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 [...]
In this article we will discuss about:- 1. Introduction to Flame-Hardening 2. Methods of Flame-Hardening 3. Operating Variables 4. Gases Used 5. Steels for Flame-Hardening 6. Applications 7. Advantages and Disadvantages. Contents: Introduction to Flame-Hardening Methods of Flame-Hardening Operating Variables for Flame-Hardening Gases Used for Flame-Hardening Steels for Flame-Hardening Applications of Flame-Hardening Advantages and Disadvantages of Flame-Hardening 1. Introduction to [...]
In this article we will discuss about:- 1. Introduction to Laser Hardening 2. Metallurgical Variables of Laser Hardening 3. Advantages and Disadvantages. Introduction to Laser Hardening: Laser beams are invisible electromagnetic radiations in the infra-red portion of the spectrum, and are increasingly being used for surface-hardening of ferrous materials to improve mechanical properties like wear resistance and even fatigue resistance. [...]
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 [...]
In this article we will discuss about:- 1. Introduction to Induction-Hardening 2. Steels for Induction Hardening 3. Types of Induction Coils 4. Methods 5. Metallurgical Control 6. Advantages and Disadvantages. Contents: Introduction to Induction-Hardening Steels for Induction-Hardening Types of Induction Coils for Induction-Hardening Methods of Induction-Hardening Metallurgical Control in Induction-Hardening Advantages and Disadvantages of Induction-Hardening 1. Introduction to Induction-Hardening of [...]
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 [...]
The die is most important part in die casting machine which will be discussed here in detail. Dies for all the machines are similar in construction as there is little difference in the method of holding and operating them. Generally it is made into two halves so that the casting can be easily removed from it after solidification. One part [...]
In this article we will discuss about the process and moulds of centrifugal casting. Process of Centrifugal Casting: i. True Centrifugal Casting: In this process, the castings are made in a hollow, cylindrical mould rotated about an axis common to both casting and mould; the axis may be horizontal, vertical or inclined. Usually the mould is rotated in horizontal plane. [...]