Laser beam welding of DP980 dual phase steel at high temperatures

Author(s)

de Andrade Ferreira, Caroline Cristine ^[1] ; Braga, Vagner ^[1] ; Mota de Siqueira, Rafael Humberto ^[1] ; de Carvalho, Sheila Medeiros ^[1] ; Fernandes de Lima, Milton Sergio ^[1]

Affiliation

^[1] Inst Adv Studies, Photon Div, Trevo Amarante 1, BR-12228001 Sao Jose Dos Campos, SP - Brazil

• Document type: Journal article
• Source: OPTICS AND LASER TECHNOLOGY; v. 124, APR 2020.
• Web of Science Citations: 0

Abstract

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 degrees 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. (AU)

• FAPESP's process: 16/11309-0 - The study, development and application of a hybrid process: Additive Manufacturing (AM) plus High Speed Machining/Grinding (HSM/G)
• Grantee: Reginaldo Teixeira Coelho
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 16/16683-8 - Experimental development of high temperature laser welding for ultra-high strength steels for aerospace applications
• Grantee: Milton Sergio Fernandes de Lima
• Support Opportunities: Regular Research Grants