A heated plate is built into the wall of a large room. The room is maintained at 300 K. The exposed surface of the plate is main
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Answer:
a) The minimum acceptable value is 387.5 HV using Vickers hardness test.
b) The minimum acceptable value is 39.4 HRC using Rockwell C hardness test.
Explanation:
To get the tensile strength of a material from its hardness, we multiply it by an empirical constant that depends on things like yield strength, work-hardening, Poisson's ratio and geometrical factors. The incidence of cold-work varies this relationship.
According to DIN 50150 (a conversion table for hardness), the constant for Vickers hardness is ≈ 3.2 (an empirical approximate):
According to DIN 50150, the constant for Rockwell C hardness test is ≈31.5 around this values of tensile strength:
Answer:
The volume percent of graphite is 91.906 per cent.
Explanation:
The volume percent of graphite () is determined by the following expression:
Where:
- Volume occupied by the graphite phase, measured in cubic centimeters.
- Volume occupied by the ferrite phase, measured in cubic centimeters.
The volume of each phase can be calculated in terms of its density and mass. That is:
Where:
,
- Masses of the graphite and ferrite phases, measured in grams.
,
- Densities of the graphite and ferrite phases, measured in grams per cubic centimeter.
Let substitute each volume in the definition of the volume percent of graphite:
Let suppose that 100 grams of cast iron are available, masses of each phase are now determined:
If ,
,
and
, the volume percent of graphite is:
The volume percent of graphite is 91.906 per cent.
Answer:
a) , b)
, c)
, d)
, e)
Explanation:
a) The coefficient of performance of the reversible refrigeration cycle is:
The temperature of the hot reservoir is:
b) The coefficient of performance is:
c) The temperature of the hot reservoir can be determined with the help of the following relation:
d) The coefficient of performance is:
e) The temperature of the cold reservoir is: