Effect of Multi-pass SMAW Welding on the Surface Hardness and Microstructure of Carbon Steel AISI 1050

Abstract

The objective of this work is to investigate the chemical composition, mechanical, and metallurgical properties of welded the carbon steel plates by electrode E7Cr utilize a shielded metal arc welding (SMAW) to weld three cases include one, two, and three passes. The material of the carbon steel plate was of type AISI 1050 with a thickness of 18mm, the diameter of the electrode was 3.2mm. A surface welding was used as a deposit on the surface of base metal with welding parameters of welding current = 90-140A, voltage = 21V. The welded workpiece was tested by a chemical composition analysis, Vickers hardness test, and microstructure test. The results refer that the chemical composition analysis of deposited weld metal achieved an increase in the alloying element of C, Cr, and Mn. The microstructure test of welding zone gives the microstructure different of the base metal, which it consists of a mixture of fine-grain Ferrite, dendrite, coarse dendrites, and Cr-carbide, especially in the third pass. The Vickers hardness test of the third layer had an estimate much higher than of the other layers.