Original Article

Improvement of hardness and thermal fatigue resistance of austenitic stainless-steel weld metal deposited on 5CrMnMo hot die steel by addition of Cr, Mn and Mo

Faculty of Materials Science and Technology, Kim Chaek University of Technology, Pyongyang, 999093, Democratic People’s Republic of Korea

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Received: 21 October 2025
Accepted: 11 December 2025

Abstract

Due to superior properties in the hot state, the 5CrMnMo hot die steel is widely used in casting, forging, etc. However, it is damaged by thermal fatigue by sustained heating-cooling during service. In this paper, the hardness and thermal cycling of weld metal used for depositing the worn 5CrMnMo hot die steel is studied. Welding electrodes were prepared by coating with coating materials containing Cr, Mn and Mo on the φ4 mm austenitic stainless-steel wires. Manual welding was used to weld the medium-carbon chromium nickel austenite weld metal onto cylindrical specimens made from 5CrMnMo hot die steel. High frequency generator working with 20 kHz was used for the thermal cycling test. The microstructural analysis and hardness testing of deposition layer were performed. The results showed superior thermal fatigue resistance of weld metal compared with 5CrMnMo. The hardness of the weld metal is approximately 40 HV_0.5 higher than that of 5CrMnMo after 2500 thermal cycles. Therefore, this technique is an effective method for repairing the worn 5CrMnMo hot die steel using welding method.