Application of Neutron Diffraction in Analysis of Residual Stress Profiles in the Cylinder Web Region of an as-Cast V6 Al Engine Block with Cast-In Fe Liners

Residual stress profiles were measured by neutron diffraction in Al2O3/Y-TZP ceramic composites containing 5 and 40 vol.% Y-TZP fabricated by conventional slip casting and by a novel tape casting route. Residual stresses in the zirconia are tensile and increase as its volume fraction decreases. For the alumina matrix, residual stress is compressive and increases with the zirconia volume fraction. In the composite with 5 vol.% zirconia, the processing route does not have an influence on residual stresses. However, in the composite with 40 vol.% zirconia, residual stresses are different in the samples obtained by both processing routes.

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Residual Stress Measurements of Explosively Clad Cylindrical Pressure Vessels

Journal of Pressure Vessel Technology ◽

10.1115/1.4004615 ◽

2011 ◽

Vol 134 (1) ◽

Cited By ~ 4

Author(s):

D. J. Taylor ◽

T. R. Watkins ◽

C. R. Hubbard ◽

M. R. Hill ◽

W. A. Meith

Keyword(s):

Residual Stress ◽

Neutron Diffraction ◽

Axial Direction ◽

Pressure Vessels ◽

Explosive Cladding ◽

Residual Stress State ◽

Reverse Yielding ◽

Metallurgical Bond ◽

Stress Profiles ◽

Clad Steel

Tantalum refractory liners were explosively clad into cylindrical pressure vessels, some of which had been previously autofrettaged. Using explosive cladding, the refractory liner formed a metallurgical bond with the steel of the pressure vessel at a cost of induced strain. Two techniques were employed to determine the residual stress state of the clad steel cylinders: neutron diffraction and mechanical slitting. Neutron diffraction is typically nondestructive; however, due to attenuation along the beam path, the cylinders had to be sectioned into rings that were nominally 25 mm thick. Slitting is a destructive method, requiring the sectioning of the cylindrical samples. Both techniques provided triaxial stress data and useful information on the effects of explosive cladding. The stress profiles in the hoop and radial directions were similar for an autofrettaged, nonclad vessel and a clad, nonautofrettaged vessel. The stress profiles in the axial direction appeared to be different. Further, the data suggested that residual stresses from the autofrettage and explosive cladding processes were not additive, in part due to evidence of reverse yielding. The residual stress data are presented, compared and discussed.

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Mitigation of cylinder distortion in aluminum alloy engine blocks via heat treatment process optimization

10.32920/ryerson.14644455 ◽

2021 ◽

Author(s):

Anthony Lombardi

Keyword(s):

Heat Treatment ◽

Residual Stress ◽

Neutron Diffraction ◽

Solution Heat Treatment ◽

Treatment Process ◽

Tensile Residual Stress ◽

Engine Block ◽

Engine Blocks ◽

In Situ Neutron Diffraction

Lightweighting has become an important factor in the automotive industry due to stringent government regulations on fuel consumption and increased environmental awareness. Aluminum alloys are 65% lighter than cast iron enabling significant weight reduction. However, there are several significant challenges associated to the use of hypoeutectic Al-Si alloys in engine block applications. This dissertation investigated the factors influencing the susceptibility of in-service cylinder distortion as it is deleterious to engine operating efficiency, leading to environmental (increased carbon emissions) and economic (expensive recalls) repercussions. The initial segment of this dissertation sought to quantitatively confirm the cause of cylinder distortion by investigating distorted and undistorted service tested engine blocks. This analysis involved measurement of macro-distortion using a co-ordinate measuring machine, in-depth microstructural analysis, measurement of tensile properties, and residual stress mapping along the length of the cylinder bores (neutron diffraction). Upon determining the cause of distortion, the second phase of this project optimized the solution heat treatment parameters to mitigate future distortion in the engine blocks. This optimization was carried out by varying heat treatment parameters to maximize engine block strength. In addition, a pioneering application of in-situ neutron diffraction, along with a unique engine heating system, was used to develop a time-dependent correlation of residual stress relief during heat treatment, assisting in process optimization. The results indicate that the distorted engine block had high tensile residual stress, specifically at cylinder depths greater than 30 mm, while the undistorted block had mainly compressive stress. The maximum distortion occurred near the center portion of the cylinder (~60 mm), which had a combination of coarse microstructure (lower strength) and high tensile residual stress. As such,distortion can be prevented via maximization of strength and reduction in tensile residual stress. Lab scale castings and in-situ neutron diffraction were used to successfully develop an optimal heat treatment process to increase engine block integrity. These experiments found that solution heat treatment at 500 °C for 2 h increased tensile yield strength by 15-20% over engines produced using the current process. Furthermore, tensile residual stress was completely relieved by this heat treatment, reducing the susceptibility to in-service distortion. Solutionizing at temperatures above 500 °C was deemed unsuitable for engine block production due to incipient melting, which deteriorates strength.

