Nitriding

2005 ◽  
pp. 227-244
Keyword(s):  
Heat Treatment ◽  
Surface Hardening ◽  
Elevated Temperatures ◽  
Surface Hardness ◽  
Ion Nitriding ◽  
Gear Teeth ◽  
Gas Nitriding ◽  
Aerospace Applications ◽  
High Shock ◽  
Hardening Heat Treatment

Abstract Nitriding is a surface hardening heat treatment that introduces nitrogen into the surface of steel while it is in the ferritic condition. Gas nitriding using ammonia as the nitrogen-carrying species is the most commonly employed process and is emphasized in this chapter. Nitriding produces a wear- and fatigue-resistant surface on gear teeth and is used in applications where gears are not subjected to high shock loads or contact stress. It is useful for gears that need to maintain their surface hardness at elevated temperatures. Gears used in industrial, automotive, and aerospace applications are commonly nitride. This chapter discusses the processes involved in gas, controlled, and ion nitriding.

Troubleshooting

2003 ◽  
pp. 185-191
Keyword(s):  
Heat Treatment ◽  
Treatment Process ◽  
Salt Bath ◽  
Heat Treatment Process ◽  
Ion Nitriding ◽  
Gas Nitriding ◽  
Salt Bath Nitriding

Abstract Problems often occur during nitriding, just as with any other heat-treatment process. They can take the form of process problems, steel problems, and machining problems. Troubleshooting is a process of elimination and plain detective work. One must be both observant and systematic during the troubleshooting procedure. This chapter discusses the procedure for troubleshooting problems with gas nitriding, salt bath nitriding, and ion nitriding.

scholarly journals The Influence of Post-Heat-Treatments on the Tensile Strength and Surface Hardness of Selective Laser Melted AlSi10Mg

2017 ◽  
Vol 370 ◽  
pp. 171-176 ◽  
Author(s):  
Leonhard Hitzler ◽  
Amandine Charles ◽  
Andreas Öchsner
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Precipitation Hardening ◽  
Elevated Temperatures ◽  
Surface Hardness ◽  
Heat Treatments ◽  
Age Hardening ◽  
Material Strength ◽  
Post Heat Treatment ◽  
Treatment Procedure

Recent investigations revealed major fluctuations in the material properties of selective laser melted AlSi10Mg, which corresponded with the varying precipitation-hardening state of the microstructure, caused by the differing dwell times at elevated temperatures. It was indicated that a subsequent heat treatment balances the age-hardening and results in a homogenized material strength. In order to further investigate this statement selective laser melted AlSi10Mg samples were subject to multiple post-heat-treatments. Subsequently, the surface hardness and tensile strength was determined and compared with the as-built results. The post-heat-treatment led to an arbitrary occurrence of rupture, indicating a successful homogenization, coupled with a remarkable improvement in ductility, but to the costs of a lowered tensile strength, which was highly dependent on the chosen heat-treatment procedure.

Surface Hardening Treatment in Use of CO Gas and Post-Heat Treatment in C.P. Titanium and Titanium Alloys

2006 ◽  
Vol 118 ◽  
pp. 109-114 ◽  
Author(s):  
Y.Z. Kim ◽  
T. Murakami ◽  
Takayuki Narushima ◽  
Yasutaka Iguchi ◽  
Chiaki Ouchi
Keyword(s):  
Heat Treatment ◽  
Titanium Alloys ◽  
Layer Thickness ◽  
Surface Hardening ◽  
Surface Hardness ◽  
Type Alloy ◽  
Post Heat Treatment ◽  
Maximum Surface ◽  
Hardening Treatment ◽  
Co Gas

