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

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2157
Author(s):  
Markus Baumann ◽  
René Selbmann ◽  
Matthias Milbrandt ◽  
Verena Kräusel ◽  
Markus Bergmann
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Stress Reduction ◽  
Experimental Tests ◽  
Wire Drawing ◽  
Residual Stress Distribution ◽  
Forming Process ◽  
Die Geometry ◽  
Residual Stress State ◽  
Process Modification

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.

scholarly journals Concept for controlled adjustment of residual stress states in semi-finished products by gradation extrusion

2021 ◽  
Author(s):  
René Selbmann ◽  
Markus Baumann ◽  
Mateus Dobecki ◽  
Markus Bergmann ◽  
Verena Kräusel ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Experimental Tests ◽  
Residual Stress Distribution ◽  
Forming Process ◽  
Compressive Stresses ◽  
Energy Consuming ◽  
Stress States ◽  
Set Up ◽  
Time And Energy

AbstractThe residual stress distribution in extruded components and wires after a conventional forming process is frequently unfavourable for subsequent processes, such as bending operations. High tensile residual stresses typically occur near the surface of the wire and thus limit further processability of the material. Additional heat treatment operations or shot peening are often inserted to influence the residual stress distribution in the material after conventional manufacturing. This is time and energy consuming. The research presented in this paper contains an approach to influence the residual stress distribution by modifying the forming process for wire-like applications. The aim of this process is to lower the resulting tensile stress levels near the surface or even to generate compressive stresses. To achieve these residual compressive stresses, special forming elements are integrated in the dies. These modifications in the forming zone have a significant influence on process properties, such as degree of deformation and deformation direction, but typically have no influence on the diameter of the product geometry. In the present paper, the theoretical approach is described, as well as the model set-up, the FE-simulation and the results of the experimental tests. The characterization of the residual stress states in the specimen was carried out by X-ray diffraction using the sin2Ψ method.

scholarly journals Influence of a modified drawing process on the resulting residual stress state of cold drawn wire

2018 ◽  
Vol 190 ◽  
pp. 04004
Author(s):  
Markus Baumann ◽  
Alexander Graf ◽  
René Selbmann ◽  
Katrin Brömmelhoff ◽  
Verena Kräusel ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Wire Drawing ◽  
Industrial Applications ◽  
Drawing Process ◽  
Die Geometry ◽  
Residual Stress State ◽  
Drawing Die ◽  
Process Modification ◽  
The Wire

Torsion bars are used in automotive engineering as well as in other industrial applications. Such elements are produced by bending cold drawn wires. In conventional drawing processes tensile residual stresses occur near the surface of the wire. Small bending radii, which are required in limited assembly spaces, result in component failure due to reduced formability. Additional operations such as heat treatment or shot peening are necessary to influence the residual stress of the wire and to improve the dynamic stability of the torsion bar. The aim of the research is to reduce tensile residual stresses near the surface of the wire in order to eliminate process steps and to enhance formability. Therefore, a forming technology is developed by using a modified drawing die geometry on the basis of gradation extrusion. Finite element simulation is used to investigate the influences of element geometry, number of elements and process modification on the resulting residual stresses after wire drawing of a steel alloy. The results are evaluated and compared with the conventional wire drawing process. Furthermore, the requirements for the design of an experimental test device will be outlined as well as the measurement of the residual stresses by using X-ray diffraction.

FEM and Contour Method Study of Quenching Residual Stress of 7050 Aluminum Alloy Cross-Shaped Component

2017 ◽  
Vol 887 ◽  
pp. 89-95 ◽  
Author(s):  
Yang Li ◽  
Yun Xin Wu ◽  
Hai Gong ◽  
Feng Xiao
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Stress Distribution ◽  
Stress Reduction ◽  
Residual Stress Distribution ◽  
Contour Method ◽  
Fe Model ◽  
Residual Stress Field ◽  
Heat Transfer Theory ◽  
7050 Aluminum Alloy

In order to study the quenching residual stress of typical aluminum alloy component used in aerospace, the finite element (FE) model of quenching process of 7050 aluminum alloy cross-shaped component was established based on heat transfer theory and elastic-plastic mechanics theory, the distribution regularities of quenching residual stress field of cross-shaped component was analyzed. The results indicate that the residual stress distribution of web of cross-shaped component is similar to the residual stress distribution of thick plate, the large tensile stress concentration is exist in web plate and the connection part of the stiffener with a certain influence area. The error data of the component contour deformation were processed and the component deformation contour was fitted, which makes the test result of the contour method and FE simulation result have good consistency. The results of the study provides guidance for quenching residual stress reduction of aviation aluminum alloy components and provides the basis for calculating of machining deformation of monolithic component.

