板坯表面热喷涂工艺对45Mn钢冷弯性能的影响

ffect of hot spraying process on slab surface on cold bending property of 45Mn steel

针对45Mn钢零件加工过程中折弯开裂的问题,分析了其折弯开裂的原因,并介绍了通过板坯热喷涂工艺改善45Mn钢冷弯性能的生产实践。结果表明:钢板表面存在全脱碳层和晶间氧化层,弯折时外表面受拉应力,全脱碳层内晶间氧化处应力集中形成微裂纹成为起裂源,是45Mn钢零件加工过程中折弯开裂的主要原因;在化学成分和基体组织形貌相同的情况下,45Mn钢表面晶间氧化是影响其冷弯性能的主要因素;在热轧前采用板坯热喷涂防氧化涂料工艺,可以有效抑制钢板表面晶间氧化的形成,改善45Mn钢冷弯性能,使其180°弯曲不开裂,且对其抗拉强度、屈服强度和伸长率均无明显影响。

Aiming at the problem of bending cracks during the processing of 45Mn steel parts,the causes of bending cracks were analyzed and the production practice of improving the cold bending property of 45Mn steel through the slab hot spraying process was introduced.The results show that the presence of a fully decarburized layer and an intergranular oxide layer on the plate surface,along with the tensile stress on the outer surface during bending,lead to stress concentration at the interface of these layers,resulting in microcracks that serve as the initiation point for cracking.This is the primary cause of bending cracks during the processing of 45Mn steel parts.Under the condition of identical chemical composition and matrix microstructure,the intergranular oxidation on the surface of 45Mn steel is the main factor affecting its cold bending property.The application of a hot spraying anti-oxidation coating process on the slab before hot rolling can effectively inhibit the formation of intergranular oxidation on the plate surface,improving the cold bending property of 45Mn steel,enabling it to bend 180°without cracking,and there is no significant impact on its tensile strength,yield strength and elongation.