scholarly journals Experimental Investigation concerning the Influence of Electrochemical Machining on Process Chain induced Residual Stress States

Procedia CIRP ◽  
2020 ◽  
Vol 95 ◽  
pp. 726-730
Author(s):  
T. Bergs ◽  
B. Rommes ◽  
E. Kohls ◽  
H. Meyer ◽  
A. Klink ◽  
...  
Keyword(s):  
Residual Stress ◽  
Experimental Investigation ◽  
Electrochemical Machining ◽  
Process Chain ◽  
Stress States

Generation and Determination of Compressive Residual Stresses of Short Penetration Depths

2013 ◽  
Vol 768-769 ◽  
pp. 580-586 ◽  
Author(s):  
Regina Weingärtner ◽  
Jürgen Hoffmeister ◽  
Volker Schulze
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Fatigue Limit ◽  
Electrochemical Machining ◽  
Beneficial Effects ◽  
Integral Width ◽  
High Gradients ◽  
Stress States ◽  
Penetration Depths

Generating compressive residual stress states with high gradients and low penetration depths offers high capability regarding increase of fatigue limit of parts. In this work the determination of such specific residual stress distributions by using X-ray diffraction and a little material removal is introduced. Measurements are compared using two interference peaks of different penetration depths, at which confocal microscopy enables high accuracy in determination of the step sizes in electrochemical machining. Furthermore the realisation of these states by two different peening processes using micro blasting media is described. The suitability of the processes micro peening and ultrasonic wet peening as surface treatment methods to improve fatigue limit are shown. Micro peening is based on the shot peening principle with small shots and ultrasonic wet peening on the acceleration of small blasting particles by cavitation. The investigations were conducted at AISI 4140 in a quenched and tempered state. Besides the residual stresses and the integral width of interference peaks as well as the depth distributions, the surface topography was examined. The beneficial effects of these conditions on the fatigue limit in bending tests are described.

scholarly journals Statistical analysis of the reproducibility of residual stress measurements in cold extruded parts

2021 ◽  
Author(s):  
Fabian Jaeger ◽  
Alessandro Franceschi ◽  
Holger Hoche ◽  
Peter Groche ◽  
Matthias Oechsner
Keyword(s):  
Residual Stress ◽  
Statistical Analysis ◽  
Stress Measurement ◽  
Industrial Applications ◽  
Cold Extrusion ◽  
X Ray Diffraction ◽  
Forming Process ◽  
X Ray ◽  
Stress States ◽  
Key Aspects

AbstractCold extruded components are characterized by residual stresses, which originate from the experienced manufacturing process. For industrial applications, reproducibility and homogeneity of the final components are key aspects for an optimized quality control. Although striving to obtain identical deformation and surface conditions, fluctuation in the manufacturing parameters and contact shear conditions during the forming process may lead to variations of the spatial residual stress distribution in the final product. This could lead to a dependency of the residual stress measurement results on the relative axial and circumferential position on the sample. An attempt to examine this problem is made by the employment of design of experiments (DoE) methods. A statistical analysis of the residual stress results generated through X-Ray diffraction is performed. Additionally, the ability of cold extrusion processes to generate uniform stress states is analyzed on specimens of austenitic stainless steel 1.4404 and possible correlations with the pre-deformed condition are statistically examined. Moreover, the influence of the coating, consisting of oxalate and a MoS2 based lubricant, on the X-Ray diffraction measurements of the surface is investigated.

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.

Measurements of Residual Stress in the Layers of Thin Film Micro-Gas Sensors

2000 ◽  
Vol 657 ◽  
Author(s):  
Youngman Kim ◽  
Sung-Ho Choo
Keyword(s):  
Thin Film ◽  
Mechanical Properties ◽  
Residual Stress ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Micro Gas Sensor ◽  
Thin Film Layer ◽  
Film Layer ◽  
The Difference ◽  
Stress States

ABSTRACTThe mechanical properties of thin film materials are known to be different from those of bulk materials, which are generally overlooked in practice. The difference in mechanical properties can be misleading in the estimation of residual stress states in micro-gas sensors with multi-layer structures during manufacturing and in service.In this study the residual stress of each film layer in a micro-gas sensor was measured according to the five difference sets of film stacking structure used for the sensor. The Pt thin film layer was found to have the highest tensile residual stress, which may affect the reliability of the micro-gas sensor. For the Pt layer the changes in residual stress were measured as a function of processing variables and thermal cycling.

