钛微合金化S355JR钢板冲击不合原因分析及改进措施

针对普阳钢铁有限公司生产的6 mm厚钛微合金化S355JR薄规格钢板出现室温冲击不合的问题,对其化学成分、组织性能及生产工艺进行了分析。结果表明,连铸二冷强冷细化了TiN颗粒,使加热时更多的有效Ti溶解并于轧后析出,导致铁素体硬化是钢板常温冲击不合的原因。为此,在不便改变连铸工艺的前提下,调整了S355JR钢的化学成分,严格控制C、Ti含量,并将Mn质量分数由1.2%降至1.0%,有效地改善了6 mm厚S355JR钢板的常温冲击性能,提高了产品合格率。

Cause analysis of impact unqualified of titanium microalloyed S355JR plate and its countermeasures

According to the problem of impact unqualified at room temperature of 6 mm thickness S355JR plate in Puyang Iron and Steel Co.,Ltd., the chemical composition, microstructure property and production processes were analyzed. The results showed that the TiN was refined,more effective Ti was dissolved during heating and precipitated after rolling,and resulted in ferrite hardening by strong cooling of secondary cooling of contnuous casting,which was the reason for the impact unqualified of the plate at room temperature. To this effect, on the premise of keeping the continuous casting process unchanged, the chemical composition of S355JR steel was optimized of including strictly controlling the C and Mn content, and reducing the Mn element mass fraction from 1.2% to 1.0%. The practical production show that the impact property at room temperature of 6 mm S355JR plate wasimproved obviously, and the qualification rate of product was increased.