Heat Treatment

Question 1

What must be added to iron before it can be heat treated?

Answer 1

Carbon.

Question 2

Steel becomes what when heated?

Answer 2

Austenite.

Question 3

Ferrite is produced by what?

Answer 3

A slow cooling process.

Question 4

Martensite is cooled how?

Answer 4

Rapidly.

Question 5

How is tempering achieved and what effect does to have?

Answer 5

Heated to below its critical temperature and held there until it become soaked, then cooled at room temperature in still air. Tempering reduces a metals brittleness, relieves stress and improves ductility and toughness.

Question 6

Annealing is what?

Answer 6

Softening steel and relieving internal stress. Heated to 50 deg oboe its critical temperature and cooled slowly in the furnace.

Question 7

How is case hardening achieved?

Answer 7

Carburising. Heating steel to high temp with lots of carbon material which infuses the steel.
Nitriding. Stell heated to 1000 deg and surrounded with Ammonia gas, which separates into Nitrogen and hydrogen. the Nitrogen is absorbed into the steel.

Question 8

What are the two test for hardness?

Answer 8

Rockwell and Birnell

Question 9

Testing impact strength is achieved how?

Answer 9

Charpy and Izod tests.

Question 10

What are the four ways that steel can be tested?

Answer 10

Hardness
Tensile strength
Fatigue strength
Impact resistance