オーステナイト系高マンガン鋼の温度0°～100℃間での平均熱膨張係数におよぼす合金元素の影響

抄録

In order to develop new austenitic manganese steels for structural nonmagnetic and wear resistant applications that have almost same mean thermal expansion coefficient as carbon steel in the temperature range between 0°C and 100°C, an investigation has been made of the effects of various alloying elements, C, N, Cr, Mn, on the thermal dilatation curve and Neel temperature that is found from the temperature dependence of the magnetization. The results obtained are as follows :
Mean thermal expansion coefficient α of austenitic manganese steels increases with increasing content of C and N, while it decreases with increasing manganese content. α vs. Cr content curve shows a minimum value. Following linear regression equation that relates α to the chemical composition is obtained.
α(×10^-6/°C)=19.72+2.32(%C)+1.39(%N)-0.31(%Mn)
+0.028(%Cr)²-0.41(%Cr)+0.14(%ε')
where, (%ε') represents the volume percent of HCP ε' martensite. The effects of alloying elements on the Néel temperature show a reverse tendency comparing with those on α. It is also found that α tends to decrease with raising Néel temperature. The dependence of the α below Néel temperature on chemical composition can be estimated by the change resulting from substantially the variation of spontaneous volume magnetostriction by alloying.