scholarly journals Creep of Thick-Walled Cylinders under Internal Pressure at High Temperature, and Measurement of Residual Stresses

1964 ◽  
Vol 13 (126) ◽  
pp. 163-168 ◽  
Author(s):  
Shuji TAIRA ◽  
Ryoichi KOTERAZAWA ◽  
Ryuichi OHTANI
Keyword(s):  
High Temperature ◽  
Residual Stresses ◽  
Internal Pressure

The structure, phase composition, and residual stresses of diffusion boride layers formed by thermal-chemical treatment on the die steel surface

2021 ◽  
Vol 23 (2) ◽  
pp. 147-162
Author(s):  
Undrakh Mishigdorzhiyn ◽  
◽  
Nikolay Ulakhanov ◽  
Aleksandr Tikhonov ◽  
Pavel Gulyashinov ◽  
...  
Keyword(s):  
Phase Composition ◽  
High Temperature ◽  
Low Temperature ◽  
Residual Stresses ◽  
Diffusion Layer ◽  
Chemical Treatment ◽  
Steel Surface ◽  
Boron Content ◽  
Die Steel ◽  
Temperature Mode

Introduction. Control and management of technological residual stresses (TRS) are among the most critical mechanical engineering technology tasks. Boriding can provide high physical and mechanical properties of machine parts and tools with minimal impact on the stress state in the surface layers. The purpose of this work is to determine the temperature modes of diffusion boriding, contributing to a favorable distribution of TRS in the surface layer of die steel 3Kh2V8F. The paper considers the results of studies on the TRS determination by the experimental method on the UDION-2 installation in diffusion layers on the studied steel surface. Boriding was carried out in containers with a powder mixture of boron carbide and sodium fluoride as an activator at a temperature of 950 °C and 1050 °C for 2 hours. The obtained samples of steels with a diffusion layer were examined using an optical microscope and a scanning electron microscope (SEM); determined the layers' microhardness, elemental, and phase composition. The experiments resulted in the following findings: as the boriding temperature rose from 950 °C to 1050 °C, the diffusion layer's thickness increased from 20 to 105 μm. The low-temperature mode of thermal-chemical treatment (TCT) led to the formation of iron boride Fe2B with a maximum boron content of 6 % and a microhardness up to 1250 HV. A high-temperature mode resulted in FeB formation with a top boron content of 11 % and a microhardness up to 1880 HV. Results and Discussions. It is found that boriding at 950 °C led to a more favorable distribution of compression TRS in the diffusion layer. However, significant TRS fluctuations in the diffusion layer and the adjacent (transitional) zone could affect the operational properties after TCT at a given temperature. An increase in the TCT temperature led to tensile TRS's appearance in the layer's upper zone at a depth of up to 50 μm from the surface. Despite tensile stresses on the diffusion layer surface after high-temperature TCT, the distribution of TCT is smoother than low-temperature boriding.

scholarly journals Effect of Process Parameters and High-Temperature Preheating on Residual Stress and Relative Density of Ti6Al4V Processed by Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 930 ◽  
Author(s):  
Martin Malý ◽  
Christian Höller ◽  
Mateusz Skalon ◽  
Benjamin Meier ◽  
Daniel Koutný ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Residual Stresses ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Stress Reduction ◽  
Laser Melting ◽  
Preheating Temperature ◽  
Laser Velocity

The aim of this study is to observe the effect of process parameters on residual stresses and relative density of Ti6Al4V samples produced by Selective Laser Melting. The investigated parameters were hatch laser power, hatch laser velocity, border laser velocity, high-temperature preheating and time delay. Residual stresses were evaluated by the bridge curvature method and relative density by the optical method. The effect of the observed process parameters was estimated by the design of experiment and surface response methods. It was found that for an effective residual stress reduction, the high preheating temperature was the most significant parameter. High preheating temperature also increased the relative density but caused changes in the chemical composition of Ti6Al4V unmelted powder. Chemical analysis proved that after one build job with high preheating temperature, oxygen and hydrogen content exceeded the ASTM B348 limits for Grade 5 titanium.

Relieving of Residual Stresses in Metal Workpieces at High and Low Temperatures

2021 ◽  
Vol 887 ◽  
pp. 651-656
Author(s):  
Marina V. Polonik
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Residual Stresses ◽  
Low Temperatures ◽  
Creep Properties ◽  
Processing Modes ◽  
Properties Of Materials ◽  
High And Low Temperatures ◽  
Temperature Heating ◽  
High Temperature Heating

On the basis of previously accumulated irreversible deformations, and, consequently, residual stresses, the process of removing residual stresses in metal workpieces under the action of low and high temperatures is simulated. Boundary value problems are solved and here are described regularities that are responsible for removing residual stresses for processing modes: high-temperature heating - cooling, high-temperature heating - holding - cooling, low-temperature heating - holding - cooling. The holding stage is modeled, taking into account the creep properties of materials under Norton creep conditions. According to the dependences of the obtained exact solutions, it is shown that it is the holding process that leads to the relaxation of residual stresses.

