Alloying Effect on Nitrided Case Characteristics of Nitralloy 135M and AISI 4140 Steel

2021 ◽  
Author(s):  
Olga K. Rowan ◽  
Michael A. Pershing
Keyword(s):  
Surface Hardening ◽  
White Layer ◽  
Case Hardening ◽  
Microstructure Development ◽  
Layer Formation ◽  
Alloying Effect ◽  
Aisi 4140 ◽  
Computational Thermodynamic ◽  
Nitrided Case ◽  
Case Characteristics

Abstract Nitriding surface hardening is commonly used on steel components for high wear, fatigue and corrosion applications. Case hardening results from white layer formation and coherent alloy nitride precipitates in the diffusion zone. This paper evaluates the microstructure development in the nitrided case and its effects on the hardness in both the white layer and the substrate for two industry nitriding materials, Nitralloy 135M and AISI 4140. Computational thermodynamic calculations were used to identify the type and amount of stable alloy nitrides precipitation and helped explain the differences in the white layer hardness, degree of porosity at the surface, and the hardening effect within the substrate. Some initial insights toward designing nitriding alloys are shown.

Effects of Sequential Cuts on White Layer Formation and Retained Austenite Content in Hard Turning of AISI52100 Steel

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Xiao-Ming Zhang ◽  
Xin-Da Huang ◽  
Li Chen ◽  
Jürgen Leopold ◽  
Han Ding
Keyword(s):  
Layer Thickness ◽  
Process Parameters ◽  
Retained Austenite ◽  
Hard Turning ◽  
White Layer ◽  
Layer Formation ◽  
White Layer Thickness ◽  
Austenite Content ◽  
Sequential Cuts ◽  
White Layer Formation

This technical brief is the extension of our previous work developed by Zhang et al. (2016, “Effects of Process Parameters on White Layer Formation and Morphology in Hard Turning of AISI52100 Steel,” ASME J. Manuf. Sci. Eng., 138(7), p. 074502). We investigated the effects of sequential cuts on microstructure alteration in hard turning of AISI52100 steel. Samples undergone five sequential cuts are prepared with different radial feed rates and cutting speeds. Optical microscope and X-ray diffraction (XRD) are employed to analyze the microstructures of white layer and bulk materials after sequential cutting processes. Through the studies we first find out the increasing of white layer thickness in the sequential cuts. This trend in sequential cuts does work for different process parameters, belonging to the usually used ones in hard turning of AISI52100 steel. In addition, we find that the white layer thickness increases with the increasing of cutting speed, as recorded in the literature. To reveal the mechanism of white layer formation, XRD measurements of white layers generated in the sequential cuts are made. As a result retained austenite in white layers is identified, which states that the thermally driven phase transformations dominate the white layer formation, rather than the severe plastic deformation in cuts. Furthermore, retained austenite contents in sequential cuts with different process parameters are discussed. While using a smaller radial feed rate, the greater retained austenite content found in experiments is attributed to the generated compressive surface residual stresses, which possibly restricts the martensitic transformation.

Rhenium as a Perspective Anodic Material in Materialogy of Surface at Electric Spark of Alloying

2020 ◽  
Vol 992 ◽  
pp. 615-620
Author(s):  
Valeriy I. Ivanov ◽  
L.A. Konevtsov ◽  
V.F. Aulov
Keyword(s):  
Anode Material ◽  
Surface Hardening ◽  
Materials Science ◽  
Practical Interest ◽  
Steel Grade ◽  
Layer Formation ◽  
Hardening Coatings ◽  
New Development ◽  
Coating Method ◽  
Kinetics Of

