In this topic discuses about hot working and cold working process which is mostly important topic in manufacturing technology, we are all known that metals flows as plasticity under action of applied forces . It may be described as hot working and cold working depending upon whether the metal is worked above re-crystallization temperature , the temperature at which new grains are formed in the metal is known as re crystallization temperature..
Hot working : The working of metal above re-crystallization temperature is called hot working.
Advantages :
- Porosity largely eliminated
- Grain structure of metal is refined
- Impurities of metal uniformly distributed
- Mechanical properties of metal are improved
Disadvantages :
- Requires expensive tools
- Produce poor surface finish due to rapid oxidation and scale formation
- Difficult maintain correct temperature range for working .
Hot working processes :
Hot rolling : This is method of converting large sections into desired shapes. Ex : forming bars, sheets, angles,rails, I-beams,plates and other structural sections
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgd9HoN_LU3cEeyp0AB32yp7-qyYRh6_icXCajnCUyBTcrwg8uVZr84_phn2tyO7zLrVVw4j9gDFhm1AE-ahwfuirFzUKWY75ehSxaOJSkURY2PCVKMIW5C9wV1K9Ygb1bSxyYlzaagjMQ/s320/laminage_chaud_kieffer640_0.jpg) |
Sheets producing |
Hot forging : It consist of heating the metal to plastic state and then the pressure is applied to form in desired shape and size, The pressure is applied by hand tools, power hammer ,other forging machines.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjoZeyLnhfl6Ah3BPkbrWZ-rgEpZ8BelbWw4I909dj88QUorv0zO7GOvQT22Ocf_3CACYRgtPYcRmse2SeFUrv7Aj93Uydhs92K_xtOG5GwRXa3iH8hvIOpl8k6wFqKM5qKcWk8m61HesU/s320/SSF-Hot-Forged-Super-Duplex-Bolt.jpg) |
Bolt produced by hot forging |