Кл.слова (ненормированные):
Low-carbon steel -- Laser welding -- Heat affected zone -- Structure -- Toughness
Аннотация: Microstructure of laser welds of the X70 low-carbon pipe steel was studied. High cooling rates after laser welding and non-uniform distribution of carbon in the ferrite-pearlite base metal caused formation of regions with increased microhardness (up to 650 НV) in inter-critical heat affected zone (ICHAZ). These regions consisted of finely dispersed degenerate upper bainite and martensite-austenite constituents of a slender shape and small fraction of a massive shape along the boundaries of bainite laths, as well as twinned martensite. High concentration of martensite-austenite constituents (10–16%) and residual stresses in ICHAZ, as well as a dendritic martensitic structure with carbide interlayers along the boundaries of martensite laths in fusion zone were the main reasons of sharp decrease in charpy impact energy of the welded samples. High microhardness of the laser welds was decreased down to 320 HV and their brittleness was improved by annealing. Also, in ICHAZ, degenerate upper bainite and the regions of martensite-austenite constituents decayed forming tempered sorbite and Fe2C and Fe3C carbides, respectively. Charpy impact energy of the welds doubled after annealing compared to the welds without annealing, and ductile-brittle transition temperature decreased down to –60°С.
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Держатели документа:
Institute of Strength Physics and Materials Science of Siberian Branch Russian Academy of Sciences, 2/4, pr. Akademicheskii, Tomsk, 634055, Russian Federation
Khristianovich Institute of Theoretical and Applied Mechanics of the Siberian Branch of the Russian Academy of Sciences, 4/1, Institutskaya str., Novosibirsk, 630090, Russian Federation
Kirensky Institute of Physics of the Siberian Branch of the Russian Academy of Sciences (SB RAS), Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russian Federation
Доп.точки доступа:
Derevyagina, L. S.; Gordienko, A. I.; Orishich, A. G.; Malikov, N. S.; Surikova, M. N.; Volochaev, M. N.; Волочаев, Михаил Николаевич