Influence of Resulting Microstructures on Abrasive and Sliding Wear of a Structural ASTM A242 Steel Welded by GMAW

Abstract

The aim of the present work was to verify the effect of microstructures on the wear resistance of an ASTM A242 structural steel welded joint, comparing it with the behavior of the base metal. The joints were produced using the GMAW process and AWS ER70S-6 wire electrode. The welding was automated, in flat position, using V-groove and with an eletronic power source operating in CC+. Microstructural features of welded joints and worn surfaces as well as wear mechanisms were characterized using scanning electron microscopy, optical microscopy and laser interferometry. The wear resistance was analyzed by different wear tests: Dry Sand/Rubber Wheel Tests, defined by ASTM G65-16 and Linearly Reciprocating Ball-on-Flat Sliding Microwear, similar to that described by ASTM G133-16. The Rubber Wheel wear test indicated a general behavior of the weld joint, since the test range is limited by the width of the rubber wheel. In this test weld joint (weld metal and part of the coarse grain heat affected zone (CGHAZ)) showed better wear resistance than the base metal. The sliding microwear was used to analyze weld regions separately. In this sense, tests were performed on the base metal, weld metal and CGHAZ, since this region was covered by the Rubber Wheel wear test. Results showed a higher wear resistance in CGHAZ than in weld metal, and the lower wear resistance was observed in the base metal. This could be attributed to the higher plastic deformation in base metal.

Key-words:
Welding; Abrasive wear; Sliding wear; Structural steel