铸坯取样位置对经济型双相不锈钢2101热塑性的影响

为了解大型铸锭在轧制过程中产生边裂的原因,通过对比铸坯中部和边部的成分、不同温度下相比例、两相硬度差等的变化规律,利用光学显微镜,扫描电子显微镜和电子背散射衍射观察分析试验钢的微观组织和断口形貌,分析了边部容易开裂的原因.结果表明,和中部相比,边部晶粒细小,且铁素体含量较多,但边部开裂更严重.这说明晶粒尺寸和相比例并不是影响使边部开裂严重的主要原因.而和中部比,铸锭边部试样两相硬度差较大,使两相在热变形过程中应变分配不均匀,容易在相界处产生应力集中,导致开裂.同时边部析出物较中部多,相界析出物的产生破坏了基体的连续性,容易在相界处产生显微裂纹,导致开裂.

Influence of the sample position of the cast on the thermoplasticity of lean duplex stainless steel 2101

To understand the reasons behind edge cracks of large-scale cast ingot during hot deformation, this paper compared the compositions, phase ratios at different temperatures, and differences in the hardness of two phases in the middle and edges of cast ingots. The microstructure and fracture morphology of the samples were observed by optical microscopy, scanning electron microscopy, and electron back-scattered diffraction. The results indicate the presence of smaller grains and larger ferrite content in the edge portion than in the middle. However, edge cracking is also more serious than middle cracking, which indicates that grain size and phase proportion are not the main factors influencing the side cracking of ingots. Compared with that of the middle portion, the hardness difference between the two phases of the ingot edge is larger. Thus, the strain distribution of the two phases varies during hot deforma-tion, and stress concentration occurs along the phase boundary. More precipitates are observed in the phase boundary of the ingot edge than in that of the middle specimens, and these precipitates are believed to destroy the continuity of the matrix, leading to microc-racks.