<p class="AMSmaintext1">In this paper the effect of rapid cooling during arc welding on the structure of fusion layer and heat affected zone (HAZ) of high-carbon low alloyed steel have been studied. The main idea was that despite of high carbon content (1.2%) it is necessary to achieve quenching in HAZ. Due to proper chemical composition of welded steel martensite start temperature Ms is about 20 ^oC, therefore austenitic structure of quenched metal is preserved after rapid cooling. Exposition of HAZ to excessive heat during welding cycle leads to local precipitation of carbides from austenite and thus raising of Ms. In this case some amount of martensite was present in structure after cooling along with austenite and carbides. Microstructure, microhardness and chemical composition of remelted electrode metal, fusion zone and HAZ were studied by means of optical microscopy, SEM, EDX and microhardness testing.</p>

The composition of the solder, which provides the necessary technological properties of the product, namely, electrical conductivity and mechanical strength of the junction was selected. The possibility of brazing beryllium bronze with a silver contact plate by furnace brazing using fluxes based on NaCl: CaCl2: CaF2 salts, respectively (24: 61: 15% mass) in the atmosphere was established. The possibility of brazing BrB2 beryllium bronze in the atmosphere using a research flux based on the eutectic of the NaCl – CaCl2 system (28…72% wt.) adding 15% CaF2 over a copper layer is shown. The technology for brazing beryllium bronze BrB2 with silver contact plates with silver solder PSr68 has been developed. The brazing process is combined with the hardening operation, which allows avoiding additional thermal operations; flux residues are removed during hardening and do not actually need additional cleaning operations; applied solder, flux components and technologies for applying a layer of copper are not scarce and relatively cheap, which can significantly reduce the cost of the product, subject to the requirements of the technical specifications. A technological process that makes it possible to refuse of using vacuum systems and toxic fluxes has been developed.

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