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Evaluation of the Residual Stress in the Cold Spray Technique Using Smooth Particle Hydrodynamics Modelling and Neutron Diffraction

Materials Science Forum ◽

10.4028/www.scientific.net/msf.777.205 ◽

2014 ◽

Vol 777 ◽

pp. 205-212 ◽

Cited By ~ 2

Author(s):

Michael Saleh ◽

Vladimir Luzin ◽

Kevin Spencer

Keyword(s):

Residual Stress ◽

Neutron Diffraction ◽

Cold Spray ◽

Smooth Particle Hydrodynamics ◽

Glass Substrates ◽

Material Deposition ◽

Spray Technique ◽

Particle Hydrodynamics ◽

Stress Profiles ◽

Thick Coatings

Cold spray is a material deposition technique in which powdered metals are deposited onto metallic and glass substrates as a means of improving functionality, repair or protection of the underlying substrate. The residual stress that builds up in the material during spraying is closely linked to the coating’s integrity and the bonding mechanism. Neutron diffraction residual stresses measurements were carried out at the OPAL research reactor, ANSTO, using the KOWARI strain scanner to investigate an Al-6061 sample with a fine through-thickness resolution of 0.5 mm. The experimentally determined through thickness stress profiles of the macroscopically thick coatings were used to validate FE calculations made for 100 μm thick coatings using the Smooth Particle Hydrodynamics, SPH, techniques. A pronounced plastic strain gradient was apparent in the tested and modelled samples indicative of the significant residual macro-stresses which develop in the cladding/substrate during the deposition. Around the deposited particle’s periphery (in the jetting region) the temperatures are significant, this lends itself to the presence of grain refinement at the periphery of sprayed particles and the propagation of dynamic recrystallization which is closely coupled with the thermal softening of the particle.

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Effect of Varying Cold-Drawing Deformation on Residual Stresses Measured by Neutron Diffraction in Steel Rods

Materials Science Forum ◽

10.4028/www.scientific.net/msf.571-572.51 ◽

2008 ◽

Vol 571-572 ◽

pp. 51-56 ◽

Cited By ~ 1

Author(s):

Jesus Ruiz-Hervias ◽

Vladimir Luzin ◽

Henry Prask ◽

T. Gnaeupel-Herold ◽

Manuel Elices Calafat

Keyword(s):

Residual Stress ◽

Neutron Diffraction ◽

True Strain ◽

Cold Drawing ◽

Pearlitic Steel ◽

Stress Profile ◽

Degree Of Deformation ◽

Residual Stress Profile ◽

Stress Profiles ◽

Tyre Industry

Cold-drawing is employed to fabricate wires and rods, which are mainly used as structural reinforcements in construction as well as in the tyre industry. As a consequence of processing, a residual stress profile is developed. In this paper, residual stress profiles are measured by neutron diffraction in cold-drawn pearlitic steel rods subjected to different deformations (true strain from 0.3 to 1.7). The results show that the residual stress profile produced by cold-drawing is similar in all the samples, irrespective of the degree of deformation.

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Mitigation of cylinder distortion in aluminum alloy engine blocks via heat treatment process optimization

10.32920/ryerson.14644455.v1 ◽

2021 ◽

Author(s):

Anthony Lombardi

Keyword(s):