Comparison of Internal and Residual Stresses Measured by Strain-Dip Test and XRD during High Temperature Deformation of Al-Mg Solid Solutions

2013 ◽  
Vol 768-769 ◽  
pp. 351-357
Author(s):  
H. Sato ◽  
Y. Enomoto ◽  
K. Omote ◽  
S.I. Tanaka
Keyword(s):  
High Temperature ◽  
Residual Stresses ◽  
Internal Stress ◽  
Applied Stress ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Deformation Condition ◽  
Internal Stresses ◽  
Principal Stresses ◽  
Dip Test

Creep behavior of solid solution alloys are reasonably explained by concepts of the “internal and effective stress of high temperature deformation”. The internal stress is considered to be brought by formation of dislocation substructures, and the dislocation structures should have caused long range stress filed in interior of materials. Thus, residual stresses should also be brought by the same origin. In this paper, measurements of the residual stresses after creep deformation by 2D-Xray method are attempt, and the stresses are compared with so-called the “internal stress of high temperature deformation” measured by strain-dip stress-transient test. Although, the stress tensor depends on the deformation condition, the relation with the applied stress show complex manner at a glance. The maximum principal stresses, however, show relatively smaller than the applied stress, and fairly agree with that measured by strain-dip stress-transient technique. Importance of further considerations of the origin of so-called internal stresses is suggested.

scholarly journals Investigation on origins of residual stresses in Ni-NiO system by X-ray diffraction at high temperature

1993 ◽  
Vol 03 (C9) ◽  
pp. C9-987-C9-997 ◽  
Author(s):  
Chun Liu ◽  
Anne-Marie Huntz ◽  
Jean-Lou Lebrun
Keyword(s):  
High Temperature ◽  
Residual Stresses ◽  
X Ray Diffraction ◽  
X Ray

On Determining Reference Stresses for High Temperature Thin/Thick Tube Bends

2005 ◽  
Author(s):  
Abheek Basu ◽  
Khosrow Zarrabi ◽  
Lawrence Ng
Keyword(s):  
High Temperature ◽  
Internal Pressure ◽  
Explicit Expression ◽  
Finite Volume ◽  
Limit Analysis ◽  
Volume Analysis ◽  
Reference Stress ◽  
First Time

It is well known that tube/pipe bends have some degree of ovality caused during their manufacture. For the first time, based on limit analysis, the authors previously presented an explicit expression for calculation of the reference stress of tube/pipe bends with varying degrees of ovality that are subjected to uniform internal pressure. The present paper assesses this expression using an elastic-creep finite volume analysis. This is due to availability of an in-house finite volume code. It is shown that the references stresses predicted by proposed expression correlate well with those computed using elastic-creep analyses for tube/pipe bends with various degrees of ovality.

Experimental and Analytical Leak Characterization for Axial Through-Wall Cracks in a Liquids Pipeline

2014 ◽  
Author(s):  
Mohamed R. Chebaro ◽  
Nader Yoosef-Ghodsi ◽  
David M. Norfleet ◽  
Jason H. Bergman ◽  
Aaron C. Sutton
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Internal Pressure ◽  
Crack Opening ◽  
Full Scale ◽  
Leak Rate ◽  
Propagation Mechanism ◽  
Element Analysis ◽  
Fea Model ◽  
Experimental Findings

Three pipeline sections containing defects of interest were non-destructively tested in the field, cut out and shipped to a structural laboratory to undergo full-scale testing. The common objectives of the experiments were to determine (1) the leak initiation pressure and (2) the leak rate at various specified internal pressures. While two spools (Specimens A and B) contained through-wall cracks, the third (Specimen C) had a partial through-wall crack with similar characteristics. The capacity of through-wall defects to withstand a level of internal pressure without leaking is due to the resultant local, compressive hoop residual stresses. Specimen C underwent full-scale pressure cycling to further comprehend the crack propagation mechanism in order to correlate it to field operation and analytical fatigue life predictions. To enhance the understanding of the physical crack behaviour as a function of internal pressure, a comprehensive finite element analysis (FEA) model was built using SIMULIA’s Abaqus software. The model inputs incorporated results from the above-mentioned laboratory tests, in addition to extensive radial, circumferential and axial residual stress measurements using the X-ray diffraction (XRD) technique, obtained on three pipe spools cut out from the same line. The resulting crack opening parameters from FEA were input into a closed-form fluid mechanics (FM) model, which was calibrated against a computational fluid dynamics (CFD) model, to determine the corresponding leak initiation pressures and leak rates. These outcomes were then compared to experimental findings. The FEA and FM models were subsequently employed to carry out a parametric study for plausible combinations of feature geometries, material properties, operational pressures and residual stresses to replicate field conditions. The key outcome from this study is the experimental and analytical demonstration that, for given fluid properties and pressures, the leak threshold and leak rate for through-wall cracks are primarily dependent upon the crack geometry and local residual stress distributions.

Sign in / Sign up

Export Citation Format

Share Document