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Laser beam welding of DP980 dual phase steel at high temperatures

2019; Elsevier BV; Volume: 124; Linguagem: Inglês

10.1016/j.optlastec.2019.105964

1879-2545

Caroline Cristine de Andrade Ferreira, Vágner Braga, Rafael Humberto Mota de Siqueira, Sheila Medeiros de Carvalho, Milton Sérgio Fernandes de Lima,

Hydrogen embrittlement and corrosion behaviors in metals

Dual phase steels have been used in safety components for the automotive industry and represents a standard in terms of energy absorbing steel alloys. After welding, these components present a martensitic transformation in the fusion and heat-affected zones with an intrinsic brittleness. The current contribution presents a procedure where the DP980 steel sheet is kept at a given temperature during and after the laser weld in order to generate bainite instead of martensite. The results using an isothermal treatment at 527 °C shown a microstructure composed by grain boundary and bainitic ferrite and retained austenite with a constant hardness in the base material and heat-affected and fusion zones of 280 HV. The room temperature welds present hardness values between 320 and 500 HV. The high-temperature welds also shown a decrease in the maximum residual stress at the weld centerline by 1/3, with a consequential reduction in the warp of the joined component.