International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 07 | July -2017
p-ISSN: 2395-0072
www.irjet.net
A Review on the Effect of Cryogenic Treatment on Metals Mr. Chitrang A. Dumasia1, Dr. V. A. Kulkarni2, Mr. Kunal Sonar3 1M.E-Final
Year, Department of Production Engineering, Dr. D. Y. Patil College of Engineering Akurdi, Pune, India. 2Head of Department, Department of Production Engineering, Dr. D. Y. Patil College of Engineering, Akurdi, Pune, India. 3Project Guide, Prinz Automech, MIDC, Bhosari, Pune, India. ---------------------------------------------------------------------***--------------------------------------------------------------------
Abstract - Cryogenic treatment is an add-on process to
conventional heat treatment process in material processing technology. It is a one-time permanent treatment which affects the whole section of the component. It is not like the coatings of superior materials over other metal surfaces that only affects the surface of components. Cryogenic treatments are proved to be a good way to reduce the retained austenite content and improve the performance of materials by improving its martensite structure. Objectives of cryogenic treatments are to increase material’s strength, hardness, wear resistance, ductility, & toughness, to obtain fine grain size, to remove internal stresses, to improve machinability, cutting properties of tools, to improve surface properties, electrical properties & magnetic properties. This paper aims to review about various cryogenic treatments involved in treating various materials so far and their effect on their properties. The summary of this review paper tells about the properties improved due to the cryogenic treatment and the reason behind them.
To obtain fine grain size To increase ductility and toughness To remove internal stresses induced by non-uniform cooling from high temperature during casting and welding To improve machinability To improve cutting properties of tool To improve surface properties
Key Words: Cryogenic Treatment, Heat Treatment, Austenite, Martensite, Wear resistance, Ductility Fig. 1-DCT cycle [7]
1. INTRODUCTION All Metals may not possess desired properties in their final product. Alloying and Heat treatments are two methods which are widely used to control material properties. Heat treatment is the controlled heating and cooling operations performed on the material. It is an operation or combination of operations which include heating at a specific rate, soaking at a temperature for some specific time and cooling at some specified rate. The aim of it is to obtain the desired microstructure to achieve some desired properties like physical, mechanical, magnetic & electrical properties. When the material is subjected to heat treatment the atomic structure may change due to movement of dislocations, increases or decrease in solubility of atoms, increase in grain size, formation of new grains, formation of new different phase and change in crystal structure etc. [16].
1.1 Cryogenic Treatment
Objectives of Heat Treatments are as below:
The cryogenic treatment can be classified into three different temperature regimes [10]:
To increase strength and hardness To increase wear resistance
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Word Cryogenic is made of two Greek words: Kryo: Which means Very cold (frost) Genics: Which means to produce [2] This is a technology where everything we process gets frozen at ultra-low temperatures of -193°C. Then everything is held down at temperatures around of -193 °C for 12-48 hours followed by gradual ascend and tempering. This process consists of controlled cooling of conventionally hardened materials to a specified temperature followed by controlled heating of the materials back to the ambient temperature for subsequent tempering process.
(1) Cold Treatment (CT, ≥193 K or -80 °C) (2) Shallow Cryogenic Treatment (SCT, 193–113 K or 80 °C to -160 °C)
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