37Si Mn Cr Ni Mo V钢微区成分、显微组织与断裂性能关系的研究

本文通过对37Si Mn Cr Ni Mo V钢强韧化研究，综合考察了现代主要强韧化工艺的强韧化水平，论述了热处理制度、微区成分、显微组织与断裂性能之间的关系。通过透射电镜观察，电子探针分析及其模拟计算，提出了试验用钢中孪晶马氏体的形成条件，分布状态以及对断裂韧性的影响。强调指出微区成分是热处理中最重要的结构参量。应用统计学方法建立了热处理制度与微区成分之间的关系。研究结果表明；微区成分越均匀，材料的断裂韧性就越高，这是因为微区成分决定了马氏体的亚结构。根据设计的各种热处理工艺所获得的微观组织及所具有的断裂性能，并结合对微区成分、原始组织的研究结果，提出了遗传热处理新工艺。与现行工艺相比，在保持材料等强度条件下，提高断裂韧性值25%，在等强、等断裂韧性的条件下，比超高温淬火工艺样品的冲击韧性值提高65%以上。达到了工艺、成分、组织的优良配合并使之材料的强韧性能得以充分发挥。

INFLUENCE OF MICROAREA CHEMICAL COMPOSITION AND MICROSTRUCTURE ON FRACTURE PROPERTIES OF A MEDIUM CARBON ULTRAHIGH STRENGTH STEEL

This article deals with the effect of heat treating processes on microarea chemical composition, Micro-structure and fracture properties of ultrahigh strength steel 37 SiMnCrNiMoV. The condition of formation of twined martensite in the steel and effect of its distribution on fracture properties were examined by TEM observation, electron microprobe analysis and imitative calculations. It was emphasized that microarea chemical composition seems to be the most important microsstrctural parameter in determining the morphology and distribution of martensite on which depends the strength and toughness of the steel. The contributions of various microstructural details to strength and toughness of the steel was analysed and a new"inherit ing"heat treatment was developed with which the KEC value of the steel can be increased by 25%, in comparison with commercial heat treatment, and the Ak value of the steel can be increased by 65%, in comparison with ultrahigh temperature quenching.