Effect of ۳۱۶L stainless steel laser welding pulse frequency on corrosion behavior in sulfuric acid solution

Stainless steels, especially austenitic stainless steels ۳۱۶L, due to the presence of special alloying elements such as nickel, molybdenum and chromium and the formation of a surface layer on their surface, exhibit very high and desirable mechanical properties, corrosion resistance and weldability, is used in various industries. In this study, the joining of two pieces of stainless steel ۳۱۶L using Nd:YAG pulsed laser welding was investigated and the effect of pulse frequency on the quality, hardness of the joint and resistance to uniform and pitting corrosion in a sulfuric acid environment was investigated. The solidification behavior of the weld metal and ferrite present in the structure was investigated using WRC-۱۹۹۲ chart, which indicated solidification as FA, with the presence of ferrite in the weld metal being confirmed by XRD characterization. Increasing the pulse frequency increases the G/R and G×R ratios, which leads to the formation of coaxial grains in the weld center. This increase in pulse frequency also significantly increases the resistance to uniform and pitting corrosion of the weld metal. This phenomenon can be attributed to microstructural changes resulting from the formation of more uniform and coaxial grains due to the regular and dense arrangement of grains in the welding zone, on the effect of increasing the heat input and reducing the temperature. In addition, Increasing the frequency reduces the hardness of metals due to the effect of increasing the pulse frequency, and increasing the heat input and reducing the thermal gradient, due to increasing the grain sizes.

کلیدواژه ها:

Nd:YAG Pulsed Laser Welding ، Stainless Steel ۳۱۶L ، Microstructure ، Corrosion