抄録
The present investigation was carried out to know the effect of alloying elements on austenite grain size of high purity iron alloys. The single or combined effects of alloying elements i.e. aluminium, nitrogen, carbon, silicon, and (or) manganese were examined. The results obtained are summarized as follows.
1) A ustenite grain size of pure iron-nitrogen alloys was somewhat refined as the content of acid soluble nitrogen was increased up to about 0.02% while that of pure iron-aluminium alloys was not infl uenced with an increase of acid soluble aluminium of less than 0.5%.
2) The austenite grain size of pure iron alloys was not affected by the increase in AlN and the coarse grains of nearly the same size were observed.
3) Carbon had a strong effect on the austenite grain refinement in the range of concentration of less than about 0.05%, while in the range from 0.1 to 0.5% the fine grained austenite was not affected by a furtheri ncrease in carbon content, and there was a trend for the grains to be coarsened when the content of carbon was increased beyond 0.5%.
4) Carbon did not show any function to prevent or disturb the austenite grain coarseni ng.
5) The grain size of the fine grained austenite in iron-carbon alloys was not influenced by the presence of nitrogen, aluminium or by the precipitated AlN. It was controlled mainly by the carbon content itself.
6) The austenite grain was refined by the addition of silicon in the range less than 0.2%, while it was coarsened by the presence of silicon more than 0.2% in the range less than 2.1%.
7) The austenite grain was slightly refined by the addition of manganese in the range less than 13.7%.
8) The austenite grain was finest and the grain size number was 8 to 10 in the alloys containing more than two of carbon, AlN, silicon, and manganese. Carbon played a main role for the grain refinement also in these alloys.
9) The presence of AlN was effective to raise the coarsening temperature, though it was not effective to to the austenite grain refinement.
