THE EFFECT OF STRONG FLOW VARIATIONS ON MICRO STRUCTURE AND VIOLENCE ON THE LOW CARBON STEEL WELDING PROCESS USING THE SMAW WET UNDERWATER WELDING METHOD

Abstract

This study uses a quantitative descriptive method, with low carbon steel material. These materials will be welded with strong stresses 60A, 90A and 120A using the welding method SMAW Wet Underwater Welding. In this study, using seam V with a 60^o angle, the machine to test the hardness, while for the microstructure test using an Olympus PME microscope (Metallurgical Microcope with Inverted). The measurement of chemical composition was carried out using specimens of the Optical Chemistry Spectrometer spectrum. (SMAW wet underwater welding). Wet welding underwater welding (SMAW wet underwater welding).

The average level of hardness in raw material is 159 VHN and ferrite micro structures dominate more than pearlite. While the material after going through the welding process of SMAW wet underwater welding in the area of acicular ferrite (AF) microstructure, the most dominant specimen with a current strength of 90A, it is also very much in the ferrite microstructure weld area with the second most dominant phase (FSP) in the specimen with a current strength of 90A.. There is an influence of current strength on the hardness level of welding results of low carbon steel alloys with current strengths of 60A, 90A and 120A. Specimens with a current variation of 90A in the HAZ section have a higher average hardness level of 244 VHN when compared to variations in current strength of 60A and 120A, namely 230 VHN and 218,666 VHN. The hardness value in the HAZ region is highest when compared to weld and metal regions. This is supported in the microstructure test in which the HAZ region shows the dominant level of acicular ferrite (AF) compared to other regions. While the weld metal area has ferrite levels with the second parallel phase (FSP) which is dominant when compared to other regions.