Search results for "Hydrogen embrittlement"
showing 7 items of 7 documents
Fatigue crack growth behaviour of four structural steels in air and in a geothermal fluid environment
1992
Abstract In recent years the exploitation of geothermal energy has expanded rapidly in Italy. This has created a requirement for improved drilling technology, to reduce the number of failures occuring in the drills, which is more frequent than in oil wells. This paper deals with the results obtained in FCCR tests of four materials both in air and in two types of aggressive environments. Deterioration takes place by fatigue, corrosion fatigue and hydrogen embrittlement. It is concluded that the steel G105 is a suitable substitute for S135 in drill pipes, and inspections between drillings may be adequate to prevent failure for small-curvature wells.
A Mechano-Chemical Coupling for Hydrogen Diffusion in Metals Based on a Thermodynamic Approach
2014
Hydrogen diffusion in metals is still an ongoing topic of research due to its technical relevance (hydrogen embrittlement, hydrogen storage...). In the last decades, significant progress in understanding the time evolution of the hydrogen concentration in solids was completed. This paper presents a modeling of hydrogen diffusion with a general and thermodynamically based diffusion concept coupled with mechanical and chemical aspects. This model was previously used to simulate the oxidation of a metal [1][2]. This concept has been upgraded to offer a thoroughly macroscopic behavior law used to simulate hydrogen diffusion in metal parts under mechanical loadings. The thermodynamic approach of…
Study of the Hydrogen Embrittlement Sensitivity of an X4CrNiMo 16.5.1 Stainless Steel and the Associated Electron Beam Weld
2015
X4CrNiMo 16.5.1 steel (commercial name APX4) is a low carbon martensitic stainless steel known for its remarkable mechanical characteristics and its good resistance to corrosion. The use of APX4 in the manufacture of high pressure gas vessels requires a thorough understanding of its resistance to Hydrogen Embrittlement (HE) as the gas can contain traces of hydrogen, and martensitic steels, and their welds, are generally very sensitive to HE. This paper deals with the first part of this study, involving the characterization of the microstructure and the mechanical properties of each zone of the electron beam weld (melted zone and four different heat affected zones), and the investigation of …
Towards a Study of Effects on Hydrogen Diffusion into T40 Titanium Alloys
2015
In a global study of titanium alloys behavior in specific aqueous solution (embrittlement, corrosion and corrosion under stresses), the present work focuses on hydrogen diffusion into the metal and the consequences on its microstructure. Two ways of hydrogen charging were used to investigate this issue (gaseous and cathodic charging). The final aim is to determine a fitted method to create an identified microstructure and then to perform accelerated aging tests of titanium U-Bend samples into an autoclave with a specific environment. Hydrogen absorption and formation of titanium hydride have been studied by SEM analyses and by X-ray diffraction methods.
Grain-boundary modelling of hydrogen assisted intergranular stress corrosion cracking
2018
Abstract A novel hybrid strategy for modelling intergranular hydrogen embrittlement in polycrystalline microstructures is proposed. The technique is based on a grain-boundary integral representation of the polycrystalline micro-mechanics, numerically solved by the boundary element method, coupled with an explicit finite element model of the intergranular hydrogen diffusion. The intergranular interaction between contiguous grains in the aggregate is modelled through extrinsic cohesive-frictional traction-separation laws, whose parameters depend on the concentration of intergranular hydrogen, which diffuses over the interface according to the Fick’s second law, inducing the weakening of the i…
Investigating the effect of residual stress on hydrogen cracking in multi-pass robotic welding through process compatible non-destructive testing
2021
Abstract In this paper, the effect of Welding Residual Stress (WRS) on the size and morphology of hydrogen-induced cracks (HIC) is studied. Four samples were manufactured using a 6-axis welding robot and in two separate batches. The difference between the two batches was the clamping system used, which resulted in different amounts of welding deformation and WRS. The hydrogen cracks were intentionally manufactured in the samples using a localised water-quenching method, where water was sprayed over a specific weld pass in a predetermined position. The Phased-Array Ultrasonic Testing (PAUT) system was implemented during the welding process (high-temperature in-process method), to detect the …
Localized hydrogen cracking in the austenitic phase of a duplex stainless steel
1996
The aim of this study is to investigate the role of hydrogen on the mechanical behavior of an austenitic phase, in the particular situation of duplex stainless steels. In these duplex alloys, in presence of hydrogen, the ferritic phase is embrittled by hydrogen and the resistance to cracking is mainly related to the behavior of the austenitic phase. Thus, a discussion of the role of hydrogen at the crack tip of a duplex alloy (as function of the microstructure) has been proposed by T. Perng and C.J. Altester after experiments conducted in gaseous environment. A similar experimental approach has been followed in this study; slow strain rate tests (SSRT) have been performed on duplex stainles…