scholarly journals Influence of carbonitriding conditions on phase composition and residual stresses for 20MnCr5 low alloy steel

2021 ◽  
Vol 47 (2) ◽  
pp. 790-799
Author(s):  
Richard J Katemi ◽  
Jeremy Epp
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Alloy Steel ◽  
Retained Austenite ◽  
Case Depth ◽  
Martensite Phase ◽  
Stress Distributions ◽  
Low Alloy Steel ◽  
The Core ◽  
Core Hardness

This paper reports an investigation of the influence of carbonitriding conditions for 20MnCr5 low alloy steel. Three gaseous carbonitriding conditions were investigated based on different carbon and nitrogen potentials to attain varying levels of carbon between 0.62 and 0.93% mass, whereas for nitrogen between 0.19 and 0.26% mass at the surface. Analysis of retained austenite and residual stress distributions was conducted using X-ray diffraction technique. The effective case depth varied between 900 and 1200 µm. The case microstructures were characterized by varying proportions of retained austenite and martensite, while the core contained essentially bainitic microstructures. The maximum amount of retained austenite which occurred at a depth of 50 µm from the subsurface ranged between 30 and 70% mass and significantly influenced the level of surface micro-hardness whereas the core hardness remaining relatively constant at 450 HV1. High values of residual stresses in martensite phase were observed. The signs, magnitudes, distributions and location of maximum compressive residual stresses were highly influenced by the maximum fraction of retained austenite. Retained austenite of 30%, 50% and 70% mass at the surface lead to peak compressive residue stresses of -280, -227, and -202 MPa at depths of 555, 704, and 890 μm, respectively. Keywords: Carbonitriding, retained austenite, martensite, residual stress, XRD.

scholarly journals Investigations of Residual Stress Distributions in Retained Austenite and Martensite after Carbonitriding of a Low Alloy Steel

2014 ◽  
Vol 996 ◽  
pp. 550-555
Author(s):  
Richard J. Katemi ◽  
Jeremy Epp ◽  
Franz Hoffmann ◽  
Matthias Steinbacher
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Alloy Steel ◽  
Retained Austenite ◽  
Stress Distributions ◽  
Low Alloy Steel ◽  
X Ray Diffraction ◽  
Carbon And Nitrogen ◽  
Stress States ◽  
Nitrogen Contents

Specimens of low alloy steel were carbonitrided under different conditions to attain varying levels of carbon and nitrogen contents. The residual stress depth distribution was evaluated in martensite and retained austenite by X-ray diffraction. Beside standard evaluations, triaxial residual stress states with σ33≠0 in both phases were also considered. High values of residual stresses in both phases were observed. The sign, magnitude and location of maximum compressive residual stresses were greatly influenced by the level of carbon and nitrogen contents.

scholarly journals Influence of Tempering and Cryogenic Treatment on Retained Austenite and Residual Stresses in Carbonitrided 18CrNiMo7-6 Low Alloy Steel

2019 ◽  
Vol 38 (1) ◽  
pp. 71-82
Author(s):  
Richard J. Katemi ◽  
Jeremy Epp
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Alloy Steel ◽  
Retained Austenite ◽  
Cryogenic Treatment ◽  
Thermal Stabilization ◽  
Gas Analysis ◽  
Low Alloy Steel ◽  
Mass Percent ◽  
Carbon And Nitrogen Content

This work investigated the influence of tempering conditions coupled with cryogenic treatment on thermal stabilization of retained austenite and residual stress distributions in carbonitrided 18CrNiMo76 low alloy steel samples. The carbonitriding conditions were set to enable attaining surface carbon and nitrogen content of 0.87 and 0.34 mass.-percent respectively. After carbonitriding, some of the samples were subjected to varying tempering conditions followed by cryogenic treatment at -120 °C using nitrogen gas. Analysis of both retained austenite and residual stresses was conducted using X-ray diffraction. In the as-quenched state, carbonitrided samples contained 52 mass.-percent. Samples that were directly subjected to the cryogenic treatment after quenching retained only about 20 mass.-percent of austenite. Samples subjected to variant tempering conditions coupled with cryogenic treatment retained at least 30 masses.-percent of austenite. A thermal stabilization of retained austenite which increases with increasing temperature was identified. On tempering at 240°C for 14 hours retained austenite becomes unstable and decomposes to bainite leading to the low initial amount of retained austenite before cryogenic treatment. It can be concluded that the tempering process coupled with cryogenic treatment leads to an increasing hardness, to higher compressive residual stresses as well as to a shift of the location of maximum compressive residual stress toward the surface.

Study on Residual-Stress Redistributions During the Process of Manufacture of a Vessel Penetration Set-On Joint

2009 ◽  
Author(s):  
Nobuyoshi Yanagida ◽  
Kazuo Ogawa ◽  
Koichi Saito ◽  
Ed Kingston
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Alloy Steel ◽  
Steel Plate ◽  
Three Dimensional ◽  
Hole Drilling ◽  
Low Alloy Steel ◽  
Butt Weld ◽  
Control Rod ◽  
Inner Surface

