Pengaruh Welding Time Terhadap Struktur Mikro Dan Kekerasan, Sambungan Lap Baja Tahan Karat Feritik Aisi 430 Dengan Metode Resistance Spot Welding

Abstract

Abstract : Spot welding is one of plate joining technique, which is common used in automotive industries, railway coach bodies and ship construction. The objectives of this research were to find out microstructure and hardness value of lap joint of AISI 430 steel. The variable of this research was welding time. In this research, thickness of base metal was 0.8-mm. Variation of welding time values were 1, 2, and 3 second. The joint system type was used single lap joint JIS Z 3139. Two plates welded in 1.79 volt. These testing and examination include the hardness, macro and microstructure. The results of this research show that increasing spot welding time was increase hardness value and nugget size. In HAZ grain border, carbide (Cr₂₃C₆) precipitation was increase as the increasing of welding time. The hardness value raises with the increase of welding time. The weld metal hardness, in martensite, ferite δ and ferite α microstructure as the effect of air-cooling treatment, in range of 340.7-356.7 Kg/mm² and decrease at PMZ, HAZ and weld metal.

Keywords: Spot welding, lap joint, welding time, hardness