研究了0Cr32Ni7Mo4N双相不锈钢热轧后冷轧和直接冷轧的成形性能, 分析了室温下α相和γ相的塑性变形机制以及经过热轧、冷轧及固溶处理后的组织演变规律, 并测试了2种成形工艺冷轧板热处理后的力学性能和耐蚀性能, 分别采用OM和SEM观察金相和腐蚀形貌. 结果表明: 实验钢在热轧后板边部开裂, 切边后经热处理再冷轧, 成形性良好; 铸态钢坯经过1100 ℃固溶处理后直接冷轧, 成形性能与其相当. 室温下α相的变形机制为多系滑移形成位错胞状结构, γ相为单系滑移和机械孪晶; 冷轧板随着热处理温度升高, 组织变得更均匀, 析出物颗粒数量减少; 直接冷轧的钢板经热处理后, 抗拉强度达到1082.9 MPa, 延伸率为29.3%, 在3.5%NaCl溶液中临界点蚀电位为1060 mV, 经过65%HNO₃溶液腐蚀后失重率为0.05 g/(m²·h), 与常规热轧加冷轧后的钢板相当.

Duplex stainless steels consist of a two phase microstructure involving α-ferrite and γ-austenite. These alloys have a remarkable combination of mechanical properties together with good corrosion resistance under critical working conditions and are suitable for marine and petro-chemical applications. However, the poor hot workability of these materials makes the industrial processing of flat products particularly critical. Many investigations focus on the mechanisms and behaviors of hot deformation on these materials. Several factors are frequently reported give rise to hot cracking: phase proportions, size and morphology of both phases, softening mechanisms in constituting phases, microstructural evolution during hot work, and strain partitioning between α and γ. On the contrary, few studies have been carried on cold rolling performance. Hot cracking should be avoid during forming process of duplex stainless steel, the more effective way of manufacturing in such materials is also needs research. In this work, the formability of 0Cr32Ni7Mo4N duplex stainless steel was studied in the hot rolling and directly cold rolling processes. The deformation mechanism of α and γ phase at room temperature, the microstructure evolution after hot rolling, cold rolling and solution treatment were investigated. Mechanical properties and corrosion resistance of two kinds of cold-rolled sheets were tested. The metallography and corrosion morphology were observed by OM and SEM. The results show that cracks emerged along the edge of hot-rolled plate even it was reheated three times, and it has good cold rolling formability after cutting edge of the plate. On the other hand the as-cast billet solution-treated at 1100 ℃ has good cold rolling performance. Deformation mechanism of α phase at room temperature is that multi-slip system form dislocation cell structure, while single slip model and mechanical twins appear in γ phase. As the temperature of heat-treatment raised, microstructure became more homogeneous and the amount of precipitate particles decreased. The experimental results show that the tensile strength of cold-rolled sheet after heat-treatment reaches 1082.9 MPa and the elongation is 29.3%. Critical pitting potential of the specimen in 3.5%NaCl liquor is 1060 mV; weight loss after intergranular corrosion in 65%HNO₃ solution is 0.05 g/(m²·h).