Stress Rupture Research Articles

Effect of Hot Isostatic Pressing on Microstructures and Stress-Rupture Properties of CM 939 Weldable Alloy

Effect of hot isostatic pressing (HIP) treatment on the microstructure and the stress rupture properties of CM 939 Weldable alloy have been investigated. The results shown that the HIP has the function of densification and homogenization, all of the microporosity have been almost removed, the segregation of the alloy have been reduced, the microstructure became better, the stress rupture life of CM 939 Weldable alloy have been obviously improved, Meanwhile, the data dispersion of stress rupture properties have been reduced for the alloy after HIP.

A study of tensile and bending properties of 3D-printed biocompatible materials used in dental appliances

In the last years, a large number of new biocompatible materials for 3D printers have emerged. Due to their recent appearance and rapid growth, there is little information about their mechanical properties. The design and manufacturing of oral appliances made with 3D printing technologies require knowledge of the mechanical properties of the biocompatible material used to achieve optimal performance for each application. This paper focuses on analysing the mechanical behaviour of a wide range of biocompatible materials using different additive manufacturing technologies. To this end, tensile and bending tests on different types of recent biocompatible materials used with 3D printers were conducted to evaluate the influence of the material, 3D printing technology, and printing orientation on the fragile/ductile behaviour of the manufactured devices. A test bench was used to perform tensile tests according to ASTM D638 and bending tests according to ISO 178. The specimens were manufactured with nine different materials and five manufacturing technologies. Furthermore, specimens were created with different printing technologies, biocompatible materials, and printing orientations. The maximum allowable stress, rupture stress, flexural modulus, and deformation in each of the tested specimens were recorded. Results suggest that specimens manufactured with Stereolithography (SLA) and milling (polymethyl methacrylate PMMA) achieved high maximum allowable and rupture stress values. It was also observed that Polyjet printing and Selective Laser Sintering technologies led to load–displacement curves with low maximum stress and high deformation values. Specimens manufactured with Digital Light Processing technology showed intermediate and homogeneous performance. Finally, it was observed that the printing direction significantly influences the mechanical properties of the manufactured specimens in some cases.

Can Oceanic Core Complexed Faults Be Reactivated by Strike-Slip Earthquakes? Rupture and Coulomb Stress Changes from the 2020 Mw 6.6 Vernadsky Earthquake, Equatorial Atlantic

Can Oceanic Core Complexed Faults Be Reactivated by Strike-Slip Earthquakes? Rupture and Coulomb Stress Changes from the 2020 Mw 6.6 Vernadsky Earthquake, Equatorial Atlantic

On the Variations of Phase Interface Microstructure and the Effects on Stress Rupture Property of Nickel-Based Single Crystal Superalloy after Thermal Exposure

On the Variations of Phase Interface Microstructure and the Effects on Stress Rupture Property of Nickel-Based Single Crystal Superalloy after Thermal Exposure

Effect of Solution Treatment on Microstructure and Stress Rupture Properties of Precipitation Hardened In718 Superalloy Fabricated by Laser Powder Bed Fusion Process

Effect of Solution Treatment on Microstructure and Stress Rupture Properties of Precipitation Hardened In718 Superalloy Fabricated by Laser Powder Bed Fusion Process

Dependence of Stress Rupture Properties on Competing Deformation Modes of a Novel Ni-Based Superalloy

Dependence of Stress Rupture Properties on Competing Deformation Modes of a Novel Ni-Based Superalloy

Effect of Carbon Content on the Microstructure and Stress Rupture Properties of Nickel-Based K4750 Superalloy

Effect of Carbon Content on the Microstructure and Stress Rupture Properties of Nickel-Based K4750 Superalloy

Effect of Phosphorous Content on Microstructure and the Stress Rupture Properties of 15cr–15ni Titanium Modified Austenitic Stainless Steel

Effect of Phosphorous Content on Microstructure and the Stress Rupture Properties of 15cr–15ni Titanium Modified Austenitic Stainless Steel

Deformation and Damage Mechanisms During Stress Rupture of Waspaloy after Vacuum Solution Plus Aging Treatment

