About Residual Stress State of Castings: The Case of HPDC Parts and Possible Advantages through Semi-Solid Processes

2022 ◽  
Vol 327 ◽  
pp. 272-278
Author(s):  
Elisa Fracchia ◽  
Federico Simone Gobber ◽  
Claudio Mus ◽  
Yuji Kobayashi ◽  
Mario Rosso
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Casting Process ◽  
Ray Method ◽  
Premature Failure ◽  
Thin Walls ◽  
Residual Stress State ◽  
Semi Solid ◽  
Pressure Die Casting

Nowadays, one of the most crucial focus in the aluminium-foundry sector is the production of high-quality castings. Mainly, High-Pressure Die Casting (HPDC) is broadly adopted, since by this process is possible to realize aluminium castings with thin walls and high specific mechanical properties. On the other hand, this casting process may cause tensile states into the castings, namely residual stresses. Residual stresses may strongly affect the life of the product causing premature failure of the casting. Various methods can assess these tensile states, but the non-destructive X-Ray method is the most commonly adopted. Namely, in this work, the residual stress analysis has been performed through Sinto-Pulstec μ-X360s. Detailed measurements have been done on powertrain components realized in aluminium alloy EN AC 46000 through HPDC processes to understand and prevent dangerous residual stress state into the aluminium castings. Furthermore, a comparison with stresses induced by Rheocasting processes is underway. In fact, it is well known that Semi-Solid metal forming combines the advantages of casting and forging, solving safety and environmental problems and possibly even the residual stress state can be positively affected.

Modelling shattered rim cracking in railroad wheels

2011 ◽  
Vol 225 (6) ◽  
pp. 593-604
Author(s):  
V Sura ◽  
S Mahadevan
Keyword(s):  
Residual Stress ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress State ◽  
Intensity Factor ◽  
Residual Stresses ◽  
Equivalent Stress ◽  
Crack Tip ◽  
Residual Stress State

Shattered rim cracking, propagation of a subsurface crack parallel to the tread surface, is one of the dominant railroad wheel failure types observed in North America. This crack initiation and propagation life depends on several factors, such as wheel rim thickness, wheel load, residual stresses in the rim, and the size and location of material defects in the rim. This article investigates the effect of the above-mentioned parameters on shattered rim cracking, using finite element analysis and fracture mechanics. This cracking is modelled using a three-dimensional, multiresolution, elastic–plastic finite element model of a railroad wheel. Material defects are modelled as mathematically sharp cracks. Rolling contact loading is simulated by applying the wheel load on the tread surface over a Hertzian contact area. The equivalent stress intensity factor ranges at the subsurface crack tips are estimated using uni-modal stress intensity factors obtained from the finite element analysis and a mixed-mode crack growth model. The residual stress and wheel wear effects are also included in modelling shattered rim cracking. The analysis results show that the sensitive depth below the tread surface for shattered rim cracking ranges from 19.05 to 22.23 mm, which is in good agreement with field observations. The relationship of the equivalent stress intensity factor (Δ K eq) at the crack tip to the load magnitude is observed to be approximately linear. The analysis results show that the equivalent stress intensity factor (Δ K eq) at the crack tip depends significantly on the residual stress state in the wheel. Consideration of as-manufactured residual stresses decreases the Δ K eq at the crack tip by about 40 per cent compared to that of no residual stress state, whereas consideration of service-induced residual stresses increases the Δ K eq at the crack tip by about 50 per cent compared to that of as-manufactured residual stress state. In summary, the methodology developed in this article can help to predict whether a shattered rim crack will propagate for a given set of parameters, such as load magnitude, rim thickness, crack size, crack location, and residual stress state.

