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将60mm厚控轧控冷态的E690海洋平台钢板分别进行730、760、790、820、850、880、910℃的淬火处理,使用扫描电镜和透射电镜对淬火后钢板的组织进行观察和分析。结果表明:730℃加热保温,奥氏体首先在粒状贝氏体晶界处形核,细小奥氏体成独立的岛状沿晶界分布;760℃进行保温,奥氏体在沿晶界生长过程中发生合并;加热温度进一步升高到790℃,奥氏体不仅在原粒状贝氏体晶界成网状分布,晶内也开始有细小奥氏体生成;820℃及以上温度保温,奥氏体晶粒尺寸在1～3μm。未奥氏体化的粒状贝氏体在加热过程中发生回复和再结晶,晶内的M/A岛不断的分解并逐渐扩散消失。
The 60mm thick rolled and controlled E690 offshore platform steel plates were subjected to quenching at 730, 760, 790, 820, 850, 880 and 910 ℃ respectively. The microstructure of the quenched steel plate was observed and analyzed by scanning electron microscopy and transmission electron microscopy. The results show that austenite first nucleates at grain boundary of granular bainite and austenite distributes along independent grain boundaries along the grain boundary at 760 ℃. The austenite grows along the grain boundary at 760 ℃, In the process of merger occurred; heating temperature further increased to 790 ℃, austenite not only in the original grain-like bainite grain boundaries distribution, the austenite also began to form fine; 820 ℃ and above temperature insulation, austenite Body grain size in 1 ~ 3μm. The non-austenitized granular bainite recovered and recrystallized during heating, and the M / A island in the crystal continuously decomposed and gradually disappeared.