Question

Briefly explain all types of engineering fractures?

5. Why steel is the most metallic materials used in engineering?

6. How can you determine the strength of specimen if you don't have tensile test machine in your lab but you have other machines?

Answer 1

Types of engineering fracture are :-

Characteristics

Terms used

Strain to failure	Ductile	Brittle
Crystallographic mode	Shear	Cleavage
Apperance	Fibrous and gray	Granular and bright
Crank Propagation	Along grain boundaries	Through grains

Ductile fracture is the extensively deformation of plastic or necking. In this, there is a massive amounts of enegy absorption and slow propagation before the fracture occurs. But any error in the design process does not result in catastrophic failure.

Brittle fracture is a very rapid cracking of material under stress where there is a little bit of error in material, plastic degradation occurs before the fracture. There are two types of fracture: Transgranular and intergranular fracture this depend upon whether the grain boundaries are stronger or weaker than the grains.

Shear fracture, is also known as slip surface in this fracture the relative movement is parralel to the fracture. This occurs in a small displacement.

Cleavage fracture also appear as crystallline fracture, (cleavage is known as the break of a crystal face where a new crystal face is formed where the mineral broke )  most of the grains have failed by cleavage, resulting in bright, reflective facets. It is associated with low energy brittle fracture.

5) Steel is the most meatallic material used in engineering becuase

• it is an alloy, combination of iron and carbon.
• High tensile strength than other alloy
• Low cost
• Ease of production
• Highly versatility

Presence of higher levels of carbon increase strength and hardness, and decrease the ductility and weldability.