冷却速率对直接淬火钢组织和性能的影响  

Effect of Cooling Rate on Microstructures and Properties of Directly Quenched Steel

作　　者：梁晓军[1] 焦四海[1] 王聪[1] 姜洪生[2] 

机构地区：[1]宝钢研究院冶金工艺研究所 [2]宝钢分公司,上海201900

出　　处：《机械工程材料》2007年第2期16-18,39,共4页Materials For Mechanical Engineering

摘　　要：对含微量硼的钢与无硼钢在不同冷速下直接淬火试样的组织进行了观察,分别测定了含硼钢与无硼钢的连续冷却转变(CCT)曲线,以及轧制后不同温度回火试样的拉伸强度。结果表明:硼的添加会使贝氏体转变Bs点降低,生成粗大的针状或板条状贝氏体组织,这种贝氏体组织越多,它的强度就越低;无硼钢在慢冷情况下(15℃／s),Bs点较高,易于形成粒状贝氏体组织,该组织与马氏体形成的混合组织使强度较高。为避免粗大贝氏体区,对于含硼钢,适宜采用快速冷却;而对于无硼钢,应尽量降低冷却速率。The microstructure of two kinds of directly quenched steel specimens was observed, CCT curves of them were measured, and tensile test was performed with tempered specimens at different tempering temperatures after rolling. The bainite start point （B5） decrease when boron was added and bainite ferrite with large acicular or lathy shape led to low strength. However, for the boron free steel at a slower cooling rate, grain bainite is apt to be transformed because B5 was much higher than that of boron bearing steel. And this kind of bainite mixed with martensite can achieve good strength. Therefore, to avoid of large bainite transformation region, fast cooling rate is appropriate for the boron bearing steel, but for the boron free steel, lower cooling rate is preferable.

关 键 词：直接淬火 冷却速率 贝氏体转变点 力学性能 

分 类 号：TG335[金属学及工艺—金属压力加工] TG162.8