Study on the Grain Growth in Weld-Heat Affected Zone (Report 2)

Abstract

In Report 1 of this study, the authors showed that grain growth during thermal cycles can be calculated using the grain growth equation during isothermal heating.
It is considered that weld thermal cycles consist of heating cycle, isothermal holding and cooling cycle. Therefore, in this report, grain growth during these cycles under various conditions was examined using commercial-purity nickel.
The effect of the initial grain size (the grain size before the thermal cycle) on grain growth during thermal cycles was also examined.
It was found that the method to estimate the grain size during linear thermal cycles could be obtained, giving the level of initial grain size.
Results obtained are as follows;
1) Grain growth during heating cycle, isothermal holding and cooling cycle under various conditions can be calculated using the method proposed in the Report 1 of this study.
2) Grain growth during various thermal cycles are as shown in Figs. 2, 4 and 6.
3) The effect of initial grain size on grain size after thermal cycles varies according to the condition of the thermal cycles, as shown in Fig. 10.
4) The effect of multiple thermal cycle on the grain size can be calculated as shown in Fig. 12.
5) If the condition of thermal cycle is given and the thermal cycle can be considered as a linear form at near the peak temperature, grain size after this thermal cycle can be obtained using Figs. 13, 14 and 15.