Role of Alloying Elements

Question 1

What does alloying mean?

Answer 1

Addition of alloying elements to steel to reach a desirable alloy steel property

Question 2

What is the purpose of alloying?

Answer 2

1) Improve mechanical properties at ordinary, high, and low temperatures
2) Improve toughness at any minimum hardness/strength
3) Increase corrosion resistance
4) Increase hardenability
5) Increase wear resistance
6) Improve magnetic properties

Question 3

What happens to steel when it’s alloyed with Carbon?

Answer 3

Most important single alloying element in steel and form cementite and other carbides within the microstructure. As Carbon increases so does the strength, but this decreases ductility.

Question 4

What happens to steel when it’s alloyed with Manganese?

Answer 4

Increases strength and hardenability (ability to achieve hardness).

Used as a deoxidizer of the melt during manufacturing.

Contributes to strength and hardness but to a lesser degree than Carbon.

Question 5

What happens to steel when it’s alloyed with Silicon?

Answer 5

Silicon slightly increases the ferrite strength without decreasing ductility.

Principle deoxidizer used in steel making.

Question 6

What happens to steel when it’s alloyed with Tungsten?

Answer 6

Helps steel retain hardness and strength at high temperatures by producing fine grains.

Question 7

What happens to steel when it’s alloyed with Chromium?

Answer 7

Chromium increases resistance to corrosion and oxidation, increases hardenability, toughness and improves high-temperature strength.

Question 8

What happens to steel when it’s alloyed with Nickel?

Answer 8

Nickel improves low and high temperature properties while increasing ductility, strength and toughness.

Nickel strengthens the ferrite and changes cooling rate transformations so nickel steel is easier to heat treat.

Question 9

What happens to steel when it’s alloyed with Molybdenum?

Answer 9

Molybdenum increases the hardenability, toughness, and strength at elevated temperatures.

Question 10

What happens to steel when it’s alloyed with Aluminum?

Answer 10

Aluminum can be used as an oxidizer and controls grain size during production

Question 11

What are the 4 residual elements that can be found in steel?

Answer 11

1) Phosphorus: decreases ductility and toughness

2) Sulfur: decreases ductility toughness and weldability. Can be supplemented with Manganese to for MnS to improve machinability

3) Oxygen: drastically decreases toughness

4) Hydrogen: embrittles the steel