40Cr圆钢热顶锻开裂的分析及改进措施

Cracking Analysis of 40Cr Hot-rolled Round Steel During Upset Forging and Its Countermeasure

采用金相显微镜和扫描电子显微镜对准Φ60 mm 40 Cr圆钢热顶锻开裂缺陷进行了检验和能谱分析。结果表明:铸坯皮下气泡在轧制过程中形成显微裂纹并扩展是导致顶锻开裂的主要原因,炼钢过程中充分脱氧,中间包开浇过热度小于45℃,保证中间包烘烤温度和时间,可以有效避免铸坯皮下气泡缺陷的产生。

The cracking defects in Φ60 mm 40 Cr round steel are inspected and analyzed by metallographic microscope and scanning electron microscope. The results show that the main reason resulting in the crack in upsetting is the micro-cracks formed during rolling process under cast billet skin. In the process of making steel, the fully deoxidation, the degree of casting superheat less than 45 ℃ and the appropriate temperature and time of tundish baking can effectively avoid the emergence of cast skin blowhole defect.