Residual Stress in Tools and Components in Case of Thermo-Mechanical Metal Forming Processes

2011 ◽  
Vol 681 ◽  
pp. 340-345 ◽  
Author(s):  
Alexander Grüning ◽  
Markus Lebsanft ◽  
Berthold Scholtes
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Process Parameters ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Manufacturing Operations ◽  
Challenging Tasks ◽  
Steel Aisi ◽  
Stress States ◽  
Adapted Process

Residual stresses play a key role in thermo-mechanically coupled forming processes for industrial mass production. They are an unavoidable consequence of the alternating inhomogeneous fields of temperature and mechanical stress developing in tools and components dependent on the process parameters applied. Because of their influence on the behavior of the components produced, a great interest exists to get reliable information about origin and distribution of the relevant residual stress fields and to understand the basic principles of their formation. In this paper the development of residual stress in tools (steel AISI H11) used for the thermo-mechanical forming operation of cylindrical flange shafts (steel SAE 6150) is outlined. The loading situation of the tool is simulated by thermal fatigue tests, providing information about cyclic stress and plastic deformation during the manufacturing process. Furthermore the residual stress states of the flange shafts manufactured are presented and discussed. Chip forming manufacturing operations are challenging tasks and tensile residual stresses can be avoided using adapted process parameters.

scholarly journals Effect of Process Parameters and High-Temperature Preheating on Residual Stress and Relative Density of Ti6Al4V Processed by Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 930 ◽  
Author(s):  
Martin Malý ◽  
Christian Höller ◽  
Mateusz Skalon ◽  
Benjamin Meier ◽  
Daniel Koutný ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Residual Stresses ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Stress Reduction ◽  
Laser Melting ◽  
Preheating Temperature ◽  
Laser Velocity

The aim of this study is to observe the effect of process parameters on residual stresses and relative density of Ti6Al4V samples produced by Selective Laser Melting. The investigated parameters were hatch laser power, hatch laser velocity, border laser velocity, high-temperature preheating and time delay. Residual stresses were evaluated by the bridge curvature method and relative density by the optical method. The effect of the observed process parameters was estimated by the design of experiment and surface response methods. It was found that for an effective residual stress reduction, the high preheating temperature was the most significant parameter. High preheating temperature also increased the relative density but caused changes in the chemical composition of Ti6Al4V unmelted powder. Chemical analysis proved that after one build job with high preheating temperature, oxygen and hydrogen content exceeded the ASTM B348 limits for Grade 5 titanium.

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.

Influence of Initial and Welding Residual Stresses on Low Cycle Fatigue and Ratcheting Response Simulations of Elbows

2017 ◽  
Author(s):  
Nazrul Islam ◽  
Tasnim Hassan
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Low Cycle Fatigue ◽  
Simulation Models ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Girth Welding ◽  
Stress States ◽  
Welding Processes

Earlier studies [1] showed that the ANSYS software package customized with an advanced rate-independent constitutive model was unable to simulate some of the low-cycle fatigue responses of elbow components. Hence, simulations are performed to investigate the influence of manufacturing and welding residual stresses on elbow low-cycle fatigue responses. The sequentially coupled thermo-mechanical finite element analysis is performed to determine the initial residual stress states in elbows due to the elbow manufacturing processes and welding of elbows to straight pipes. Real-time girth-welding processes are taken into account to simulate the welding induced residual stress field. Incorporating these initial residual stresses in the computations, low-cycle fatigue and strain ratcheting responses are simulated by ANSYS. The simulation responses demonstrate that the influence of manufacturing and welding residual stresses in elbows on its low-cycle fatigue responses is negligible. Hence, the question remains what is missing in the simulation models that some of the elbow low-cycle fatigue responses cannot be simulated.

