenite with a Nb content of 0.043% has a austenite coarsening temperature of 950 ℃. The austenite grain size obtained by water quenching below 950 ℃ is fine, which leads to better impact toughness of the test steel. After quenching at 850 ℃, the hardness of the test steel first increases and then decreases with the increase of quenching holding time. In order to make the test steel reach the hardness index requirement of NM500, the quenching holding time can not be too long and the control should be below 40 min.