夹杂物对模拟焊接粗晶区铁素体形核作用研究

EFFECT OF INCLUSION ON FERRITE NUCLEATION IN SIMULATED COARSE GRAIN HEAT AFFECT ZONE

利用粘结(Bonding)试验方法,在Gleeble-3800热模拟试验机上进行加热加压试验,研究了不同夹杂物(Ti2O3、TiO2、TiN)在钢-夹杂物界面处的作用效应,同时探讨了铁素体的形核机理。结果表明,在Fe-1.50%Mn-0.20%Si合金体系下,C、Si、Mn元素均对A3温度和铁素体相变驱动力存在显著影响。在焊接热循环作用下,不同夹杂物在钢-夹杂物界面处的作用效应不同,其诱导铁素体形核的机理也存在差异。其中Ti2O3粉末在界面上不发生反应,但通过吸收粉末与基体界面附近区域的Mn形成贫Mn区,促进了铁素体相变;TiO2粉末在界面上与钢发生化学反应,造成界面附近形成贫Mn区、贫Si区,并且贫Mn对A3温度提高的影响远大于贫Si对A3温度降低的影响,所以促进了铁素体相变;TiN粉末在界面上和钢不发生反应,也不能促进铁素体相变。

Method of bonding was carried out on Gleeble-3800 thermal simulation test machine to study the role action of different inclusions （ Ti203 , TiO2 , TiN） at the interface of steel- inclusion, and to research the mechanism of ferrite nucleation. The results showed that the elements of C, Si and Mn affected A3 temperature and driving force of phase transformation obviously under the alloy system of Fe-1.50% Mn-0.20% Si. Different inclusions played different roles at the interface of steel-inclusion, and the mechanism of ferrite nucleation was also different. Ti203 powder didn＇ t react with steel, but poor Mn area was formed by absorbing Mn around the interface of steel-inclusion, and promoted the ferrite transformation; TiO2 powder reacted with steel which caused poor Mn and Si area. In addition, the effect of Mn on A3 temperature which was far greater than that of Si, so TiO2 also improved ferrite transformation ; On the contrary, TiN powder at interface didn＇ t react with steel, and also could not improve ferrite transformation.