Cryogenic treatment of materials: Cutting tools and polymers

Abstract

Cryogenic treatment (CT), a supplementary process to conventional heat treatment process, is the process of deep-freezing materials at cryogenic temperatures to enhance the mechanical and physical properties of materials being treated. CT is one of the field in which the materials to be treated play a very imperative role in its technological development. Some of its successful applications in nonferrous materials defy the conventional reasoning that the only affect it has is to convert retained austenite to martensite. For example tungsten carbide cutting tools, electronics materials, some plastics, composites, and polymers show significant improvements that cannot be supported by the conventional theories as to why the process works. CT technologies have applications in wide range of areas including cutting tools, polymers, plastics, power industry, medicine, rocket propulsion and space simulation, food processing, to name but a few of them. The execution of CT on cutting tool materials increases wear resistance, hardness, and dimensional stability and reduces tool consumption and down time for the machine tool set up, thus leading to cost reductions. Similarly, improvements in wear resistance, hardness, dimension stability, crystallinity, tensile strength and elongation have been reported for polymers subjected to CT. The effects of CT on tool materials (steels and carbides) and polymers along with their applications are reviewed for manufacturing industry in this chapter. Although it has been confirmed that CT can improve the service life of tools and polymers, the degree of improvement experienced and the underlying mechanism remains ambiguous. The steps involved in CT are critical enough to account for the significant incongruity in post-treated performance of treated materials. If we look toward the next century, the topic of the-state-of the art and future developments in CT areas has several aspects to it. Firstly it is essential to look at the history of the development of CT. It is equally important to evaluate the current status of science of CT and to identify research and development trends in this area which can act as starting point for future developments. In this chapter, an attempt has been made to present the past, present, and future of CT technology for tool materials and polymers.