Surface hardening treatment of titanium materials in use of CO gas was studied including investigation of post heat treatment under vacuum. C.P. titanium, α+β type SP-700 alloy with Ti-4.5%Al-3%V-2%Mo-2%Fe and β type alloy with Ti-15%Mo-5%Zr-3%Al were used. Surface hardening was conducted by heating these materials at 1073K for 21.6ks in Ar-5%CO gas. Subsequently, specimens subjected to surface hardening were heated at 1073k for various time periods under vacuum. While the maximum surface hardness value was the largest in C.P. titanium and the least in SP-700 alloy, hardening layer thickness was the thickest in β type alloy and the thinnest in C.P. titanium. Surface hardening in C.P. titanium was brought about by solid solution hardening due to oxygen and carbon. Enrichment of these elements in the surface layer of both titanium alloys caused continuous variations of the microstructure such as β to α+β, or their volume fractions in the surface hardening layer. Post heat treatment at 1073K increased the maximum surface hardness and hardening layer thickness with an extension of the heating time in C.P. titanium, but the surface maximum hardness decreased continuously in β type titanium alloy. Post heat treatment could remove the thin oxide layer formed by surface hardening treatment.

Through-Hardening Gears

2000 ◽  
pp. 21-32
Keyword(s):  
Heat Treatment ◽  
Case History ◽  
High Surface ◽  
Surface Hardness ◽  
Factors Affecting ◽  
History Of ◽  
Gear Rack ◽  
Design And Manufacture ◽  
Hardening Heat Treatment ◽  
Quenching And Tempering

Abstract Through-hardening heat treatment is generally used for gears that do not require high surface hardness. In through hardening, gears are first heated to a required temperature and then cooled either in the furnace or quenched in air, gas, or liquid. Four heat treatment methods are primarily used for through-hardened gears: annealing, normalizing and annealing, normalizing and tempering, and quenching and tempering. This chapter begins with a discussion of these through-hardening processes. This is followed by sections providing some factors affecting the design and hardness levels of through-hardened gears. Next, the chapter reviews the considerations related to distortion of through-hardened gears. It then discusses the applications of through-hardened gears. Finally, the chapter presents a case history of the design and manufacture of a through-hardened gear rack.

Thermal diffusion chromium plating of structural carbon steel 20 by high frequency currents

2021 ◽  
pp. 137-145
Author(s):  
N. I. Kitaev ◽  
Yu. V. Yakimovich ◽  
M. Yu. Shigaev ◽  
S. Ya. Pichkhidze
Keyword(s):  
High Frequency ◽  
Surface Hardness ◽  
Chromium Powder ◽  
Gear Teeth ◽  
Chromium Plating ◽  
High Shock ◽  
Temperature Diffusion ◽  
Diffusion Metallization ◽  
Steel 20 ◽  
Structural Carbon Steel

To increase the service life of the gear teeth made of steel 20, operating under high shock loads, their main surfaces were subjected to high-temperature diffusion metallization, namely, chromium plating with high-frequency currents. As a result of diffusion metallization, the surface hardness increased 5.1–5.4 times – from 156–159 HV to 800–866 HV, and the strength level 3.3 times – from 250 to 820 mAh. Optimal parameters for the diffusion metallization: current I = 0.25–0.3 kA, power Pe = 8–10 kW, hardening τ = 8–10 min. By the method of scanning electron microscopy, it was found that after diffusion saturation of the surface of the gear teeth with chromium, the steel has a homogeneous structure with clearly pronounced transition layers, the average thickness of the diffusion layer was 0.06 mm. Energy dispersive analysis showed that after diffusion metallization with chromium powder, the basic composition of the steel remained constant, only the qualitative ratio of the components changed. X-ray phase analysis revealed the presence of an αFe-phase with the incorporation of Cr on the surface of the sample.

MST 2.5Al-16V

Alloy Digest ◽  
1960 ◽  
Vol 9 (2) ◽  
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Shear Strength ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Base Alloy ◽  
Heat Treating ◽  
Age Hardening ◽  
Temperature Performance ◽  
Hardening Heat Treatment

Abstract MST 2.5A1-16V is a titanium-base alloy having a favorable combination of strength, formability and resistance to creep at elevated temperatures. It responds to an age-hardening heat treatment. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and compressive and shear strength as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ti-24. Producer or source: Mallory-Sharon Metals Company.

