Materials Engineering: The Three Main Heat Treatment Processes

MATERIALS Engineering

Learning outcome-2

Ac 2.1

The three main heat treatment processes are:

 Quenching.

 Normalizing.

 Annealing.

Quenching It is a process of heating the steel to a higher temperature to get fine grained and homogeneous austenite and the steel is cooled at the rate faster then the critical cooling rate. Fig 1 http://i00.i.aliimg.com/photo/v0/1100448518/shaft_induction_hardening_equipment.jpg Normalizing

This process is similar to annealing but it is heated above the upper critical temperature and allowed to cool in open air.

Fig 2 http://www.aberfoyle-mt.com/images/ht4.jpg Annealing it is the process of heating the steel slowly to upper critical point and held at that temperature for some time and

It must be high safety during operation. And the correctness of shape to assure the engine efficiency.

Manufacturing process:

The first grade titanium is chosen which is having high strength and light weight property and low density capable of resisting temperature about 800˚F (427˚c)

The molten alloy is is poured into the ceramic pads and heated in furnace and slowly cooled and the ceramic pad is removed and machined finally. Fig4 https://www.google.co.in/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRxqFQoTCO-aq6uK5cgCFUSPlAodsuIGag&url=http%3A%2F%2Fktwop.com%2Fcategory%2Fengineering%2F&psig=AFQjCNE09cGnZrOe6RrdRqnV4XgsOxN8RA&ust=1446118526083448 Failure of even one blade could cause engine stopped or serious damage to the engine. Manufacturing monocrystal blades is very expensive and requires some advanced operations and very slow cooling.

The blades are coated with ceramic layer which prevents the surfaces from intensive heat and the metal is heated for some time and quenched in water which makes the blade resist high temperature.

Fig

The hole needs to be large enough to slide onto the tube and come off around the bend.

Cold rolling

Metal forming process in which the steel pipe is given to the machine and slowly the pipe is bent to a maximum angle. There will be variations in the diameter of steel after cold rolling. When cold processed the shape is permanently deformed or changed. And this is because of the dislocations in the grain structure which move through the crystal structure.

Each grain has a large number of dislocations which is visible only under powerful microscope. Cold rolling can also be used to harden the material.

Liquid process effecting the structural properties and parental material

When a metal solidifies from its molten state – millions of tiny crystals start to grow depending on the time taken to cool. Cooling the cased metal instantly results in refined crystal grains. The longer the time the larger are the crystal’s growth.

Mechanical process effecting the structural properties and parental