Hardness analysis for low-temperature plasma nitriding RF-DC of TIG welding joint Al 6061 sheets

Abstract

Automotive part such a block machine, piston crowns, piston rings, and piston-cylinder are made by Aluminum Alloy 6061 that has a standard of hardness. Several parts of the piston require a joint under a welding process which unfortunately decreases mechanical properties of the joint welding area, especially the hardness. The high temperature causes the reduction of hardness during TIG Welding process. RF-DC plasma nitriding with a gas ratio of 70% Nitrogen and 30 % Argon at low temperatures below 200°C can elevate the hardness of the welding joint. The highest increase of the hardness was achieved by 4 hours nitriding. EDS result showed an increase of nitrogen in their lattice. Solid solution hardening mechanism in this plasma nitriding process was occurred because of the strained lattice of aluminum.Automotive part such a block machine, piston crowns, piston rings, and piston-cylinder are made by Aluminum Alloy 6061 that has a standard of hardness. Several parts of the piston require a joint under a welding process which unfortunately decreases mechanical properties of the joint welding area, especially the hardness. The high temperature causes the reduction of hardness during TIG Welding process. RF-DC plasma nitriding with a gas ratio of 70% Nitrogen and 30 % Argon at low temperatures below 200°C can elevate the hardness of the welding joint. The highest increase of the hardness was achieved by 4 hours nitriding. EDS result showed an increase of nitrogen in their lattice. Solid solution hardening mechanism in this plasma nitriding process was occurred because of the strained lattice of aluminum.