TY - CONF A1 - Frei, J. A1 - Rethmeier, Michael T1 - Overview and new developments in research on resistance spot welding of advanced high strength steels N2 - The safe joining of new, freshly developed steel types keeps challenging the industry–and is assumed to go on in doing so. In the body-in-white production, these materials are mainly joined using resistance spot welding. During the past ten years, various investigations on resistance spot welding of advanced high strength steels have been carried out at Fraunhofer IPK and the Federal Institute for Materials Research and Testing (BAM). This paper aims to give an overview about both the top former and recent studies and results. The investigated topics are the influences of manufacturing conditions as initial gaps and restraints on spot welds, their impact on the fatigue strength of a joint and the cracking-wise safe weldability of AHSS. Caused by non-ideal manufacturing conditions, cracks in spot welds (e.g. caused by liquid metal embrittlement) are still regarded as a potential risk in industrial practice. Therefore, a method to evaluate the safe weldability regarding the cracking susceptibility was developed for AHSS. The method is easy to perform, even without expensive laboratory equipment. It allows the end user to establish a material ranking regarding the cracking susceptibility of the handled steels. Recently, coupled thermo-mechanical finite element modelling has been used to describe critical stress-strain conditions responsible for the occurrence of liquid metal embrittlement, and to improve the understanding of the process. T2 - The 5th International Conference on Steels in Cars and Trucks CY - Amsterdam-Schiphol, The Netherlands DA - 19.06.2017 KW - Advanced high strength steels KW - Resistance spot welding KW - Cracking susceptibility KW - Liquid metal embrittlement KW - Material ranking KW - Fatigue strength KW - Gaps KW - Finite element method PY - 2017 SP - 1 EP - 8 AN - OPUS4-43189 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael T1 - European perspective on 21st century BIW joining challenges N2 - •Main Welding Technologies in the Automotive: RSW and laserbeam welding •Light Weight Design leads to increasing use of AHSS and UHSS which results in higher demands for the joining technology •Joining Multi-Material Structures offers opportunities for “new” Thermal-Mechanical Joining Processes and Hybrid Processes •In the coming years a trend towards sustainable manufacturing can be seen. Comparison between laserbeam and RSW will be a tight match! T2 - AWS Sheet Metal Welding Conference XVll CY - Livonia, MI, USA DA - 19.10.2016 KW - Resistance spot welding KW - Laser beam welding KW - Lightweight concepts KW - AHSS KW - Weld cracks PY - 2016 AN - OPUS4-38339 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Frei, Julian A1 - Rethmeier, Michael T1 - Influence of manufacturing conditions on the cracking susceptibility of AHSS during resistance spot welding N2 - The complex microstructure and the advanced mechanical properties of AHSS steel types lead to an increased susceptibility to weld cracking, especially during resistance spot welding under ‘rough’ manufacturing conditions. Various activities have been conducted in recent years at the Federal Institute for Materials Research and Testing (BAM) and the Fraunhofer IPK on this matter. Understandings about the safe spot weldability and the process of crack-forming itself were gained, and solutions for handling this issue given. The performed work includes investigations on the influence of initial gaps as well as restraint intensity. An experimental method for the determination of the general cracking susceptibility, i.e. a material ranking of AHSS in respective to current restraints was developed. Coupled mechanical and thermal simulations of the welding process show the present internal stress-strain-conditions and values responsible for the formation of cracks, deepening the understanding of the process. By using this easy to perform and material-independent method for the determination of the cracking susceptibility in resistance spot welded joints, small and medium sized companies can profit by rapidly evaluating the joinability of their handled material combinations as well as OEMs. T2 - Sheet Metal Welding Conference XVII CY - Livonia, Michigan, USA DA - 18.10.2016 KW - Welding under external loading KW - Cracking susceptibility of AHSS KW - Resistance spot welding KW - Initial gap PY - 2016 SP - Session 1-2, 1 EP - Session 1-2, 15 AN - OPUS4-38137 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Rethmeier, Michael A1 - Suwala, Hubert ED - Bleck, W. ED - Raabe, D. T1 - Influence of crack-imperfections on mechnical properties of resistance spot welded ferritic-austenitic steel sheet combinations N2 - In order to respond to the challenge of the intensifying energy crisis and to meet customer requirements for automobiles, such as weight reduction for energy saving and enhancement of passenger safety, new materials have to be applied in the automotive industry. Modern Steel types with advanced mechanical properties and a complex microstructure are used. These Steel types have an increased susceptibility to weid cracking, especially during resistance spot welding. Since the influence of weid cracks on the mechanical properties of spot welded joints is not sufficiently known, specifications offen require crack-free welds. Therefore it is necessary to examine the actual effect of crack-imperfections in resistance spot welded sheets on its fatigue and impact behavior. The influence of cracks in the welding area of resistance spot welded dissimilar joints between a ferritic- and an austenitic FeMn-steel sheet has been studied. Investigations of crack-free welds and crack-afflicted welds with focus on fatigue strength were made according to the Wöhler fatigue test. The Investigation of the fatigue behavior of resistant spot welded sheets is done by analyzing the quotient of force and the oscillation amplitude. By comparing the stiffness curves and load cycles between a crack-free weid and weid with cracks. Beside the fact that it was nearly impossible to specifically produce crack-afflicted specimen by welding operations, there were later on found no significant influences of those cracks on fatigue life time behavior. T2 - 2nd HMnS -2nd International conference on high manganese steels 2014 CY - Aachen, Germany DA - 31.08.2014 KW - Resistance spot welding KW - Frequency KW - Stiffness KW - Advanced high strength steels KW - FeMn-steels KW - Cracking KW - Defects PY - 2014 SP - A-107, 1-5 AN - OPUS4-32549 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Weber, Gert A1 - Gaul, Holger A1 - Rethmeier, Michael ED - Kolleck, R. T1 - Joining of ultra high strength steels for lightweight body shell design in automobile manufacturing T2 - 50th IDDRG anniversary conference - Tools and technologies for the processing of ultra high strength steels CY - Graz, Austria DA - 2010-05-31 KW - Advanced high strength steels KW - Resistance spot welding KW - Weldbonding KW - Lightweight body shell design KW - Process reliability PY - 2010 SN - 978-3-85125-108-1 DO - https://doi.org/10.3217/978-3-85125-108-1-094 SP - 885 EP - 898 PB - Verlag der Technischen Universität Graz CY - Graz, Austria AN - OPUS4-22472 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weber, Gert A1 - Göklü, S. T1 - Resistance Spot Welding of Advanced High Strength Steels - Influence of Welding Parameters and Electrode Cap Type T2 - International Conference of IIW CY - Prague, Czech Republic DA - 2005-07-14 KW - Resistance spot welding KW - Advanced high-strength steels (AHSS) PY - 2005 SP - 22 pages PB - IIW CY - Prag AN - OPUS4-10302 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weber, Gert A1 - Göklü, S. T1 - Resistance Spot Welding of High-Strength Multi-Phase Steels T2 - 3rd International Seminar on Advances in Resistance Welding CY - Berlin, Germany DA - 2004-11-17 KW - Resistance spot welding KW - Multi-phase steels KW - Advanced high-strength steels KW - AHSS PY - 2004 SP - 18 EP - 35 PB - SWANTEC Software and Engineering CY - Hoersholm, Denmark AN - OPUS4-4722 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -