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Taguchi-Based GRA Method for Multi-Response Optimization of Spool Bore in EHSV Made Up of Stainless Steel 440C
Published in Catalin I. Pruncu, Jamal Zbitou, Advanced Manufacturing Methods, 2023
R. Pranav, Md. I. Equbal, Azhar Equbal, K. Kishore
An EHSV, shown in Figure 4.1, is an electrically operated valve which regulates the hydraulic fluid sent to the actuator. It also offers accurate positional control, velocity and pressure control, force with good post-movement damping characteristics. The body of the EHSV is made of stainless steel (SS) 440C, which possesses high carbon content, shows higher strength, modest corrosion resistance and also has good hardness and wear resistance property. Grade 440C can be post-heat-treated to achieve the maximum wear resistance, hardness and strength among all the stainless steel alloy families. Table 4.1 presents the composition of 440C graded stainless steel. WEDM of 440C graded stainless steel is done using a brass wire electrode of 0.25 mm diameter with a vertical arrangement. ROBOFIL 240CC 5 axis CNC WEDM machine, manufactured by Charmilles (Figure 4.2), was used to conduct the experimentation in accordance with Taguchi L9 OA.
Heat Treatment by Induction
Published in Valery Rudnev, Don Loveless, Raymond L. Cook, Handbook of Induction Heating, 2017
Valery Rudnev, Don Loveless, Raymond L. Cook
The amount of chromium in MSS is typically within 11% to 18%. Higher chromium content is accompanied by a higher carbon concentration. Carbon concentration in MSS can vary to a noticeable extent. For example, carbon content of such MSS grades as ASTM 403, 410, and 416 is less than 0.15%. Some grades of MSS have medium carbon content (e.g., grades 420 may have 0.35% C). In contrast, the carbon content of other grades may be substantially higher. Stainless steels 440A (0.6%–0.75% C), 440B (0.75%–0.95% C), 440C, and 440F (0.95%–1.2% C) could serve as typical examples of high carbon grades of MSS. As expected, steels with higher carbon content can be hardened to higher hardness levels.
Materials and the Sources of Stresses
Published in Neville W. Sachs, Practical Plant Failure Analysis, 2019
There are five different families of stainless steels and their basic divisions and properties are as follows: Austenitic − These are the familiar 300 series stainless steels. They typically contain large amounts of chromium and nickel for corrosion resistance and some have other additions such as molybdenum for pitting resistance. They are not magnetic and cannot be thermally heat treated but respond well to cold working and are readily weldable. Types 302 and 304 are the most common. (Some heavily cold worked 300 series stainless steels are very slightly magnetic.)Ferritic − These are some of the 400 series stainlesses and have high chromium contents but little else in the way of alloying elements. They are magnetic, cannot be hardened by heat treatment, and can only be moderately strengthened by cold working. They have good ductility and excellent resistance to stress corrosion cracking. The most common ferritic stainless is Type 430.Martensitic − These are thermally hardenable, magnetic, straight chromium alloys with moderate corrosion resistance. In the annealed state their ductility and corrosion resistance are comparable to the ferritic alloys. However, their ability to be thermally hardened to tensile strengths greater than 1400 MPa (~200,000 psi) makes them valuable for applications where good corrosion resistance and strength are required. Common alloys include Type 410, which is used for general purpose applications, and Type 440C, which is primarily used for cutlery and industrial knives.Precipitation hardening − These magnetic alloys typically contain chromium and nickel as their principal alloying elements, but they also have small quantities of columbium, aluminum, copper, and/or tantalum as their precipitating agents. Their primary advantage is that parts can be machined in the annealed state then, at relatively low temperatures, less than 600°C (~1100°F), precipitation hardened to very high strengths with minimal distortion. Their corrosion resistance and ductility are comparable to the similarly hardened martensitic alloys. Common grades include “13.8” (13% chrome and 8% nickel), “15-5”, and “17-4”.Duplex − The duplex stainless steels have a structure that is a combination of austenite and ferrite, with a combination of the good corrosion resistance of the 300 series austenitic and the stress corrosion cracking resistance of the 400 series ferritic stainlesses. The result is an alloy that has both good corrosion resistance and high strength. It cannot be thermally hardened and can be welded but temperature control is very important. The most common grade is Alloy 2205 but there are several others plus specialty heat exchanger tube materials.
Experimental investigation on the performance of AISI 440C martensitic stainless steel against the formation of white etching areas under sliding dynamic loading
Published in Tribology - Materials, Surfaces & Interfaces, 2022
Extensive research is continuing to extend the life of bearings from the premature failure of WECs by implementing alternatives in lubrication and material aspect. This study attempts to investigate the alternatives on the material aspect. AISI 440C stainless steel components are commonly used in environments that are subjected to corrosion. AISI 440C steel consists of around 16% of chromium and an adequate amount of carbon (1%). M7C3 (M = Fe, Cr, Mo, V) carbides exist in the martensitic structure before tempering. M23C6 carbides are identified together with M7C3 carbides after tempering [13]. The higher content of chromium in steel acts as a strong hydrogen trap and inhibits the diffusion of hydrogen. Along with that, the addition of Cr results in the development of a passive film on the surface and thus prevents the formation of nascent steel surface [10]. Chromium forms into a thin, coherent chromium oxide film when it is exposed to air and makes the steel electrically insulated. This electrically insulating passivation film can reduce the exposure of the nascent steel surface to the atmosphere and thus can reduce the diffusion of atomic hydrogen from the lubricant. Carbon content in the solid solution ensures 59–61 HRC of hardness, which is essential for the bearing application. It is also confirmed that corrosion inhibitors reduce the generation and diffusion of hydrogen into steel [14]. Therefore, it is decided to study the performance of AISI 440C steel as an alternative material against WEAs. The preventative mechanism of WEC formation includes changing the tribochemistry of the oil, as well as varying the steel composition, heat treatment of the bearing material, presence of vanadium carbide nanoparticles and retained austenite [5]. Ciruna et al. [15] found that AISI 440C stainless steel performed better than AISI 52100 steel against hydrogen impregnation and has a longer fatigue life. Hydrogen deteriorates the mechanical properties of bearing steel, including fatigue resistance [15,16]. The presence of Vanadium in AISI 440C enhances the hydrogen trapping behaviour of steel. In vanadium-added steel, the hydrogen de-trapping is very slow, and hydrogen trapping takes place rapidly [17].