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本文报导了影响低碳Fe-Mn-B系钢粒状贝氏体组织的形态与强韧性的某些规律。研究表明: 低碳Fe-Mn-B系钢在一定成份及冷速下可获得全粒状贝氏体组织。0.12%C-3%Mn-0.003%B钢粒状贝氏体中基体是位错密度较高的铁素体,其中的“小岛”由马氏体及残余奥氏体组成。不同条件的低碳Fe-Mn-B系钢粒状贝氏体中残余奥氏体量约为7～10%。随相变时冷速增大、奥氏体晶粒减小、及锰量升高与Ms点降低,粒状贝氏体中小岛的弦长减小。同时,随碳量升高及奥氏体晶粒增大,使小岛总量增加。粒状贝氏体组织的强度随小岛总量的增多而增加。韧性随小岛弦长的减小而提高,同时也随小岛总量的减少而提高。回火处理是进一步提高粒状贝氏体韧性并使钢获得强韧性良好的有效途径。
This paper reports some of the laws that affect the morphology and toughness of granular bainite in low carbon Fe-Mn-B steels. The results show that the low-carbon Fe-Mn-B steel can obtain all-granular bainite structure with certain composition and cooling rate. 0.12% C-3% Mn-0.003% B In steel granular bainite, the matrix is ferrite with higher dislocation density, and the “islands” consist of martensite and retained austenite. Different conditions of low-carbon Fe-Mn-B steel granular bainite retained austenite is about 7 ~ 10%. As the cooling rate increases, the austenite grain size decreases, the manganese content increases and Ms decreases, while the chord size of the granular bainite decreases. At the same time, with the increase of carbon content and the increase of austenite grains, the total island is increased. The strength of granular bainitic tissue increased with the increase of the total amount of islets. Toughness increases with decreasing chord of the island and also increases with decreasing total island size. Tempering is to further improve the toughness of granular bainite and steel to obtain good toughness and effective way.