改善工程机械用型钢冲击韧性的实践

为解决高强度高韧性工程机械用型钢质量波动的问题,研究了钢种成分、夹杂物、魏氏组织等对低温冲击韧性的影响。采取适当降低锰和钒含量、使用铝脱氧及整体塞棒包全保护浇铸等措施,并对铸坯加热制度等进行了优化。优化后的产品性能及稳定性显著提高,一次检验合格率100%,屈服强度平均461MPa,抗拉强度平均602MPa,断后伸长率平均22%,-5℃冲击值平均61J,金相组织中魏氏组织基本消除,晶粒度7.5~8.0级。

Practice of improving impact toughness of section steel for construction machinery

In order to solve quality fluctuation problems of section steel with high strength and high toughness for construction machine, the influences of chemical composition, inclusions and Widmannstaetten structure on low temperature impact toughness were analyzed. Several measures, such as reducing content of manganese and vanadium, adopting aluminum deoxidizing and full protection casting with stopper ladle, and optimizing billet heating procedures were applied to improve the steel performance. After these measures were applied, high and stable performance of this section steel was obtained. The testing pass rate reached 100 %,the average yield strength was 461 MPa, the average tensile strength was 602 MPa, the average elongation was 22 ~, the impact value at the temperature of -5 ℃ was up to 61 J, and Widmannstaetten structure in microstructure was basically eliminated with a high grain grade between Class 7. 5 to Class 8. 0.In order to solve quality fluctuation problems of section steel with high strength and high toughness for construction machine, the influences of chemical composition, inclusions and Widmannstaetten structure on low temperature impact toughness were analyzed. Several measures, such as reducing content of manganese and vanadium, adopting aluminum deoxidizing and full protection casting with stopper ladle, and optimizing billet heating procedures were applied to improve the steel performance. After these measures were applied, high and stable performance of this section steel was obtained. The testing pass rate reached 100 %,the average yield strength was 461 MPa, the average tensile strength was 602 MPa, the average elongation was 22 ~, the impact value at the temperature of -5 ℃ was up to 61 J, and Widmannstaetten structure in microstructure was basically eliminated with a high grain grade between Class 7. 5 to Class 8. 0.