Mechanical Engineering - Machine Design - Discussion

Well, as a direct answer for the question, it is B. Decreases.

Decreases with the time at which the material is subjected to the heat, as long as the material is subjected to the heat, as long as the toughness decrease, also the strength of the flame is important factor proportional to how fast and short time the material takes to decrease its toughness.

And that is general saying, and for specif sayings, it does depend on the material properties, such as type, its yield strength, Ultimate strength, its Critical points of reaching the toughness, etc.

Toughness is total energy absorbed by the material before failure or/ toughness is the area under the Stress-strain curve of a material.

Thus when a material is heated it becomes ductile or simply soft and thus less stress is required to deform the material and curve will shift down and area under curve decreases thus toughness decreases.

Toughness increases.

While heating a metal, it's fluidity increases, Metals become more ductile, hence ultimate tensile strength increases. It becomes more plastic, hence absorbing more energy before fracture. Thus toughness increases.

If the increament in temperature toughness increases then why we doing tempering anyone can tell I think that if we heated the queched the material then strenght increases and hardness reducess so toughness also reducess.

Another perspective into this: Toughness is the area under stress-strain curve, with increase in temperature ductility increases which in turn will increase the area under stress-strain curve

Toughness is defined as property of material in order to observe energy in plastic region. Hence when it is heated its property elapse hence toughness will decrease.

With increase in temperature ductility, malleability and toughness increase. But with the increase in temperature-yield stress and modulus of elasticity decreases.

Toughness is a property of material that can absorb up to failure.

When heating the material will becomes softened, so that the toughness will becomes reduced.

When material undergoes hot working process, its ductility and toughness increases. In cold working process its hardness and strength increases.

When the material is heated the randomness of the molecules present in it increases, which results in decreasing toughness of the material.