稀土对GDL-1型贝氏体钢的显微组织及力学性能的影响

Effects of rare earth on microstructure and mechanical properties of GDL-1 bainite steel

研究了稀土对GDL-1型贝氏体钢在空冷状态的贝氏体组织、亚结构及其力学性能的影响。结果表明,随混合稀土含量的增加贝氏体条中的亚结构更加细化,亚片条、亚单元数量增加,在稀土含量为0.018wt%-0.022wt%状态,亚片条宽度尺寸0.2-0.9μm,亚单元宽度尺寸30-250nm。亚片条、亚单元之间为稳定的残留奥氏体,并对应强韧性大幅度提高。当稀土含量达到0.042wt%,强韧性降低,与钢中夹杂物显著增加有关。并从激发形核-台阶长大模型出发分析了RE对显微组织影响的原因。

The effects of rare earth on bainitic microstructure,substructure and mechanical properties of GDL-1 bainitic steel air cooled were investigated. It is found that the substructure in bainitic plates(subplate and subunit)is finer with increasing of the mixed rare earth content in the steel. For the rare earth content of 0.018%-0.022% in the bainite steel,the width of subplates is 0.2μm-0.9μm, subunits 30nm-250nm,which are divided by stable residual austenites between subplates and subunits, resulting in the dramatic increase of strength and toughness. As rare earth content is up to 0.042%, the decrease of strength and toughness results from the increase of inclusions in the steel. The mechanism of effects of RE on microstructure of GDL-1 steel is analyzed on the basis of sympathetic nucleation-ledgwise growth model.