Deformation and Damage Mechanisms During Stress Rupture of Waspaloy after Vacuum Solution Plus Aging Treatment

Improved strength of carbon nanotube yarn by high temperature jule anealing process with tension

CNT spun yarn is expected to be used for high-strength wire rods, but at present, it does not reach the mechanical strength of carbon fiber, which has already been put into practical use. Recently, it has been proposed that an electric heating method with tension is effective as a method of increasing the strength of CNT spun yarn. In this study, in order to make this method more practical, we introduced a new process to increase the density by passing the CNT spun yarn over ethanol absorbent cotton before heating. By introducing this process, we succeeded in stabilizing the high-temperature heat treatment (3000 K) and succeeded in significantly increasing the strength to a maximum tensile rupture stress of 2.61 GPa (untreated: 1.31 GPa).

ВЛИЯНИЕ ВОЗДЕЙСТВИЯ СВЕРХВЫСОКОЧАСТОТНОГО ИЗЛУЧЕНИЯ НА МЕХАНИЧЕСКИЕ И СТРУКТУРНЫЕ ХАРАКТЕРИСТИКИ ПЛАСТИКА НА ОСНОВЕ ВЫСОКОМОЛЕКУЛЯРНОГО ТЕХНИЧЕСКОГО ПОЛИМЕРА АКРИЛОНИТРИЛ – БУТАДИЕНА – СТИРОЛА

The effect of microwave monitoring of the development and mechanical characteristics of poly(acrylonitrile-butadiene-styrene) plastic has been studied, and the calculated effect of microwave absorption measurement has been carried out. It is shown that with the desire to develop the microwave development of the ability to deform almost twice from 1.2 % for the original sample to 2.7 % for the sample exposed to microwave radiation, i.e. the material becomes more flexible. At values of thermal energy of microwave radiation absorbed by poly(acrylonitrile-butadiene-styrene) plastic from 0 to 750 · 108 J/m3, the rupture stress gradually decreases and, with a further increase to 1560 · 108 J/m3, increases to practically the values for the original sample. An assumption is made that microwave radiation leads to a change in the structure and mechanical characteristics of the material under study as a result of exposure to oxygen from the air.

Major influencing factors for the nucleation of the 15 November 2017 Mw 5.5 Pohang earthquake

The occurrence mechanism and key factors to induce the 15 November 2017 MW5.5 Pohang earthquake are investigated through combined interpretation of active fault zone, stress field evolution, earthquake source properties, fault structure, and spatiotemporal seismicity change. Analysis of historical earthquakes suggests the presence of active faults spawning moderate-size earthquakes around the Pohang Enhanced Geothermal System. The instrumental seismicity suggests that the faults were kept loaded until the occurrence of the Pohang earthquake. The Coulomb stress changes induced by the 2016 ML 5.8 (MW5.4) Gyeongju earthquake and the 2011 MW9.0 Tohoku-Oki earthquake suggest additional stress loading on the faults. The spatial distribution and focal mechanism solutions of mainshock and aftershocks illuminate a complex segmented fault structure. The fault geometry suggests that the fluid injection was made at the northeastern fault-segment conjunction. Numerical modeling of stress transfer and rupture dimension suggests that a ML3.1 (MW3.3) earthquake 7 months before the mainshock loaded the stress of tens of kilopascals around the hypocenter of mainshock. A series of the seismic activities including the Tohoku-Oki earthquake and local moderate-size earthquakes as well as high-pressure fluid injection contributed to the occurrence of the Pohang earthquake.

Stress Rupture Life Prediction Method for Notched Specimens Based on Minimum Average Von Mises Equivalent Stress

Creep tests were carried out on notched plate specimens of nickel-based superalloy GH4169 with different stress concentration coefficients. It was found that the duration of the first stage of the creep curve increases with the increase of stress concentration coefficient, while the fracture ductility decreases with the increase of stress concentration coefficient. To predict the life of notched plate specimens, four constitutive models were used to analyze the stress and strain of the notches. It was found that the average Von Mises equivalent stress (AVES) on the minimum notch section first decreases and then increases with the creep time, resulting in a minimum value. The minimum average Von Mises equivalent stress (MAVES) is considered as the characteristic stress of notched specimens in this paper. The creep life equation is fitted according to the results of creep tests of smooth specimens, and then the predicted life of notched specimens is obtained by substituting the minimum average Von Mises equivalent stress of notched specimens into the creep equation. The prediction results of the four constitutive models are within 2 times the dispersion band, and the three-stage model is within the 1.5 times dispersion band.

