White Layer Control on AISI 316L Using Temperature and Gas Nitriding Diffusion Stage Process

2017 ◽  
Vol 11 (8) ◽  
pp. 613
Author(s):  
Komang Astana Widi ◽  
Wardana Wardana ◽  
Wahyono Suprapto ◽  
Yudy Surya Irawan
Keyword(s):  
White Layer ◽  
Aisi 316L ◽  
Gas Nitriding ◽  
Diffusion Stage ◽  
Stage Process ◽  
Layer Control

White Layer Control in Gas Nitriding Process Using an Oxygen Sensor

2012 ◽  
Vol 579 ◽  
pp. 278-286 ◽  
Author(s):  
Han Ming Chen ◽  
Yu Chi Lin ◽  
Yong Chwang Chen
Keyword(s):  
Flow Rate ◽  
Output Voltage ◽  
Oxygen Sensor ◽  
White Layer ◽  
Experimental Results ◽  
Nitriding Process ◽  
Hardness Distribution ◽  
Gas Nitriding ◽  
Layer Control

There are many advantages in nitriding process, but the formation of white layer sometimes results in trouble. The formation of white layer can be reduced by controlling the nitriding atmosphere appropriately. In this experiment, the nitriding atmosphere is prepared by mixing NH3 and H2. An oxygen sensor is used to detect the condition of the atmosphere, and the value of output voltage (EMF) is used as a signal for controlling the flow rate of H2. The experimental results show that the thickness of white layer can be reduced effectively by controlling the flow rate of H2 through the voltage reading of the atmosphere. Meanwhile, the hardness and the depth of nitriding layer could still be maintained. For nitriding at 550 °C, no white layer is formed when EMF is controlled above 1160 mV and a satisfying hardness distribution of the nitriding layer can be obtained when EMF is controlled at 1140 mV.

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.

scholarly journals Effect of Adjusted Gas Nitriding Parameters on Microstructure and Wear Resistance of HVOF-Sprayed AISI 316L Coatings

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1760 ◽  
Author(s):  
Pia Kutschmann ◽  
Thomas Lindner ◽  
Kristian Börner ◽  
Ulrich Reese ◽  
Thomas Lampke
Keyword(s):  
Wear Resistance ◽  
Low Temperature ◽  
Process Management ◽  
Surface Activation ◽  
Aisi 316L ◽  
Spray Coatings ◽  
Gas Nitriding ◽  
Surface Distance ◽  
Diffusion Depth ◽  
Sprayed Coating

Gas nitriding is known as a convenient process to improve the wear resistance of steel components. A precipitation-free hardening by low-temperature processes is established to retain the good corrosion resistance of stainless steel. In cases of thermal spray coatings, the interstitial solvation is achieved without an additional surface activation step. The open porosity permits the penetration of the donator media and leads to a structural diffusion. An inhomogeneous diffusion enrichment occurs at the single spray particle edges within the coating’s microstructure. A decreasing diffusion depth is found with increasing surface distance. The present study investigates an adjusted process management for low-temperature gas nitriding of high velocity oxy-fuel-sprayed AISI 316L coatings. To maintain a homogeneous diffusion depth within the coating, a pressure modulation during the process is studied. Additionally, the use of cracked gas as donator is examined. The process management is designed without an additional surface activation step. Regardless of surface distance, microstructural investigations reveal a homogeneous diffusion depth by a reduced processing time. The constant hardening depth allows a reliable prediction of the coatings’ properties. An enhanced hardness and improved wear resistance is found in comparison with the as-sprayed coating condition.

scholarly journals Effective Duration of Gas Nitriding Process on AISI 316L for the Formation of a Desired Thickness of Surface Nitrided Layer

2014 ◽  
Vol 13 ◽  
pp. 04021
Author(s):  
Hassan R. S. Mahmoud ◽  
Syafiq A. Yusoff ◽  
Azman Zainuddin ◽  
Patthi Hussain ◽  
Mokhtar Ismail ◽  
...  
Keyword(s):  
Nitrided Layer ◽  
Nitriding Process ◽  
Aisi 316L ◽  
Gas Nitriding

scholarly journals Effect of Nitriding Potential KN on the Formation and Growth of a “White Layer” on Iron Aluminide Alloy

2020 ◽  
Author(s):  
Ngoc Minh Le ◽  
Christian Schimpf ◽  
Horst Biermann ◽  
Anke Dalke
Keyword(s):  
Electron Backscatter Diffraction ◽  
White Layer ◽  
Optical Emission ◽  
Compound Layer ◽  
Nitrogen Atmosphere ◽  
Iron Aluminide ◽  
X Ray Diffraction ◽  
Gas Nitriding ◽  
Nitriding Potential ◽  
Backscatter Diffraction

