炭素鋼のTTA曲線（恒温オーステナイト化曲線）について
1977 年 41 巻 9 号 p. 851-855
詳細
1977 年 41 巻 9 号 p. 851-855
The TTA (Time-Temperature-Austenitization) diagram was determined for a commercial pure iron, an eutectoid steel and various hypo-eutectoid steels (0.1, 0.4 and 0.6% carbon), using a newly designed experimental apparatus previously reported.
It has been observed that in the TTA diagram the starting time of the transformation shifts to the left side with the increased over-heating and finally reaches 0 sec at 950°C in the commercial pure iron, and at 840°C in the hypo-eutectoid and eutectoid steels. Therefore there exists an upper limiting temperature at the zero-time axis that coincides with the upper limit of the transformation start on super-rapid heating.
The transformation finish line with the degree of over-heating in the hypo-eutectoid steel shifts to the left side above Ae3, but it does not show the same behaviour below Ae3; in other words, there is a refraction point at the Ae3 point. It follows that the shape of the finish line in hypo-eutectoid steel is different from those in pure iron and eutectoid steel.
