Strength and Impact Toughness of High Strength Steel Weld Metals : Influence of Welding Method, Dilution and Cooling Rate

• Producing welds with properties matching those of the steel is a challenge at high strength levels. The present study has investigated how the choice of welding method affects weld metal mechanical properties through effects on dilution and cooling rate. Butt welds were produced in 12 mm plates in 777 MPa and 1193 MPa yield strength steels. Conventional arc welding methods including manual metal arc, gas metal arc welding, rapid arc welding and submerged arc welding were used as well as laser-gas metal arc hybrid welding. Filler materials with nominal yield strengths between 810 and 1000 MPa were used. Cooling times between 800 C and 500 C were varied between 5s and 15s and measured by insertion of thermocouples into the weld pool.High quality welds were produced efficiently with all welding methods even though dilution varied between 3%, for manual metal arc welding, to 73% for laser-hybrid welding. Low dilution, rapid cooling and single pass welding contributed to higher strength. Overmatching weld metal strength was achieved for the less strong steel and weld yield strengths of >1000 MPa were recorded for the stronger steel. Fracture in transverse tensile testing was always located in base material or HAZ. Impact toughness was higher for lower strength and low dilution. Results are discussed relating choice of welding method and cooling rate to weld metal properties for different steel strength levels.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Bearbetnings-, yt- och fogningsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Manufacturing, Surface and Joining Technology (hsv//eng)

Nyckelord

Welding

high strength steels

weld metal

strength

hardness

toughness

dilution

Production Technology

Produktionsteknik

Manufacturing and materials engineering

Produktions- och materialteknik

Publikations- och innehållstyp

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