The following points highlight the seven main types of annealing of steels.They are: 1. Full Annealing 2. Homogenising (Diffusion) Annealing 3. Process Annealing 4. Spheroidisation Annealing 5. Partial Annealing 6. Bright Annealing 7. Stress-Relieving Annealing. Type # 1. Full Annealing: Full annealing, or annealing consists of heating the steel to a temperature above its upper critical temperature, soaking there for [...]
In this article we will discuss about:- 1. Meaning of Retained Austenite 2. Advantages and Disadvantages of Retained Austenite 3. Methods for Transformation. Meaning of Retained Austenite: Austenite transforms to martensite between Ms and Mf temperatures as it is essentially an athermal transformation. However, this transformation never goes to completion, i.e. 100% martensite (Mf temperature line is illustrated as dotted [...]
In this article we will discuss about the features and principles of case-hardening of steels. Features of Case-Hardening of Steels: The case-hardening, where the chemical composition of steel surface is changed, has two important features: 1. The chemical composition of the steel is changed when it is in solid state. 2. The chemical composition changes only of the desired surface [...]
In this article we will discuss about:- 1. Introduction to Carburising of Steels 2. Structure and Properties 3. Mechanism of Carburising of Steels 4. Theory 5. Depth 6. Plasma Carburising 7. Carburising Furnaces. Contents: Introduction to Carburising of Steels Structure and Properties of Carburised Steels Mechanism of Carburising of Steels Theory of Carburising of Steels Depth for Carburisation of Steels [...]
In this article we will discuss about:- 1. Introduction to Nitriding 2. Operations before Nitriding 3. Process of Nitriding 4. White Layer or Compound Layer 5. Plain Carbon Steels for Nitriding 6. Effects of Microstructure 7. Advantages and Disadvantages. Contents: Introduction to Nitriding Operations before Nitriding Process for Nitriding White Layer or Compound Layer of Nitriding Plain Carbon Steels for [...]
In this article we will discuss about the meaning and classification of heat treatment furnaces. Meaning of Heat Treatment Furnaces: Heat treating furnaces are essentially heating chambers, i.e., a refractory vessel which holds the steel stock as well the heat. The furnace chamber is heated with some source of heat. The supply of heat has to be regulated depending on [...]
The following points highlight the seven main types of batch furnaces used for heat treatment of steel. The types are: 1. Box-Type Batch Furnace of Steels 2. Bogie-Hearth Furnace of Steels 3. Muffle Furnace of Steels 4. Pit Furnace (Vertical Furnace) of Steels 5. Bell Furnaces of Steels 6. Salt Bath Furnaces of Steels 7. Fluidized-Bed Furnaces of Steels. Type [...]
As tempering is the process of reheating a hardened steel up to a temperature, maximum A1, it is a low temperature process. It can be performed in a: (a) Oil-bath furnace (b) Salt bath furnace (c) Lead bath (d) Forced-air circulation furnace. 1. Oil-Bath Furnace: Oils can be used as a medium for quick transfer of heat for tempering, or [...]
The following points highlight the two main types of continuous furnaces used for heat treatment of steel. The types are: 1. Rotary-Hearth Furnace 2. Straight-Chamber Continuous Furnaces. Type # 1. Rotary-Hearth Furnace: In a rotary-hearth furnace, as illustrated in Fig. 10.14, the hearth of the heating chamber rotates around a vertical axis inside a stationary roof and inner as well [...]
In this article we will discuss about the procedure adopted for heat treatment of general engineering steels. Heat Treatment of Carbon Steels: Carbon steels in the range of 0.25% to 0.60% carbon find large number of applications in the form of bars and forgings. These are commonly given normalising treatment. The temperatures for normalising are given in table 12.1 (b). [...]