Crack Initiation in Railway Wheels Resulting From Rolling Contacts

2011 ◽  
Author(s):  
Steven L. Dedmon ◽  
Huseyin Guzel
Keyword(s):  
Crack Initiation ◽  
Residual Stresses ◽  
Cold Work ◽  
Finite Element Analyses ◽  
Metallic Inclusion ◽  
Destructive Testing ◽  
Rolling Contacts ◽  
Complex Relationships ◽  
Property Changes ◽  
Railway Wheels

Classic shelling of a railway wheel begins with crack initiation resulting from wheel rail interactions. This investigation shows the complex relationships that occur between contact stress, cold work, residual stresses, and temperatures from brake heating and non-metallic inclusion types which can lead to the formation of shelling cracks. Our investigation also includes an explanation of how these interactions affect mechanical properties such as yield strength, elastic modulus, and ductility. In turn, mechanical property changes also affect how cold work and its associated residual stresses develop under cyclic loading. Destructive testing and Finite Element Analyses were used in support of this work.

Effect of Non-Metallic Inclusion Size and Residual Stresses on Gigacycle Fatigue Properties in High Strength Steel

2008 ◽  
Vol 44-46 ◽  
pp. 33-42 ◽  
Author(s):  
Kazuaki Shiozawa ◽  
L. Lu
Keyword(s):  
Fatigue Life ◽  
Crack Initiation ◽  
Residual Stresses ◽  
Fatigue Fracture ◽  
Fracture Mode ◽  
Stress Amplitude ◽  
High Strength ◽  
Inclusion Size ◽  
Metallic Inclusion ◽  
Amplitude Level

Fatigue fracture of some high-strength steels occurs at small defect in the subsurface zone of a material at low stress amplitude level and in a high-cycle region of more than 106 cycles (gigacycle fatigue life), whereas surface fatigue crack initiation occurs at high-stress amplitude and low cycles. There is a definite stress range where the crack initiation site changes from a surface to a subsurface defect, giving a step-wise S-N curve or a duplex S-N curve. From the experimental results, fatigue fracture mode was classified into three types, such as, surface inclusion induced fracture mode, subsurface inclusion induced fracture mode without granular bright facet (GBF) area and that with the GBF, depending on stress amplitude level and stress ratio. The GBF area was observed in the vicinity of a non-metallic inclusion at the fracture origin inside the fish-eye in gigacycle fatigue regime. It was made clear from the discussion with fracture mechanics that the transition of fracture mode was affected by compressive residual stresses on the specimen surface. Fracture-mode transition diagram was proposed through the experimental and theoretical investigation. Also, from the evaluation of the fatigue life based on the estimated subsurface crack growth rate from the S-N data, effect of inclusion size on the dispersion of fatigue life was explained, and S-N curve for subsurface inclusion-induced fracture depended on the inclusion size was provided.

scholarly journals Simulation-driven product development of cast components with allowance for process-induced material behaviour

2020 ◽  
Vol 7 (1) ◽  
pp. 78-85
Author(s):  
J Jansson ◽  
J Olofsson ◽  
K Salomonsson
Keyword(s):  
Residual Stresses ◽  
Finite Element Analyses ◽  
Material Behaviour ◽  
Large Magnitude ◽  
Strength Differential ◽  
Design Engineers ◽  
Process Simulations ◽  
Specific Material ◽  
And Performance ◽  
Complex Relationships

Abstract This paper presents a methodology that can be used to consider local variations in thermomechanical and thermophysical material properties, residual stresses, and strength-differential effects in finite element analyses of cast components. The methodology is based on applying process simulations and structural analyses together with experimentally established, or already available literature data, in order to describe element-specific material variations. A cast-iron cylinder head was used in order to evaluate the influence of several simplifications that are commonly performed in computer aided engineering. It is shown that non-trivial errors of a potentially large magnitude are introduced by not considering residual stresses, compressive behaviour, temperature dependence, and process-induced material property variations. By providing design engineers with tools that allow them to consider the complex relationships between these aspects early in the development phase, cast components have the potential to be further optimized with respect to both weight and performance.

