TY - JOUR
T1 - The effect of improved cooling on the microstructure and mechanical properties of friction stir-welded advanced high-strength dual-phase steel
AU - Mahmoudiniya, Mahdi
AU - Kokabi, Amir Hossein
AU - Goodarzi, Massoud
AU - Kestens, Leo A.I.
PY - 2021
Y1 - 2021
N2 - The heat-affected zone (HAZ) softening is considered one of the most significant challenges during welding of ferrite–martensite dual-phase (DP) steels. In fact, the strain localization in the softened area results in a premature fracture that degrades the mechanical properties of the joint. Herein, the objective is to investigate the effectiveness of improved cooling using a high thermal diffusivity backing plate (BP) to reduce HAZ softening and enhance the mechanical properties of friction stir-welded DP700 steel. Accordingly, friction stir butt welding of DP700 steel was conducted using copper and mild steel BPs. The findings show that the replacement of steel BP with copper significantly reduces the weld temperature. It is also observed that the thermal diffusivity of the BP has a substantial effect on the microstructure development and mechanical properties of the welded joint. Increasing the thermal diffusivity of the BP results in a reduction of HAZ softening from 20 to 7 HV and improving tensile strength and total elongation of the joint by 40 MPa and 6.2%, respectively. Work hardening behavior and absorbed energy before the fracture are significantly improved by the replacement of steel BP with a copper.
AB - The heat-affected zone (HAZ) softening is considered one of the most significant challenges during welding of ferrite–martensite dual-phase (DP) steels. In fact, the strain localization in the softened area results in a premature fracture that degrades the mechanical properties of the joint. Herein, the objective is to investigate the effectiveness of improved cooling using a high thermal diffusivity backing plate (BP) to reduce HAZ softening and enhance the mechanical properties of friction stir-welded DP700 steel. Accordingly, friction stir butt welding of DP700 steel was conducted using copper and mild steel BPs. The findings show that the replacement of steel BP with copper significantly reduces the weld temperature. It is also observed that the thermal diffusivity of the BP has a substantial effect on the microstructure development and mechanical properties of the welded joint. Increasing the thermal diffusivity of the BP results in a reduction of HAZ softening from 20 to 7 HV and improving tensile strength and total elongation of the joint by 40 MPa and 6.2%, respectively. Work hardening behavior and absorbed energy before the fracture are significantly improved by the replacement of steel BP with a copper.
KW - dual-phase steels
KW - electron back scattered diffraction analysis
KW - friction stir welding
KW - martensite tempering
KW - mechanical properties
UR - http://www.scopus.com/inward/record.url?scp=85090468758&partnerID=8YFLogxK
U2 - 10.1002/srin.202000253
DO - 10.1002/srin.202000253
M3 - Article
AN - SCOPUS:85090468758
VL - 92
JO - Steel Research International
JF - Steel Research International
SN - 1611-3683
IS - 2
M1 - 2000253
ER -