Influence of Cooling Intensity on Residual Stress State of TIG Dressing Zone for T-Joint Welded Toe

2011 ◽  
Vol 148-149 ◽  
pp. 1289-1294 ◽  
Author(s):  
Kun Zhou ◽  
Chun Yuan Shi ◽  
Cheng Jin
Keyword(s):  
Finite Element Method ◽  
Residual Stress ◽  
Finite Element ◽  
Stress State ◽  
Residual Stresses ◽  
Residual Stress Distribution ◽  
Residual Stress State ◽  
Cooling Intensity ◽  
Stress Layer ◽  
Spray Treatment

Using finite element method, the residual stress distribution of the TIG dressed welded toe followed by spray treatment with different cooling intensity was calculated. And the residual stresses of welded toe were also measured by using the blind-hole method. The results indicate that with the increase of cooling intensity, the longitudinal residual stresses in welded toe are gradually transited from tensile residual stresses to compressive ones, and there is no significant change for transverse residual stresses, and the depth of compressive stress layer increases at the welded toe region.

scholarly journals MICRO-SCALE STUDY OF RESIDUAL STRESSES IN CR2O3 COATINGS SPRAYED BY APS

2020 ◽  
Vol 27 ◽  
pp. 42-47
Author(s):  
Franck Decroos ◽  
Cécile Langlade ◽  
Eric Bourillot ◽  
Geoffrey Darut ◽  
Manuel Francois
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Atmospheric Plasma ◽  
Forming Process ◽  
Characterization Methods ◽  
Residual Stress State ◽  
Microwave Microscopy ◽  
Early Failures ◽  
Material Forming

Whichever the application field, every material forming process generates residual stresses on the surface. While they are likely to enhance the aimed properties of the final mechanical part, these stresses may also drastically reduce them and result in early failures. Therefore, understanding the residual stress state remains a major challenge when coating complex parts, especially as most characterization methods at the microscopic scale involve specific sample preparation procedures which may affect the residual stresses field. This work investigates the residual stress state that exists in chromium oxide coatings deposited via Atmospheric Plasma Spray (APS), using two pioneering techniques featuring high spatial resolution: Scanning Microwave Microscopy and Raman Micro-Spectroscopy. The first technique combines the measurement of microwave electromagnetic capacities of a Vector Network Analyzer with the subnanometric resolution of an Atomic Force Microscope: it thus enables performing depth investigations at very accurately defined positions of the probe on the surface. The second technique relies on the principle of photons inelastic scattering and involves a laser beam aiming at the material sample: it allows a fine characterization of the microstructure as well as defects and stresses detection via molecular vibratory signatures. The investigation scale is limited here to a few cubic micrometers. Due to the highly localized scales of our investigations, which also depend on the device, the objective of our procedure required that the comparison should be made not on individual points but on definite mapped areas, every spot being analyzed and post-treated one after another, with optimum measuring parameters. Results have been correlated with XRD measurements to cross-check the average amount of stress observed over a wider area.

Effect of Misalignment and Weld Induced Residual Stresses on the Local Buckling Response of Pipelines

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Aiman Al-Showaiter ◽  
Farid Taheri ◽  
Shawn Kenny
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Oil And Gas ◽  
Local Buckling ◽  
Welding Residual Stress ◽  
Combined Stress ◽  
Residual Stress State ◽  
Girth Welding ◽  
Welding Processes

The aim of the present study is to develop numerical modeling procedures to simulate and study the effect of girth weld induced residual stresses and geometric imperfections on the behavior of conventional carbon steel oil and gas pipelines. The effect of welding residual stresses was obtained through computational simulations of the multipass girth weld process. The numerical procedures were calibrated using available pubic domain data on stainless steel. The methodology for conducting the welding simulation is presented. A parametric analysis was conducted using the finite element methods to evaluate the effects of welding residual stress due to girth welding processes, joint-to-joint misalignment associated with the girth weld, internal pressure, axial force, and diameter to wall thickness ratio on the local buckling response of pipelines. The pipeline moment-curvature response was examined to determine the influence of these parameters. For the parameters investigated, results from this study have demonstrated the significance of residual stress state due to welding processes and girth weld misalignment on the local buckling response of pipelines subjected to monotonic loading with combined stress state.

Failure Mechanisms of Equal and Unequal Wall Thickness Hybrid Maraging Steel-P20 Tubular Joints: Effects of Welding Residual Stresses

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Alireza Ebrahimi ◽  
Shawn Kenny ◽  
Mohsen Mohammadi
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Maraging Steel ◽  
Wall Thickness ◽  
Mechanical Performance ◽  
Fe Modeling ◽  
Residual Stress State ◽  
Welded Pipe ◽  
Pipe Joint

Abstract Joining an additively manufactured component to a forged or cast part through welding processes has recently attracted the attention of engineers and scientists. This technique integrates the technical benefits of additive manufacturing (AM) technology with conventional processes that may be more cost-efficient. In this paper, the effect of residual stresses on the mechanical performance of a hybrid welded pipe joint connecting an additively manufactured maraging steel (MS1) pipe segment with a conventional P20 steel tube having an equivalent outside diameter was studied. A sequentially coupled thermo-mechanical continuum finite element (FE) modeling procedure to predict the residual stress state on circumferential pipe hybrid MS1-P20 joints subjected to multi-axial loads was developed and validated. Available experimental data on a welded pipe joint with conventional stainless steel (SUS304) were used to calibrate the model. The FE modeling procedures were further validated for the hybrid MS1-P20 joint. The predicted residual stress state was mapped on the pipe joint with equal and unequal wall thickness joint transitions. The mechanical performance of these pipe joints was evaluated with the application of internal pressure, uniaxial tension, and flexural loads. The major contribution of this study was the proposition of a new concept of hybrid joints, where a significant transition of the load was expected. The new hybrid joint concept was presented to meet the existing design criteria requirements without sacrificing other parameters (e.g., component weight and manufacturing expense) and facilitate the production of hybrid components using AM techniques.

Experimental Investigation on the Residual Stresses Induced by a Plastic Forming Process

2010 ◽  
Vol 452-453 ◽  
pp. 821-824 ◽  
Author(s):  
Giuseppe Lamanna ◽  
Luigi Grassia ◽  
Vascione Ascione
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Trial And Error ◽  
Forming Process ◽  
Cross Sectional ◽  
Residual Stress State ◽  
Stretch Bending ◽  
Bending Process ◽  
Plastic Forming

The extrusion of a space frame must be followed by forming operations of some kind to obtain the desired shape/curvature, for example a stretch bending process. Therefore, one has to face with problems as production tolerances and cross-sectional distortions of the curved product. In house experience combined with trial–and–error procedures have been traditionally used to cope with the said problems. Aircraft frames show significant residual stresses as a consequence of plastic forming processes. A great number of variables, such as initial frame length and/or final additional stretch, can influence the stress state of frames determining their life and efficiency under operating loading conditions. In the present paper, we refer about the experimental evaluations of the residual stress state of aircraft frames which have carried out taking into account different process parameters. The experimental results obtained and discussed show some interesting trends: they demonstrate that the residual stresses of the formed component can be controlled and reduced.

Mechanical Property Scatter in CFCCs

1998 ◽  
Author(s):  
Marc Steen ◽  
Constantina Filiou
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Mechanical Response ◽  
Ceramic Matrix Composites ◽  
Strength Properties ◽  
Matrix Cracking ◽  
Control Mode ◽  
Residual Stress State ◽  
The Matrix

The tensile response of continuous fibre reinforced ceramic matrix composites (CFCCs) is not expected to show the large variation in strength properties commonly observed for monolithic ceramics. Results of recent investigations on a number of 2D reinforced CFCCs have nevertheless revealed a considerable scatter in the initial elastic modulus, in the first matrix cracking stress and in the failure stress. One school of thought considers that the observed variability is caused by experimental factors. Elaborate testing programmes have been set up to clarify the origins of this scatter by investigation of the effects of control mode, loading rate, specimen shape, etc.. Another school explains the scatter by the presence of (axial) residual stresses in the fibres and in the matrix. Although plausible, this hypothesis is difficult to verify because experimental determination of the residual stress state in CFCCs is not straightforward. In addition, with the available methods it is impractical to determine the residual stresses in every test specimen. This approach is indeed required for establishing the relationship between the magnitude of the residual stresses and the experimentally observed scatter. At IAM a method has been developed and validated which allows to quantify the axial residual stress state in individual CFCC specimens by subjecting them to intermittent unloading-reloading cycles. The method as well as the derived relationship between residual stress state and scatter in mechanical response will be presented.

