Author: Edward J. JankowskyPublisher:
ISBN:
Category :
Languages : en
Pages : 9
Book Description
The Hydrogen Embrittlement Susceptibility of a High Strength Steel Containing Uranium
Author: Edward J. JankowskyScientific and Technical Aerospace Reports
Author: U.S. Government Research Reports
Author: Hydrogen Embrittlement (HE) Susceptibility of High Strength Tempered Martensite Steels
Author: Tuhin DasPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
"Hydrogen embrittlement (HE) is identified as a serious problem even after decades of extensive research, in various industries starting from aerospace to fastener. HE is primarily responsible for the degradation of mechanical performances of a number of metals and alloys that are used nowadays. Among them, high strength steels owing to their widespread applications also suffer from HE failures to a great deal. Hence, this thesis focuses on fundamental issues influencing the susceptibility of three different grades of high strength steels designed for fastener applications.The present work includes investigation of mechanical properties both in presence and absence of hydrogen, microstructural characterisations and direct hydrogen quantification. The mechanical property test methodology is a modification of the ASTM F1624 standard test method to determine hydrogen embrittlement threshold in steels, which facilitates a unique approach to investigate the HE susceptibility of these steel grades. The microstructural characterisation process involves scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) to identify the potential hydrogen trap states in microstructure, both qualitatively and quantitatively. Microstructural characterisation also provides useful information to predict local microstructural evolution in the presence of hydrogen and stress. Altogether, a structure-property relationship has been developed for these materials employing a comprehensive investigation process. In addition to it, fracture surface mapping using SEM indicates the mechanisms of failure associated with HE process in these materials. And finally, direct hydrogen quantification methodology using thermal desorption spectroscopy (TDS) provides further experimental evidence to the above-mentioned facts. Thus, in this work a combined approach involving various research techniques and knowledge has been utilised to investigate the susceptibility of the steel grades and rank them according to their performances under the influence of hydrogen." --
The Problem of Hydrogen in Steel
Author: A. R. ElseaPublisher:
ISBN:
Category : Steel
Languages : en
Pages : 42
Book Description
This memorandum introduces the problem of delayed, brittle failures associated with hydrogen in steel, particularly high-strength steel. It is intended to help the steel user determine if he has such a problem. The effects of hydrogen on the mechanical properties of steel are dealt with, and the behavior of material susceptible to delayed, brittle failure is described. Also, the effects of such factors as strength level, magnitude of applied stress, hydrogen content, steel composition, test temperature, and strain rate on hydrogen embrittlement and the susceptibility to hydrogen-induced, delayed, brittle failure are discussed. Possible sources of hydrogen in steel and the types of tests useful in determining the susceptibility to delayed failure are outlined. (Author).
An Integrated Experimental and Numerical Investigation of Hydrogen Embrittlement Susceptibility and Mechanism(s) in Martensitic Steels
Author: Tuhin DasPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
"Hydrogen Embrittlement (HE) is a serious engineering problem for a wide range of industries starting from fastener, oil & gas to aerospace and nuclear. After several decades of extensive research, the HE problem has not been mitigated to a satisfactory level. HE in general, comprises of numerous layers of complexities involving hydrogen metal interactions, hydrogen diffusion and fracture, where each of these phenomena are entangled with one another to a certain degree. High strength martensitic steels which are known for structural and critical engineering applications suffer premature failure due to HE, to a great extent. The interactions of the hydrogen with the complex microstructure of these martensitic steels further enhances the challenges of mitigation. Therefore, the aim of the current research is to develop a better understanding on the susceptibility and mechanism(s) of HE failure of these materials, by studying the key factors affecting their embrittlement. In order to carry out the investigation, a combined approach based on experiments and numerical modeling has been adopted. As a first step, the HE susceptibility of high strength martensitic steels was evaluated using conventional slow strain rate testing methodology, in bending. A stress coupled hydrogen diffusion finite element analysis (FEA) model integrated with a cohesive zone model was developed to simulate the HE test. The primary factors influencing material susceptibility to HE were studied using the model, and the evaluation of critical hydrogen concentration as a metric of material susceptibility was demonstrated. Following the first study, a new approach involving rapid fracture test in four-point bending was proposed to assess HE susceptibility and mechanism(s). Stress coupled hydrogen diffusion FEA was also performed to calculate both stress and hydrogen concentration distributions in the domain, while simulating the test. A mechanistic description rooted in hydrogen enhanced decohesion (HEDE) mechanism was used to corroborate the mechanical test results, and fundamental understanding on the role of strength, microstructure and plasticity influencing HE susceptibility of materials, was also developed.The difference in susceptibility obtained from the rapid HE test, for two different quench and tempered martensite steels with similar strength level and microstructural features were explained using advanced microstructural characterization techniques, FEA and nanoindentation. The role of local microstructure affecting the micromechanics of HE fracture was discussed.Finally, hydrogen diffusion along the interface boundaries in a typical martensitic microstructure was investigated using centroidal Voronoi based FEA model. The influences of packet boundaries and prior austenite grain boundaries on the output hydrogen flux and concentration were studied. The presence of retained austenite in the microstructure affecting the diffusion of hydrogen was also studied. An overall understanding on hydrogen diffusion characteristics in a martensitic microstructure was demonstrated for better prediction of HE fracture.Thus, the current research provides fundamental understanding on the HE susceptibility of martensitic steels, as well as mechanistic insights, that could be instrumental in tackling the HE problem"--
Reports Received by Division of Technical Information Extension
Author: U.S. Atomic Energy Commission. Division of Technical InformationPublisher:
ISBN:
Category : Nuclear energy
Languages : en
Pages : 904
Book Description
Nuclear Science Abstracts
Author: Hydrogen Embrittlement Testing of Ultra High Strength Steels and Stampings by Acid Immersion
Author: Metals Technical CommitteePublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
This standard describes a test method for evaluating the susceptibility of uncoated cold rolled and hot rolled Ultra High Strength Steels (UHSS) to hydrogen embrittlement. The thickness range of materials that can be evaluated is limited by the ability to bend and strain the material to the specified stress level in this specification.Hydrogen embrittlement can occur with any steel with a tensile strength greater than or equal to 980 MPa. Some steel microstructures, especially those with retained austenite, may be susceptible at lower tensile strengths under certain conditions. The presence of available hydrogen, combined with high stress levels in a part manufactured from high strength steel, are necessary precursors for hydrogen embrittlement.Due to the specific conditions that need to be present for hydrogen embrittlement to occur, cracking in this test does not indicate that parts made from that material would crack in an automotive environment. Results from this test should be considered in conjunction with the strain state of the material and the operating environment of the part when selecting any UHSS. Since this test method is comparative, the most information can be gained if a control sample of known performance is evaluated along with the material being studied. Aggressive mass reduction targets for ground vehicles have led to the development of a new generation of high strength steels. Very high tensile strength as well as the presence of retained austenite as a major microstructural constituent make these steels susceptible to hydrogen embrittlement.
Hydrogen Re-embrittlement Susceptibility of Ultra High-strength Steels
Author: D. J. Figueroa GordonPublisher:
ISBN:
Category :
Languages : en
Pages : 290
Book Description