TY  - JOUR
A1  - Reisgen, Uwe
A1  - Schleser, Markus
A1  - Mokrov, Oleg
A1  - Ahmed, Essam
T1  - Uni- and bi-axial deformation behavior of laser welded advanced high strength steel sheets
JF  - Journal of materials processing technology
N2  - Bead-on-plate butt joints of 2.5 mm hot rolled DP600/DP600 and 1.2 mm cold rolled TRIP700/TRIP700 steel sheets were performed using 6 kW CO2 laser beam welding. The welding speed ranged from 1.5 to 3.0 and from 2.1 to 3.9 m/min in DP/DP and TRIP/TRIP steel weldments respectively. A top surface helium gas was used as a shielding gas at a flow rate of 20 l/min. Metallographic examinations and transverse tensile testing (DIN EN 895: 1995) were carried out to characterize the weldments. The formability of base metals and weldments were investigated by standard Erichsen test (DIN EN ISO 20482). It was found that the uniaxial plastic behavior of both DP600 and TRIP700 base metals was in agreement with Swift and modified Mecking–Kocks models respectively. In a perpendicular tensile test to the weld line, all specimens were fractured at the base metal however the strengths were somewhat higher than those of base metal. There was a significant reduction in formability caused by welding of both DP/DP and TRIP/TRIP steel weldments and the formability has been improved with the increase of the welding speed.
Y1  - 2010
U6  - http://dx.doi.org/http10.1016/j.jmatprotec.2010.08.003
SN  - 0924-0136
VL  - 210
IS  - 15
SP  - 2188
EP  - 2196
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Reisgen, Uwe
A1  - Schleser, Markus
A1  - Mokrov, Oleg
A1  - Ahmed, Essam
T1  - Shielding gas influences on laser weldability of tailored blanks of advanced automotive steels
JF  - Applied surface science
N2  - The effects of shielding gas types and flow rates on CO2 laser weldability of DP600/TRIP700 steel sheets were studied in this work. The evaluated shielding gases were helium (He), argon (Ar) and different mixtures of He and Ar. Weld penetration, tensile strength and formability (Erichsen test) of laser welds were found to be strongly dependent upon the shielding gas types. The ability of shielding gas in removing plasma plume and thus increasing weld penetration is believed to be closely related to ionization potential and atomic weight which determine the period of plasma formation and disappearance. It was found that the higher helium shielding gas flow rate, the deeper weld penetration and the lower weld width.
Y1  - 2010
U6  - http://dx.doi.org/10.1016/j.apsusc.2010.08.042
SN  - 0169-4332 (E-Journal); 0169-4332 (Print)
VL  - 257
IS  - 5
SP  - 1401
EP  - 1406
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Ahmed, Essam
A1  - Reisgen, Uwe
A1  - Schleser, Markus
A1  - Mokrov, Oleg
T1  - On formability of tailor laser welded blanks of DP/TRIP steel sheets
JF  - Science and technology of welding and joining
N2  - This paper aims to evaluate the formability of tailor welded blanks of dual phase (DP600)/transformation induced plasticity (TRIP700) steel sheets. In this work, bead on plate butt joints of 2·5 mm DP600 and 1·2 mm TRIP700 steel sheets were performed using CO2 laser beam welding. Microhardness measurements and transverse tensile testing were carried out to characterise the welds. The formability of base metals and welds were investigated by standard Erichsen test. In a perpendicular tensile test to the weld line, all specimens were fractured at the TRIP base metal, and the strengths were somewhat higher than those of base metal. There was a significant reduction in formability caused by welding of the DP600/TRIP700 steel sheets, and the formability increased with increasing welding speed.
Y1  - 2010
U6  - http://dx.doi.org/10.1179/136217110X12731414739754
SN  - 1743-2936
VL  - 15
IS  - 5
SP  - 337
EP  - 342
PB  - Maney
CY  - Leeds
ER  -