The effect of block braking on the residual stress state of a solid railway wheel

1998 ◽  
Vol 212 (2) ◽  
pp. 145-158 ◽  
Author(s):  
G Donzella ◽  
M Scepi ◽  
L Solazzi ◽  
F Trombini
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress State ◽  
Safety Margin ◽  
Experimental Tests ◽  
Railway Wheel ◽  
Residual Stress State ◽  
Calculated Stress ◽  
Differential Quenching ◽  
Thermal Fatigue Strength

A finite element, numerical model of a solid railway wheel was perfected permitting the simulation of a block braking operation. The analyses performed, backed by experimental tests, permitted the degree of variation in the residual stress state (induced by differential quenching heat treatment and successive tempering) caused by particularly heavy braking to be evaluated. The results highlight the influence of the main braking parameters (force and time) and the thermal history previously suffered by the wheel. Finally, the thermal fatigue strength of the component, although in an approximate way, was checked on the basis of the calculated stress state and through the introduction of the data of a real and particularly significant route into the model. This demonstrated the broad safety margin with which the wheel operates and also brought to light the dangerous nature of particularly severe braking which can drastically modify the residual stresses induced by the heat treatment, moving them towards tensile stresses.

scholarly journals Identification of Residual Stress Phenomena Based on the Hole Drilling Method in Explosively Welded Steel-Titanium Composite

2014 ◽  
Vol 59 (3) ◽  
pp. 1119-1123 ◽  
Author(s):  
A. Karolczuk ◽  
M. Kowalski ◽  
K. Kluger ◽  
F. Żok
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress State ◽  
Welding Process ◽  
Hole Drilling ◽  
Titanium Layer ◽  
Hole Drilling Method ◽  
Bimetallic Composite ◽  
Residual Stress State ◽  
Drilling Method

Abstract The hole drilling method was used to determine residual stresses in bimetallic composite manufactured by explosive welding process. The analyzed bimetal consist of titanium Grade 1 (6mm) and S355J2+N steel (40mm). The aim of the paper is to establish the influence of the heat treatment on residual stress state in titanium layer. Residual stress calculations were performed according to standards developed by strain gauge manufacturer (TML) and ASTM standards. The main conclusion is the heat treatment considerably changes the residual stress state in titanium layer from tensile stress state (no heat treatment) to compression stress state (after the heat treatment).

Flank-Load-Carrying Capacity of Case Hardened Gears With Grinding Burn

2011 ◽  
Author(s):  
Bernd-Robert Ho¨hn ◽  
Karsten Stahl ◽  
Peter Oster ◽  
Thomas Tobie ◽  
Simon Schwienbacher ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Carrying Capacity ◽  
Experimental Testing ◽  
Load Capacity ◽  
Experimental Tests ◽  
Load Carrying Capacity ◽  
Grinding Burn ◽  
Residual Stress State ◽  
Load Carrying

A high geometric accuracy of case-hardened gears requires a grinding process after heat treatment. Inappropriate grinding conditions can induce surface tempering, alter hardness and lead to an unfavorable residual stress state. This effect is commonly known as grinding burn. The influence of grinding burn on the flank-load-carrying capacity was systematically investigated within a research project. The results of experimental tests and the analysis of surface and near subsurface parameters allowed a correlation between grinding burn grade, material characteristics and flank-load-carrying capacity. A main result of this project is a proposal for the calculation of surface durability of gears which implicates the influence of grinding burn. This paper summarizes results of the experimental testing and the accompanying analyses. The main focus herein is the consideration of an altered hardness and residual stress state in a material-physically based model for calculating the load capacity of gears.

scholarly journals Influence of Steel Grain Size on Residual Stress in Grinding Processing

2010 ◽  
Vol 638-642 ◽  
pp. 2389-2394 ◽  
Author(s):  
Masahide Gotoh ◽  
Katsuhiro Seki ◽  
M. Shozu ◽  
Hajime Hirose ◽  
Toshihiko Sasaki
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Grain Size ◽  
Stress State ◽  
Mechanical Grinding ◽  
Fine Grained ◽  
Residual Stress State ◽  
Analysis Methods ◽  
Average Grain Size ◽  
Fine Grained Steels

The fine-grained rolling steels NFG600 and the conventional usual rolling steels SM490 were processed by sand paper polishing and mechanical grinding to compare the residual stress generated after processing. The average grain size of NFG600 and SM490 is 3 μm and 15μm respectively. Therefore improvement of mechanical properties for such fine-grained steels is expected, it is important to understand the residual stress state of new fine-grained materials with processing. In this study, multi axial stresses of two kinds of specimens after polishing and grinding were measured by three kinds of analysis methods including cos-ψ method. As a result, as for σ33, the stress of NFG was compression, though that of SM490 was tension.

