GH36A合金电渣重熔Mg含量的控制

Control of Magnesium Content in the GH36A Alloy during ESR

    摘要
  • 摘要: 本文根据文献热力学数据,导出了反应;
    Mg%F0+O%=MgO(s)
    的标准自由能变化ΔG°=-505009+145.03T,J.mol-1(1780 ≤ T ≤ 2000°k)进而用热力学分析了GH36合金在含MgO或MgF2渣系中电渣重熔合金中Si、Mn等成分对产生或保持合金中含有 ≥ 0.0020Wt%Mg的不可能性,提出了含Mg的GH36A合金电渣重熔时自耗电极中含有少量Al的必要性。研究了原始Al含量(Al0)、原始Mg含量(Mg0)以及熔渣成分对锭中Mg含量Mg的影响。当渣池温度为1690±10℃,0.32 ≤ Al0 ≤ 0.62Wt%,0.0035 ≤ Mg0 ≤ 0.0140Wt%,熔渣成分为0.10 ≤ NMgO ≤ 0.30,0.05 ≤ NAl2O3 ≤ 0.21,NCaO ≤ 0.15范围,建立了GH36A合金电渣重熔控制Mg的关系式。
    研究发现,含有适量的Mg、Al的GH36A合金可大幅度地提高合金在650℃,372.65×106Pa的缺口、光滑持久寿命,消除合金缺口敏感性。

     

    Abstract: According to the eutccticum content of the Fe-Mg system,the standard free energy change of the following reaction is calculated.The result is as follows
    Mg(g)=Mg1%(Fe) △G°=-108,993 + 63.25 T,J/g-at
    It is then impossible to produce or retain Mg content ≥ 0.002% by means of Si or Mn in the GH36 alloy while ESR is conducted with slag containing MgO or MgF2.The necessity of containing a few Al in consumanle-electrode during ESR has been proposed.The effect of the original contents of Al,Mg and the the composition of slag system CaF2-MgO-Al2O3-CaO on the content of Mg in ingot is investigated.At temperature of the slag pool is about 1690±10℃, 0·32 ≤ Alo ≤ 0.62wt%,0.0035 ≤ Mgo ≤ 0.014 0 wt% and in the mole concentration range of the slag. 0.10 ≤ NMgo ≤ 0.30,0.05 ≥ NAt2O3 ≤ 0.21, NCaO ≤ 0.15, the Mg content in the GH36A alloy after ESR may be controled.
    It is found that the smooth and notched stress rupture life of the GH36A alloy contained suitable Mg and Al contents may be substantialy improved,and the notch sensitivity of the alloy may be eliminated under esting temperature of 650℃ and stress of 372.65Mpa

     

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