Search

The paper studies the structure and microhardness of the heat-affected zone, welding area in low carbon and low alloy steel 09G2S (AISI A516 grade 55), and the coating created by two-pass manual metal arc welding with the addition of titanium carbonitride nanoparticles. It is shown that the microhardness dependence on the distance to the coating surface is divided into four zones. The microstructure of each zone is studied by using the optical and scanning tunneling microscopies. It is found that the formation of highly dispersed acicular ferrite and globular bainite structures in the deposition superheat zone of surfacing is favorable for the improvement of the coating–base metal composition impact toughness.

Austenitic stainless steels are frequently used for hydrogen applications due to their high ductility at low temperatures and lower hydrogen environment embrittlement compared to ferritic steels. We study the effect of electrochemical hydrogen saturation up to 40 h on tensile behavior and fracture mechanisms in high-nitrogen austenitic 17Cr–24Mn–1.3V–0.2C–1.3N steel. Hydrogen saturation weakly influences the characteristic of stress–strain curves, but decreases steel ductility, yield stress, and ultimate tensile stress. Hydrogenation provides a change in steel fracture peculiarities—a hydrogen-assisted thin brittle surface layer of ≈5 μm and ductile subsurface layer of 50–150 μm in width in hydrogen-saturated specimens. The subsurface layer shows ductile transgranular fracture with elongated dimples and flat facets. The central parts of fracture surfaces for hydrogenated specimens show ductile fracture mode similar to hydrogen-free state, but they include numerous secondary cracks both for central part and for transition zone between ductile central part and subsurface layer associated with highest hydrogen saturation. The possible reasons of decrease in hydrogen-associated ductility and change in fracture character are discussed.

The Institute of Strength Physics and Materials Science (Siberian Department, Russian Academy of Sciences) has developed a process for electron-beam deposition of powdered composite materials on metallurgically-produced parts. A unique electron-beam deposition device, the LUNa-10, for reinforcement of blower nozzles used in blast-furnace casting and for reinforcement of crystallizers in continuous steel casting machines was developed and placed into service at the West Siberian Metallurgical Combine (Novokuznetsk). This paper describes some characteristics of the electron-beam deposition process for composite coatings, and the properties of such coatings as a function of composition and purpose.