A Unique Structure of Highly Stable Interphase and Self‐Consistent Stress Distribution Radial‐Gradient Porous for Silicon Anode

AbstractStress failure and continued growth of the solid electrolyte interface are the main factors contributing to the failure of lithium‐ion batteries with silicon (Si) anode. Conventional porous structures typically result in a reduction in the strength and tap density of Si materials. Due to the high melting point and chemical stability of Si, there are limited methods to prepare its porous structure. Here, a method for preparing core–shell gradient porous Si with a high‐strength core and a high‐porosity shell is presented. The high‐strength core can withstand enormous volume change stress. The rich porous structure of the shell ensures the stable existence of SEI. The Si anode material with a core–shell gradient porous structure delivers a discharge capacity of 2127 mAh g−1 (1488 mAh cm−3) after 100 cycles at 1 A g−1, cycling stability with more than 1059 mAh g−1 even after 500 cycles at 2 A g−1, and a rate capability of 1916 mAh g−1 at 4 A g−1. These results suggest that the core–shell gradient porous structure provides a new research strategy to address the stress rupture and continuous SEI growth in Si‐based anode materials during charge/discharge.

Microstructural stability and mechanical properties of GH742 Ni-based wrought superalloy for turbine disk applications

Microstructural stability and mechanical properties were investigated in a Ni-based wrought superalloy during long-term thermal exposure at 650 °C and 700 °C for up to 7500h. The results demonstrate that the morphology of primary γ′ precipitate has no significant change after long-term thermal exposure, and it exhibits excellent thermal stability both at 650 °C and 700 °C. However, the morphology of secondary γ′ precipitates transformed from complex flower-like to rounded cubic during long-term exposure at 700 °C. The coarsening of tertiary spherical γ′ precipitates occurs with increasing thermal exposure time, and its coarsening behavior is consistent with Ostwald ripening theory. M23C6 carbides coarsen at grain boundaries and form continuous film with increasing time, resulting in the embrittlement of grain boundary. The multimodal distribution of γ′ precipitates results in high strength of the alloy after long-term thermal exposure. Both the strength of the alloy after exposure at 650 °C and 700 °C for 7500 h are not less than that of the alloy after standard heat treatment. The stress rupture lifetime tests at 650 °C/873 MPa increases firstly and then decreases with increasing exposure time at 650 °C and 700 °C. The increase of stress rupture lifetime is attributed to the supplementary precipitation and growth of finest tertiary γ′ precipitates, while the decrease of it is attributed to the γ′ evolution and the coarsen of M23C6 carbides.

Assessment of Creep Properties Using Small Punch Test for a 9%Cr-Mo-Co-B Power Plant Steel

The present study provides a feasible method to evaluate creep properties for a 9%Cr-Mo-Co-B power plant steel by comparing two sets of data obtained from small punch tests and conventional uniaxial creep tests. The method includes three steps: firstly, conduct a series of small punch tests and conventional creep tests in different load and temperature conditions; secondly, convert the load and central deflection data obtained from the small punch test to stress and strain data; thirdly, determinate the best fit correlation factor by comparing the two sets of data in selected creep models. It is found that two sets of data show a similar trend in stress–rupture time relation, stress–minimum strain rate relation and LMP–stress relation. The correlation factor, ksp, can effectively bridge the gap between the load in small punch test and the stress in conventional creep test. For a high-Cr martensitic heat-resistant steel named as CB2, the ksp value 1.4 can make a good prediction for rupture time, while for minimum creep rate and the Larson–Miller parameter, the ksp value 1.4 will lead a conservative prediction in the low-stress range.

