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本文对中碳空冷贝氏体/马氏体复相组织精细结构、强韧性变化规律及其机制进行了研究。研究结果表明,空冷贝氏体/马氏体组织中,下贝氏体分割原奥氏体晶粒,使马氏体板条束细化,孪晶马氏体量减少,具有优于油淬马氏体的组织结构。但在低温回火阶段,空冷B/M组织的强度低于回火马氏体组织,且由于空冷过程中晶界形成部分连续的Fe_3C薄膜,使其脆化从而韧性低于回火马氏体组织。经中温回火,空冷B/M组织晶界网状碳化物消除,组织结构优越性得以发挥。在与回火马氏体组织强度相同的情况下,韧性高出回火马氏体组织40～50kg·mm~(-3/2),且也高于等温B/M组织。
In this paper, the fine structure, toughness and toughness of air-cooled bainite / martensite composite microstructure were studied. The results show that in the air-cooled bainite / martensite, the lower bainite is divided into austenite grains, the martensite lath beam is refined and the amount of twin martensite is reduced, which is better than oil quenching The structure of martensite. However, in the low-temperature tempering stage, the strength of air-cooled B / M microstructure is lower than that of tempered martensite, and due to the continuous Fe_3C film formed in the grain boundary during the air-cooling process, the B_ organization. After tempering at medium temperature, air-cooled B / M grain boundary network carbides eliminate the superiority of the organizational structure to play. Compared with tempered martensite, the toughness is higher than that of tempered martensite by 40 ~ 50kg · mm ~ (-3/2) and higher than isothermal B / M.