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本文利用冲击韧性试验、扫描电镜、离子探针及俄歇谱议等手段研究讨论了合金元素Si和Mn对Si-Mn-Mo-V钢在淬火和低温回火状态下韧性的影响规律。研究结果表明:当钢中不含Si或含有少量Si面单独加入Mn,则由于Mn-P在晶界共偏析的原因,使P在晶界的浓度大为增加,导致了钢在淬火和低温回火状态下沿晶断裂的发生,从而降低了钢的韧性水平。在高Mn(2％Mn)钢中加入Si,由于Si在晶界的富集及Si-P的相互排斥作用,使P在晶界的偏析浓度下降。从而在一定程度上抑制了晶界脆性的发展和晶界断裂的发生,使钢的韧性水平显著提高。 本文还研究了Si和Mn对Si-Mn-Mo-V钢低温回火脆性(350℃脆性)的影响。实验结果表明:低温回火脆性既与杂质元素的晶界偏析有关,又与ε碳化物向渗碳体转化及渗碳体沿原奥氏体晶界成薄片状析出有关,由于Si和Mn既能影响杂质元素,特别是P在晶界的偏聚,又能影响ε碳化物向渗碳体转化,故Si和Mn对Si-Mn-Mo-V钢低温回火脆性发生的温度和强烈程度均有显著的影响。
In this paper, the influence of alloying elements Si and Mn on the toughness of Si-Mn-Mo-V steel under both quenching and low-temperature tempering conditions was studied by impact toughness test, scanning electron microscopy, ion probe and Auger spectroscopy. The results show that when the steel contains no Si or contains a small amount of Si surface, Mn alone is added, the concentration of P in the grain boundary greatly increases due to Mn-P co-segregation at grain boundaries, Tempering along the crystal fracture occurs, thereby reducing the level of toughness of steel. The addition of Si to high Mn (2% Mn) steels decreases the segregation concentration of P at the grain boundaries due to the enrichment of Si at the grain boundaries and the mutual repulsion of Si-P. Thus to a certain extent, inhibited the development of grain boundary brittleness and the occurrence of grain boundary fracture, so that the toughness of steel significantly increased. The effect of Si and Mn on the low temperature temper embrittlement (350 ℃ brittleness) of Si-Mn-Mo-V steel was also studied. The experimental results show that the low temperature temper brittleness is not only related to the grain boundary segregation of impurity elements, but also to the transformation of ε carbide to cementite and the precipitation of cementite along the original austenite grain boundaries. Since Si and Mn are both Can affect the impurity elements, especially P in the grain boundary segregation, but also affect the ε carbides to cementite transformation, so Si and Mn on Si-Mn-Mo-V steel temper brittleness temperature and intensity Have a significant impact.