Influence of pass reduction in cold rolling on damage evolution in deep drawing of rotationally symmetric cups

IOP Conference Series Materials Science and Engineering, vol. 1157, pp. 012050

Abstract

Abstract Improvement of component performance by controlling the damage state after metal forming enables a reduction in sheet thickness and, consequently, in component weight and material cost. To establish methods for controlling damage in finished parts, the entire process chain from steelmaking and casting through hot and cold rolling to deep drawing must be considered. Previous research has shown that in hot rolling of an S355 steel, the influence of pass reduction on damage in the hot strip disappears when the accumulated pass reduction becomes large. However, the influence of cold rolling parameters on damage and specifically on its evolution in subsequent forming processes has not yet been systematically investigated. In the present work, specimens of the the mentioned S355 steel are cold rolled with two different pass reductions and heat treated to obtain a DP800 dual phase steel. These specimens are deep drawn into rotationally symmetric cups with variation of the drawing die radius. Sheet specimens and deep drawn cups are investigated using scanning electron microscopy to determine the respective void area fractions. While no influence of height reduction on the void area fraction after cold rolling is found, the void area fraction after deep drawing differs with variation of the pass reduction. This effect is connected to the formation of a larger number of small voids in the material rolled with a larger pass reduction.

Authors 5

1. Matthias Nick corresponding Aachen Laboratory for Machine Tools and Production Engineering (WZL)

   RWTH Aachen University

   Affiliation as printed

   Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University, Campus-Boulevard 30, 52074 Aachen, Germany

2. Conrad Liebsch Aachen Institute of Metal Forming

   RWTH Aachen University

   Affiliation as printed

   Institute of Metal Forming (IBF) of RWTH Aachen University, Intzestr. 10, 52072 Aachen, Germany

3. Ingo Felix Weiser Aachen Laboratory for Machine Tools and Production Engineering (WZL)

   RWTH Aachen University

   Affiliation as printed

   Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University, Campus-Boulevard 30, 52074 Aachen, Germany

4. G. Hirt Aachen Institute of Metal Forming

   RWTH Aachen University

   Affiliation as printed

   Institute of Metal Forming (IBF) of RWTH Aachen University, Intzestr. 10, 52072 Aachen, Germany

5. Thomas Bergs Aachen Laboratory for Machine Tools and Production Engineering (WZL) Fraunhofer Institute for Production Technology IPT

   RWTH Aachen University · Fraunhofer Institute for Production Technology IPT

   Affiliation as printed

   Fraunhofer Institute for Production Technology IPT, Steinbachstr. 17, 52074 Aachen, Germany

   Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University, Campus-Boulevard 30, 52074 Aachen, Germany