Hardenability is a measure of the capacity of a steel to be hardened in depth when quenched from its austenitizing temperature.
[ME 2016, Set-1]
The Jominy End Quench Test ASTM A 255 measures Hardenability of steels. Hardenability is a measure of the capacity of a steel to be hardened in depth when quenched from its austenitizing temperature. Hardenability of a steel should not be confused with the hardness of a steel.
For a ductive material,toughness is a measure of ability to absorb energy up to the fracture point.
(a) Resistance to scrateling is resistance to abrasion.
(b) Toughness is the ability to absorb energy upto fracture.
(c) Proof resilence is the ability to absorb energy till elastic limit.
(d) Hardness the resistance to indentation.
ε = n (1 + e) = 1n (1 + 0.35) = 0.3
At UTS point: n = ε
σ = σ0 (1 + e) = 400 (1 + 0.35)
540 = k(0.3)0.3
Strength decreases as dislocation movement becomes easier.
Cyaniding: Carbon & Nitrogen diffuses to surface and rapidly quenched in case hardening.
Charpy Test - Toughness
Knoop Test - Microhardness
Spiral Test - Fluidity
Cupping Test - Formability