scholarly journals 3D Digital Simulation for Material Damage Mechanism Identification in a Railway Carriage Pressure Vessel

2018 ◽  
Author(s):  
Alessandra Caggiano ◽  
Roberto Teti
Keyword(s):  
Pressure Vessel ◽  
Digital Simulation ◽  
Damage Mechanism ◽  
Material Damage

Effect of Carbide Content on Temper Embrittlement of 2.25Cr1Mo Steel

2016 ◽  
Author(s):  
Yian Wang ◽  
Guoshan Xie ◽  
Zheng Zhang ◽  
Xiaolong Qian ◽  
Yufeng Zhou ◽  
...  
Keyword(s):  
High Temperature ◽  
Pressure Vessel ◽  
High Stress ◽  
Temper Embrittlement ◽  
Damage Mechanism ◽  
Pressure Vessels ◽  
Nondestructive Method ◽  
Operating Conditions ◽  
Low Alloy Steels ◽  
Carbide Content

Temper embrittlement is a common damage mechanism of pressure vessels in the chemical and petrochemical industry serviced in high temperature, which results in the reduction of roughness due to metallurgical change in some low alloy steels. Pressure vessels that are temper embrittled may be susceptible to brittle fracture under certain operating conditions which cause high stress by thermal gradients, e.g., during start-up and shutdown. 2.25Cr1-Mo steel is widely used to make hydrogenation reactor due to its superior combination of high mechanical strength, good weldability, excellent high temperature hydrogen attack (HTHA) and oxidation-resistance. However, 2.25Cr-1Mo steel is particularly susceptible to temper embrittlement. In this paper, the effect of carbide on temper embrittlement of 2.25Cr-1Mo steel was investigated. Mechanical properties and the ductile-brittle transition temperature (DBTT) of 2.25Cr-1Mo steel were measured by tensile test and impact test. The tests were performed at two positions (base metal and weld metal) and three states (original, step cooling treated and in-service for a hundred thousand hours). The content and distribution of carbides were analyzed by scanning electron microscope (SEM). The content of Cr and Mo elements in carbide was measured by energy dispersive X-ray analysis (EDS). The results showed that the embrittlement could increase the strength and reduce the plasticity. Higher carbide contents appear to be responsible for the higher DBTT. The in-service 2.25Cr-1Mo steel showed the highest DBTT and carbide content, followed by step cooling treated 2.25Cr-1Mo steel, while the as-received 2.25Cr-1Mo steel has the minimum DBTT and carbide content. At the same time, the Cr and Mo contents in carbide increased with the increasing of DBTT. It is well known that the specimen analyzed by SEM is very small in size, sampling SEM specimen is convenient and nondestructive to pressure vessel. Therefore, the relationship between DBTT and the content of carbide offers a feasible nondestructive method for quantitative measuring the temper embrittlement of 2.25Cr-1Mo steel pressure vessel.

The Spherical Indentation Approach for Fracture Toughness Evaluation: A Study Based on the Energy Release Rate

2018 ◽  
Author(s):  
Tairui Zhang ◽  
Weiqiang Wang ◽  
Aiju Li
Keyword(s):  
Fracture Toughness ◽  
Energy Release Rate ◽  
Energy Release ◽  
Release Rate ◽  
Damage Mechanism ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Spherical Indentation ◽  
Material Damage ◽  
Fracture Tests

In this study, we investigated the drawbacks of previous studies regarding the evaluation of fracture toughness from spherical indentation tests (SITs). This was achieved by an examination of the material damage mechanism during indentation tests, uniaxial tensile tests, and Mode I/II fracture tests. A new approach based on the energy release rate was proposed in this study to evaluate the fracture toughness of ductile metals. Scanning electron microscope (SEM) observations revealed that the mechanism for material damage during an indentation test was different with the material damage in uniaxial tensile tests and Mode I fracture tests, but similar to that in Mode II fracture tests. Thus, the energy release rate during SITs should be correlated with JIIC. Compared with previous studies, this new proposed method was more consistent with the actual damage mechanism and did not rely on the specific critical damage values. Experiments on SA508, SA533, 15CrMoR, and S30408 revealed that the maximum error from this energy release rate-based approach was no more than 13% when compared with their conventional counterparts (compact tension tests), and thus can meet the precision requirement of engineering applications.

Practice of RBI in Refinery and Chemical Plants of China

2012 ◽  
Author(s):  
Xin Ma ◽  
Yi Xie
Keyword(s):  
Research And Development ◽  
Pressure Vessel ◽  
Cost Control ◽  
Pilot Project ◽  
Damage Mechanism ◽  
Chemical Plants ◽  
Effective Management ◽  
Pilot Projects ◽  
Process Plant ◽  
Standards Development

An overview of Risk-based Inspection (RBI) practice in Refinery and Chemical Plants of China is presented in this paper, including methodology review and research, pilot project, comprehensive implementation, regulations and standards development. The interest for RBI in China resulted from a need for improved safety, cost control and more effective management of inspections. Since 2000, several inspection institutes and universities took the initiative and started working on research and development of an appropriate RBI implementation in China. Several researches and pilot projects during the last few years led to a progressive acceptance of the RBI technique in the country. The results of these projects are new improved regulations on pressure vessel and piping safety techniques, which have been formally approved. The regulations are accompanied by standards on pressure equipment damage mechanism identification and RBI implementation guidance, which are been preparing by CSEI, HGMRI and JSSEI. RBI studies for almost 300 process plant units have already been conducted in China. This paper also presents the RBI methodology and software ORBIT Onshore which has been used in a significant number of RBI studies in China.

