Hydrogen Brittleness of Austenitic Steels

2010 ◽  
Vol 638-642 ◽  
pp. 104-109 ◽  
Author(s):  
Valentin G. Gavriljuk ◽  
Vladyslav N. Shyvanyuk ◽  
S. M. Teus
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Hydrogen Embrittlement ◽  
Line Tension ◽  
Austenitic Steels ◽  
Alloying Elements ◽  
Hydrogen Brittleness ◽  
Conduction Electrons ◽  
Electronic Concept ◽  
Dislocation Sources

The electronic concept for hydrogen embrittlement (HE) of austenitic steels is developed based on the hydrogen-caused increase of the concentration of free (i.e. conduction) electrons. It is shown that, as consequence, the shear module locally decreases, which in turn leads to the decrease in the stress for activation of dislocation sources, the line tension of dislocations, the distance between the dislocations in pileups and, in consistency with the theory of hydrogen-enhanced localized plasticity (HELP), promotes the reversible hydrogen brittleness. The analysis of the electronic and elasticity approaches to HELP is carried out using the experimental data. The effect of alloying elements on the mechanical properties is studied and a concept for design of hydrogen-resistant austenitic steels is proposed.

Mechanism of Hydrogen Embrittlement of Austenitic Steels

2007 ◽  
Vol 539-543 ◽  
pp. 4249-4254 ◽  
Author(s):  
V. Shivanyuk ◽  
Valentin G. Gavriljuk ◽  
Jacques Foct
Keyword(s):  
Hydrogen Embrittlement ◽  
Line Tension ◽  
Austenitic Steels ◽  
Hydrogen Atoms ◽  
Conduction Electrons ◽  
Metallic Character ◽  
Spin Resonance ◽  
Localization Of Plastic Deformation ◽  
Dislocation Sources ◽  
Strain Dependent

Three main hypotheses of hydrogen embrittlement (HE) of austenitic steels are discussed based on the studies of the interatomic interactions, hydrogen-induced phase transformations and dislocations properties. Measurements of electron spin resonance and ab initio calculations of the electron structure witness that the concentration of conduction electrons increases due to hydrogen, which enhances the metallic character of interatomic bonds. The hypothesis of brittle hydrogen-induced phases is disproved by the studies of the silicon-alloyed steels: the silicon-caused increase in the fraction of the εH martensite is accompanied by the decrease of HE. Studies of strain-dependent internal friction have shown the hydrogen-caused decrease in the start stress of microplasticity and increase in the velocity of dislocations in accordance with HELP hypothesis. A mechanism of HELP is proposed based on the hydrogencaused enhancement of the metallic character of interatomic bonds, which results in the local decrease of the shear modulus within the hydrogen atmospheres round the dislocations. As consequence, the line tension of the dislocations followed by the hydrogen atoms decreases, which finds its expression in the early start of dislocation sources, decreased distance between dislocations in the pile-ups and increased velocity of dislocations. A mechanism of localization of plastic deformation is proposed based on the observations of the hydrogen-enhanced concentration of equilibrium vacancies.

ALLEGHENY LUDLUM TYPE 205

Alloy Digest ◽  
1997 ◽  
Vol 46 (10) ◽  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Magnetic Permeability ◽  
Cold Working ◽  
High Strength ◽  
Heat Treating ◽  
Austenitic Steels

Abstract Allegheny Stainless Type 205 is a chromium-manganese nitrogen austenitic high strength stainless steel that maintains its low magnetic permeability even after large amounts of cold working. Annealed Type 205 has higher mechanical properties than any of the conventional austenitic steels-and for any given strength level, the ductility of Type 205 is comparable to that of Type 301. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fatigue. It also includes information on corrosion resistance as well as heat treating, machining, and joining. Filing Code: SS-640. Producer or source: Allegheny Ludlum Corporation. Originally published March 1996, revised October 1997.

scholarly journals An Additive Model to Predict the Rheological and Mechanical Properties of Polypropylene Blends Made by Virgin and Reprocessed Components

Recycling ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 2
Author(s):  
Francesco Paolo La Mantia ◽  
Maria Chiara Mistretta ◽  
Vincenzo Titone
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Additive Model ◽  
Industrial Process ◽  
Theoretical Predictions ◽  
Experimental Values ◽  
Polypropylene Blends ◽  
Polypropylene Sample

In this work, an additive model for the prediction of the rheological and mechanical properties of monopolymer blends made by virgin and reprocessed components is proposed. A polypropylene sample has been reprocessed more times in an extruder and monopolymer blends have been prepared by simulating an industrial process. The scraps are exposed to regrinding and are melt reprocessed before mixing with the virgin polymer. The reprocessed polymer is, then, subjected to some thermomechanical degradation. Rheological and mechanical experimental data have been compared with the theoretical predictions. The results obtained showed that the values of this simple additive model are a very good fit for the experimental values of both rheological and mechanical properties.

scholarly journals A Short Review on the Phase Structures, Oxidation Kinetics, and Mechanical Properties of Complex Ti-Al Alloys

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1677
Author(s):  
Hooi Peng Lim ◽  
Willey Yun Hsien Liew ◽  
Gan Jet Hong Melvin ◽  
Zhong-Tao Jiang
Keyword(s):  
Mechanical Properties ◽  
Oxidation Kinetics ◽  
Mass Gain ◽  
Short Review ◽  
Al Alloys ◽  
Alloying Elements ◽  
Isothermal Exposure ◽  
Solid Solution Strengthening ◽  
Phase Structures ◽  
Solution Strengthening

This paper reviews the phase structures and oxidation kinetics of complex Ti-Al alloys at oxidation temperatures in the range of 600–1000 °C. The mass gain and parabolic rate constants of the alloys under isothermal exposure at 100 h (or equivalent to cyclic exposure for 300 cycles) is compared. Of the alloying elements investigated, Si appeared to be the most effective in improving the oxidation resistance of Ti-Al alloys at high temperatures. The effect of alloying elements on the mechanical properties of Ti-Al alloys is also discussed. Significant improvement of the mechanical properties of Ti-Al alloys by element additions has been observed through the formation of new phases, grain refinement, and solid solution strengthening.

