EFFECT OF POST WELD HEAT TREATMENT TEMPERATURE VARIATION ON MICROSTRUCTURE AND HARDNESS DISTRIBUTION OF GTAW WELDING PROCESS OF HIGH CARBON STEEL WITH ER308 AS FILLER METAL

• Main Author: FIDEL ADRIANA (NIM. 13713034), MUHAMMAD
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/23231
• Institution: Institut Teknologi Bandung

Welding is a process to join two materials. Usually, filler metal used in welding process has same mechanical characteristics with the materials that are going to be joined. In this research, a filler metal with different characteristics is used. Two high carbon steel (0.76 wt% C) bar is joined by GTAW methods with ER308 as filler metals, which is stainless steel. The welding process used Argon as shielding gas and single V-butt as joint design. This joint then chopped into four speciment and tempered with three variation; 400oC, 500oC, and 600oC, for 45 minutes. Next, a metallography is conducted to observe the microstructure of base metal, heat affected zone, and weld metal areas. The results shows that the microstructure of HAZ consist martensite and retained austenite. As the tempering temperature goes higher, the retained austenites are transformed into martensite, and the martensites are transformed into tempered martensite. The microstructure also shows that a dark band was formed in fusion line. The dark band consist of carbide precipitation of chromium. Then, a hardness test was conducted along the specimen. The results shows that the hardness of base metal are declining as the temperature went higher, but the hardness of the weld metal are raising. This was caused by carbon diffusion from base metal to weld metal.