Predominant Solidification Modes of 316 Austenitic Stainless Steel Coatings Deposited by Laser Cladding on 304 Stainless Steel Substrates

AISI 304 austenitic steel is one of the stainless steels most widely used as a substrate for coating using a laser as a heat source (laser cladding). The AISI 316 steel contains similar quantities of alloying elements as 304 steel, with the addition of 2 pct molybdenum, which provides greater corrosion resistance compared to 304 steel. Due to its better mechanical and corrosion resistance, AISI 316 steel was used here as a coating to improve the properties of a 304 substrate. The depositions were evaluated considering their geometric and microstructural characteristics, which were correlated with variations of the deposition parameters. The power, speed, and amount of coating metal added were altered, while the other parameters were kept constant. Increases of power and speed resulted in an increase of the diluted region, whereas increase of the amount of coating material led to decreased dilution. Two main types of solidification were observed in the same depositions: one with austenite ( γ ) as the primary phase, and the other with ferrite ( δ ) as the primary phase. Different substructures were apparent in the same type of solidification.