X-Ray Diffraction Measurements of Residual Stress Induced by Surface Compressing Methods

2012 ◽  
Vol 729 ◽  
pp. 199-204 ◽  
Author(s):  
Dávid Cseh ◽  
Valéria Mertinger
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Surface Region ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardened Alloy ◽  
Compressive Stresses ◽  
Machine Parts ◽  
Stress States ◽  
Operational Behaviour

Residual stresses have a fundamental effect on the operational behaviour and lifetime of industrial products. The fatigue resistance of machine parts can be increased by introducing residual compressive stresses into the surface region. For certain machine parts especially in the vehicle industry the residual stress is strongly demanded by the quality control. For this reason, measuring the stress accurately is becoming increasingly important. The Almen test, which only gives a qualitative result, is widely used in the industry. Shot peening and rolling are methods which are suitable for creating elastic residual stresses. This paper examines the technologies used by Rába Futómű Nyrt. to increase the lifetime by means of residual stress. We performed analysis of the residual stress of samples shot peened the same way but under different heat treatment states. We compared the residual stress values of burnished and hardened shaft joints, and the residual stress states of gear made of hardened alloy, comparing the carbonized ones to ones which were shot peened under small intensity.

Residual Stresses in Steel-Titanium Composite Manufactured by Explosive Welding

2012 ◽  
Vol 726 ◽  
pp. 125-132 ◽  
Author(s):  
Aleksander Karolczuk ◽  
Krzysztof Kluger ◽  
Mateusz Kowalski ◽  
Fabian Żok ◽  
Grzegorz Robak
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Residual Stresses ◽  
Hole Drilling ◽  
Element Analysis ◽  
Welded Steel ◽  
Hole Drilling Method ◽  
Drilling Method ◽  
Before And After ◽  
Stress States

The main aim of the paper is determination of residual stresses in explosively welded steel-titanium bimetal. The analysis considers two bimetallic specimens: before and after the heat treatment. In residual stress determination the hole drilling method along with finite element analysis were applied. The results show different residual stress states depending on the heat treatment. The obtained results are confirmed by thermal stress calculation.

Prediction by Genetic Algorithm and Measurement by Center Hole Drilling of Residual Stresses of MAG Weldment

2009 ◽  
Vol 83-86 ◽  
pp. 738-745
Author(s):  
G.H. Farrahi ◽  
G.H. Majzoobi ◽  
A. Fadaee
Keyword(s):  
Genetic Algorithm ◽  
Residual Stress ◽  
Residual Stresses ◽  
Crack Growth ◽  
Growth Rates ◽  
Welding Process ◽  
Fatigue Tests ◽  
Hole Drilling ◽  
Grinding Operations ◽  
Crack Growth Rates

In the present work, specimens were cut out from St-37 plates with 19 mm thickness. The thickness of plates was reduced to 12.5 mm by milling and grinding operations. Then a standard V-shaped fillet was made on one edge of the plates. Two plates were butt-welded by standard metal arc gas (MAG) welding process. Residual stresses induced by welding were measured on 20 specimens by centre hole drilling. Load controlled axial fatigue tests were carried out to determine the fatigue life of specimens. Crack growth rates were obtained from experiment. Fractography of specimens was performed. Genetic Algorithm (GA) was employed for prediction of residual stress value in weldments using the crack growth rates obtained from experiments. The results show that, by using the measured crack growth rates and GA model, residual stresses can be estimated with a good approximation.

scholarly journals Investigation on micro-residual stress distribution near hole using nanoindentation: Effect of drilling speed

2019 ◽  
Vol 52 (9-10) ◽  
pp. 1252-1263 ◽  
Author(s):  
Abhishek Kumar Tiwari ◽  
Amit Kumar ◽  
Navin Kumar ◽  
Chander Prakash
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Process Parameters ◽  
Residual Stress Distribution ◽  
Stress Generation ◽  
Work Piece ◽  
Drilling Speed ◽  
Drilling Operation

