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利用膨胀法结合金相-硬度法,在Formast-F全自动相变仪上测定了60mm厚Q690D钢连续冷却转变静态CCT曲线,研究了冷却速度对显微组织、硬度的影响。结果表明:当冷速小于1℃/s时,转变产物为铁素体、珠光体和贝氏体;当冷速为1~3℃/s,转变产物为铁素体、贝氏体;当冷速为5~40℃/s,转变产物为贝氏体、马氏体;当冷速大于40℃/s时,转变产物为完全马氏体;当冷速小于20℃/s时,显微硬度逐渐升高;当冷速在20~100℃/s时,显微硬度在390 HV左右。
The static CCT curve of 60 mm thick Q690D steel was measured on the Formast-F automatic phase change instrument by the expansion method combined with the metallographic - hardness method. The effect of cooling rate on the microstructure and hardness was studied. The results show that when the cooling rate is less than 1 ℃ / s, the transformation products are ferrite, pearlite and bainite. When the cooling rate is 1 ~ 3 ℃ / s, the transformation products are ferrite and bainite. The cooling rate is 5 ~ 40 ℃ / s, and the transformation products are bainite and martensite. When the cooling rate is more than 40 ℃ / s, the transformation product is completely martensite. When the cooling rate is less than 20 ℃ / s, Microhardness gradually increased; when the cooling rate at 20 ~ 100 ℃ / s, the microhardness of about 390 HV.