Document Type : Research Paper

Authors

1 chamran university

2 1 Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz, Ahvaz, 61357-83151, Iran

10.22050/ijogst.2021.302007.1609

Abstract

Fin-pass rolls are the latest series of rolls at ERW pipe production lines that are forming the sheets to tubular shape and adjusting the edges of the sheet for welding. The rolls (made of AISI 8622 steel) lose their useful function after about ten years of operation due to severe wear and change of their original surface profile. To repair these rolls, the worn portions were removed by grinding and replaced by a ring of AISI D2 high carbon steel. After a short time of service (about one year), the edge of the repair-ring exposed to severe spalling and fracture. The present study investigated the causes of rapid failure of the AISI D2 repair-ring and proposed a solution to the problem. The surface morphology, hardness and wear resistance were studied. Also, for closer investigation of the failure mechanism, the stress analysis of fin-pass rolls was studied using ABAQUS 6.14 finite element software. The main cause of spalling was inherent brittleness of the AISI D2 steel and presence of high stress concentration at edges of the repair-ring. To overcome this problem, carburized AISI P20 steel, case hardened AISI 4140 steel, and hard chromium electroplated AISI 4140 steel were replaced and the resulted properties were studied. The highest resistance to spalling and wear occurred with carburized AISI P20 steel because of the high surface hardness and the gradual increase of toughness from the surface to the depth at carburizing process which increases the wear resistance and retarding the growth of fatigue cracks.

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