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Heat Treatment of Cast Iron
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
Normalizing treatment may be done by increasing the temperature to above the transformation range (900°C–950°C) and soaking it for a particular time depending upon the thickness of casting followed by air cooling. Normalizing enhances mechanical properties like hardness and tensile strength and restore as-cast properties that have been altered by other heat-treating processes, such as graphitizing or preheating and postheating associated with repair welding.
Metal Industries
Published in Charles E. Baukal, Industrial Combustion Pollution and Control, 2003
Heat treating involves the thermal treatment of metal to produce some type of enhanced performance characteristic. Typical material improvements include surface hardening, strengthening the part, relieving stresses, and improving ductility. Typical thermal treatments include annealing, brazing, carburizing, normalizing, sintering, and tempering.
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)).