Physical Metallurgy - Study Mode
[#76] Match the microstructural state of the following steels with. their respective heat treatments Group-I Group-II P. Eutectoid steel homogenised at 900°C and quenched in water at room temperature 1. Ferrite, martensite and retained austenite Q. A 0.4% C steel soaked at 750°C and quenched in water at room temperature. 2. Pearlite and carbide R. Normalised 1%C steel. 3. Martensite and retained austenite S. Eutectoid steel subjected to normalising 4. Pearlite
Correct Answer
(C) P-4, Q-3, R-2, S-1
[#77] For the same volume fraction, size and size distribution of precipitates, the highest strength in a precipitation-hardened material is obtained when the precipitates are
Correct Answer
(C) nucleated on dislocation substructure
[#78] In the homogenous nucleation, as compared to heterogeneous nucleation
Correct Answer
(A) undercooling is more and the critical radius of the spherical surface of the nucleus r cr is smaller
[#79] Choose the correct statements. P. Interstitial atoms diffuse slower than substitutional atoms Q. In pure metals the vacancy concentration increases with temperature R. Martensitic transformation is athermal in nature S. Atoms in the grain boundary diffuse slower than in the bulk at relatively lower temperatures.
Correct Answer
(B) Q, R
[#80] During load Vs load-line displacement measurement for the determination of J 10 conipliance is measured at intervals to estimate
Correct Answer
(D) crack opening displacement