低成本360 MPa级高韧性钢组织及力学性能研究

Study on Microstructure and Mechanical Properties of Low-Cost 360 MPa Grade High Toughness Steel

通过增加[C]含量降低[Mn]、[Cr]及[Nb]合金含量,试制360 MPa级高韧性钢,研究了低成本360MPa级高韧性钢的组织和力学性能的演变。力学性能方面,钢板强度略降低,断后伸长率提高3%,韧脆转变温度升高5℃左右,-80℃冲击韧性较优;组织方面,钢板的针状铁素体含量明显降低,多边形铁素体含量和尺寸明显增加,同时在钢板心部出现珠光体;微观组织方面,>15°的大角度晶界比例由46.3%降低至37.5%,明显降低。合金成本降低后,组织类型产生变化,强度和韧性变差,但满足-80℃低温性能要求,具有较好的推广前景。

A 360 MPa grade high-toughness steel was trial-produced by increasing the carbon[C]content while reducing the manganese[Mn],chromium[Cr],and niobium[Nb]alloy contents.This study explores the evolution of the microstructure and mechanical properties of this low-cost steel.Regarding mechanical properties,the steel plate exhibited a slight decrease in strength,a 3%increase in elongation after fracture,and an increase of approximately 5℃in the ductile-to-britle transition temperature.Its impact toughness at-80 was notably superior.In terms of microstructure,the steel plate showed a significant reduction in acicular ferrite content,with a notable increase in polygonal ferrite content and size,with pearlite also observed in the core region of the steel plate.Microstructurally,the proportion of high-angle grain boundaries(>15°)decreased markedly from 46.3%to 37.5%.Although the reduction in alloy cost led to changes in microstructure type and a slight decrease in strength and toughness,the steel still met the requirements for low-temperature applications at-80 C and is indicating favorable prospects for promotion.