高硼不锈钢板的组织演化及制备工艺研究

Microstructure evolution and preparation technologies of high borated stainless steel plates

采用常规"模铸"工艺制备的高硼不锈钢热加工性能差,而且成品板的强度较高但塑性差,难以进行再加工。针对这些难点,分别基于"模铸+复合轧制"以及"薄带连铸+热轧"工艺,成功制备出2.1%(质量分数)B不锈钢板,研究了不同制备工艺对组织演化和力学性能的影响规律,并对热加工性能和塑性改善的机理进行了探讨。结果表明:与常规热轧相比,"复合轧制"能有效改善高硼不锈钢板的边裂,而且由于复合板包覆层对高硼不锈钢层具有几何约束的作用,成品板塑性显著改善,伸长率为15.5%,是常规工艺所制备不锈钢板的2.4倍;在(亚)快速凝固条件下,2.1%B不锈钢铸带中硼化物的细微化和弥散化效果较为明显。热轧变形后,边部区域的硼化物的平均粒径小于3.0μm,固溶处理后,薄板的室温伸长率为14.1%。上述研究结果为难加工、塑性差的金属材料的制备工艺的开发提供了新的思路。

The ingots of high B stainless steels present quite poor workability at elevated temperature. Moreover, the finished plates of high B stainless steels with high strength shows small room-temperature uniform elongation, which makes it difficult to accomplish the further processing. Stainless steel plates with 2.1 wt.% B added were prepared by two different preparation technologies, mold casting + composite rolling and twin roll strip casting + hot rolling, respectively. The effects of preparation technologies on both the microstructure evolution and their mechanical properties were analyzed. As the results showed, the edge-cracking of composite plate was remarkably alleviated during hot rolling. And due to the geometrical-constraint effect from the cladding layers, the tensile elongation of solution-treated composite sample was enhanced to 15.5%, 2.4 times that of non-composite plate. The dispersed and fine borides were obtained in 2.1 wt.% B stainless steel casting strip under the condition of(sub-) rapid solidification. After hot rolling, the borides broke into finer grains and their average diameter decreased to be below 3.0 μm. The tensile elongation of the solution-treated samples could reach 14.1%. The above results provide new inspiration on the production for the hard-processing materials with poor plasticity.