Zr处理对含Ti低碳微合金钢中氮化物的影响

Effect of Zr Treatment on Nitride in Low Carbon Ti-Microalloyed Steels

以含Ti低碳微合金钢为研究对象,通过实验和热力学计算研究了Zr质量分数对钢中氮化物的影响规律.结果表明:随着钢中Zr质量分数由0.0020%增加至0.0200%,钢中氮化物数量密度和面积占比明显增加,氮化物类型逐渐由TiN变为(Ti y,Zr 1-y)N,(Ti y,Zr 1-y)N中Zr/Ti原子数比逐渐增加,(Ti y,Zr 1-y)N由以TiN为主转变为以ZrN为主.热力学计算结果发现精炼过程无TiN,ZrN等氮化物析出,氮化物主要在凝固过程析出.当钢中Zr质量分数为0.0020%时,凝固过程只有TiN析出;而当Zr质量分数≥0.0046%,逐渐有ZrN在凝固末期析出.随着凝固过程温度的降低,(Ti y,Zr 1-y)N具备热力学析出条件.当钢中Zr质量分数由0.0046%增加至0.0200%,(Ti y,Zr 1-y)N开始析出温度逐渐增加,TiN在(Ti y,Zr 1-y)N中占比逐渐减小.最后,当采用Zr-Ti复合脱氧时,钢中Zr质量分数应控制在0.0020%~0.0050%.

The effect of Zr content on nitrides in low carbon Ti-microalloyed steels was studied by experiment and thermodynamic calculation.The results show that with the increase of Zr content from 0.0020%to 0.0200%,the number density and area proportion of nitrides increase obviously.The type of nitrides gradually changes from TiN to(Ti y,Zr 1-y)N and the Zr/Ti atomic ratio in(Ti y,Zr 1-y)N increases.The main nitrides in(Ti y,Zr 1-y)N gradually changes from TiN to ZrN.The thermodynamic calculation results show that there is no precipitation of TiN,ZrN and other nitrides in the refining process,and nitrides mainly precipitate in the solidification process.When Zr content is 0.0020%,only TiN precipitates during solidification,whereas when Zr content is more than 0.0046%ZrN precipitates at the late stage of solidification.As the temperature decreases,(Ti y,Zr 1-y)N fulfills the thermodynamic precipitation conditions.When Zr content increases from 0.0046%to 0.0200%,the precipitation temperature of(Ti y,Zr 1-y)N increases,but the ratio of TiN in(Ti y,Zr 1-y)N decreases.Finally,when Zr-Ti composite deoxidization is adopted,the mass fraction of Zr in steels should be controlled within the range of 0.0020%~0.0050%.