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为考察冷却工艺参数对低碳贝氏体钢组织和马氏体/奥氏体(M/A)岛的影响,利用热模拟试验机对不同Mo含量的低碳贝氏体钢进行研究。结果表明,随Mo含量增加,组织中板条贝氏体和M/A岛含量增多;增大冷速、降低终冷温度均能够细化组织,提高组织中板条贝氏体的含量及显微硬度;随着冷速的升高,M/A岛含量减少,由大颗粒的球形向细小的针状转变;终冷温度在410~350℃时,M/A岛含量和尺寸随终冷温度的降低逐渐减小,终冷温度降为330℃时,组织中短棒状M/A岛数量增多,M/A岛含量也开始增多。组织中的粒状贝氏体+板条贝氏体和其上分布的尺寸细小、形状规则的M/A岛是获得实验钢强度和韧性良好匹配的最佳组织类型。
In order to investigate the effect of cooling process parameters on low carbon bainitic steel and martensite / austenite (M / A) island, thermal simulator was used to study low carbon bainitic steels with different Mo contents. The results showed that the contents of bainite and M / A island increased with the increase of Mo content. Increasing the cooling rate and decreasing the final cooling temperature could refine the structure and increase the content of lath bainite in the tissue Microhardness. With the increase of cooling rate, the content of M / A island decreased from large spherical particles to fine acicular shape. When the final cooling temperature was in the range of 410-350 ℃, the content and size of M / A island changed with the final cooling The decrease of temperature decreases gradually. When the final cooling temperature is reduced to 330 ℃, the number of short rod M / A islands increases and the content of M / A islands begins to increase. The granular bainite + lath bainite and the small size and regular M / A island distributed in the tissue are the best tissue types for obtaining the good match of strength and toughness of experimental steel.