Effect of heat input on dissimilar welds of ultra high strength steel and duplex stainless steel: Microstructural and compositional analysis

Journal Article · Sun Jan 15 04:00:00 EST 2017 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2016.11.014· OSTI ID:22689679

The effect of heat input on the microstructure and compositional heterogeneity of welds of direct-quenched ultra high strength steel (Optim 960 QC) and duplex stainless steel (UNS S32205) was studied. The dissimilar welds were made using GMAW with a fully austenitic filler wire. In addition to grain coarsening in the heat affected zone (HAZ) of the ferritic side, it was found that an increase in heat input correlatively increased the proportional volume of bainitic to martensitic phases. Coarse ferritic grains were observed in the duplex HAZ. Higher heat input, however, had a beneficial effect on the nucleation of austenite in the HAZ. Heat input had a regulatory effect on grain growth within the austenitic weld and more favorable equiaxed austenite was obtained with higher heat input. On the ferritic side of the welds, macrosegregation in the form of a martensitic intermediate zone was observed for all the cooling rates studied. However, on the duplex side, macrosegregation in the fusion boundary was only noticed with higher cooling rates. Microstructural observations and compositional analysis suggest that higher heat input could be beneficial for the structural integrity of the weld despite higher heat input increasing the extent of adverse coarse grains in the HAZ, especially on the ferritic side. - Highlights: •The effect of heat input on dissimilar welds of UHSS and DSS was studied. •Transmutation of the microstructure was discussed in detail. •The influence of heat input on compositional heterogeneity of welds was described. •Higher heat input enhanced bainitic transformation on the ferritic side. •Macrosegregation was affected by the amount of heat input on the DSS side.

• OSTI ID: 22689679
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 123; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AUSTENITE
AUSTENITIC STEELS
BAINITE
CHEMICAL COMPOSITION
COOLING
FERRITIC STEELS
FILLERS
GRAIN GROWTH
HEAT
HEAT AFFECTED ZONE
MARTENSITIC STEELS
MICROSTRUCTURE
NUCLEATION
PHASE TRANSFORMATIONS
STAINLESS STEELS
WELDED JOINTS
WELDING
WIRES