Optimized design of wiring scheme for conductive layer in bending area of FOLED

2021 ◽  
pp. 74-84
Author(s):  
Ma Liang ◽  
◽  
Gu Jinan ◽  
Keyword(s):  
Optimal Design ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
Damage Mechanism ◽  
Material Damage ◽  
Optimized Design ◽  
Internal Opening ◽  
Conductive Layer ◽  
Cumulative Plastic Strain ◽  
Three Dimensional Finite Element

In order to solve the problem of wiring breakage in conductive layer caused by fold in bend area of FOLED and improve the efficiency of conductive layer in bend area of FOLED, the wiring scheme of conductive layer in bend area of FOLED is optimized. First of all, the polymer substrate FOLED samples are prepared, and the bending area structure is formed by stacking resin, pin, metal wires and other layers. The equivalent working condition of bending process is analyzed, and the three-dimensional finite element modeling of the bending area of FOLED is completed. According to the simulation analysis results of bending area of FOLED, it is proposed that the optimal design of Resin ply thickness is: the limiting conditions of material damage in conductive layer should be fully considered, and the material damage mechanism should be studied to ensure that the cumulative plastic strain of A-A and B-B positions is smaller at the same time without damage; the optimal design of wiring scheme for conductive layer is: using the square of optimal stress distribution to reduce the fracture angle, and the routing scheme of crossing route type > full filling type> internal opening type should be adopted.

Considerations in Using FEA for Layered Vessel Construction

2010 ◽  
Author(s):  
Trevor G. Seipp ◽  
Mark Stonehouse ◽  
Charles Ormsbee
Keyword(s):  
Pressure Vessel ◽  
Strain Curve ◽  
Material Model ◽  
Damage Mechanism ◽  
Pressure Vessels ◽  
Layered Shell ◽  
Element Analysis ◽  
Circumferential Welds ◽  
Primary Damage ◽  
Selection Of

This paper will examine some of the considerations for using finite element analysis when evaluating pressure vessels constructed using the layered-shell construction. Since the layers of the shell interact through contact and at the circumferential welds, these particular aspects are discussed. Special attention is paid to the proper selection of the initial gap between the layers. The use of an elastic-plastic stress-strain curve is also discussed. Since the material model is non-linear, the path-dependency of the loading sequence is demonstrated, including the inclusion of the initial hydrostatic test. The techniques presented will be demonstrated using an example of a typical layered shell pressure vessel. Since the evaluation of this type of vessel is usually undertaken in a fitness-for-service sense, and fatigue is often the primary damage mechanism, the remaining fatigue life of this typical pressure vessel is calculated.

Elemental mass loss in silicate minerals during x-ray analysis

1990 ◽  
Vol 48 (4) ◽  
pp. 804-805
Author(s):  
P.E. Champness ◽  
R.W. Devenish
Keyword(s):  
Mass Loss ◽  
Current Density ◽  
Damage Mechanism ◽  
Beam Current ◽  
Single Chain ◽  
Plagioclase Feldspar ◽  
X Ray ◽  
Alkali Ions ◽  
Structural Order ◽  
Sheet Silicate

It has long been recognised that silicates can suffer extensive beam damage in electron-beam instruments. The predominant damage mechanism is radiolysis. For instance, damage in quartz, SiO2, results in loss of structural order without mass loss whereas feldspars (framework silicates containing Ca, Na, K) suffer loss of structural order with accompanying mass loss. In the latter case, the alkali ions, particularly Na, are found to migrate away from the area of the beam. The aim of the present study was to investigate the loss of various elements from the common silicate structures during electron irradiation at 100 kV over a range of current densities of 104 - 109 A m−2. (The current density is defined in terms of 50% of total current in the FWHM probe). The silicates so far ivestigated are:- olivine [(Mg, Fe)SiO4], a structure that has isolated Si-O tetrahedra, garnet [(Mg, Ca, Fe)3Al2Si3AO12 another silicate with isolated tetrahedra, pyroxene [-Ca(Mg, Fe)Si2O6 a single-chain silicate; mica [margarite, -Ca2Al4Si4Al4O2O(OH)4], a sheet silicate, and plagioclase feldspar [-NaCaAl3Si5O16]. Ion- thinned samples of each mineral were examined in a VG Microscopes UHV HB501 field- emission STEM. The beam current used was typically - 0.5 nA and the current density was varied by defocussing the electron probe. Energy-dispersive X-ray spectra were collected every 10 seconds for a total of 200 seconds using a Link Systems windowless detector. The thickness of the samples in the area of analysis was normally 50-150 nm.

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