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采用Thermo-Calc热力学软件计算含铝高硼高速钢平衡凝固过程并绘制了不同铝含量下的Fe-B伪二元垂直截面图。采用OM、SEM、XRD和DSC等,分析不同铝含量(1.0 mass%,1.5 mass%,2.0 mass%)的高硼高速钢铸态组织,研究铝对相图和凝固组织的影响规律。结果表明:随着铝含量的增加,相图中的共晶点和共晶温度变化不大,但奥氏体区明显缩小,当铝含量达到1.5 mass%时缩小成闭合圈,δ-Fe将直接转变为α-Fe;铸态组织中的板条马氏体(Al≤1.0 mass%)将转变成珠光体(Al≥1.5 mass%)。过量铝(Al≥1.5 mass%)的加入促进铁素体的形成,使得合金硬度急剧降低,并使硼碳化物由网状趋于断网。计算结果与实验数据符合度较好,可为含铝高硼高速钢的研究提供指导。
Thermo-Calc thermodynamic software was used to calculate the equilibrium solidification process of aluminum-containing high boron steel and the pseudo-binary vertical section of Fe-B with different aluminum contents was drawn. The castings of high boron steel with different aluminum contents (1.0 mass%, 1.5 mass%, 2.0 mass%) were analyzed by OM, SEM, XRD and DSC. The influence of aluminum on the phase diagram and solidified structure was studied. The results show that with the increase of aluminum content, the eutectic temperature and eutectic temperature in the phase diagram change little, but the austenite area decreases obviously. When the aluminum content reaches 1.5 mass% Directly transformed into α-Fe. The lath martensite (Al≤1.0 mass%) in the as-cast structure will be transformed into pearlite (Al≥1.5 mass%). The addition of excessive aluminum (Al≥1.5 mass%) promotes the formation of ferrite, which leads to the sharp decrease of the hardness of the alloy and tends to break the network of boron carbides by the network. The calculated results are in good agreement with the experimental data, which can provide guidance for the research of high boron content aluminum high boron steel.