National Aviation University

Educational Scientific Aerospace Institute

Aircraft Faculty

Airport Technologies Department

Report of laboratory work #2

Subject: Technologies of resource management for aviation ground equipment and airports supplies

Topic: Engineering materials and heat treatment (Part 2)

Done by _____________________________________________

Checked by associate professor Puhachevska E.P.

Kyiv 2017

1. Heat treatment processes (introduction)

Heat treatment processes as a means of modifying the properties of metals have already been mentioned earlier in previous laboratory work. Table 1 summarizes and defines the more common heat treatment processes. Because of the wide range of non-ferrous metals and alloys that exist, the heat treatment processes for non-ferrous metals vary widely and all such processes are quite different to the processes used for the heat treatment of plain carbon steels. However, some of the more important processes for the heat treatment of copper-based and aluminium-based alloys will be included in this laboratory work.

TABLE 1 Heat treatment definitions

Term	Meaning
Annealed	The condition of a metal that has been heated above a specified temperature, depending upon its composition, and then cooled down in the furnace itself or by burying it in ashes or lime. This annealing process makes the metal very soft and ductile. Annealing usually precedes flow-forming operations such as sheet metal pressing and wire and tube drawing
Normalised	The condition of a metal that has been heated above a specified temperature, depending upon its composition, and then cooled down in free air. Although the cooling is slow, it is not as slow as for annealing so the metal is less soft and ductile. This condition is not suitable for flow forming but more suitable for machining. Normalizing is often used to stress relieve castings and forgings after rough machining
Quench hardened	The condition of a metal that has been heated above a specified temperature, depending upon its composition, and then cooled down very rapidly by immersing it in cold water or cold oil. Rapid cooling is called quenching and the water or oil is called the quenching bath. This rapid cooling from elevated temperatures makes the metal very hard. Only medium- and high-carbon steels can be hardened in this way
Tempered	Quench-hardened steels are brittle as well as hard. To make them suitable for cutting tools they have to be reheated to a specified temperature between 200 and 300◦C and again quenched. This makes them slightly less hard but very much tougher. Metals in this condition are said to be tempered

2. The heat treatment of plain carbon steels

Plain carbon steels are subjected to heat treatment processes for the following reasons:

• To improve the properties of the material as a whole, for example by imparting hardness to prevent wear or softness and grain refinement to improve its machining properties.

• To remove undesirable properties acquired during previous processing – for example, hardness and brittleness imparted by cold working.

The heat treatment processes we are now going to consider in order to modify the properties of plain carbon steels are:

• Through (quench) hardening.

• Tempering.

• Annealing.

• Normalizing.

• Case hardening.