Electric spark of alloying – ESA – from the standpoint of materialogy, a new stage in the development of the materials science, is a method of surface hardening that refers to technologies meeting the new development vector of the materials science, including its most important sections – surface materialogy. As an anode material, an unconventional material for the electric-spark coating method (ESA) - rhenium is of practical interest for creating protective and hardening coatings. The results of studies of the formation modes by the method of ESA are given on the surface of steel grade 35 of the alloyed layer and its properties using the anodic material from rhenium is shown. The kinetics of the doped layer formation depending on the ESD regimes, their justification is shown. It is established that with an increase of the frequency of discharge pulses in the range of 1600>fcps>20 Hz, a trend to increase the thickness of the AL hav.AL is observed, and with an increase in energy 1.8>E>0.11 J, on the contrary, there is a trend of its decrease; the latter is associated with a decrease of the pulses frequency with the increase of energy. The obtained series of the efficiency of the ESA process make it possible to predict the achievement of the required parameters of the doped layer using Re as the anode material.

Control of the Compound Zone or White Layer

2003 ◽  
pp. 65-70
Keyword(s):  
Nitric Acid ◽  
White Layer ◽  
Case Depth ◽  
Two Stage ◽  
Zone Formation ◽  
Nitrided Case ◽  
Stage Process ◽  
Standard Solution ◽  
Nitrided Sample

Abstract The compound zone is more commonly known as the white layer, simply because when the nitrided sample is sectioned through the case, and then polished and etched with a standard solution of nital (2 to 5% nitric acid and alcohol), the immediate surface etches out white in appearance above the nitrided case. This chapter focuses on the methods to control the compound zone or white layer. It first provides information on a test to determine the presence of the white layer, and discusses the processes involved in the reduction of the compound zone by the two-stage process. Next, it describes the methods for controlling compound zone formation, and, finally, reviews the factors related to the determination of case depth nitriding.

Nitriding Gears

2000 ◽  
pp. 133-158
Keyword(s):  
Fatigue Life ◽  
Liquid Medium ◽  
Case Studies ◽  
Alloy Steel ◽  
Fatigue Damage ◽  
White Layer ◽  
Case Hardening ◽  
Bending Fatigue ◽  
Gas Nitriding ◽  
Hardening Process

Abstract Nitriding is a case-hardening process used for alloy steel gears and is quite similar to case carburizing. Nitriding of gears can be done in either a gas or liquid medium containing nitrogen. This chapter discusses the processes involved in gas nitriding. It reviews the effects of white layer formation in nitrided gears and presents general recommendations for nitrided gears. The chapter describes the microstructure, overload and fatigue damage, bending-fatigue life, cost, and distortion of nitrided gears. Information on nitriding steels used in Europe and the applications of nitrided gears are also provided. The chapter presents case studies on successful nitriding of a gear and on the failure of nitrided gears used in a gearbox subjected to a load with wide fluctuations.

Influence of Cutting Speed on Surface Plastic Deformation and White Layer Formation of FGH95

2013 ◽  
Vol 589-590 ◽  
pp. 70-75 ◽  
Author(s):  
Jin Du ◽  
Zhan Qiang Liu
Keyword(s):  
Plastic Deformation ◽  
Surface Integrity ◽  
White Layer ◽  
High Reliability ◽  
Cutting Speed ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Layer Formation ◽  
Machined Surface ◽  
White Layer Formation

The superalloy parts in the aeronautical field demand high reliability, which is largely related to surface integrity. Surface integrity generally includes three parameters, such as geometric parameter, mechanical parameter and metallurgical parameter. The paper presents the influence of cutting speed on surface plastic deformation and white layer formation through orthogonal milling of FGH95 superally material. The influence of cutting speed on grain refinement of machined surface is also investigated. It is found that cutting speed has significantly effect on the surface metallurgical characteristic microstructure. The increasing of cutting speed creates severer plastic deformation. Surface plastic shear strain increases with the increasing of cutting speed, while the depth of plastic deformation decreases on contrary. White layer thickness is increased with the increasing of cutting speed. Through statistical analysis for grains number, it can be drawn that the higher the cutting speed, the more serious grains refinement.

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