Residual Stress Distribution and the Concept of Total Fatigue Stress in Laser and Mechanically Formed Commercially Pure Grade 2 Titanium Alloy Plates

2017 ◽  
Author(s):  
Kadephi V. Mjali ◽  
Annelize Els-Botes ◽  
Peter M. Mashinini
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Stress Distribution ◽  
Parent Material ◽  
Residual Stress Distribution ◽  
Laser Forming ◽  
Forming Process ◽  
Fatigue Stress ◽  
Commercially Pure ◽  
Pure Grade

This paper discusses the investigation of residual stresses developed as a result of mechanical and laser forming processes in commercially pure grade 2 Titanium alloy plates as well as the concept of total fatigue stress. The intention of the study was to bend the plates using the respective processes to a final radius of 120mm using both processes. The hole drilling method was used to measure residual strains in all the plates. High stress gradients were witnessed in the current research and possible cases analyzed and investigated. The effects of processing speeds and powers used also played a significant role in the residual stress distribution in all the formed plates. A change in laser power resulted in changes to residual stress distribution in the plates evaluated. This study also dwells into how the loads that are not normally incorporated in fatigue testing influence fatigue life of commercially pure grade 2 Titanium alloy plates. Also, the parent material was used to benchmark the performance of the two forming processes in terms of stresses developed. Residual stresses developed from the two forming processes and those obtained from the parent material were used. The residual stress values were then added to the mean stress and the alternating stress from the fatigue machine to develop the concept of total fatigue stress. This exercise indicated the effect of these stresses on the fatigue life of the parent material, laser and mechanically formed plate samples. A strong link between these stresses was obtained and formulae explaining the relationship formulated. A comparison between theory and practical application shown by test results is found to be satisfactory in explaining concerns that may arise. The laser forming process is more influential in the development of residual stress, compared to the mechanical forming process. With each parameter change in laser forming there is a change in residual stress arrangement. Under the influence of laser forming the stress is more tensile in nature making the laser formed plate specimens more susceptible to early fatigue failure. The laser and mechanical forming processes involve bending of the plate samples and most of these samples experienced a two-dimensional defect which is a dislocation. The dislocation is the defect responsible for the phenomenon of slip by which most metals deform plastically. Also the high temperatures experienced in laser forming were one of the major driving factors in bending.

Residual Stress Distribution and the Concept of Total Fatigue Stress in Laser and Mechanically Formed Commercially Pure Grade 2 Titanium Alloy Plates

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Kadephi V. Mjali ◽  
Annelize Els-Botes ◽  
Peter M. Mashinini
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Fatigue Life ◽  
Stress Distribution ◽  
Parent Material ◽  
Residual Stress Distribution ◽  
Laser Forming ◽  
Forming Process ◽  
Commercially Pure ◽  
Pure Grade

This paper discusses the investigation of residual stresses developed as a result of mechanical and laser forming processes in commercially pure grade 2 titanium alloy plates as well as the concept of total fatigue stress (TFS). The intention of the study was to bend the plates using the respective processes to a final radius of 120 mm using both processes. The hole drilling method was used to measure residual strains in all the plates. High stress gradients were witnessed in the current research and possible cases analyzed and investigated. The effects of processing speeds and powers used also played a significant role in the residual stress distribution in all the formed plates. A change in laser power resulted in changes to residual stress distribution in the plates evaluated. This study also dwells into how the loads that are not normally incorporated in fatigue testing influence fatigue life of commercially pure grade 2 titanium alloy plates. Also, the parent material was used to benchmark the performance of the two forming processes in terms of stresses developed. Residual stresses developed from the two forming processes and those obtained from the parent material were used. The residual stress values were then added to the mean stress and the alternating stress from the fatigue machine to develop the concept of TFS. This exercise indicated the effect of these stresses on the fatigue life of the parent material, laser and mechanically formed plate samples. A strong link between these stresses was obtained and formulae explaining the relationship were formulated. A comparison between theory and practical application shown by test results is found to be satisfactory in explaining concerns that may arise. The laser forming process is more influential in the development of residual stress, compared to the mechanical forming process. With each parameter change in laser forming, there is a change in residual stress arrangement. Under the influence of laser forming, the stress is more tensile in nature making the laser formed plate specimens more susceptible to early fatigue failure. The laser and mechanical forming processes involve bending of the plate samples and most of these samples experienced a two-dimensional defect, which is a dislocation. The dislocation is the defect responsible for the phenomenon of slip by which most metals deform plastically. Also, the high temperatures experienced in laser forming were one of the major driving factors in bending.

Influence of the Welded Joint on the Mechanical Behavior of Steel Piles during Static and Dynamic Deformation

2007 ◽  
Vol 345-346 ◽  
pp. 1469-1472
Author(s):  
Gab Chul Jang ◽  
Kyong Ho Chang ◽  
Chin Hyung Lee
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Mechanical Behavior ◽  
Welded Joint ◽  
Dynamic Deformation ◽  
Three Dimensional ◽  
Steel Structures ◽  
Residual Stress Distribution ◽  
Dynamic Mechanical Behavior ◽  
Steel Piles

During manufacturing the welded joint of steel structures, residual stress is produced and weld metal is used inevitably. And residual stress and weld metal influence on the static and dynamic mechanical behavior of steel structures. Therefore, to predict the mechanical behavior of steel pile with a welded joint during static and dynamic deformation, the research on the influence of the welded joints on the static and dynamic behavior of steel pile is clarified. In this paper, the residual stress distribution in a welded joint of steel piles was investigated by using three-dimensional welding analysis. The static and dynamic mechanical behavior of steel piles with a welded joint is investigated by three-dimensional elastic-plastic finite element analysis using a proposed dynamic hysteresis model. Numerical analyses of the steel pile with a welded joint were compared to that without a welded joint with respect to load carrying capacity and residual stress distribution. The influence of the welded joint on the mechanical behavior of steel piles during static and dynamic deformation was clarified by comparing analytical results

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