Fatigue behavior of laser and hybrid laser-TIG welds of high-strength low-alloy steels

0509287 - ÚPT 2020 DE eng A - Abstract
Šebestová, Hana - Horník, Petr - Mrňa, Libor - Horník, Vít - Hutař, Pavel - Jambor, M. - Doležal, P.
Fatigue behavior of laser and hybrid laser-TIG welds of high-strength low-alloy steels.
Lasers in Manufakturing. LIM 2019. Book of Abstracts. München: WLT, 2019.
[Lasers in Manufakturing. LIM 2019. 24.06.2019-27.06.2019, München]
Grant - others:GA AV ČR StrategieAV21/17
Program: StrategieAV
Institutional support: RVO:68081731 ; RVO:68081723
Keywords : laser welding * hybrid laser-TIG welding * high-strength low-alloy steel * fatigue
OECD category: Mechanical engineering

The hybrid laser-tungsten inert gas welding technology was applied to butt weld 3-mm-thick high-strength low-alloy (HSLA) steel sheets. Although the carbon equivalent number of HSLA steel is relatively low, rapid cooling rates accompanying laser welding promote the formation of quenching microstructures in the fusion and heat affected zone of such alloy. The intent of low-current arc addition was to preheat the material to reduce the cooling rate and thus to modify the weld structure. High-cycle fatigue tests were performed to evaluate the effect of heat input on fatigue behavior of S460MC and S700MC laser and hybrid welds. Laser welding led to the dramatic drop in fatigue properties of the samples, especially for S700MC. Preliminary fatigue tests at the 350-MPa level of stress amplitude revealed that the preheating has rather a negative effect on fatigue lifetime of S460MC while increasing arc current increased the fatigue lifetime of S700MC hybrid welds. During detailed high-cycle fatigue tests allowing to construct the S-N curves, a positive effect on fatigue lifetime of S700MC has not been proved. The presence of surface notches probably influences the fatigue behavior of welded samples much stronger than local microstructural changes.
Permanent Link: http://hdl.handle.net/11104/0302027