Abstract: Effect of 0.78~0.92% Mn on structure and mechanical properties of ϕ20 mm hot-rolled coil of 0.20% carbon cold-heading steel has been analyzed and studied. End-rolling temperature of hot-rolling coil is 880 ℃,slow-cooling. Results show that with increasing Mn in steel from 0.78% to 0.92% ,the tensile strength of coil increases from 485 MPa to 508 MPa,i. e. that increases by 23 MPa；the elongation decreases from 31% to 28% ,i. e. decreases by 3 point of percentage, and the reduction of area decreases from 58% to 52% ,i. e. decreases by 6 point of percentage； the HRB hardness value increases by 4.5. The size of ferrite groups in structure of test steel reduces from 28μm to 18μm，the pearlite content in structure increases form 23% to 26% and the pearlite lamellar spacing decreases slightly;the hardenability of steel improves.

摘要： 分析研究了 Mn含量0.78%-0.92%对0.20%碳冷镦钢Φ20 mm热轧盘条组织和力学性能的影响。盘条热轧的终轧温度为880℃,缓冷。结果表明,Mn含量由0.78%增加至0.92%时,盘条抗拉强度由485 MPa升高至508 MPa,增加了 23 MPa,伸长率由31%降至28%,下降了3个百分点,断面收缩率由58%降52%,下降6个百分点;HRB硬度值增加4.5;试验钢组织中铁素体晶粒尺寸由28μm降低至18 μm,珠光体比例由23%增加至26%;且珠光体片层间距有所减小,淬透性能提高。

关键词: Mn含量, 低碳冷镦钢SWRCH22A, 热轧盘条, 组织, 力学性能