AbstractThis paper investigates the effect of nitriding potential under well-defined gas nitriding conditions on the formation and growth of a compound layer called “white layer” on a FeAl40 (with the composition of 40 at. pct Al) iron aluminide alloy. The nitriding potential was systematically varied in the range of 0.1 to 1.75 bar−1/2 at 590 °C for 5 hour nitriding time with an ammonia-hydrogen-nitrogen atmosphere. Characterization of the microstructure and phases formed within the white layer was performed using optical and scanning electron microscopy, X-ray diffraction (XRD), electron backscatter diffraction (EBSD), and glow discharge optical emission spectroscopy (GDOES). Experimental results indicated that the nitriding potential strongly influences morphology and crystal structure of the white layer. The nitride compound layer consists of the phases γ′-Fe4N, ε-Fe2-3N, and AlN. A mechanism is proposed for the formation and growth of the white layer, depending on the effect of the nitriding potential.

An Investigation of the Melt-Out and Heat Checking Phenomena in Surface Modified Hot Die Steel for Aluminum Die Casting

2006 ◽  
Vol 118 ◽  
pp. 443-450
Author(s):  
Kuk Tae Youn ◽  
Young Mok Rhyim ◽  
Jong Hoon Lee ◽  
Young Sang Na ◽  
Wee Do Yoo ◽  
...  
Keyword(s):  
Crack Initiation ◽  
White Layer ◽  
Nitrided Layer ◽  
Molten Metals ◽  
Die Steel ◽  
Gas Nitriding ◽  
Die Steels ◽  
Shock System ◽  
Surface Modified ◽  
Heat Checking

For hot die steel, failure is mostly caused by heat checking and melt-out on its surfaces which are in contact with molten metals. In the present research, resistances to melt-out and heat checking of surface modified H13 hot die steels, such as gas nitriding(GN) and micro-blasting(MB), were investigated. The evaluation of melt-out behavior was carried out by measuring the mean depth from the original surface after immersion. To examine the thermal fatigue resistance, a cyclic thermal shock system consisting of induction heating and water spray quenching was constructed. The value of Lm is proposed as the index representing the susceptibility to crack initiation and propagation. The melt-out depth was the lowest for the GN treated surface. MB-GN and MB-GN-MB treated specimens also showed good resistance to melt-out. In the case of GN treatment, while the white layer was completely melted out, the diffusion layer still existed even after immersion for 43 hours. This implies that nitriding significantly reduced the rate of melt-out. From the total crack number, it is seen that crack initiation was reduced to the extent of half after surface treatment. This result means that the residual compressive stress and nitrided layer were beneficial to crack initiation resistance.

Electron diffraction detection of ordliking in annealed PbTe thin film

1990 ◽  
Vol 48 (4) ◽  
pp. 1018-1019
Author(s):  
Karimat El-Sayed
Keyword(s):  
Thin Film ◽  
Electron Diffraction ◽  
Lead Telluride ◽  
Structural Basis ◽  
Face Centered Cubic ◽  
X Ray ◽  
Polycrystalline Thin Films ◽  
Stage Process ◽  
Diffraction Patterns ◽  
Face Centered

Lead telluride is an important semiconductor of many applications. Many Investigators showed that there are anamolous descripancies in most of the electrophysical properties of PbTe polycrystalline thin films on annealing. X-Ray and electron diffraction studies are being undertaken in the present work in order to explain the cause of this anamolous behaviour.Figures 1-3 show the electron diffraction of the unheated, heated in air at 100°C and heated in air at 250°C respectively of a 300°A polycrystalline PbTe thin film. It can be seen that Fig. 1 is a typical [100] projection of a face centered cubic with unmixed (hkl) indices. Fig. 2 shows the appearance of faint superlattice reflections having mixed (hkl) indices. Fig. 3 shows the disappearance of thf superlattice reflections and the appearance of polycrystalline PbO phase superimposed on the [l00] PbTe diffraction patterns. The mechanism of this three stage process can be explained on structural basis as follows :

Process \'prǎ|,ses\n: The Action of Moving Forward Progressively from One Point to Another on the Way to Completion

1979 ◽  
Vol 44 (1) ◽  
pp. 3-30 ◽  
Author(s):  
Carol A. Pruning
Keyword(s):  
Process Model ◽  
Communicative Behaviors ◽  
Adult Level ◽  
Remedial Programs ◽  
Stage Process ◽  
The Way

A rationale for the application of a stage process model for the language-disordered child is presented. The major behaviors of the communicative system (pragmatic-semantic-syntactic-phonological) are summarized and organized in stages from pre-linguistic to the adult level. The article provides clinicians with guidelines, based on complexity, for the content and sequencing of communicative behaviors to be used in planning remedial programs.

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