Effect of Chromium Plating of AISI 321 Alloy at 1000°C on Fatigue Resistance

The fatigue strength of the AISI 321 austenitic steel alloy was investigated in this study using chrome plating at 1000°C. Re-diffusion heat treatment at 1050°C for both coated and uncoated models’ microscopic examination was also performed on the samples obtained from the coating and fatigue tests. Surface analysis of all samples was performed using an X-ray diffraction (XRD) device. We conclude that the fatigue life of chromium plating at 1000°C leads to a reduction in fatigue life. A possible explanation is that the phases of the coating layer consist of compounds that lack plasticity, which is due to the increased chromium content and the reduced area subject to stress. The fatigue life improved after heat treatment at 1050 °C, but the coating phases remained unchanged. The austenite phase, which is characterized by plasticity, tends to increase the fatigue life of alloys heat treated at 1050 °C. This phase can only be obtained if the temperature is higher than 925 °C. Chromium plating causes the austenitic structure to transform into the ferrite phase. The increase in resistance for the uncoated alloy was greater than that for the chromium-plated alloy.