Adjusting the Residual Stress State in Wire Drawing Products via In-Process Modification of Tool Geometries

Abstract

After conventional forming processes, the residual stress distribution in wires is frequently unfavorable for subsequent processes, such as bending operations. High tensile residual stresses typically occur near the wire surface and normally limit further processability of the material. Additional heat treatment operations or shot peening are often used to influence the residual stress distribution in the material after conventional manufacturing, which is time- and energy-consuming. This paper presents an approach for influencing the residual stress distribution by modifying the forming process, especially regarding die geometry. The aim is to reduce the resulting tensile stress levels near the surface. Specific forming elements are integrated into the dies to achieve this residual stress reduction. These modifications in the forming zone have a significant influence on process properties, such as plastic strain and deformation direction, but typically do not influence product geometry. This paper describes the theoretical approach and model setup, the FE simulation, and the results of the experimental tests. The characterization of the residual stress states in the specimen was carried out through X-ray diffraction using the sin2Ψ method.

Residual Stress Engineering for Wire Drawing of Austenitic Stainless Steel X5CrNi18-10 by Variation in Die Geometries—Effect of Drawing Speed and Process Temperature

“…The tool setup of the experimental device for the drawing process includes the interchangeable specific die with additional convex or concave geometric elements presented in the introduction, and for further details, it is referred to [ 5 , 16 , 17 , 18 ]. A solid lubricant (LOCTITE LB 8191) was applied to each of the samples, and additionally, lubrication with high-alloyed drawing oil was used during forming.…”

“…A solid lubricant (LOCTITE LB 8191) was applied to each of the samples, and additionally, lubrication with high-alloyed drawing oil was used during forming. For the current investigations, the drawing tools [ 5 , 18 ] were upgraded to include temperature measurements and were further adapted for drawing at higher speeds. In Figure 3 and Figure 4 , the drawing tool setups are presented.…”

“…In Figure 3 and Figure 4 , the drawing tool setups are presented. The experimental investigations presented in this paper are divided into two different drawing speeds to investigate how the wire drawing speed influences the formation of residual stresses on the wire surface while using the same drawing die geometries as in [ 5 , 17 , 18 ]. Overall, 20 mm/s and 2000 mm/s were selected.…”

“… ( a ) Conventional wire drawing die (schematic view) [ 4 ]. ( b ) Typical residual stress distribution after wire drawing [ 5 ]. …”

“…Using convex and concave geometry, it could be shown by means of FE simulations and experimental investigations that the tensile residual stresses close to the surface could be influenced and specifically reduced compared to the application of a conventional die geometry [ 5 , 18 ]. In these processes, however, the processing speed of 20 mm/s was atypical for wire drawing, and the effect of near-surface process-related wire temperatures was not considered.…”