Surface Characterization of a Nitrided Low Alloy Steel

2011 ◽  
Vol 312-315 ◽  
pp. 70-75
Author(s):  
Mourad Keddam ◽  
R. Kouba ◽  
Redoune Chegroune ◽  
B. Bouarour
Keyword(s):  
Alloy Steel ◽  
Surface Characterization ◽  
Surface Hardness ◽  
Xrd Analysis ◽  
Compound Layer ◽  
Iron Nitrides ◽  
Low Alloy Steel ◽  
Nitrogen Concentrations ◽  
Nitriding Potential ◽  
Nitride Layers

The 32CrMoV13 low alloy steel was gas nitrided at 550°C, for three time durations (6.5, 13 and 20 h) and under a variable nitriding potential (1, 2.2 and 6 atm-0.5). The generated nitride layers were characterized by SEM observations, XRD and GDOS analyses as well as microhardness testing. The XRD analysis indicates that the compound layer was composed of and iron nitrides and CrN phase. The surface hardness (inside the compound layer) was found to be dependent on the nitriding potential value, its value increases as rises. It was shown by GDOS analysis that the upper and lower nitrogen concentrations at the (compound layer / diffusion zone) interface are approximatively: 4 and 0.88 wt. % N, respectively.

scholarly journals Microstructure and Fracture Toughness of Nitrided D2 Steels Using Potential-Controlled Nitriding

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 139
Author(s):  
Ki-Hong Kim ◽  
Won-Beom Lee ◽  
Tae-Hwan Kim ◽  
Seok-Won Son
Keyword(s):  
Fracture Toughness ◽  
Electron Backscatter Diffraction ◽  
Surface Hardness ◽  
Compound Layer ◽  
Crack Growth Behavior ◽  
Effective Technique ◽  
Aisi D2 ◽  
Nitriding Potential ◽  
Localized Plastic Deformation ◽  
Backscatter Diffraction

Potential-controlled nitriding is an effective technique for enhancing the life of steel molds and dies by improving their surface hardness and toughness against fatigue damage. In this study, the effect of the nitriding potential on the microstructure and fracture toughness of nitrided AISI D2 steels was investigated. The nitrided layers were characterized by microhardness measurements, optical microscopy, and scanning electron microscopy, and their phases were identified by X-ray and electron backscatter diffraction. As the nitriding potential increased to 2.0 atm−1/2, an increase in the surface hardness and fracture toughness was observed with the growth of the compound layer. However, both the surface hardness and the fracture toughness decreased at the higher nitriding potential of 5.0 atm−1/2 owing to the increased porosity in the compound layers, which mainly consist of the ε (Fe2–3N) phase. Additionally, by observing crack growth behavior, the fracture toughness was analyzed considering the material characteristics of the diffusion and compound layers. The fracture toughness was influenced by the location of the initial Palmqvist cracks due to the localized plastic deformation of the diffusion layer and increased crack length due to the porous compound layer.

Study of Abrasion Resistance of Steels by Micro-Scale Tests

2006 ◽  
Vol 514-516 ◽  
pp. 544-548 ◽  
Author(s):  
D. Braga ◽  
Amilcar Ramalho ◽  
Pedro Nuno Silva ◽  
Albano Cavaleiro
Keyword(s):  
White Layer ◽  
Normal Load ◽  
Surface Hardness ◽  
Compound Layer ◽  
Iron Nitrides ◽  
Abrasive Medium ◽  
Micro Scale ◽  
Coated Materials ◽  
Test Parameters ◽  
Alloy Steels

Steels continue to have a preponderant role in mechanical components under all type of wear solicitations namely, abrasion. The ability of micro-scale abrasion test for evaluating the properties of bulk materials has been widely demonstrated. However, only recently this technique was especially developed to characterize thin-coated materials. This study presents results obtained in micro-scale abrasion tests performed on different low and high alloy steels. These steel samples underwent thermal and chemical (nitriding) treatments with the aim of enhancing their surface hardness. Nitriding parameters were varied so as to obtain different structures (with and without formation of a “white layer” of iron nitrides (ε-Fe2-3N or γ’-Fe4N compound layer). Test conditions such as normal load and concentration of the abrasive medium (SiC particles in distilled water) were changed in order to obtain a 2 or 3 body wear contact type. Results obtained allowed to compare the specific wear rate ks for the different steels and treatments tested as well as to relate the influence of surface hardness and test parameters on the wear mechanisms.

Fatigue Properties of a Low-Alloy Steel with a Nano-Structured Surface Layer Obtained by Severe Mechanical Treatments

2013 ◽  
Vol 577-578 ◽  
pp. 469-472 ◽  
Author(s):  
Seyyed Mostafa Hassani-Gangaraj ◽  
A. Moridi ◽  
Mario Guagliano
Keyword(s):  
Surface Layer ◽  
Alloy Steel ◽  
Fatigue Behavior ◽  
Fatigue Crack Initiation ◽  
Xrd Analysis ◽  
Processing Parameters ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Low Alloy Steel ◽  
Structured Surface

Recent development in mechanical technologies and processes have shown that by performing traditional mechanical treatments with unusual and severe parameters it is possible to obtain metal surfaces characterized by grain size with dimension in the order of 50-100 nm. This confers peculiar and superior properties to the surface layer of material. Since the surface is the usual point of fatigue crack initiation it is expected that the parts treated this way show a better fatigue behavior with respect to the coarse grain materials, even if treated with conventional mechanical treatments. This work explores any opportunities to obtain nano-structured surface layers by means of two popular mechanical treatments, shot peening and deep rolling. To this end particularly severe processing parameters are applied on a low alloy steel fatigue test specimens. The treated surface is characterized by means of optical Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD) analysis of residual stress and roughness measurements. In the end a series of fatigue tests on smooth specimens severely treated, conventionally treated and not treated were executed. The results show the potential benefits of severe mechanical treatments and were interpreted in the light of peculiar effects of these novel treatments on the characteristics of the treated surfaces.

