H13钢中Mg-Al-O系夹杂物的形成机理及控制

 通过对保护气氛电渣重熔工艺和普通电渣重熔工艺H13钢的锻材成分、氧化物夹杂的组成分析，研究了电渣重熔工艺H13钢中Mg-Al-O系夹杂物的形成机理及控制问题，并通过Factsage软件对Mg-Al-O系夹杂物的各优势区进行了理论计算。结果表明，保护气氛电渣重熔工艺中氧质量分数较低，仅为0.001 5%，氧化物夹杂主要是MgO·Al2O3，1～3 μm的小尺寸占比达到了62.5%；普通电渣重熔工艺中氧质量分数较高，达到了0.002 4%，Mg-Al-O系夹杂物以72.5%Al2O3＋27.5%MgO·Al2O3为主，含有4%的5～8 μm大尺寸夹杂物，1～3 μm小尺寸占比仅为37.8%，尺寸偏大。钢液中镁、氧质量分数的变化对MgO·Al2O3的优势区域影响较大，高镁、低氧有利于MgO·Al2O3生成，减小H13钢中氧化物夹杂尺寸。但MgO·Al2O3会作为大尺寸碳氮化物(Ti，Nb，V)(C，N)异质形核核心，后期对此问题还要做进一步研究。

Formation mechanism and control of Mg-Al-O inclusions in H13 steel

The compositions of the forging materials and oxide inclusions in the H13 steel produced through protective atmosphere electro slag remelting process (PESR) and common electro slag remelting process(ESR)were analyzed. The formation mechanism and control of Mg-Al-O inclusions in H13 steel were studied and the dominant area was calculated through the thermodynamic software Factsage. The results showed that the oxygen content of H13 steel produced by PESR is only 0.0015%,the oxide inclusions were mainly MgO·Al2O3 and the inclusion proportion of small size at 1-3μm reached to 62.5%. However,the oxygen content of H13 steel produced by ESR reached to 0.0024%,the oxide in-clusions were mainly 72.5%Al2O3+27.5%MgO·Al2O3 and the proportion of large size at 5-8μm is 4%while the propor-tion ofthe small size at 1-3μm just accounts for 37.8%. The size of Al2O3 was larger than MgO · Al2O3. The changes of Mg] and O] content in liquid steel have great influence on the dominant area of MgO · Al2O3,and the high Mg] con-tent and low O] content were beneficial to the formation of MgO · Al2O3,but decrease the size of oxide inclusions in H13 steel. However,the inclusion of MgO · Al2O3 at large size can be the heterogeneous nuclei of (Ti,Nb,V) (C,N), which will be discussed in the future.