Experimental investigation of the mechanical response of laser-welded dissimilar blanks from advanced- and ultra-high-strength steels

• Published in: Materials & design Vol. 90; pp. 1115 - 1123
• Main Authors: Gong, Hongying, Wang, Sifan, Knysh, Paul, Korkolis, Yannis P.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 2016
• Subjects: Advanced high-strength steel; Anisotropy; Digital image correlation; Failure; High strength steels; Infrared thermography; Laser beam welding; Laser-welding; Mechanical analysis; Strain; Structural steels; Tailor-welded blanks; Tailored blanks; Temperature gradient; Tensile testing; Ultra-high-strength steel; Infrared thermography; Advanced high-strength steel; Laser-welding; Tensile testing; Tailor-welded blanks; Ultra-high-strength steel; Digital image correlation
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2015.11.057

We report experimental results on the mechanical response of dissimilar tailor-welded blanks (TWB) from an advanced- and an ultra-high-strength steel for automotive applications. These are the dual-phase steels DP 780 and DP 1180, respectively. First, we present the tensile and anisotropic properties of the two base-materials. During testing, the full-fields of strain and temperature are acquired, using the Digital Image Correlation (DIC) and Infrared Thermography (IR) techniques. The latter is critical, since both materials are prone to deformation-induced heating, which establishes a temperature gradient along the test-section, and which in turn limits the ductility observed. We then describe the laser-welding apparatus, and microstructural observations and measurements around the weld-seam. Subsequently, we test tensile coupons from the TWBs, with the weld-seam oriented transversely, 45° and parallel to the longitudinal direction of the loading. We detail the failure modes and the macroscopic load–displacement responses. Furthermore, with the aid of the DIC and IR images, we probe the local strain and temperature fields and their evolution, and correlate these to the overall response and failure of the TWB tensile coupons. [Display omitted] •Tension of DP780 and DP1180 Tailor Welded Blanks is examined with Digital Image Correlation and Infrared Thermometry.•The presence of the laser weld-seam affects the mechanical response.•The deformation-induced heating limits the ductility observed.•In every case, the TWB specimens failed earlier than base-material ones.