硼元素对FB2钢组织和力学性能的影响

Effect of element B on microstructure and mechanical properties of FB2 steel

为了研究硼含量对FB2钢组织和力学性能的影响,先对5组不同硼含量的FB2钢用维乐试剂(1 g苦味酸+5 mL盐酸+100 mL无水乙醇)浸泡腐蚀90 s后进行形貌观察与分析。通过SEM-EDS观察分析基体中M_(23)C_(6)型碳化物,然后用Image-pro plus软件对析出相的尺寸进行分析。接着采用日本岛津制造所生产的AG-XPLUS 100 kN万能试验机,对5组不同硼含量的FB2钢进行室温拉伸试验和室温冲击试验。最后对5组不同硼含量的FB2钢进行组织和力学性能的分析。结果表明,FB2钢中的硼元素可以抑制M_(23)C_(6)型碳化物的长大粗化,但是硼元素易于与氮元素形成BN夹杂物。随着硼含量的增加,M_(23)C_(6)型碳化物的平均尺寸呈现降低的趋势,BN夹杂物的单位数量和平均尺寸呈现增大的趋势。FB2钢的室温拉伸性能随着硼含量的增加先升高后降低,并且在硼质量分数为0.010%时FB2钢的室温拉伸性能达到最强。当硼质量分数由0增加到0.010%时,FB2钢的室温拉伸性能升高,这是由于硼元素的加入抑制了M_(23)C_(6)型碳化物的粗化,从而提升了FB2的强度;当硼质量分数由0.010%增加到0.030%时,FB2钢的室温拉伸性能降低是由于硼元素与氮元素结合形成了BN夹杂物,引起应力集中,且大尺寸的BN夹杂物诱发了孔洞的形成,降低了FB2钢的性能。FB2钢的冲击功随着硼含量的增加呈现降低的趋势,且当硼质量分数为0.020%和0.030%时,冲击功出现了骤降,这是由BN夹杂物的单位数量、平均尺的上升和大尺寸BN及杂物的析出导致的。

In order to study the effect of B content on the microstructure and mechanical properties of FB2 steel,five groups of FB2 steels with different B contents were immersed and corroded for 90 s with Veller′s reagent(1 g picric acid,5 mL hydrochloric acid and 100 mL anhydrous ethanol),and the morphology was observed and analyzed.Then,The M_(23)C_(6) carbide in the matrix was observed and analyzed by SEM-EDS,and the size of precipitated phase was analyzed by Image-Pro Plus software.Then,the AG-XPLUS 100 kN universal testing machine produced by Shimadzu Manufacturing Institute of Japan was used to conduct room temperature tensile test and room temperature impact test on 5 groups of FB2 steel with different B content.Finally,the microstructure and mechanical properties of five groups of FB2 steels with different B contents were analyzed.The results show that the B element in FB2 steel can inhibit the growth coarsening of M_(23)C_(6) type carbides,but B element is easy to form BN inclusions with N element.With the increase of B content,the average size of M_(23)C_(6) carbide decreases,and the unit number and average size of BN inclusions show an increasing trend.The tensile properties of FB2 steel at room temperature increase first and then decrease with the increase of B content,and the tensile properties of FB2 steel reach the maximum at 0.010% B mass percent.When the mass percent of B increases from 0 to 0.010%,the tensile properties of FB2 steel increase at room temperature because the addition of B prevents the coarsening of M_(23)C_(6) carbide,and thus improves the strength of FB2 steel.When the mass percent of B increases from 0.010% to 0.030%,the tensile property of FB2 steel decreases at room temperature because the BN inclusion formed by the combination of B element and N element causes stress concentration,and the large size BN inclusions induce the formation of holes,which reduces the properties of FB2 steel.The impact energy of FB2 steel decreases with the increase of B content,and plummets when the B mass percent is 0.020% and 0.030%,which is caused by the unit number of BN inclusions,the increase of average diameter,and the precipitation of large size BN and debris.