Modelling of temperature distribution of a square bar during spray quenching and square edge cooling effect

An AISI 304 austenitic stainless steel square bar, with a length to thickness ratio 5:1 was heated at 900°C and spray quenched with water using 4 full oval nozzles. Five thermocouples were placed in the probe to record the cooling time-temperature curves. Three were placed at mid-thickness plane, being one in the geometric centre, and the other thermocouples were placed 1/4 thickness and near surface (1 mm). In addition, another two thermocouples were placed in a 45° plane (diagonal from center to square edge), one at 1/2 diagonal and the other near the surface (1 mm from two surfaces in the diagonal, at √2 mm from the square edge). The thermocouples were placed at mid-length in order to ignore the end-cooling effects and to facilitate the computation with 1D heat transfer. In addition, the square edge cooling effect was analyzed. FEM was used to model the transient temperature distribution during cooling. It was found that the cooling rate at the square edge was a factor of 1.5 greater than the cooling rate at the surface of the center of the flat face. The distance from the edge that is affected was determined.