Effect of some of the high-melting compounds on the properties of a weld-on alloy

Abstract

1. The structure of an alloy consisting of a mixture of coarse- and fine-grain carbides and borides arranged as isolated inclusions in the base metal imparts high strength and wear resistance to the weldedon layer, thus confirming the possibility of direct high-grade alloying of the welded-on layer with highmelting compounds. 2. The main reason for the tendency of a wear-resistant welded-on alloy to form hot cracks is a lack of eutectic. Maximum tendency to hot cracking is shown by alloys with a structure of austenite and carbide eutectic in the form of thin layers in interaxial spaces between columnar crystals. Hence, when alloying the welded-on layer with borides, an increase in the latter's concentration helps to refine the primary structure and to eliminate hot cracks. 3. The optimal composition of the alloy is formed by alloying with a mixture of 10% TiB2+90% B4C (10–15%) with the following chemical composition: 0.83–0.97% C, 2.9–4.2% B, 0.07–0.09% Ti, with an electrode coating thickness per side of 1.0–1.1 mm. 4. The structure of alloys coatings applied with electrode of TBK type shows high microhardness in the component phases, which fact gives the alloy high over-all hardness and heat resistance.