Using the Vacuum Ion Nitriding Process to Improve the Quality of 38CrMoAIA Cylinder

2015 ◽  
Vol 1089 ◽  
pp. 93-96
Author(s):  
Liang Zhi Zhang ◽  
Han Zhang ◽  
Lin Yao Ding
Keyword(s):  
Mass Production ◽  
Surface Hardness ◽  
Cylinder Liner ◽  
Nitriding Process ◽  
Good Effect ◽  
Ion Nitriding ◽  
Size Change ◽  
Gas Nitriding ◽  
Hardness Gradient

In order to replace traditional gas nitriding with vacuum ion nitriding process, the 38CrMoAIA cylinder is used for the experimental research. Based on the 10 groups of cylinder specimen analysis of experimental results, surface hardness, hardness gradient, brittleness levels, nitriding depth and size change all meet the requirements of the technology of the cylinder liner. Aiming at the important link in the experiment, some problems needing attention in the process of nitride are put forward. Vacuum ion nitriding due to mature technology, good effect of nitride can be applied to mass production.

scholarly journals Physical Alteration and Color Change of Granite Subjected to High Temperature

2021 ◽  
Vol 11 (19) ◽  
pp. 8792
Author(s):  
Andor Németh ◽  
Ákos Antal ◽  
Ákos Török
Keyword(s):  
Heat Treatment ◽  
Bulk Density ◽  
Wave Velocity ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Color Change ◽  
Surface Hardness ◽  
P Wave ◽  
Ultrasound Wave ◽  
Surface Strength

Cylindrical specimens obtained from the monzogranite host rock of the National Radioactive Waste Repository of Hungary were tested at room temperature and 250 °C, 500 °C, and 750 °C of heat treatment. Reflectance spectra (color), bulk density, Duroskop surface hardness, and ultrasound-wave velocity values were measures before and after thermal stress. According to CIE L*a*b* colorimetric characteristics, the specimens’ color became brighter and yellower after the heat treatment. At 750 °C, a significant volume increase was recorded linked to the formation of macro-cracks, and it also led to the drop in bulk density. Smaller temperature treatment (250 °C) caused a minor decrease in density (−1.3%), which is higher than the reduction of density at 500 °C (−0.8%). Duroskop surface strength showed a slight decrease until 500 °C, and then a drastic decline at 750 °C. P- and S-wave velocity values tend to decrease uniformly and significantly from room temperature to 750 °C. P-wave velocity and Duroskop values have a high exponential correlation at elevated temperatures. Physical alterations originated from the differential thermal-induced expansion of minerals, the formation of micro-cracks. Mineralogical changes at higher temperatures also contribute to the volume change and the loss in strength.

scholarly journals Study the Effect of Diffusion Heat Treatments for Nickel Electroplating on the Surface Hardness of 7075 Aluminum Alloy

2016 ◽  
Vol 63 ◽  
pp. 13-21
Author(s):  
Fouad El Dahiye ◽  
Almohanad Makki ◽  
Mohamad Yehea Alnefawy
Keyword(s):  
Heat Treatment ◽  
Aluminum Alloy ◽  
Surface Hardening ◽  
Intermetallic Phase ◽  
Surface Hardness ◽  
Heat Treatments ◽  
Effect Of Temperature ◽  
7075 Aluminum Alloy ◽  
X Ray Diffraction ◽  
X Ray

In this research a surface hardening process by Ni coating and subsequent diffusion heat treatments was studied at 7075 Aluminum alloy. Nickel coatings with different thickness were obtained by change the coating time and current density. Heat treatments at 450 °C, 500 °C, and 550 °C for times (6, 12, 24) hours were performed in order to obtain surface hardening required of the aluminum alloy by diffusion of nickel into the substrate. The effect of temperature and diffusion time on surface hardness of Al 7075 alloy was studied. Surface hardness about 800 [HV] were achieved after heat treatment at 500 °C for 24 hour by diffusion of Ni in the substrate and cause of formation of Al3Ni2intermetallic phase, as x-ray diffraction tests of samples showed. While is about 670 [HV] after heat treatment at 550 °C for 24 hour because of diffusion of aluminum toward the surface of sample, as x-ray diffraction tests of samples showed.

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