钙对空冷无碳化物贝氏体/马氏体钢25Mn2SiCrCa组织性能的影响

Effect of calcium addition on microstructure and properties of air-cooled carbide free bainite /martensite steel 25Mn2SiCrCa

研究了添加微量钙0.006%对新型高强高韧空冷无碳化物贝氏体/马氏体钢25Mn2SiCrCa组织和性能的影响。结果表明,微量钙的加入不会改变实验钢的无碳化物贝氏体/马氏体组织,且对钢的强度、硬度和冲击韧性影响不大。但是,经340℃以下中低温回火后0.006%钙的加入显著降低钢的氢脆敏感性,提高钢的抗延迟断裂性能。微钙钢25Mn2SiCrCa经280℃回火后,氢脆敏感性指数由不含钙钢25Mn2SiCr的53%降至27%,经340℃回火后,氢脆敏感性指数从25Mn2SiCr的48%降至17%。

Effect of low calcium addition 0. 006% on microstructure and properties of a novel air-cooled carbide free bainite /martensite( CFB/M) steel was studied. TEM analysis shows that the small addition of calcium does not change the nature of CFB/M mixed microstructure. The mechanical testing results also demonstrate the added Ca has negligible effect on strength,hardness and impact toughness of the tested steel. However,with same amount of Ca addition( 0. 006% in mass%),significant decrease of the susceptibility to hydrogen embrittlement and thus enhanced delay fracture resistance are observed after tempering at medium or low temperatures( ≤ 340℃). For example,after tempering at 280 ℃,the hydrogen embrittlement sensitivity index EHof 25Mn2SiCrCa steel is 27% comparing with 53% for 25Mn2SiCr steel. Similar behaviors are observed at tempering temperature 340 ℃ : EH= 17% for 25Mn2SiCrCa and 48% for25Mn2SiCr steel.