论文部分内容阅读
研究F550级船板钢在820、850和910℃淬火,600℃回火条件下的热处理工艺对其低温韧性的影响。通过光学显微镜、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等实验方法,分析了组织中多边形铁素体以及M/A岛体积分数、M/A岛的形貌、尺寸及分布情况。结果表明:选择在亚温区850℃淬火后600℃回火试验钢的-80℃低温韧性最佳,达到220 J左右。在完全淬火区910℃淬火后回火,钢的主要组织为贝氏体,且大于2μm的M/A岛数量较多,这些M/A岛在晶间聚集或呈细条状或点列状分布在贝氏体铁素体板条间,这对钢的韧性起到破坏作用。经亚温处理后实验钢的组织为多边形铁素体和粒状贝氏体,铁素体细小且弥散分布。粒状贝氏体中的M/A岛体积分数较完全淬火低,且呈细小圆点状,弥散分布在贝氏体铁素体板条间,可以有效的阻止裂纹的扩展。
The effect of the heat treatment process on the low temperature toughness of F550 grade shipboard steel at 820, 850 and 910 ℃ and tempering at 600 ℃ was studied. Morphology, size and distribution of polygonal ferrite, M / A island volume fraction and M / A island were analyzed by optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) The results show that the toughness at -80 ℃ of 600 ℃ tempering test steel after quenching at 850 ℃ in sub-temperature region is the best, reaching about 220 J. After quenching in the complete quenching zone at 910 ℃, the main structure of the steel is bainite and there are more M / A islands than 2μm. The M / A islands are aggregated in the intergranular or strip-like or column-like distribution In the bainitic ferrite laths, this has the damaging effect on the toughness of the steel. The microstructure of the experimental steel after the sub-temperature treatment is polygonal ferrite and granular bainite, and the ferrite is fine and dispersed. The volume fraction of M / A island in granular bainite is lower than that of complete quenching, and it is finely dotted and diffuse distributed between bainitic ferrite laths, which can effectively prevent the crack growth.