Solidification and heat transfer behavior of 304 stainless steel

In order to understand the solidification and heat transfer behavior of 304 stainless steel, the heat transfer coefficient was evaluated between a cast steel droplet and a copper mold during the first 0.5 seconds of solidification. The effect of alloy sulfur content (0.002%S and 0.088%S) on measured heat transfer coefficient was studied. In addition, measurement of cast surface contour and determination of solidification microstructure was performed to determine the effect of heat transfer rate on surface profile and cast structure. The heat transfer coefficient (h) varied as a function of time. The coefficient was initially high and decreased as time. The heat transfer coefficient varied with position over the copper mold surface. The highest value of h (22 kW/m(2)K) was obtained at the droplet impingement point. The heat transfer coefficient also increased with increasing droplet superheat. The addition of sulfur lowered the heat transfer coefficient when results were compared at a similar superheat. Depressions were observed at the droplet impingement point. The depression became deeper with increasing superheat. This tendency was further enhanced in the case of the lower sulfur content.