Heat Treatment ◽

Residual Stress ◽

Neutron Diffraction ◽

Solution Heat Treatment ◽

Treatment Process ◽

Tensile Residual Stress ◽

Engine Block ◽

Engine Blocks ◽

In Situ Neutron Diffraction

Lightweighting has become an important factor in the automotive industry due to stringent government regulations on fuel consumption and increased environmental awareness. Aluminum alloys are 65% lighter than cast iron enabling significant weight reduction. However, there are several significant challenges associated to the use of hypoeutectic Al-Si alloys in engine block applications. This dissertation investigated the factors influencing the susceptibility of in-service cylinder distortion as it is deleterious to engine operating efficiency, leading to environmental (increased carbon emissions) and economic (expensive recalls) repercussions. The initial segment of this dissertation sought to quantitatively confirm the cause of cylinder distortion by investigating distorted and undistorted service tested engine blocks. This analysis involved measurement of macro-distortion using a co-ordinate measuring machine, in-depth microstructural analysis, measurement of tensile properties, and residual stress mapping along the length of the cylinder bores (neutron diffraction). Upon determining the cause of distortion, the second phase of this project optimized the solution heat treatment parameters to mitigate future distortion in the engine blocks. This optimization was carried out by varying heat treatment parameters to maximize engine block strength. In addition, a pioneering application of in-situ neutron diffraction, along with a unique engine heating system, was used to develop a time-dependent correlation of residual stress relief during heat treatment, assisting in process optimization. The results indicate that the distorted engine block had high tensile residual stress, specifically at cylinder depths greater than 30 mm, while the undistorted block had mainly compressive stress. The maximum distortion occurred near the center portion of the cylinder (~60 mm), which had a combination of coarse microstructure (lower strength) and high tensile residual stress. As such,distortion can be prevented via maximization of strength and reduction in tensile residual stress. Lab scale castings and in-situ neutron diffraction were used to successfully develop an optimal heat treatment process to increase engine block integrity. These experiments found that solution heat treatment at 500 °C for 2 h increased tensile yield strength by 15-20% over engines produced using the current process. Furthermore, tensile residual stress was completely relieved by this heat treatment, reducing the susceptibility to in-service distortion. Solutionizing at temperatures above 500 °C was deemed unsuitable for engine block production due to incipient melting, which deteriorates strength.

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Local Stress Variations at Bead Interruptions in Austenitic Multi-Pass Groove Welds

Volume 6: Materials and Fabrication, Parts A and B ◽

10.1115/pvp2009-77153 ◽

2009 ◽

Cited By ~ 1

Author(s):

Christopher M. Gill ◽

Paul Hurrell ◽

John Francis ◽

Mark Turski

Keyword(s):

Residual Stress ◽

Finite Element ◽

Neutron Diffraction ◽

Residual Stresses ◽

Good Practice ◽

304 Stainless Steel ◽

Stress Profile ◽

Stress Distributions ◽

Fe Modelling ◽

Stress Profiles

This paper presents finite element analyses of residual stress in an austenitic multi-pass groove weld. The aim was to establish the effect upon the residual stress of stop-start interruptions during the deposition of weld beads. Comparison of measured residual stress profiles with the residual stress distributions predicted by finite element (FE) modelling aimed to validate the FE method for predicting residual stresses around stop-start features. This paper presents a comparison of measured and modelled residual stress distributions in a series of simple welded 304 stainless steel plates. The plates were machined with a v-groove designed to be filled using eight weld passes. Samples which included interrupted weld beads contained two stop-start features in the fifth pass. In the first feature the welding power was ramped down over 15 seconds; this represented normal welding good practice. The second feature investigated was an abrupt stop, where the welding power was removed instantaneously; this represented an extreme stop. Three welded plates were considered. One contained five weld passes, such that the final pass contained stop-start features and resulted in partially filling the weld groove. Two welds plates each containing eight passes have also been considered; one contained stop-start features in the fifth pass and the other contained no stop-start features. This allowed a comparison of the effect of stop-start features and the effect that subsequent beads have upon any perturbations in the residual stresses produced. Residual stress measurements have been performed using neutron diffraction. 3D weld modelling has been carried out using VFT and the Abaqus finite element package. Results from the welding FE analyses were compared with the neutron diffraction measurements. Good agreement between the modelled and measured residual stresses is achieved in the uninterrupted 8-pass sample and after deposition of the bead containing stop-start features in the 5-pass sample. Following deposition of subseqeunt beads perturbations in the residual stress profile are retained in the neutron diffraction measurements, but all perturbations are removed from the residual stress profiles predicted using both VFT and Sysweld. This work suggests that modelling welding stop-start features is only necessary in the final weld capping passes, if residual stresses over a short length scale are of interest.

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