Stabilisation of retained austenite in laser surface melted tool steels

The stabilisation of retained austenite is investigated in a laser surface melted martensitic stainless tool steel. By comparing experimental results with the results obtained from a simple semi-empirical model, it is concluded that the microstructural refinement caused by laser melting is, most probably, the cause for the stabilisation at room temperature of large proportions of retained austenite in laser surface melted tool steels. As a consequence, the proportion of retained austenite in laser surface melted tool steels can be minimised by avoiding the use of high laser scanning speeds, which results in the formation of extremely fine dendritic structures.