Brittle fracture is more dangerous than ductile fracture because
Failure due to excessive deformation is controlled by
Fracture voids usually form at
Most often machine components fail by
Creep rate in ternary stage
Ternary stage creep is associated with
Primary Creep: This stage is mainly due to dislocation movement. The creep rate decreases with time and the effect of work hardening is more than that of the recovery process.
Secondary Creep: The rates of work hardening and recovery during this stage are equal, so the material creeps at a steady rate (minimum creep rate).
Ternary Creep: Creep rate increases with time until fracture occurs at this stage. Tertiary creep can occur due to necking of the specimen or grain boundary sliding at high temperature and this continues until specimen fractures.
Creep curve for viscous creep is shown by
Fatigue strength for non-ferrous materials is defined at X stress cycles. The value of X is
For all ferrous metals tested, and for most non-ferrous metals, these S-N diagrams become almost horizontal for values of N ranging from 1 x 106 to 5 x 107 cycles, thus indicating a well-defined endurance limit. We must note that the number of cycles are arbitrarily taken.
The destruction of the metal under the fatigue and corrosion is called
Consider the following effects of yield point:
1. Luders bands
2. Strain ageing
3. Blue brittleness
4. Orange peel effect
Q. Which of the above are true?
Luders Bands: These represents the marking on the surface of a tensile test sample, formed at the points of stress concentration like fillets.
Strain Ageing: It refers to changes in the properties of an over strained alloy with time. Strain ageing or strain-age-hardening is accompanied by hardening due to increase in stress value.
Blue Brittleness: When the temperature range of the test is raised, the yield point becomes less pronounced and blue brittleness effect is produced.
Orange Peel effects: During stretching, these markings appear on metals.
The yield strength σy Internal frictional stress σi and diameters of grain d are related as
Brinell hardness number is expressed by the equation
where, L = Load in kg
D = Dia of. ball in mm
d = dia of indentation in mm
The property of material which enables it to retain the deformation permanently is called
Plasticity is that property of a material by virtue of which it may be permanently deformed when it has been subjected to an externally applied force great enough to exceed the elastic limit.
A material to be rolled or beaten into thin sheets have this property
The ability of metal to be formed by hammering or rolling is called malleability.
The ductility of a material with work hardening
Which one of the following metal would work- harden more quickly than the others
Material exhibiting time bound behaviour are known as
The material property which depends only on the basic crystal structure is
Match List-I with List-ll and select the correct answer using the codes given below the lists:
1. Absorb energy elastically
2. Resistance against deformation
3. Making sheets
4. Permanent deformation
A B C D
(a) 3 4 2 1
(b) 4 3 1 2
(c) 1 2 3 4
(d) 3 2 1 4
Resilience is the property of material to absorb energy when it is deformed elastically.
Plasticity is the property by virtue of which it can be deformed permanently.
Hardness is. the resistance against indentation or scratch.
Malleability is the property by which metal can be drawn in the form of sheets.
Among the following material properties at room temperature
Q. Modulus of Elasticity
S. Thermal conductivity
Q. Microstructure sensitive properties are: