scholarly journals SXRD Measurements of Residual Stresses in Sintered Diamond–Cobalt Composites

2008 ◽  
Vol 571-572 ◽  
pp. 401-406
Author(s):  
H.A. Crostack ◽  
Ursula Selvadurai-Lassl ◽  
Gottfried Fischer ◽  
André Rothkirch
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Cutting Tools ◽  
Diamond Composite ◽  
Small Areas ◽  
Stress Measurements ◽  
Sintered Diamond ◽  
Stress States ◽  
Composite Cutting Tools

Diamond-cobalt composites are used for cutting tools. Residual stress after manufacture can reduce the lifetime of such composite cutting tools and, hence, the stress state needs to be well understood. Within this study, stress measurements on a cobalt diamond composite were made by SXRD to deduce stress states in the cobalt matrix using the (222) reflection. The application of different apertures allowed the investigation of stress in small areas of cobalt surrounding a diamond and in areas at different distances to a diamond. In the areas adjacent to the diamond increased residual stresses were found in the cobalt matrix. Furthermore, approximations for radial and tangential residual stresses have been derived which show to be different.

Neutron Residual Stress Measurements on Rail Sections for Different Production Conditions

2004 ◽  
Author(s):  
Vladimir Luzin ◽  
Jeffrey E. Gordon ◽  
Thomas Gnaupel-Herold ◽  
Henry J. Prask
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Two Dimensional ◽  
Strain Measurements ◽  
Stress Measurements ◽  
Triaxial Stresses ◽  
The Difference ◽  
Production Conditions

Rail sectioning with subsequent neutron diffraction experiments has been used to assess residual stresses in the rails. In this study we present the results of neutron stress measurements performed at the NIST Center for Neutron Research (NCNR) on rail sections from rails that were produced under various conditions. Specifically, these are air-cooled, air-cooled and roller-straightened, head-hardened and head-hardened and roller-straightened. More significantly, a head-hardened and roller-straightened rail was also studied after service to elucidate evolution of the service-induced residual stresses. In the latter case both a transverse-cut slice and the central region of a 0.53 m long piece were studied. Measurements on this piece are the first in which triaxial stresses have been determined for an intact rail. Neutron strain measurements with 3×3×3 mm3 spatial resolution were successfully employed for transversally cut slices to verify the difference in the stress state depending on the production process. Although examination of slices allows determination of only two-dimensional stresses in the plane of the slice, additional measurements on obliquely-cut slices, which were also carried out, and utilization of FEM gives the possibility of reconstructing the full triaxial stress distribution. Together, these approaches provide a better understanding of rail fabrication and the possibility of improving the durability and safety of rails in the future.

Residual Stress Development in Laser Machined PVD-Coated Carbide Cutting Tools

2013 ◽  
Vol 768-769 ◽  
pp. 391-397 ◽  
Author(s):  
Bernd Breidenstein ◽  
Christoph Gey ◽  
Berend Denkena
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Cutting Tool ◽  
Cutting Tools ◽  
Machining Process ◽  
Laser Machining ◽  
Residual Stress State ◽  
Stress States ◽  
The Individual ◽  
Coated Carbide

Abstract. There is growing interest in laser machining as an alternative to abrasive processes for creating cutting tool micro geometries. This technology is also suitable for creating micro geometries on cutting edges of superhard cutting tools. The pulsed nanosecond lasers, which are commonly used for this type of application, induce a high thermal load in the tool. This heat is believed to result in tensile residual stresses at the cutting edge surface, which are generally unfavorable for cutting tool performance because of the tendency to crack formation and propagation. Different levels of compressive residual stress exist after each step (sintering, grinding, shot peening, etching and PVD-coating). From investigations of commercial processes for manufacturing PVD-coated carbide cutting tools it is known that the final residual stress state of the carbide subsurface is a result of superposition of the stress states resulting from the individual process steps. In contrast to that, a laser machining process is expected to produce tensile residual stress due to the heat input. The present work describes the influence of a process chain alteration for PVD-coated carbide cutting tools by a laser machining process on the residual stress state in the finished tools.

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.

Polishing of diamond composite cutting tools

2007 ◽  
Vol 1 (4) ◽  
pp. 360 ◽  
Author(s):  
Y. Chen ◽  
L.C. Zhang ◽  
J.A. Arsecularatne
Keyword(s):  
Cutting Tools ◽  
Diamond Composite ◽  
Composite Cutting Tools

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.

Pre PVD-Coating Processes and their Effect on Substrate Residual Stress in Carbide Cutting Tools

2010 ◽  
Vol 438 ◽  
pp. 17-22 ◽  
Author(s):  
Berend Denkena ◽  
Bernd Breidenstein
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Cutting Tools ◽  
Residual Stress State ◽  
Pvd Coating ◽  
Parameter Variations ◽  
Single Process ◽  
The Stability ◽  
Cohesive Damage ◽  
Coated Cemented Carbide

Cohesive damage of PVD-coated cemented carbide cutting tools is ascribed to the residual stress state of the substrate subsurface. The present paper shows the formation of the substrate residual stress in the process chain as well as the stability of the single process steps referred to the scattering of the residual stress values. Depth resolved residual stress measurements across coating and substrate subsurface show a layer in the substrate, where possibly tensile stress occurs, from where cohesive damage may be initialized during tool use. Results of experiments are presented, where the influence of parameter variations in pre coating processes on the residual stress state is investigated. The characteristics of compressive residual substrate stress during the final PVD-process is presented as well as a correlation between coating and substrate stress.

Measurement of Residual Stresses in a Nozzle-to-Cylinder Weld After Thermal Ageing at 550°C

2007 ◽  
Author(s):  
S. Hossain ◽  
C. E. Truman ◽  
D. J. Smith ◽  
P. J. Bouchard
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Hoop Stress ◽  
Thermal Ageing ◽  
Hole Drilling ◽  
Stress Profile ◽  
Aged Condition ◽  
Steel Component ◽  
Stress Measurements ◽  
Test Treatment

This paper presents results from a programme of experimental measurements of residual stresses in a type 316H stainless steel component consisting of a nozzle welded to a cylinder. The residual stresses were measured using the deep-hole drilling (DHD) technique. The welded component had been thermally aged in a furnace at 550°C for 19,644 hours prior to the residual stress measurements. Measurements were obtained in the through-thickness section of the component at two locations: (i) in the cylinder heat affected zone (HAZ) at the flank of the nozzle-to-cylinder weld intersection and (ii) in the cylinder HAZ near the crown of the nozzle-to-cylinder weld intersection. The stress measurements made after the furnace heat soak treatment are compared with the earlier as-welded stress measurements. In comparison with as-welded residual stress measurements on the same component and with residual stresses in a service-aged (55,000 hours at 525°C) component, it was evident that the thermal soak test treatment had significantly relaxed the weld residual stresses. In particular the soak test hoop stress profile was almost identical to the service-aged condition, whereas the transverse stress distribution had only been partially relaxed by the thermal soak test.

Residual Stress Measurements in a 316L Uniaxial Samples Manufactured by Laser Powder Bed Fusion

2020 ◽  
Author(s):  
C. M. Davies ◽  
P. Sandmann ◽  
T. Ronneberg ◽  
P. A. Hooper ◽  
Saurabh Kabra
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Cross Section ◽  
316L Stainless Steel ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Stress Measurements ◽  
Compressive Stresses ◽  
Central Cross Section

Abstract Uniaxial samples have been manufactured for tension/compression testing from 316L stainless steel by laser powder bed fusion (LPBF). Samples manufactured by LPBF are known to contain high levels of residual stresses. These uniaxial samples were built from a solid cylindrical rod and subsequently machined to reduce the central cross section of the sample to the required gauge diameter and improve the surface finish. Finite element (FE) models have been developed to simulate the LPBF process of the rods, their removal from the build plate and subsequent machining into the tension/compression samples. High tensile residual stresses were predicted at the surface of the samples, balances by similar magnitude compressive stresses along their axis. Post machining however, these stresses were reduced by around 80% or more. Residual stress measurements were performed on the samples post machining using the neutron diffraction techniques. These measurements confirmed that negligible residual stresses remained in the samples post removal from the build plate and machining.

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.

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