Pengaruh Panas Masuk (Heat Input) terhadap Kekuatan Sambungan Las pada Pelat Baja Karbon Sedang

Abstract

Proper selection of welding parameters saves time, reduces cost, and improves metallurgical understanding. This study addresses how heat input affects joint strength in medium carbon steel plate. The objective was to analyze joint strength by (1) evaluating the effect of current and speed on heat input, (2) identifying main parameters in shielded metal arc welding (SMAW), and (3) evaluating heat input's effect on heat-affected zone (HAZ) width and strength. Hot-rolled steel plate (8 mm) by PT Krakatau Steel was characterized using spectrometry and microhardness testing, then welded with E7018/E6013 electrodes at 140-180 A and 15-28 cm/min. Results show a peak temperature of 1200 °C, initial temperature of 30 °C, and melting range of 1430-1530 °C. Welding current dominated heat input and HAZ width, while speed governed fusion. Preheating to ~350 °C reduced thermal gradients, cracking risk, and diffusible hydrogen. In conclusion, current and travel speed must be balanced to ensure fusion, control HAZ width, and minimize hydrogen-induced cracking.