Ball Joint Lab Report

Material Science

SKMM 2613

Topic :

Name : Wong See Ying

Matrix Number : A15KM0411

Semester Year : 2016/2017/1

Section : 02

Lecturer : Dr. Zamri Yusop

Introduction Ball joint is a crucial component in an automobile, to fully maximize its function, few ball joints need to work together. Ball joints are spherical bearings that connect the control arms to the steering knuckles. They are used on virtually every automobile made and work similarly to the ball-and-socket design of the human hip joint. Since it is a connector between the car suspension system and the tire plate of the car, its means it undergoes shear force a lot as it rotating all the time as the car is changing direction. It also

Next, heat treatment is carry out on the chromium steel. Soft annealing is first carried out to heat the material to 680-720oC, then it is cooled slowly in furnace. This will produce a maximum Brinell hardness of 241. After that the chromium steel is austenitized at 850oC inside the furnace for 30 minutes in order to ensure that the raw material is fully austenized, the temperature is uniform throughout the whole material. Then the material is harden from a temperature of 820-680°C followed by oil water quenching. En 18 alloy steel is produced. The En 18 alloy steel is then undergoes pointing. Pointing, sometimes called tagging or swaging, is a process that reduces a tube's, rod and profile end to permit it to pass through a draw die for a drawing operation. This process prepare the En 18 alloy steel for later drawing process. This process is merely a cold process with no heat

The En 18 alloy steel can be temper to a temperature of 540-680°C, then the alloy steel is soak in the constant temperature for 30 minutes and finally let it cool in still air. The improved En 18 alloy stell will have the properties of increase in toughness and relieve internal stresses caused by quenching. This means the ductility and the toughness of En 18 alloy steel will increase but hardness and strength will reduce at the same time.

Other than the ball joint as mentioned, there are also other application of this tempered En 18 steel such as gears, railway wheels and tracks. As we can see, all these product has similarity. The similarity is all of these products working in high stress and shear force condition. There are always stress and shear force acting on them which cause them to need a higher toughness instead of higher hardness. If the material used to made them is very hard, this also means the material is very brittle. This kind of material will not be able to absorb part of the impact from the stress and shear force, instead, it become easily broken or fracture if always exposed under this stress and shear condition. Thus tempered En 18 alloy steel , with increased toughness (ductility) and lower the hardness (less brittle) is a perfect material that suit their