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Common Heat Treatment Practices
Published in Bankim Chandra Ray, Rajesh Kumar Prusty, Deepak Nayak, Phase Transformations and Heat Treatments of Steels, 2020
Bankim Chandra Ray, Rajesh Kumar Prusty, Deepak Nayak
Tempering consists of heating the hardened steel to a temperature below the A1 temperature, holding at that temperature, and then followed by prolonged cooling. The aim of tempering is to relieve quenching stresses developed during hardening and increase ductility and toughness of the steel by sacrificing the hardness or strength.
Conventional and Advanced Manufacturing of Materials
Published in Ashutosh Kumar Dubey, Amartya Mukhopadhyay, Bikramjit Basu, Interdisciplinary Engineering Sciences, 2020
Ashutosh Kumar Dubey, Amartya Mukhopadhyay, Bikramjit Basu
The distinction between annealing and other heat treatments (tempering/aging) is that the former always involves the heating and holding a metal above the recrystallization temperature, whereas the temperature is much lower than the recrystallization temperature in the case of latter.
Heat Treatment of Metals
Published in Zainul Huda, Metallurgy for Physicists and Engineers, 2020
Tempering is a heat-treatment process for slightly decreasing the hardness; and for increasing the toughness of hardened steels. Tempering involves heating the steel at a temperature in the range of 150−550°C for a while followed by slow cooling. During tempering, the carbon atoms diffuse out between the iron atoms in the martensite to form the iron carbide particles, thereby relieving the strain within the martensite. The resulting microstructure is tempered martensite (Figure 15.7). This author has ensured production of tempered martensitic microstructure in forged 1050 steel for manufacturing the axle-hub of a motor-car (Huda, 2012).
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.
EBSD Microstructural studies on quenched-tempered API 5L X65 pipeline steel
Published in Philosophical Magazine, 2021
Enyinnaya G. Ohaeri, Tonye Jack, Sandeep Yadav, Jerzy Szpunar, Jiming Zhang, Jinbo Qu
Heat treating metallic materials generally results in either hardening or softening. Such variations in hardness can be challenging for pipeline steels. This is mainly because the risk of failure is higher in extremely hard pipelines. There is a need to establish the mechanical behaviour of the current pipeline steel plates after the QT process. Micro-hardness measurments were performed on each steel before and after heat treatment. Figure 6 presents the variations in hardness following the different quenching procedures. Additional statistical details about hardness data obtained from the steels are shown in Table 3. The results indicate that hardness for all as-received specimens fall within acceptable range for X65 grade steel according to standard [16]. However, there is an overall decrease in the hardness values obtained after QT. This can be traced to the microstructural changes caused by that heat treatment procedure. Particularly, the tempering process is often used to reduce hardness to meet specific steel design requirements. Several studies have revealed that decrease in hardness after tempering can be associated with the decomposition of carbide particles into ferrite matrix [20,21]. Rapid quenching in brine solution after heating at 800°C for 60 mins could have led to the formation of some martensite inside the steels. Such microstructure is generally considered as harder phase. Therefore, tempering at 550°C for another 15 mins lowers the hardness profile of the steel plates by reducing stored energy and tempered martensite evolution. Meanwhile, tempering treatment often promote recovery within martensite laths [22]. The authors also noticed that martensite was merged together even after tempering. Similar results obtained from this study indicate that QT steel plates generate significantly recovered regions within their microstructure (Figures 3–5(e,f)).
Analysis of tempering temperature and vegetable oil quenchant viscosity effect on mechanical properties of 42CrMo4 steel
Published in Cogent Engineering, 2023
Bhagyalaxmi, Ananda Hegde, Sathyashankara Sharma, PK Jayashree
Steels can be made more ductile, impact resistant, and less brittle by tempering, which is a popular technique. Carbon steels’ as-quenched toughness characteristics are frequently compromised by the rising carbon content and resulting rise in hardness and strength. Because of this, different tempering temperatures and durations can be used based on the desired mechanical properties, such as the appropriate hardness and impact toughness levels (Haiko et al., 2019). (Herbirowo et al., 2018).