ステンレス鋼るつぼで溶解したMg-9%Al-1%Zn-2%Ca合金の耐食性

抄録

  For the purpose of improving the corrosion-resistance of non-combustible magnesium alloy, the dissolution behavior of iron from stainless steel crucible to the molten alloy was investigated. Mg-9%Al-1%Zn-2%Ca (AZX912) alloy was melted at 903K, 953K, and 1003K in a stainless steel (JIS : SUS430) crucible, and the iron concentration in the alloy was analyzed. The iron concentration increased with increasing melting and holding times reaching 120ppm or more after 20 minutes at 1003K. The corrosion rate of the alloy determined by the salt water immersion test was low and independent of the iron concentration up to about 100ppm, but began to markedly increase when the iron concentration exceeded this value. EPMA analysis confirmed that iron existed in a compound made up of aluminum and manganese, and the iron concentration in the compound increased with increasing iron concentration in the alloy. The corrosion of AZX912 alloy may be caused by iron concentrated in the compound.