S355NL钢低温冲击韧性影响因素分析

Analysis on Impact Toughness of the S355NL Steel at Low Temperature

针对S355NL钢冲击韧性低的现象,从钢板的化学成分、金相组织、断口及夹杂等方面进行了分析,并重点对冶炼、连铸、轧制工序的主要参数进行了探讨。结果表明,晶粒尺寸不均匀、杂质颗粒粗大是导致低冲击韧性的主要原因。改进增加Ti含量至0.025%,优化冶炼工艺制度,控制化学成分和夹杂,优化轧制工艺参数,保证钢板的晶粒度,钢板冲击韧性初验合格率达到了93.3%。

For the phenomenon of lower impact toughness about S355NL steel, the chemical composition of the steel sheet, the microstructure, fracture and slag were analyzed. The smelting, casting, the main parameters of the rolling process were discussed. The results showed that the grain size uniform, coarse particle impurities are the main reason leading to lower impact toughness. Therefore, by increasing the content of Ti to 0.025%, optimizing the chemical composition of the smelting process control system and inclusion, optimizing the rolling process parameters to ensure the grain size of the steel sheet, the passing rate of impact toughness of steel was effectively improved.