Search Results for surface nitrogen content

Vacuum solution nitriding is a promising technique for increasing the surface hardness, load-bearing capability, and fatigue strength of martensitic stainless steels without sacrificing corrosion resistance. This article examines the effects of nitriding pressure and temperature on surface nitrogen content and case depth in four martensitic stainless steels.

Low-temperature surface hardening of stainless steel by means of gaseous processing provides a high degree of tailorability of the hard surface case without affecting corrosion resistance. This article covers the fundamental and technological aspects of the process and examines the effect of different LTSH treatments on 304 and 316 austenitic stainless steel.

In this study, 316L stainless steel samples were plasma nitrided for 64 h at 370-420 °C then subjected to surface hardness and pitting corrosion testing. The results show that interstitial hardening with nitrogen significantly improved the surface hardness as well as the pitting corrosion resistance of the austenitic stainless steel.

This article series explores the indispensable role of characterization in the development of cold spray coatings and illustrates some of the common processes used during coating development.

Proper specification, measurement, and control of annealing furnace atmospheres are critical to reduce sooting, oxidation, sticking, and distortion. This article describes how to effectively design and utilize a nitrogen-hydrogen annealing atmosphere.

Using advanced characterization techniques on surface hardened steels builds a richer understanding of the underlying metallurgical phenomena.

This article series explores the indispensable role of characterization in the development of cold spray coatings and illustrates some of the common processes used during coating development.

Accurate and continuous dew point measurement is key to maintaining the atmosphere required to achieve high quality and consistency of sintered products in powder metallurgy processing.

Heat treaters regularly seek ways to prevent and reduce rework and scrap loads by implementing procedures and tools to make sure the heat treating process meets customer expectations and specifications. One process parameter requirement is to ensure consistent atmosphere carbon content. Measuring carbon absorption into steel is commonly done to verify atmosphere consistency. This article describes an atmosphere carbon potential analyzer that provides a cost-effective way to measure carbon using a wire coil that functions in a way similar to using shim stock.

Plasma nitriding is very effective in removing the passive layer of chromium oxide formed naturally on the surface of stainless steel, but controlling the kinetics is key for optimal results.

One of the most recent success stories for thermal spray in the automotive industry involves the development of plasma transferred wire arc (PTWA) for aluminum engine blocks. Driven by the demand to increase fuel efficiency, automakers are placing emphasis on decreasing overall vehicle weight as well as improving engine efficiency by reducing internal friction losses. The surface structure of the composite coating created by the PTWA process promotes favorable lubrication, low friction, wear resistance, improved heat transfer, and decreased bore distortion in engine block cylinders.

Understanding both the origin and procedures for removing inclusions in magnesium alloys results in castings with enhanced mechanical and corrosion properties. This article provides an overview of typical inclusions found in magnesium and its alloys, various techniques used to determine inclusion content, and methods employed to reduce inclusions and their influence on properties.

Cobalt alloys are widely used to meet the demanding performance requirements of diesal and natural gas engine valvetrain applications. Alloy J513 alloy was developed to lower costs and provide higher performance while also requiring substantially less cobalt usage.

Boriding is performed by diffusing boron atoms into a metal surface and allowing the boron to react with elements present in the substrate to form metal-boride compounds. Upon diffusing enough boron into the surface, a metal-boride compound layer with high hardness precipitates and grows below the surface of the part. This article discusses boriding of ferrous alloys, including a new deep case boriding method that produces wear layer depths comparable to competitive processes such as carburizing, nitriding, thermal spray coatings, and hardfacing.

Chemical vapor deposition (CVD) of pyrolytic chromium carbide coatings (PCCCs) is proving to be a viable alternative to hard chrome plating used on cylinder piston group components. This article discusses the development and optimization of a CVD process for depositing PCCCs on piston rings and cylinder sleeves. It evaluates the coatings based on friction, wear, and adhesion properties in comparison with coatings produced by other methods.

Terahertz time-domain spectroscopy is a powerful and nondestructive analytical characterization technique for investigating ceramics, glasses, and composites.

Stress corrosion cracking is an insidious form of damage that can occur when a susceptible metal is subjected to a tensile stress in a specific environment. To relieve tensile stresses at welded joints, postweld heat treatment can be helpful in reducing the susceptibility of carbon steel fabrications to SCC. When planning to use stainless steels in chloride-containing environments, it is advisable to select alloys that have been specifically developed to resist stress chloride cracking such as ferritic-austenitic (duplex) alloys, low-carbon ferritic alloys, and 6% Mo austenitic alloys or to select high-nickel alloys.

Beryllium won a lengthy competition as the material of choice for the mirrors on the James Webb Space Telescope, set to launch in 2018. This article documents the development history leading up to that decision. It took decades to perfect powder atomization and HIP'ing processes to make optical-grade beryllium components homogeneous, isotropic, polishable, thermally and dimensionally stable, and above all, predictable.

Engineers at the Ford Motor Co. are using integrated computational materials engineering (ICME) tools, allowing them to accurately simulate the heat treatment of gears and predict phase transformation kinetics and distortion.

Laser-induced breakdown spectroscopy (LIBS) is an established technology that provides nearly instantaneous and virtually nondestructive analysis with minimal or no sample preparation and without an ionizing radiation source. This article describes the capabilities of new handheld LIBS systems.