**Author details**

*Welding - Modern Topics*

aircrafts, etc.

cables, etc.

**7. Conclusions**

due to its high toughness.

drilling machine, blades, etc.

**8. Futuristic development of high-alloy steel**

and its wide variety of products for desirable applications.

• TWIP steel: used in automobiles, ship building, infrastructure, railways,

• High-entropy steel: used as structural material in low-temperature applications

• Hadfield steel: used in railways, structural applications, shafts, gears, housing,

• High-speed steel: used as cutting tool materials due to its high hardness like

High-alloyed steels are complex alloys, along with desired chemical composition and multiple phased microstructures through various heat treatment processes. Various strengthening mechanisms through controlled heat treatment techniques are adopted to achieve excellent mechanical properties. The chapter examines the advanced methods used in the field of heat treatment routes for high-alloyed steel and focuses on their structure-property relation. The high-alloy steels acquire its enhanced mechanical properties from the modified microstructures of austenite, ferrite, martensite, and some carbides. Ferrite and austenite provide the formability, whereas martensite provides strength to the steel in addition to the low-temperature transforming phases like bainite and retained austenite to achieve better combinations of mechanical properties. The advanced thermomechanical treatments used for high-alloy steels aim to explore the possible phases that contribute to the mechanical properties. In thermomechanical routes aims on heat treatment as the microstructural qualities required for the steels are mainly achieved by post-deformation controlled heat treatment processes. From the above discussions, it can be concluded that the microstructure and its properties are based on variation in chemical composition and processing conditions. Determined by latest demands for the performance of the high-alloy steel in various applications, the progress of thermomechanical processing is introduced.

High-alloy steel has undergone significant evolution through time. Around 70% is used in various applications. These steels are highly demanding as they display various environmental, chemical, physical, and mechanical properties. Here the different proportions of alloying element in steel provide various mechanical properties. As can be seen from the foregoing, high-alloy steel plays an important role in the building and construction industries as well as in automotive industries. High-alloy steel offers economy, high performance, corrosion resistance, high strength, durability, lightweight and high performance under extreme conditions,

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Nicky Kisku Indian Institute of Technology, Kharagpur, India

\*Address all correspondence to: kiskunicky@gmail.com

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
