Chemical Heat Treatment Processes In this article I will discuss chemical heat treatment processes. (All other heat treatment processes are discussed in the previous post. This article is next part of that. So for batter understanding, also read that article.) These are: 1. Case Hardening Process (or carburising) 2. Cyniding 3. Nitriding 4. Carbo-nitriding 5. […]
The properties of metals and alloys can be changed by heating followed by cooling under definite conditions to make them suitable for specific applications. Accordingly steel can be hardened to resist cutting action and prevent abrasion. The rate of cooling and the manner of cooling are the controlling factors in heat treatment processes. Heat treatment
Types of Carbon Steel Carbon steels (or plain carbon steels) are ferrous metals. Percentage of carbon in them varies from about 0.05% to 2%. Accordingly they are classified as mild steel, medium carbon steel and high carbon steel. Mild steel is soft, medium carbon steel is tough, and high carbon steel is hard in comparison
Lever Rule & Ternary Phase Diagram Microstructural Changes: Refer to phase diagrams of previous post. Liquid phase first changes to solid-liquid phase, and finally to solid phase during cooling. If variation in the rate of cooling is slow to fast, say 200°C per hour to 200°C per second, different microstructures will develop. If we consider
Unary Phase Diagram Phase diagrams are important and essential tools to understand compositional concentrations of two or more elements. Phase Diagrams Definition: Plots showing relations between phases in equilibrium versus composition, pressure and temperature are called phase diagrams. These are also known as equilibrium diagrams. Temperature is plotted on ordinate (y-axis) and composition (in binary
Interstitial & Substitutional Solid Solution Materials are transformed into various phases under the effects of temperature and pressure. The iron is available in BCC form (α-iron), FCC form (y-iron) and BCC form again (δ-iron) at certain temperatures. The development of alloys, whether non-ferrous brass or ferrous high speed steel (H.S.S.); magnetic alnico or antifriction babbits,
Hardness Tests of Materials Definition of hardness: Hardness is a surface property. It is defined as the resistance of a material against permanent deformation of the surface in the form of scratch, cutting, indentation, or mechanical wear. Diamond is the hardest known material. In various hardness tests, the indentors are used to introduce indentation on
In order to determine the mechanical properties of materials certain tests are carried-out. Depending on the nature of tests, these are classified as follows: Destructive Tests of Materials Generally specimens are tested on machines in the laboratory under static, dynamic or impact loadings. Most common among mechanical destructive tests are the following: Now, we shall
The non-destructive testing (NDT) refers to a method of detecting internal flaws in engineering materials, machine components, and structures without breaking them. These tests are essential to ascertain absolute safety and reliability in engineering applications: particularly in strategic industries such as atomic energy, missiles, defense, aeronautics, space etc. The non-destructive testing techniques can be employed
Creep in Materials The permanent deformation (strain) of a material under steady load as a function of time is called creep. A very common observation, in which length of our waist belt increases after some duration, is due to creep effect. It is thermally actuated process, and hence is influenced by temperature. It is, however,