China
Africa
Explore chapters and articles related to this topic
Materials Used in Switched Reluctance Machines
Published in Berker Bilgin, James Weisheng Jiang, Ali Emadi, Switched Reluctance Motor Drives, 2019
Elizabeth Rowan, James Weisheng Jiang
Annealing is a form of heat treatment in which a metal is heated to a high temperature, held there for some length of time, before cooling at a specific rate. As a metal is plastically deformed, microstructure and physical properties change. Grain shapes, strain hardening, and dislocation densities are all affected. Some of the energy that is used to deform the steel is trapped in the metal as strain energy. Annealing can relieve these stresses, increase softness, ductility or toughness, or promote a specific microstructure to form in the steel. Annealing raises the metal to an elevated temperature that is below its melting point. The temperature to which the metal is raised will depend on the properties the annealing is intended to produce. A phase diagram determines the type of steel that can be produced given a specific temperature and composition [6]. Heating and cooling rates as well as time spent at a given temperature will all impact the final material properties.
Example of Tribological Systems
Published in Kenneth C. Ludema, Oyelayo O. Ajayi, Friction, Wear, Lubrication, 2018
Kenneth C. Ludema, Oyelayo O. Ajayi
For highly loaded gears, the teeth must be strong and tough enough not to bend or fracture, i.e., adequate strength and toughness. At the same time, the teeth surface must be hard enough to resist wear and contact fatigue failure. Higher hardness is often accompanied by reduction in toughness and increased susceptibility to fracture. These competing requirements in steel gears are met through appropriate heat treatment. The vast majority of steel gears are case-hardened whereby a relatively hard and wear resistance layer is produced on the surface while the core is softer touch. There are numerous methods available for case hardening of gear teeth depending on the gear steel material composition. For steel alloys with more than 0.4% carbon content, case hardening can be done induction, flame or laser processes. Surface hardness in the range of 55 to 60 Re can be achieved in such alloy while the core hardness is about 30 Rc, and typical case depth is about 1.0 to 3.0 mm. For steel alloys with 0.2% or less carbon content, case hardening usually involves carburizing heat treatment in which diffusion of carbon atoms into the surface layer at high temperature occur. The carburing step is followed by quenching and tempering. Case depth as high as 4 mm and surface hardness of 60 to 62 Rc can be achieved with case carburing heat treatment. In addition, carburing produces compressive residual stress in the case layer which is beneficial for bending and contact fatigue resistance. Other variants of case hardening commonly used in gears includes nitriding, carbonitriding, etc.
Heat Treatment of Metals
Published in Zainul Huda, Metallurgy for Physicists and Engineers, 2020
Heat treatment is the process that involves controlled heating and cooling of metals to improve their physical and mechanical properties by controlling the microstructure. The purpose of heat treatment may be to: (a) increase the strength, (b) increase/decrease hardness, (c) improve machinability, (d) improve formability, or (e) restore ductility after a cold-working operation. Heat-treatment processes include: full annealing, normalizing, hardening, tempering, recrystallization annealing, case hardening, precipitation strengthening, solution treatment, aging treatment, and the like (Zakharov, 1962; Huda, 2007). Many engineering components are given heat treatment for specific applications; these include: automotive components, aerospace components, and the like.
Dependence of pre-treatment structure on spheroidization and turning characteristics of AISI1040 steel
Published in Cogent Engineering, 2023
Harisha S R, Sathyashankara Sharma, Ramakrishna Vikas Sadanand, Achutha Kini U, Raviraj Shetty, Sathish Rao U
Heat treatment is a solid state processing technique where the heating and cooling cycles show an essential role in property alteration. Among several heat treatments available, hardening is the primary treatment to improve hardness and tensile properties. In the present work, a comparison of turning characteristics is presented by subjecting AISI1040 to spheroidization treatment (Retd & Singh, 1926). Spheroidizing treatment is one of the techniques available in the heat treatment family to improve the machinability of medium/high carbon steels. For machinability, conventional normalizing treatment may not be suitable for all steels if steel contains alloying elements. Spheroidizing treatment changes the phase particles, especially carbides, into the globular form (Finkel’shtein et al., 1963). Harder carbides cannot be softened by the available techniques, but the sharp edges of the phase particles are blunted to form a spherical shape. The sharp cornered particles present in the workpiece increase the friction between the cutting tool and the workpiece, leading to higher wear and tear of the cutting tool. Also, the size and number of the phase particles as carbides or ferrite play an important role in machinability (Naylor et al., 1976).
Manufacturing process similarity measurement model and application based on process constituent elements
Published in International Journal of Production Research, 2021
Zhongyi Wu, Weidong Liu, Weijie Zheng, Wenbin Nie, Zhenzhen Li
For pairwise alignment, the popular Needleman-Wunsch (NW) algorithm, which is a dynamic programming-based optimisation strategy, is often used to determine the best alignment of any two sequences. By decomposing a complex problem into an array of relatively simple sub-problems with a reasonable amount of computation, the NW algorithm calculates the optimal solution of each sub-problem step by step, and then determines the best answer from all solutions (Vidal, Monge, and Villalba 2018). To ensure the standardisation of process calculations, the following reasonable assumptions are established: Continuous and identical manufacturing procedure activities can be considered the detailed process of specific value-added processing activities of the same process.The heat treatment processes include annealing, normalising, quenching and tempering; heat treatment is collectively referred to as heat treatment process.The equipment used in each manufacturing process is the same.The procedure route of each product in the manufacturing process is fixed and unchanged.
A review on cryogenic treatment of tungsten carbide (WC-Co) tool material
Published in Materials and Manufacturing Processes, 2021
Tempering is one of the important metallurgical technique that is in existence since the time humans started using fire and iron.[101] In heat treatment of steel, tempering is an additional step performed by heating the material below its lower critical temperature and holding it for a certain amount of time to remove the inner stress and thereby improve the toughness. However, in regards to cryo-treatment of tungsten carbide, most of the researchers have selected tempering temperatures between 150 and 200 C for about 1.5 to 2 hours (Table 1). Few reports show that either tempering was not performed or the process details are not reported.[53,54,63,64,73,77,86,100,102,103] But the scientific reason behind the selection of tempering temperature, duration, and the number of tempering cycles was not clarified.