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.

scholarly journals Analysis of the Influence of Surface Modifications on the Fatigue Behavior of Hot Work Tool Steel Components

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7324
Author(s):  
Thomas Wild ◽  
Timo Platt ◽  
Dirk Biermann ◽  
Marion Merklein
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Surface Integrity ◽  
Fatigue Behavior ◽  
Hot Forging ◽  
Surface Modifications ◽  
Bending Test ◽  
Fatigue Properties ◽  
Machining Processes ◽  
Residual Stress State

Hot work tool steels (HWS) are widely used for high performance components as dies and molds in hot forging processes, where extreme process-related mechanical and thermal loads limit tool life. With the functionalizing and modification of tool surfaces with tailored surfaces, a promising approach is given to provide material flow control resulting in the efficient die filling of cavities while reducing the process forces. In terms of fatigue properties, the influence of surface modifications on surface integrity is insufficiently studied. Therefore, the potential of the machining processes of high-feed milling, micromilling and grinding with regard to the implications on the fatigue strength of components made of HWS (AISI H11) hardened to 50 ± 1 HRC was investigated. For this purpose, the machined surfaces were characterized in terms of surface topography and residual stress state to determine the surface integrity. In order to analyze the resulting fatigue behavior as a result of the machining processes, a rotating bending test was performed. The fracture surfaces were investigated using fractographic analysis to define the initiation area and to identify the source of failure. The investigations showed a significant influence of the machining-induced surface integrity and, in particular, the induced residual stress state on the fatigue properties of components made of HWS.

On the Change in Stress State Associated with Bond Coat Oxidation during Heat Treatment of a Thermal Barrier Coating System

1997 ◽  
Author(s):  
Y.C. Tsui ◽  
T.W. Clyne ◽  
R.C. Reed
Keyword(s):  
Heat Treatment ◽  
Stress State ◽  
Oxide Layer ◽  
Thermal Barrier Coating ◽  
Bond Coat ◽  
Driving Forces ◽  
Lateral Strain ◽  
Thermal Barrier ◽  
Residual Stress State ◽  
Barrier Coating

Abstract Thermal barrier coating systems have been heat treated in order to study the oxidation kinetics of the bond coat. All the surfaces of Ni superalloy substrates were sprayed with ~100 μm of a NiCrAlY bond coat, with or without ~250 μm of a ZrO2 top coat. Thermogravimetric analysis (TGA) was used to monitor continuously the mass change as a result of oxidation of the bond coat during heating at 1000°C for 100 hours in flowing air. In addition, some specimens were heated to 1000°C in static air, cooled to room temperature, weighed and re-heated cyclically. The total exposure time was 1000 hours. Rates of weight gain were found to be higher for the cycled specimens, despite the absence of air flow. This is attributed to damage to the oxide film, which was predominantly α-Al2O3, as a consequence of differential thermal contraction stresses. The changing residual stress state during heat treatment was predicted using a previously-developed numerical model. A thin (1 mm) substrate with ~100 μm bond coat and ~250 μm ZrO2 top coat was used in these simulations, which incorporated creep of the bond coat and the lateral strain associated with oxidation. It is concluded from these computations that, while high stresses develop in the oxide layer, the associated driving forces for interfacial debonding remain relatively low, as do specimen curvature changes. It seems likely that coating spallation after extensive oxide layer formation arises because the interface is strongly embrittled as the layer thickens.

Residual Stress State and Fatigue Behaviour of Laser Shock Peened Titanium Alloys

2006 ◽  
pp. 129-134
Author(s):  
I. Altenberger ◽  
Yuji Sano ◽  
M.A. Cherif ◽  
Ivan Nikitin ◽  
Berthold Scholtes
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Titanium Alloys ◽  
Fatigue Behaviour ◽  
Laser Shock ◽  
Residual Stress State
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