不锈钢/高硼不锈钢层状复合材料组织变化

Microstructure change in stainless steel/high boron alloyed stainless steel laminate plate

为了解决高硼不锈钢材料变形难度大、易开裂、塑性低等问题,采用复合浇铸-热轧变形工艺,制备了以难变形金属高硼不锈钢为中间层的层状复合板,研究了复合材料在铸造、热轧和固溶处理各阶段的组织特点及芯层中硼化物的相组成规律.结果表明:含硼质量分数2%～2.5%的复合板芯层的铸态组织主要以共晶组织形式凝固,含硼较高的芯层铸态组织除以共晶组织形式凝固外,还形成大块的含有Cr2B和Fe2B的过共晶硼化物相;热变形使共晶硼化物发生破碎、细化,但过共晶硼化物的体积形状变化不大;固溶处理使覆层中细小的二次析出物明显减少,这有利于复合板的力学性能,但芯层中硼化物的形貌、数量及尺寸变化不大.

To solve the problem of difficult deformation of high boron stainless steel,the boron alloyed laminate plate,containing a middle layer of difficult-to-deformation high boron stainless steel,was fabricated by composite casting and hot rolling process.Microstructures and transition characteristics of borides in middle layer during casting,hot rolling and solution treatment process were researched.The results showed that the cast microstructure of containing boron content 2%~2.5% in middle layer mainly solidified in the form of eutectic microstructure,meanwhile,the cast microstructure containing higher boron content not only solidified in the form of eutectic microstructure but also formed block Hypereutectic borides containing Cr2B and Fe2B.The eutectic borides could be broken and refined by hot rolling but the size and shape of Hypereutectic borides had little change.The solution treatment made the quantity of fine second precipitates in coating layer decreased,which would be beneficial to mechanical properties.But the shape,quantity and the size of borides in middle layer fundamentally remained unchanged.