Effect of Core Particle Size Distribution and Boron Carbide Additives in Metal-Cored Wires on the Structure and Properties of the 50Cr2Ni2MoVSi-type Deposited Metal

The influence of the granulometric composition and the content of boron carbide (B₄C) micro-additives in the core of metal powder-cored wires (MPW) on the characteristics of the electric arc surfacing process, the quality of bead formation, and the microstructure of the multilayer deposited metal, as well as its heat resistance and wear resistance, has been investigated. Wires with a diameter of 1.8 mm were manufactured for experiments to obtain wear- and heat-resistant steel grade 50Cr2Ni2MoVSi. As a reference, a wire without modifying additives and with a standard granulometric composition (50–300 µm) was used. Modification was carried out by introducing B₄C powder into the core of the MPW. It was found that the addition of 0.01 wt.% B₄C refines the structure of the deposited metal by a factor of 2.5, increases hardness by 10%, and delays the initiation of cracks, thereby improving heat resistance and wear resistance by 15–20%. Increasing the B₄C content to 0.02–0.1 wt.% raises the hardness of the deposited metal by 25%, however leads to intensive formation of solidification cracks. The use of more homogeneous and fine-dispersed powder fractions in the MPW core (50–100 µm) improves melting stability, promotes the formation of a fine-grained structure, and ensures defect-free metal.