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  - 
TY  - JOUR
A1  - Haselgruber, Nikolaus
A1  - Mautner, Karin
A1  - Thiele, Jan
T1  - Usage Space Analysis for Reliability Testing
JF  - Quality and Reliability Engineering International
N2  - During the development process of a complex technical product, one widely used and important technique is accelerated testing where the applied stress on a component is chosen to exceed the reference stress, i.e. the stress encountered in field operation, in order to reduce the time to failure. For that, the reference stress has to be known. Since a complex technical product may fail regarding numerous failure modes, stress in general is highly dimensional rather than scalar. In addition, customers use their products individually, i.e. field operation should be described by a distribution rather than by one scalar stress value. In this paper, a way to span the customer usage space is shown. It allows the identification of worst case reference stress profiles in significantly reduced dimensions with minimal loss of information. The application example shows that even for a complex product like a combustion engine, stress information can be compressed significantly. With low measurement effort it turned out that only three reference stress cycles were sufficient to cover a broad range of customer stress variety.
Y1  - 2010
U6  - http://dx.doi.org/10.1002/qre.1155
SN  - 1099-1638
N1  - Special Issue: Business and Industrial Statistics: Developments and Industrial Practices in Quality and Reliability
VL  - 26
IS  - 8
SP  - 877
EP  - 885
PB  - Wiley
CY  - New York
ER  -