Structure and Hardness of Wear-Resistant Coatings Deposited on Low-Carbon Steel upon Low-Frequency Current Modulation

• Published in: Steel in translation 2020-06, Vol.50 (6), p.387-390
• Main Authors: Saraev, Yu. N., Bezborodov, V. P., Perovskaya, M. V., Semenchuk, V. M.
• Format: Article
• Language: English
• Subjects: Arc deposition; Base metal; Chemistry and Materials Science; Coated electrodes; Current modulation; Dendritic structure; Electrodes; Grain growth; Hardness; Heat affected zone; Low alloy steels; Low carbon steels; Materials Science; Overheating; Perlite; Protective coatings; Surfacing; Wear resistance
• ISSN: 0967-0912; 1935-0988
• DOI: 10.3103/S0967091220060066

The effect of manual electric arc surfacing modes of low-alloy 09G2S steel by T-590 electrodes on their structure and hardness has been investigated. It is shown that pulse-arc surfacing of coatings by electrodes forms a fine-dendritic structure of the deposited metal. The microstructure of the heat-affected zone after surfacing consists of several regions: the overheating zone with a Widmanstätten structure and the normalization zone with a characteristic fine-grained ferrite-perlite structure. In the initial state, the base metal (09G2S steel) has a hardness of ~2500 MPa. The hardness of the deposited coating material due to strong mixing with steel is ~2700–3000 MPa and 2100–2300 MPa for the thermal impact zone. When coating in a DC mode, the heating temperature of the surfacing bath is higher, causing grain growth. When coating in pulse modes, a structure with smaller sizes of components is formed by directed low-frequency high-energy impact of the electric arc on the formed metal and due to the constant reciprocating motion of the melt with the frequency of current modulation. It is established that the application of the pulse-arc surfacing method enables preserving the previously formed hardening phases in deposited coatings.