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 [...]
Many problems occurs during carburising of steels. Some of these are: 1. Low Surface Hardness 2. Low Case Depth 3. Non-Uniform Case Depth 4. Soft Spots 5. Sooting 6. Distortion. Problem # 1. Low Surface Hardness: There are two main reasons of low surface hardness of a carburised component- Presence of large amount of retained austenite or decarburisation. There is [...]
Depending on the nature of carbonaceous atmosphere, carburising is called pack, or solid carburising, liquid carburising, or, gas carburising. But, whatever may be the method used, carburisation always takes place via a gaseous phase. Method # 1. Pack or Solid Carburising: In this method, the carburising compound is a solid carburiser, usually charcoal of 3 to 10 mm size (fines [...]
Carburised parts are generally heat treated for following reasons: 1. To develop hard and wear resistant surfaces. 2. The long lime and high temperatures during carburising may cause grain coarsening in core and or case. These may be refined to improve their properties like impact strength, etc. 3. If carburising has resulted in cementite network at the surface, it induces [...]
The following points highlights the four main methods used for nitriding of steels. The methods are:- 1. Gas-Nitriding 2. Single-Stage and Double-Stage Nitriding 3. Ionitriding (Plasma), or Glow-Discharge Nitriding 4. Liquid Nitriding. Method # 1. Gas-Nitriding: Gas nitriding is the most commonly used nitriding method. In the original method, components are heated at about 510°C (500-575°C) in an atmosphere of [...]
Carbon potential may be defined as that carbon content which a specimen of a carbon-steel foil acquires when equilibrium conditions have been achieved between the carbon potential of the carburising medium and the carbon content of the foil. Fig. 8.4 illustrates that surface carbon content may be less than the carbon potential of the atmosphere. The activity of carbon in [...]
In this article we will discuss about:- 1. Introduction to Carbonitriding 2. Hardenability of Case for Carbonitriding 3. Case-Depth and Concentration-Gradient 4. Retained Austenite 5. Quenching Media. Contents: Introduction to Carbonitriding Hardenability of Case for Carbonitriding Case-Depth and Concentration-Gradient for Carbonitriding Retained Austenite for Carbonitriding Quenching Media for Carbonitriding 1. Introduction to Carbonitriding: Carbonitriding (as well as cyaniding) is the [...]