Effect of equal-channel angular pressing (ECAP) and current density of cathodic hydrogen charging on hydrogen trapping in the low-alloy steel

The aim of the work: the investigation of a fracture mechanism in 09G2S low-alloy steel welded sample with K-shaped grooving on a thermal impact area (TIA) after equal channel angular pressing (ECAP) and tempering + ECAP. There are carried out impact bending tests of 09G2S steel welded samples in which Menage incision is carried in the TIA. Micro-fractograms are presented and the analysis of a fracture mechanism in Menage samples of 09G2S steel with welded joints subjected to impact bending at the temperature of 233ºK is carried out. It is shown that the fracture of welded samples subjected to tempering and the ECAP in the TIA is ductile and characterized with the presence of a dimple micro-relief as well as basic metal fracture. In its turn, 09G2S welded steel strengthened by means of the ECAP as a result of impact bending at the temperature of 233ºK is fractured quasi-brittle in the TIA. At the same time there are observed facets of quasi-microchip, micro-cracks and micro-dimples. A mixed fracture is also characteristic expressed in the interchange of brittle and ductile areas.

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COMBINING OF MATERIAL STRAIN PROCESSING METHODS

Bulletin of Bryansk state technical university ◽

10.30987/article_5db95e85a4a413.79050731 ◽

2019 ◽

Vol 2019 (10) ◽

pp. 19-24

Author(s):

Афанасий Иванов ◽

Afanasiy Ivanov

Keyword(s):

Uniaxial Tension ◽

Alloy Steel ◽

The State ◽

Strength Increase ◽

Low Alloy Steel ◽

Combined Method ◽

Stress Strain ◽

Steel 09G2s ◽

Angular Pressing ◽

Destruction Mechanism

The purpose of the work consists in the investigation of stress-strain properties and destruction mechanism of low-alloy steel 09G2S subjected to extrusion and uniformly channel angular pressing (UCAP). The combined method of Strain processing consists in the successive use of extrusion methods and UCAP. There is shown an example of low-alloy steel 09G2S strengthening with the use of extrusion and UCAP. There are presented data on stress-strain properties and destruction mechanism of steel 09G2S samples at uniaxial tension at the state of delivery and after strengthening. Strength increase and steel plasticity decrease is shown. On the basis of the results of fractal graphics analysis a viscous character of steel 09G2S destruction at the state of delivery and after extrusion and UCAP is defined.

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Tribological Behavior at Dry Sliding by Electric Current of Cu-Cr-S Alloy after Equal Channel Angular Pressing

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.721.430 ◽

2016 ◽

Vol 721 ◽

pp. 430-435 ◽

Cited By ~ 1

Author(s):

Lembit Kommel

Keyword(s):

Electrical Conductivity ◽

Wear Rate ◽

Equal Channel Angular Pressing ◽

Wear Mechanism ◽

Current Density ◽

Thermomechanical Processing ◽

Energy Dispersive Spectrometer ◽

Electrical Current ◽

Angular Pressing ◽

Electrical Current Density

The wear tests of ultrafine-grained Cu-0.68Cr-0.02S energy alloy after equal channel angular pressing followed heat treatment were carried out in alloy-graphite sliding pair system without lubricant at different contact electrical current density. The sutable microstructure, mechanical properties and electrical conductivity of severely deformed alloy have been formed on the samples with different levels of parameters of thermomechanical processing. The microstructure and wear surfaces of the samples have been studied using optical microscope and field emission scanning electron microscope equipped with energy dispersive spectrometer. The results illustrated that the mass loss at wear, wear rate and wear mechanism depend on microstructure, hardness and electrical conductivity of test materials as well as normal pressure stress and electrical current density on the contact surface. The mechanical and physical properties of alloy, testing parameters and their influence on the wear rate as well as wear mechanism are analyzed.

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Hydrogen Induced Mechanical Property Behavior of Dissimilar Weld Metal Interfaces

Volume 3: Materials Technology; Jan Vugts Symposium on Design Methodology of Offshore Structures; Jo Pinkster Symposium on Second Order Wave Drift Forces on Floating Structures; Johan Wichers Symposium on Mooring of Floating Structures in Waves ◽

10.1115/omae2011-50009 ◽

2011 ◽

Cited By ~ 3

Author(s):

Jamey A. Fenske ◽

Martin W. Hukle ◽

Brian D. Newbury ◽

J. R. Gordon ◽

Rick Noecker ◽

...

Keyword(s):

Weld Metal ◽

Strain Rate ◽

Crack Growth ◽

Alloy Steel ◽

Slow Strain Rate ◽

Low Alloy Steel ◽

Hydrogen Charging ◽

Curve Crack ◽

Metal Interfaces ◽

Tearing Resistance

A series of catastrophic failures between alloy 625 weld metal (referred to as ‘A625’) and AISI 8630 low alloy steel forgings (referred to as ‘8630’) on cathodically-charged subsea equipment demonstrate the need to gain a better understanding of the hydrogen-induced tearing resistance of these interfaces as well as similar types of interfaces also currently used in the field. Other dissimilar metal weld interfaces in use include ASTM A182 F22 (referred to as ‘F22’) welded with A625. Similar metal alternatives are also in use, including F22 welded with low alloy steel (referred to as ‘LAS’). Slow strain rate single-edge notched bend tests under hydrogen charging conditions were used to establish ‘R-curve’ crack growth resistance trends for the F22-A625 and F22-LAS weld metal interfaces. Differences in ‘R-curve’ crack growth behavior between the different weld metal interfaces have been observed and compared to R-curve results from 8630-A625 interfaces. The F22-LAS interface demonstrates the most tearing resistance under slow strain rate after hydrogen charging followed by the F22-A625 and then the 8630-A625 interface. Subtle differences between the weld metal microstructures are described and provide a possible explanation regarding the difference in ‘R-curve’ behavior.

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