Sensitivity of Macro- and Micro-Residual Stress States of Steel Surfaces to Thermal Influences Caused by Grinding Burn and Laser Treatments

2013 ◽  
Vol 768-769 ◽  
pp. 412-419
Author(s):  
Bernd Eigenmann ◽  
Antje Zösch ◽  
Martin Seidel
Keyword(s):  
Residual Stress ◽  
Threshold Values ◽  
Materials Properties ◽  
X Ray ◽  
Grinding Burn ◽  
Laser Treatments ◽  
Annealing Effects ◽  
Calibration Samples ◽  
Steel Surfaces ◽  
Stress States

Thermal influences, introduced intentionally or unintentionally do have significant effects on surfaces of steel components. Materials properties are reduced by annealing effects or even re-hardening zones can occur. Grinding, one of the most important technological processes for preci-sion manufacturing of hardened steel components, is an important source of thermal influences to steel surfaces. In pronounced cases, these influences are referred to as grinding burn. They are known as possible reasons for gray stains as well as development of cracks and pittings on heavy-duty gears and on roller bearings. The basic effect of thermal influences on the material is a change of the macro- and micro-residual stress states. Therefore, the knowledge of these residual stress states is of fundamental importance. The paper treats the mechanisms of grinding which can lead to thermal influences. Some characteristic appearances of grinding burn are shown and characterized by X-ray macro- and micro residual stress determinations. It is shown that defined laser treatments can be used to create reproducible thermal influences similar to grinding burn. Their effects are also characterized by X-ray residual stress measurements. The sensitivities of X-ray and metallographical investigations are compared. Defined laser traces are proposed as calibration samples for magnetic and eddy current measurements which allow to determine threshold values for the actual apparatus and measuring problem.

Residual Stress Engineering in Fatigue Resistant Welds

2013 ◽  
Vol 768-769 ◽  
pp. 613-619
Author(s):  
Majid Farajian ◽  
Zuheir Barsoum ◽  
Arne Kromm
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Body Of Knowledge ◽  
Fatigue Design ◽  
Welding Technology ◽  
Stress Engineering ◽  
Solid Foundation ◽  
Stress States ◽  
The Many ◽  
Quantitative Consideration

The developments in the field of residual stress determination during the last decades have contributed to a better understanding of the origins and sources of residual stresses in different engineering disciplines. The many investigations concerning the behavior of residual stresses under mechanical loading have also provided a solid foundation to clarify the important aspects of residual stresses and fatigue. The question that arises now is if this available body of knowledge is being used effectively in the field of welding technology to design and construct structures with better fatigue performances. In this paper the necessity of the development of the concept residual stress engineering for welds in which wanted residual stress states are tailored for specific cases by appropriate means will be discussed. The possibilities of the quantitative consideration of the benefits in the fatigue design codes will be presented in a practical example.

Thermomechanical Simulation of Single Splat Solidification and Cooling in Plasma Spray Forming

2010 ◽  
Vol 102-104 ◽  
pp. 719-723
Author(s):  
Liang Rong Zhu ◽  
Hao Ping Zeng ◽  
Wen Ji Xu ◽  
Hong You Li
Keyword(s):  
Residual Stress ◽  
Plasma Spray ◽  
Steel Substrate ◽  
Element Model ◽  
Spray Forming ◽  
Plasma Spray Forming ◽  
Initial Stage ◽  
Minimum Residual ◽  
Thermomechanical Simulation ◽  
Stress States

Mechanical strength and service life of the coatings manufactured by plasma spray forming are significantly reduced by residual stresses. A 2D finite element model constructed for temperature and residual stress simulation of a single stainless steel splat solidifying and cooling on the carbon steel substrate is presented in this paper. Simulated results show that the temperature of the splat rim is higher than that of the central part during the initial stage of solidification, and the temperature difference between the two parts reverse thereafter. The minimum residual stress locates at the rim of the top surface of the splat, and the maximum residual stress, which decreases when the substrate is preheated to a higher temperature, situates at the rim of the interface. Stresses appear as tensile stresses within the splat and compressive stresses within the substrate. The research can provide quantitative understanding of the temperature and residual stress states at the splat level.

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