Exploration of the competing failure during the stress rupture process for 9Cr-CrMoV dissimilar welded joint

The competing failure mechanism between the heat affected zone (HAZ) of CrMoV steel and weld metal (WM) was found by the stress rupture tests for the 9Cr-CrMoV dissimilar welded joints. The stress rupture occurred in the HAZ of CrMoV steel for the welded joint by the 9Cr steel without element W, yet the failure location shifted to the WM for the welded joint by the 9Cr steel with element W. The precipitates in the WM were mainly the Cr- and Mo-rich M23C6 type carbides. While the W-rich particles were detected in the region of the WM near the fusion line. The partially melted BM2 and its movement into the WM during welding could trigger the formation of the W-rich particles. Thus, the formation of the harder and more brittle W-rich particles in the WM near the fusion line is considered as the crucial factor to result in the failure transition.

Coupled effect of temperature and stress on the microstructure and stress rupture behavior of 9% Cr-CrMoV dissimilar welded joints

Based on the practical application requirements, the weld rotor was chosen as a preferable candidate to adapt to the higher steam temperature. In this study, the rupture behavior and fracture mode for the 9% Cr-CrMoV dissimilar welded joints are investigated. The specimens both rupture in the heat affected zone of CrMoV steel with a ductile rupture mode. The rupture time of the specimen under lower stress at higher temperature is shorter than that under higher stress at lower temperature. Additionally, the microstructure observation shows that the increased temperature can accelerate the precipitation and growth of the second phase particles. The micro-voids caused by these particles can reduce the ductility of the welded joint and resultantly lead to the premature fracture.

Effects of W Addition on Microstructure and 650 °C Mechanical Properties of Ti-Al-Sn-Zr-Mo-Nb-W-Si Alloy

The influence of W addition on microstructure and mechanical properties of Ti-Al-Sn-Zr-Mo-Nb-W-Si high temperature titanium alloys are investigated by optical microscope (OM), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), tensile tests and large stress endurance tests at 650 °C. The results show that W is mainly solubilized in β phase. Microstructure observations indicate an obvious reduction in the size of transformed β structure (βt), primary α phase (αp) and the thickness of secondary lamellar α phase (αL), with the increase of W content. It is also observed that adding more W could improve the elongation, tensile strength and large stress rupture properties at 650 °C. However, combined with previous research, adding more β stabilizing elements could refine the size of each phase, which will be detrimental to the high temperature yield strength of the alloy. Therefore, in order to reasonably utilize the strengthening effect of W and make the alloy have high yield strength and tensile strength at 650 °C, its content should be controlled between 1 ~ 2 wt%

On the impact of post weld heat treatment on the microstructure and mechanical properties of creep resistant 2.25Cr\u20131Mo\u20130.25V weld metal

Creep resistant low-alloyed 2.25Cr-1Mo-0.25V steel is typically applied in hydrogen bearing heavy wall pressure vessels in the chemical and petrochemical industry. For this purpose, the steel is often joined via submerged-arc welding. In order to increase the reactors efficiency via higher operating temperatures and pressures, the industry demands for improved strength and toughness of the steel plates and weldments at elevated temperatures. This study investigates the influence of the post weld heat treatment (PWHT) on the microstructure and mechanical properties of 2.25Cr-1Mo-0.25V multi-layer weld metal aiming to describe the underlying microstructure-property relationships. Apart from tensile, Charpy impact and stress rupture testing, micro-hardness mappings were performed and changes in the dislocation structure as well as alterations of the MX carbonitrides were analysed by means of high resolution methods. A longer PWHT-time was found to decrease the stress rupture time of the weld metal and increase the impact energy at the same time. In addition, a longer duration of PWHT causes a reduction of strength and an increase of the weld metals ductility. Though the overall hardness of the weld metal is decreased with longer duration of PWHT, PWHT-times of more than 12 h lead to an enhanced temper resistance of the heat-affected zones (HAZs) in-between the weld beads of the multi-layer weld metal. This is linked to several influencing factors such as reaustenitization and stress relief in the course of multi-layer welding, a higher fraction of larger carbides and a smaller grain size in the HAZs within the multi-layer weld metal.