Stress Corrosion Cracking (SCC) of Nickel-Base Weld Metals in PWR Primary Water

2013 ◽  
Vol 747-748 ◽  
pp. 723-732 ◽  
Author(s):  
Ru Xiong ◽  
Ying Jie Qiao ◽  
Gui Liang Liu
Keyword(s):  
Residual Stresses ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Surface Condition ◽  
Cold Work ◽  
Corrosion Cracking ◽  
Pressurized Water ◽  
Weld Metals ◽  
Surface Residual Stresses ◽  
Primary Water

This discussion reviewed the occurrence of stress corrosion cracking (SCC) of alloys 182 and 82 weld metals in primary water (PWSCC) of pressurized water reactors (PWR) from both operating plants and laboratory experiments. Results from in-service experience showed that more than 340 Alloy 182/82 welds have sustained PWSCC. Most of these cases have been attributed to the presence of high residual stresses produced during the manufacture aside from the inherent tendency for Alloy 182/82 to sustain SCC. The affected welds were not subjected to a stress relief heat treatment with adjacent low alloy steel components. Results from laboratory studies indicated that time-to-cracking of Alloy 82 was a factor of 4 to 10 longer than that for Alloy 182. PWSCC depended strongly on the surface condition, surface residual stresses and surface cold work, which were consistent with the results of in-service failures. Improvements in the resistance of advanced weld metals, Alloys 152 and 52, to PWSCC were discussed.

scholarly journals Influence of local residual stresses on fatigue crack initiation

2021 ◽  
Vol 31 ◽  
pp. 3-7
Author(s):  
M. Mlikota ◽  
S. Schmauder ◽  
K. Dogahe ◽  
Ž. Božić
Keyword(s):  
Fatigue Crack ◽  
Crack Initiation ◽  
Residual Stresses ◽  
Fatigue Crack Initiation

A Simple Approach for Including Weld Residual Stresses in the Calculation of Pipe Circumferential Through-Wall Crack Opening Displacements

2016 ◽  
Author(s):  
Richard Olson
Keyword(s):  
Residual Stresses ◽  
Axial Force ◽  
Analytic Solution ◽  
Crack Opening ◽  
Bending Moment ◽  
Generalized Solution ◽  
Finite Element Analyses ◽  
Opening Displacement ◽  
Crack Face ◽  
Basic Equations

Current methodologies for predicting the crack opening displacement (COD) of circumferentially through-wall cracked pipe do not include the effect of weld residual stresses (WRS). Even the most advanced COD prediction methodology only includes the effect of applied axial force, bending moment, and crack face pressure. For some years, it has been known that weld residual stresses do alter the COD, but there has been no convenient way to include them in a COD prediction without doing case-specific finite element analyses. This paper documents a generalized solution for including WRS effects on COD. The model uses a closed-form analytic solution to approximate the crack face rotations that the WRS would induce which, subsequently, can be added to the typical axial force-bending-crack face pressure COD solution. The methodology is described and the basic equations for the solution are presented. Following this, application to cases to evaluate the efficacy of the approach are presented which show a mixture of results ranging from amazingly good to “of questionable value” with respect to the FEA results.

The BWR RPV Internals Management Program of the German NPP Gundremmingen, Units B and C: Results and Conclusions

2002 ◽  
Author(s):  
Martin Widera
Keyword(s):  
Heat Treatment ◽  
Crack Initiation ◽  
Residual Stresses ◽  
Surface Condition ◽  
Management Program ◽  
Post Weld Heat Treatment ◽  
Interim Result ◽  
The Core ◽  
Weld Heat ◽  
Core Shroud

Due to the core shroud cracks reported from numerous BWRs including the German KWU type BWR Wuergassen, a RPV internals management program for the Gundremmingen NPP (KRB-II) has been initiated in 1994. Major steps and the main results of this program are presented. As an interim result, surface condition of the weld regions and controlled post weld heat treatment (PWHT) in order to reduce the residual stresses seem to play an important role for resistance to crack initiation and growth. To support these assumptions, results of related R&D projects of the German utilities (VGB) are presented.

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