The stress-redistribution phenomenon in a vessel penetration set-on joint due to post-weld heat treatment (PWHT) was studied using finite element (FE) analyses and mocked-up experiments. The mocked-up consisted of a nickel-based alloy (NCF600) tube welded onto an alloy-82 cladded, low-alloy steel plate (SQV2A) using an alloy-182 butt weld. The angle of the tube to the plate surface was 45 degrees, simulating a side hill, a control rod drive (CRD), and a stub-tube nozzle attachment used in boiling-water reactor (BWR) plants. PWHT at a temperature of 625 °C was conducted after welding and then the inner surface of the tube was machined. Three-dimensional FE modeling was performed to simulate the cladding, the butt weld, the PWHT, and the inner-surface machining of the tube. Thermal elasto-plastic and thermal elasto-plastic creep analyses were conducted to simulate the process of residual-stress build up and its redistribution by PWHT. To validate the FE analysis, the residual stresses in the mocked-up specimen were experimentally measured using the deep-hole-drilling (DHD) and sectioning methods. The analytical and experimental results revealed that residual-stress redistributions in the mocked-up specimen were different in circumferential positions. High-residual stresses in the low-alloy steel plate were particularly mitigated during the PWHT. The stress relief in the low-alloy steel plate primarily controlled the global stress balance between the cladding, the weld metal, and the stub tube.

The Effectiveness of Cold Rolling for Residual Stress Reduction in Quenched 7050 Aluminium Alloy Forgings

2016 ◽  
Vol 716 ◽  
pp. 521-527 ◽  
Author(s):  
Ran Pan ◽  
Catrin Mair Davies ◽  
Wei Zhang ◽  
Zhusheng Shi ◽  
Thilo Pirling ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Cold Rolling ◽  
Stress Reduction ◽  
Stress Distributions ◽  
Effective Technique ◽  
The Core ◽  
Cold Rolled ◽  
Neutron Diffraction Technique

Residual stresses are often introduced into aluminum alloys through quenching processes performed to generate the required microstructure. Such residual stresses are known to be deleterious to the integrity of the component. Methods to mitigate residual stresses in quenched components are therefore of great importance. Cold rolling has been proposed as an effective technique to remove residual stresses in large components. In this work, the effectiveness of cold rolling in reducing the residual stresses in quenched blocks AA7050 has been quantified using the neutron diffraction technique. Neutron diffraction measurements have been performed on two blocks one quenched and the other quenched & cold rolled block. Comparing the residual stress distributions pre and post rolling it has been found that cold rolling almost eliminates the tensile residual stresses in the core of the block, however it generates large tensile residual stresses d in a shallow region near the surface of the block.

Welding Residual Stresses Depending on Solid-State Transformation Behaviour Studied by Numerical and Experimental Methods

2011 ◽  
Vol 681 ◽  
pp. 85-90 ◽  
Author(s):  
Christoph Heinze ◽  
Arne Kromm ◽  
Christopher Schwenk ◽  
Thomas Kannengiesser ◽  
Michael Rethmeier
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Retained Austenite ◽  
Weld Zone ◽  
High Strength ◽  
Filler Materials ◽  
Stress Distributions ◽  
State Transformation ◽  
Synchrotron Diffraction ◽  
Solid State Transformation

The development of high-strength structural steels with yield strengths up to 1000 MPa results in the requirement of suitable filler materials for welding. Recently designed low transformation temperature (LTT) alloys offer appropriate strength. The martensitic phase transformation during welding induces compressive residual stress in the weld zone. Therefore, the mechanical properties of welded joints can be improved. The present paper illustrates numerical simulation of the residual stresses in LTT-welds taking into account the effect of varying Ms/Mf-temperatures, and therefore different retained austenite contents, on the residual stresses. Residual stress distributions measured by synchrotron diffraction are taken as evaluation basis. A numerical model for the simulation of transformation affected welds is established and can be used for identification of appropriate Ms-temperatures considering the content of retained austenite.

Relationship Between Deep Case Carburizing and Residual Stress in Rolling Contact Service

2021 ◽  
Author(s):  
Jason Meyer ◽  
Stefan Habean ◽  
Dan Londrico ◽  
Justin Sims
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Retained Austenite ◽  
Contact Fatigue ◽  
Case Depth ◽  
Rolling Contact ◽  
Exact Nature ◽  
Residual Stress State ◽  
Compressive Residual Stresses

Abstract The proposition that compressive residual stresses are beneficial in improving the service life of components subject to rolling contact fatigue is well documented. However, the exact nature of the relationship between effective case depth (ECD) and the residual stress state is not well understood for components with deep case depth (>0.050inches, 1.27mm). It is expected that compressive residual stresses will gradually transition to tensile stresses as the case depth increases beyond a threshold value. In addition, the strain-induced transformation of retained austenite and its influence on the residual stress state of components resulting from service will be explored. This study will measure the residual stress state of components prepared with various ECD before and after simulated service with the goal of determining where the compressive to tensile transition occurs. Residual stress and retained austenite measurements will be conducted using X-ray diffraction.

On the Mechanics of Residual Stresses in Girth Welds

2006 ◽  
Vol 129 (3) ◽  
pp. 345-354 ◽  
Author(s):  
P. Dong
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Relative Importance ◽  
Stress Distributions ◽  
Unified Framework ◽  
Joint Geometry ◽  
Weld Residual Stress ◽  
Girth Welds ◽  
Welding Procedure

In this paper, some of the important controlling parameters governing weld residual stress distributions are presented for girth welds in pipe and vessel components, based on a large number of residual stress solutions available to date. The focus is placed upon the understanding of some of the overall characteristics in through-wall residual stress distributions and their generalization for vessel and pipe girth welds. In doing so, a unified framework for prescribing residual stress distributions is outlined for fitness-for-service assessment of vessel and pipe girth welds. The effects of various joint geometry and welding procedure parameters on through thickness residual stress distributions are also demonstrated in the order of their relative importance.

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