PLASMA NITRIDING OF AISI 5140 LOW ALLOY STEEL ASSISTED WITH HOLLOW CATHODE DISCHARGE AT LOW PRESSURE

2018 ◽  
Vol 25 (04) ◽  
pp. 1850086 ◽  
Author(s):  
ENBO WANG ◽  
HAO YANG ◽  
LIANG WANG
Keyword(s):  
Alloy Steel ◽  
Hollow Cathode ◽  
Plasma Nitriding ◽  
Compound Layer ◽  
Low Pressure ◽  
Optical Microscope ◽  
Hollow Cathode Discharge ◽  
Low Alloy Steel ◽  
X Ray Diffraction ◽  
Diffusion Layers

Plasma nitriding of AISI 5140 low alloy steel was carried at pressures ranging from 100[Formula: see text]Pa–500[Formula: see text]Pa for 4[Formula: see text]h with hollow cathode discharge assistance. The treated samples were characterized by optical microscope, microhardness tester, X-ray diffraction and electrochemical workstation. The results show that the compound layer is about 5[Formula: see text][Formula: see text]m in thickness and the depth of surface hardening layer is about 240[Formula: see text][Formula: see text]m for the sample nitrided at 100[Formula: see text]Pa for 4[Formula: see text]h. The hardness value of nitrided surface is about 830[Formula: see text]HV[Formula: see text], which is about 2.9 times higher than that (290[Formula: see text]HV[Formula: see text]) of the substrate. There is no obvious difference in the thickness of compound and diffusion layers, surface microhardness and phase composition of nitrided layers in comparison with that of samples nitrided at pressure 300 and 500[Formula: see text]Pa used by conventional plasma nitriding. But plasma nitriding with low pressure can effectively reduce the assumption of nitriding gas and amount of exhausted emission.

Evaluation of the Diffusion Coefficient of N in γ' Iron Nitride: Influence of the Nitriding Potential

2009 ◽  
Vol 283-286 ◽  
pp. 133-138 ◽  
Author(s):  
Mourad Keddam ◽  
B. Bouarour ◽  
R. Kouba ◽  
Redoune Chegroune
Keyword(s):  
Diffusion Coefficient ◽  
Cross Sections ◽  
Xrd Analysis ◽  
Compound Layer ◽  
Potential Effect ◽  
Iron Nitride ◽  
Gas Nitriding ◽  
Potential Value ◽  
Nitriding Potential ◽  
Logarithmic Relationship

This work deals with a study of the nitriding potential effect on development of the compound layer during the gas nitriding of Armco Fe samples. The gas nitriding experiments were performed in an atmosphere of partially dissociated gas ammonia (NH3) at 520 °C under a nitriding potential varying from 0.25 to 3.5 atm-0.5 during 2 h. Through this experimental work including XRD analysis, optical and SEM observations of the cross-sections of the treated samples, it is shown that the microstructural nature of the compound layer depends upon the nitriding potential value. By use of the inverse problem based on a diffusion model previously published, it was possible to estimate the diffusion coefficient of N in ' iron nitride as a function of the applied nitriding potential. XRD analysis has shown that the compound layer was composed of iron nitride. A linear semi-logarithmic relationship relating the nitriding potential to the diffusion coefficient of nitrogen in iron nitride was also derived.

Ultra-high surface hardness in nitrogen ion implanted low alloy steel

2002 ◽  
Vol 53 (6) ◽  
pp. 385-391 ◽  
Author(s):  
A.O Olofinjana ◽  
Z Chen ◽  
J.M Bell
Keyword(s):  
Alloy Steel ◽  
High Surface ◽  
Surface Hardness ◽  
Low Alloy Steel ◽  
Nitrogen Ion ◽  
Ion Implanted

On Corrosion Resistance Of Austenitic Stainless Steel Clad Layer on a Low Alloy Steel

2018 ◽  
Vol 32 (3) ◽  
pp. 20
Author(s):  
Manas Kumar Saha ◽  
Ritesh Hazra ◽  
Ajit Mondal ◽  
Santanu Das
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Austenitic Stainless Steel ◽  
Alloy Steel ◽  
Low Alloy Steel ◽  
Clad Layer

Hot deformation simulation of modified AISI 5120 low alloy steel

2017 ◽  
Author(s):  
Diego Boschetti ◽  
Ana Paola Braga ◽  
Paula Fernanda da Silva Farina
Keyword(s):  
Alloy Steel ◽  
Hot Deformation ◽  
Low Alloy Steel ◽  
Deformation Simulation
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