Investigating the Effect of High Power Diode Laser (HPDL) Surface Treatment on the Corrosion Behavior of 17-4 PH Martensitic Stainless Steel

Laser surface treatment conducted using a high power diode laser (HPDL) to improve the corrosion resistance of AISI 17-4 PH stainless steel is conducted and investigated. Based on microstructure and corrosion behavior study, standoff distance (SOD) of 60 to 80 mm, laser power of 1000 to 1400 W and scanning speed of 5 to 8 mm/s were considered as process parameters. The martensite formed in this alloy is of a lath morphology and has a dislocated substructure. Microscopic studies have revealed the formation of a Cu-rich phase in the samples aged at temperatures below 550 degrees C. The martensite phase was seen to terminate at packet boundaries where two groups of laths belonging to two distinct orientation variants met. After HPDL treatment the microhardness and corrosion resistance of the 17-4 PH stainless steel were examined. Whereas the microhardness was altered accordingly with variation of the chosen laser operating parameters, the corrosion resistance showed no great improvement.