ANALISIS VARIASI JUMLAH PERLAKUAN HEAT STRAIGHTENING DAN TRAVEL SPEED MENGGUNAKAN TORCH GTAW PADA HASIL PENGELASAN MATERIAL PIPA STAINLESS STEEL 304 TERHADAP NILAI KEKERASAN, STRUKTUR MIKRO, DAN LAJU KOROSI

Abstract

This study analyzed heat straightening using GTAW torch heating on SA-312 TP304 material with repair variations of 2x, 4x, and 6x, as well as travel speeds of 50 mm/min and 70 mm/min. The analysis includes microstructure, hardness, and corrosion rate using a three-electrode cell. Results show that specimens with 70 mm/min travel speed and 2x heat straightening have the highest hardness in the weld metal, HAZ, and base metal, valuing 165.5 kgf/mm², 170.5 kgf/mm², and 171.8 kgf/mm², respectively. Significant microstructural differences are seen in the HAZ at of 50 mm/min travel speed, where austenite and ferrite phases thickened at grain boundaries. Specimens with 50 mm/min travel speed and 6x heat straightening produced the highest heat input, resulting a weld bead width of 12.60 mm, while specimens with 70 mm/min travel speed and 2x heat straightening had the lowest heat input with a weld bead width of 10.75 mm. specimens with 6x heat straightening at 50 mm/min travel speed have the highest corrosion rate of 0.9515 mm/year, whereas specimens with 2x treatment at 70 mm/min have the lowest corrosion rate of 0.1656 mm/year. This study shows that heat straightening is directly proportional to the corrosion rate and inversely proportional to hardness