终冷温度对不同成分700MPa级耐候钢组织和性能的影响

Effect of finishing cooling temperature on microstructure and properties of 700 MPa grade weathering steel

针对两种不同成分的700 MPa级超高强度耐候钢,利用金相显微镜、扫描电镜及透射电镜进行了组织观察,检验了硬度,研究了终冷温度在550~680℃之间变化对试验钢组织和性能的影响。结果表明,在其它工艺相同的情况下,终冷温度控制在约600℃,两种成分的试验钢均可得到良好的组织和性能;随着终冷温度的降低,钢的显微组织由多边形铁素体和少量珠光体转变为铁素体和贝氏体为主,铁素体基体上均匀分布着细小析出相;添加Mo的试验钢贝氏体含量高;硬度呈现先升高后降低的趋势。

Against 700 MPa grade high strength weathering steel with two different compositions,the microstructure was studied by means of optical microscope,transmission electron microscopy and hardness tester.The effects of finishing cooling temperature from 550 ℃ to 680 ℃ on microstructure and properties were researched.The results show that the microstructure and properties with two different composition steels can be reached at 600 ℃ or so.With the finishing cooling temperature reducing,the distribution of microstructure of test steel changes from polygonal ferrite and a little pearlite to ferrite and bainite.The content of bainite in test steel with Mo is more than first one.The disperse precipitates in ferrite can be found evenly distribute.Meanwhile,the trend of hardness increases at first,and then decreases after climax.