Stress Optical Behavior of Rubber Networks at Large Deformations

1966 ◽  
Vol 39 (5) ◽  
pp. 1436-1450
Author(s):  
K. J. Smith ◽  
D. Puett
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Statistical Theory ◽  
Natural Rubber ◽  
Large Deformations ◽  
Strong Support ◽  
Theoretical Development ◽  
Statistical Parameters ◽  
Strain Behavior ◽  
Optical Behavior

Abstract The birefringence of natural rubber networks at large deformations has been investigated experimentally and compared with the simultaneously determined stress—strain behavior. Our data is analyzed using a statistical theory of flexibly jointed chains, derived herein, which is believed to be more significant for the particular range of deformation used than the theories of Treloar and of Kuhn and Grün. In addition, the experimental data of Saunders is commented on in light of our theoretical development. We find that for network extensions exceeding those of the Gaussian region there is little correlation between the observed and theoretical behavior of the stress and birefringence (based upon the theory of flexibly jointed chains) and this lack of agreement is attributed to the fact that the statistical parameters needed for the description of the optical chain properties differ in magnitude from those required for the mechanical properties. Furthermore, by considering the points of incipient crystallization the strain behavior of the stress-optical coefficient is highly indicative of nonGaussian behavior rather than crystallization, and therefore yields strong support for the position that nonGaussian behavior does exist in rubber networks.

Mathematical Model of the Sintering Process of Iron-Copper Bearings

2007 ◽  
Vol 23 ◽  
pp. 119-122
Author(s):  
Cristina Teișanu ◽  
Stefan Gheorghe ◽  
Ion Ciupitu
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Mathematical Model ◽  
Regression Analysis ◽  
Function Optimization ◽  
Chemical Compositions ◽  
Sintering Process ◽  
Molybdenum Disulphide ◽  
Iron Copper ◽  
Antifriction Properties

The most important features of the self-lubricating bearings are the antifriction properties such as friction coefficient and wear resistence and some mechanical properties such as hardness, tensile strength and radial crushing strength. In order to improve these properties new antifriction materials based on iron-copper powders with several additional components (tin, lead and molybdenum disulphide) have been developed by PM techniques. To find the optimal relationship between chemical compositions, antifriction and mechanical properties, in this paper a mathematical model of the sintering process is developed, which highlighted the accordance of the model with data by regression analysis. For the statistical processing of the experimental data the VH5 hardness values of the studied materials were considered. The development of mathematical model includes the enunciation of the model, the establishment of the performance function (optimization) and the establishment of the model equations and verifying. The accordance of the model with experimental data has been highlighted by regression analysis

Tests on Mechanical Properties and Anti-Penetration Performance of Steel-Fiber Reactive Powder Concrete

2013 ◽  
Vol 671-674 ◽  
pp. 1761-1765
Author(s):  
Yong Liu ◽  
Chun Ming Song ◽  
Song Lin Yue
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Fracture Toughness ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Steel Fiber ◽  
Reactive Powder Concrete ◽  
Calculation Results ◽  
Reactive Powder ◽  
Penetration Tests

In order to get mechanical properties ,some RPC samples with 5% steel fiber are tested, many groups data were obtained such as compressive strength, shear strength and fracture toughness. And a group of tests on RPC with 5% steel-fiber under penetration were also conducted to validate the performance to impact. The penetration tests are carried out by the semi-AP projectiles with the diameter of 57 mm and earth penetrators with the diameter of 80 mm, and velocities of the two kinds of projectiles are 300～600 m/s and 800～900 m/s, respectively. By contrast between the experimental data and the calculation results of C30 reinforced concrete by using experiential formula under penetration, it shows that the resistance of steel-fiber RPC to penetration is 3 times as that of general C30 reinforced concrete.

Effect of Hydrogen on Mechanical Properties of Pipeline API 5L X70 Steel

2011 ◽  
Vol 146 ◽  
pp. 213-225 ◽  
Author(s):  
T. Bellahcene ◽  
J. Capelle ◽  
Méziane Aberkane ◽  
Z. Azari
Keyword(s):  
Mechanical Properties ◽  
Hydrogen Embrittlement ◽  
Hydrogen Absorption ◽  
Fatigue Tests ◽  
The Finite Element Method ◽  
Effective Distance ◽  
Bending Tests ◽  
Fatigue Initiation ◽  
Api 5L X70 Steel ◽  
Special Soil

The aim of this work is to study the effects of hydrogen absorption on mechanical properties of pipe API 5L X70 steel. This study is conducted in special soil solution NS4 with pH 6.7 It show that the tensile properties like yield stress, ultimate strength and elongation at failure reduced under hydrogen embrittlement. Several fatigue tests (three (03) points bending tests) on roman tile specimens with notch are performed. Fatigue initiation is detected by acoustic emission. A comparison between specimens electrolytically charged with hydrogen and specimens without hydrogen absorption is made and it has been noted that fatigue initiation time is reduced when hydrogen embrittlement occurs. The field of elastoplastic stresses near the notch is computed by the finite-element method with the Abaqus software package. Effective distance and stress are calculated with the volumetric approach and the Notch intensity Factor of the roman tile specimen is determined for each loading value used in our tests.

Sign in / Sign up

Export Citation Format

Share Document