Tensile ability of liquid film in the later stage of casting solidification
The later stage of metal solidification is a dangerous period for hot crack generation. Investigating the tensile strength of liquid films is important to improve casting quality given that the liquid film between crystal grains has a certain preventative effect on thermal cracking. The analytic formula is obtained through a calculus-based method, and the relationship between the radius of the curvature of the liquid film and grain spacing is first quantified based on mass conservation. Moreover, the indirect relationship between the tensile strength of the liquid film and grain spacing is obtained. Analytical results show that the radius of the curvature of the liquid film gradually decreases as the grain spacing is increased in the absence of liquid metal supplementation, and an extremum of the radius of curvature exists. However, the extreme value obtained in this study is different from that obtained in a previous study. The maximum of the tensile strength of the liquid film corresponds to the extremum of the radius of curvature. Crystal grains will not produce hot cracks if the shrinkage tension does not exceed this maximum value during solidification. This study provides an important reference for the establishment of the solidification process.