Estudio de la zona afectada por el calor y el metal de soldadura de cordones soldados con diferentes procesos sobre chapas de acero de grano ultrafino

N.M RAMINI DE RISSONE, HERNÁN G. SVOBODA, ESTELA S. SURIAN, DAGOBERTO SANTOS, IVANI DE S. BOTT

San Pablo

Congreso; 2º Latin American Welding Congress, IIW INTERNATIONAL CONGRESS XXXIV CONSOLDA- National Welding Congress; 2008

Asociación Brasilera de Soldadura

The present work studies the effect of four welding processes, including modern and more conventional techniques, on the heat affected zone (HAZ) of an ultrafine grained steel, produced by specific annealing treatments (during 5, 60 and 180 minutes at 800 ºC) performed after controlled rolling. The welding processes employed were Plasma (PAW) and Gas Metal Arc (GMAW) undertaken in three operational modes, short circuit (GMAW-SC), double pulse (GMAW-DP) and surface tension transfer ( GMAW-STT). The processes parameters were registered for each method and the bead on plate welds and adjacent zones were studied to determine grain size, microconstituent volume and microhardness. In all cases the GMAW-DP process exhibited the highest average and effective power while the PAW process exhibited a lower effective and an intermediate level of average of power. Grain refinement was observed in the coarse grained HAZ (HAZ-GG). For heat treatment of 5 and 60 minutes, the grain sizes accompanied the tendency of the process power. The GMAW processes resulted in higher volume fractions of martensite – austenite (MA) constituent for the higher power levels, and differed with the type of transfer. For the PAW process the volume fraction of this constituent was lower than for the other processes. An increase in the HAZ hardness relative to the base metal was observed for all cases, and especially so in the HAZ-CG. The highest hardness values obtained for all regions analyzed were produced by the PAW process.