Study of Microstructure and Residual Stresses in Dissimilar Al/Steels Welds Produced by Cold Metal Transfer

2008 ◽  
Vol 571-572 ◽  
pp. 347-353 ◽  
Author(s):  
L. Agudo ◽  
S. Weber ◽  
Haroldo Pinto ◽  
Enno Arenholz ◽  
Juergen Wagner ◽  
...  
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Stress State ◽  
Residual Stresses ◽  
Intermetallic Phase ◽  
Metal Transfer ◽  
Parent Material ◽  
Cold Metal Transfer ◽  
Residual Stress State ◽  
Cold Metal

Recently a new welding technique, the so-called ‘Cold Metal Transfer’ (CMT) technique was introduced, which due to integrated wire feeding leads to lower heat input and higher productivity compared to other gas metal arc (GMA) techniques. Here microstructure formation and residual stress state in dissimilar steel to aluminum CMT welds are investigated. The intermetallic phase seam between the filler and the steel is only a few micrometers thick. Residual stress analyses reveal the formation of the typical residual stress state of a weld without phase transformation. Both in longitudinal and in transversal direction compressive residual stresses exist in the steel plate parent material, tensile residual stresses are present in the heat affected zone of the steel and the aluminum alloy. The area containing tensile residual stresses is larger in the aluminum alloy due to its higher heat conductivity than in the steel. Due to the symmetry in the patented voestalpine welding geometry and the welding from bottom and face side of the weld, the residual stress distributions at the top and at the bottom side of the weld are very similar.

Mechanical Property Scatter in CFCCs

1999 ◽  
Vol 122 (1) ◽  
pp. 69-72 ◽  
Author(s):  
M. Steen ◽  
C. Filiou
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Mechanical Response ◽  
Ceramic Matrix Composites ◽  
Strength Properties ◽  
Matrix Cracking ◽  
Control Mode ◽  
Residual Stress State ◽  
The Matrix

The tensile response of continuous fibre reinforced ceramic matrix composites (CFCCs) is not expected to show the large variation in strength properties commonly observed for monolithic ceramics. Results of recent investigations on a number of two-dimensional reinforced CFCCs have nevertheless revealed a considerable scatter in the initial elastic modulus, in the first matrix cracking stress and in the failure stress. One school of thought considers that the observed variability is caused by experimental factors. Elaborate testing programmes have been set up to clarify the origins of this scatter by investigation of the effects of control mode, loading rate, specimen shape, etc. Another school explains the scatter by the presence of (axial) residual stresses in the fibres and in the matrix. Although plausible, this hypothesis is difficult to verify because experimental determination of the residual stress state in CFCCs is not straightforward. In addition, with the available methods it is impractical to determine the residual stresses in every test specimen. This approach is indeed required for establishing the relationship between the magnitude of the residual stresses and the experimentally observed scatter. At IAM a method has been developed and validated which allows to quantify the axial residual stress state in individual CFCC specimens by subjecting them to intermittent unloading-reloading cycles. The method as well as the derived relationship between residual stress state and scatter in mechanical response will be presented. [S0742-4795(00)01101-7]

Hydrogen Interaction with Residual Stresses in Steel Studied by Synchrotron X-Ray Diffraction

2013 ◽  
Vol 772 ◽  
pp. 91-95 ◽  
Author(s):  
Eitan Dabah ◽  
Thomas Kannengiesser ◽  
Dan Eliezer ◽  
Thomas Boellinghaus
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
High Energy ◽  
Steel Sample ◽  
Stainless Steel Sample ◽  
X Ray Diffraction ◽  
High Hydrogen ◽  
X Ray ◽  
Residual Stress State

The residual stress state in a material has an important role in the mechanism of cracking, induced or assisted by hydrogen. In this contribution, the beamline EDDI in BESSY II instrument in Berlin was used in order to investigate the influence of hydrogen upon the residual stresses state existing in a Supermartensitic stainless steel sample. The method used for investigating the residual stresses is the “sinus square ψ” method. This method involves the usage of high energy X-ray diffraction in order to measure the residual stress state and magnitude. It was found that hydrogen presence has a significant influence upon the magnitude of the residual stresses, as its value decreases with high hydrogen content. This effect is reversible, as hydrogen desorbs from the sample the residual stress magnitude gains its initial value before hydrogen charging.

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