ANALISIS PENGARUH VARIASI PREHEAT PADA SAMBUNGAN FCAW TERHADAP KEKERASAN DAN STRUKTUR MAKRO BAJA ASTM A36

Abstract

Flux Cored Arc Welding (FCAW) is widely used in steel construction because of its high productivity and ability to produce high-quality welded joints. Preheat temperature is an important parameter that influences the welding thermal cycle, thereby affecting the mechanical properties and macrostructural characteristics of welded joints. This study aimed to investigate the effect of preheat temperature variations on the Vickers hardness distribution and macrostructural characteristics of FCAW welded joints in ASTM A36 steel. Welding was performed under three preheat conditions: without preheat, preheat at 75°C, and preheat at 150°C. Vickers hardness (HV10) testing and macrostructural examination were conducted, and the results were analyzed using a descriptive comparative approach. The results showed that increasing the preheat temperature produced different responses in each region of the welded joint. The Base Metal (BM) exhibited a decreasing hardness trend, the Heat Affected Zone (HAZ) showed an increasing hardness trend, while the Weld Metal (WM) maintained relatively stable hardness values. Macrostructural observations revealed improved weld penetration, a wider HAZ, and the elimination of crack defects with increasing preheat temperature. However, slag inclusion and lack of fusion defects were still observed under all preheat conditions. Overall, preheat temperature influenced both the hardness distribution and macrostructural characteristics of FCAW welded joints in ASTM A36 steel. Based on macrostructural evaluation, a preheat temperature of 150°C provided better weld quality, although it resulted in a wider HAZ.