Residual stresses are induced in the material during manufacturing operations, which considerably affect the fatigue performance and the lifespan of a mechanical work piece. The nature, magnitude, and distribution of residual stresses decide their beneficial or detrimental effects. Past research efforts concluded that mechanical process parameters influence residual stress nature, distribution, and the magnitude. Nevertheless, how residual stress generation depends on the process parameters, is not well investigated especially in the case of a drilling operation. In fact, the residual stress field is required to be regulated near drilled holes to improve the fatigue strength of structural joints, especially in the aircraft industry. Accordingly, this work attempts to estimate the drilling-induced micro-residual stress distribution near the drilled hole. In addition, the effect of drilling speed on residual stress distribution has also been studied. A nanoindentation technique is used to follow-up precise distribution of micro-residual stresses near the holes drilled at three different drilling speeds of 700, 900, and 1100 r/min. The outcomes indicate the presence of compressive residual stresses near the hole. In addition, an increase in residual stress level is noticed with an increase in the drilling speed up to 900 r/min. A uniform distribution of residual stresses is observed near the hole when drilled at a higher drilling speed of 1100 r/min. These findings may be useful in planning an improved drilling operation to produce beneficial residual stress distribution. This may ultimately improve the fatigue strength and the service life of mechanical components or structures with drilled holes.

Effect of Residual Stress, Temperature and Adhesion on Wheel Surface Fatigue Cracking

2008 ◽  
Author(s):  
Daniel H. Stone ◽  
Scott M. Cummings
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Contact Stress ◽  
Fatigue Cracking ◽  
Fatigue Tests ◽  
Operating Conditions ◽  
Defect Prevention ◽  
Class C ◽  
Research Consortium

The Wheel Defect Prevention Research Consortium (WDPRC) conducted an analysis pertaining to the fatigue cracking of wheel treads by incorporating the effects of residual stresses, temperature, and wheel/rail contact stress. Laboratory fatigue tests were conducted on specimens of wheel tread material under a variety of conditions allowing the analysis to properly account for the residual stresses accumulated in normal operating conditions. Existing literature was used in the analysis in consideration of the effects of contact stress and residual stress relief. This project was performed to define a temperature range in which the life of an AAR Class C wheel is not shortened by premature fatigue and shelling. Wayside wheel thermal detectors are becoming more prevalent on North American railroads as a means of identifying trains, cars, and wheels with braking issues. Yet, from a wheel fatigue perspective, the acceptable maximum operating temperature remains loosely defined for AAR Class C wheels. It was found that residual compressive circumferential stresses play a key role in protecting a wheel tread from fatigue damage. Therefore, temperatures sufficient to relieve residual stresses are a potential problem from a wheel fatigue standpoint. Only the most rigorous braking scenarios can produce expected train average wheel temperatures approaching the level of concern for reduced fatigue life. However, the variation in wheel temperatures within individual cars and between cars can result in temperatures high enough to cause a reduction in wheel fatigue life.

Assessment and Minimization of the Residual Stress in Dissimilar Laser Welding

2007 ◽  
Vol 7-8 ◽  
pp. 139-144 ◽  
Author(s):  
Khaled Y. Benyounis ◽  
Abdul Ghani Olabi ◽  
J.H. Abboud
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Process Parameters ◽  
Random Order ◽  
Travel Speed ◽  
Maximum Principal Stress ◽  
Hole Drilling ◽  
Hole Drilling Method ◽  
Maximum Residual Stress ◽  
Input Variables

Establishing the relationship between process parameters and the magnitude of residual stresses is essential to determine the life of welded components. It is the aim of this paper to develop mathematical models to assess residual stresses in the heat-affected zone of dissimilar butt jointed welds of AISI304 and AISI1016. These models determine the effect of process parameters on maximum residual stress. Laser power, travel speed and focal position are the process input parameters. Plates of 3 mm thick of both materials were laser welded using a 1.5 kW CW CO2 Rofin laser as a welding source. Hole-drilling method was used to compute the maximum principal stress in and around the HAZ of both sides of the joint. The experiment was designed based on a three factors five levels full central composite design (CCD). Twenty different welding runs were performed in a random order, 6 of them were centre point replicates and the maximum residual stresses were calculated for each sample. Design-expert software was used to fit the experiential data to a second order polynomial. Sequential F test and other adequacy measures were used to check the model’s performance. The results show that the developed models explain the residual stress successfully. Using the developed models, the main and interaction effect of the process input variables on the residual stresses at either side of the weld were investigated. It is found that all the investigated laser parameters are affecting the performance of the residual stress significantly.

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