溶接熱影響部の結晶粒粗大化に関する研究
熱サイクル時の工業用純ニッケル,銅ならびにアルミニウムの結晶粒成長の定量的取り扱い
1973 年 42 巻 2 号 p. 134-145
詳細
1973 年 42 巻 2 号 p. 134-145
Grain growth in weld-heat affected zone has a detrimental effect on the properties of welded joint. Therefore, the authors tried to investigate grain growth during weld thermal cycles systematically.
In this report, it is intended to estimate grain growth during thermal cycles quantitatively using data of grain growth during isothermal heating.
From the experiment of isothermal heating on the grain growth of commercial-purity nickel, deoxidized copper and commercial-purity aluminum, it was confirmed that equation (2) is suitable as the isothermal grain growth equation. The values of constants in this equation were obtained from the data of isothermal heating.
To determine grain size during weld thermal cycles, the following method was adopted. Namely, weld thermal cycles were divided into small steps by Δt and the isothermal grain growth equation (2) was applied to each step. By piling up grain growth on these steps, grain size at temperature Ti during weld thermal cycle was represented by the equation (6) or (7).
Weld thermal cycles were applied on commercial-purity nickel, deoxidized copper and commercial-purity aluminum. Grain size was measured on the specimens quenched from various temperatures during applied thermal cycles. Measured grain size was compared with the one calculated using the above mentioned method, i.e. the equation (6) or (7). Accorhing to the result, measured value fairly well corresponds with calculated value.
Consequently, it is considered that, in the materials of commercial purity, grain size after any thermal cycle can be calculated using the above mentioned method. Therefore, this method is useful to estimate grain growth in weld-heat affected zone.
