51. Various method of hardening of steel.
Hall Petch, Work Hardening, Solid Solution Strengthening, Precipitation Hardening and Martensic Transformation.
52. Define Quenching?
Material is heated up to the suitable temperature and then quenched in water or oil to harden to full hardness according to the kind of steels.
53. Define Tempering?
Tempering is a heat treatment technique applied to ferrous alloys, such as steel or cast iron, to achieve greater toughness by decreasing the hardness of the alloy.
54. Difference between natural and artificial aging.
Artificial Aging is done at elevated temperatures.
Natural Aging is done at room temperature.
55. Cast iron is a _________?
56. Speed of Aeroplane is measured by _________? : Pitot Tube.
57. What is Hess Law?
According to the Hess law the energy transfer is simply independent of the path being followed. If the reactant and the product of the whole process are the same then same amount of energy will be dissipated or absorbed.
58. How much Watt means 1Hp? :- 746.2 watt
59. why Entropy decreases with increase in temperature?
ds = dQ/T, Entropy is inversely proportional to the temperature so, as temperature increases, entropy decreases.
60. Work done in free expansion process is : zero.
Mechanical Engineering Important Question