WE Student Seminar: Bryan Lara & William Seifert

Bryan Lara

Graduate Research Associate, Welding Engineering, advised by Dr. Antonio Ramirez

Exploration of additive manufacturing technology to improve materials joining for the transportation industry 

Abstract

The introduction of advanced high strength steels (AHSS) to body-in-white designs has hindered Resistance Spot Welding joining. Adequate performance should be achieved with minimal modification to the existing capital assets and production routes in OEM assembly facilities. With the use of interlayer technology, the joining of AHSS/AHSS and dissimilar Al/AHSS materials via Resistance Spot Welding (RSW) creates an opportunity to weld incompatible materials. Welding these materials brings forth two distinct challenges. First, AHSS/AHSS welds are problematic with respect to weld toughness and strength as a result of their chemistry. Second, dissimilar welds between AHSS/Al joints are problematic as a result of metallurgical incompatibility (electrical/thermal conductivity, melting point, crystal structure) and the formation of intermetallic compounds.

Bio

Received an A.S Degree in Welding Technology from a Community College. Obtained a B.S Degree in Welding Engineering from The Ohio State University. 

William Siefert

Graduate Research Associate, Welding Engineering, advised by Dr. Bioan Alexandrov

Cross Weld Tensile Testing using Digital Image Correlation to determine local yielding properties of Dissimilar Metal Welds

Abstract

Qualification for weld strength is typically accomplished using cross weld tensile testing. This style of testing only gives the global behavior of the welded joint and limited materials properties, such as elongation at failure and tensile strength of the material where final failure occurs. Qualification for welded structures usually requires the weldment fail in the base metal. Final failure in cross weld tensile tests in the base metal does not provide information about the actual weld metal and heat affected zone properties. There may be weaker points in the microstructure that cannot be identified in a global cross weld tensile test due to being constrained by surrounding microstructures. Additionally, the traditional cross weld tensile test fails to quantify how strain accumulates and transfers in the microstructure at various loads. Using Digital Image Correlation (DIC) in combination with tensile testing, local strain of the various microstructures present across the weld was obtained for ferritic to austenitic dissimilar metal welds (DMW), as well as for a typical “matching” steel filler metal weld with a higher tensile strength than the base metal. This test also showed where and how strain accumulated and transferred during tensile loading of various welded microstructures. Local yield stresses of each region were also obtained. Obtaining such local properties provides insight into design and service limits of welded components in service.

Bio

Will Siefert First Year Master Student - anticipated graduation of spring 2021. Likes metals, cars and their applications.