Askmemetallurgy Latest Questions
GATE MT 2021 Q52. At 25 °C, iron corrodes in a deaerated acid of pH 3 with a corrosion current density of 4 µA cm-2. The corrosion potential (V) is: (round off to 2 decimal places). Given: βc = 0.1 V per decade of current density Exchange current density of hydrogen on iron surface = 10-9 A cm-2 R = 8.314 J mol-1 K-1, F = 96500 C mol-1All potentials are with reference to standard hydrogen electrode.
GATE MT 2021 Q51. A thick steel plate containing 0.1 wt.% C is carburized at 950 °C. The plate’s surface carbon concentration is maintained at 1.1 wt.% C. After 9 hours, the depth (in mm) below the surface at which the carbon concentration is 0.6 wt.% C will be: (round off to 2 decimal places).Given: Diffusivity of carbon in γ-Fe at 950 °C = 1.6 x 10-11 m2 s-1 Error function table:
GATE MT 2021 Q50. A hypothetical binary eutectic phase diagram of A – B is shown below. An alloy with 5 wt.% B solidifies with no convection. Assuming steady state, the critical temperature gradient (in K mm-1) required to maintain planar solidification front is:(round off to nearest integer). Given: Diffusivity of B in liquid = 10-9 m2 s-1 Velocity of solidification front = 4 µm s-1
GATE MT 2021 Q49. An infinite metal plate has a central through-thickness crack of length 𝟖𝟎/𝝅 mm. The maximum applied stress (in MPa) that the plate can sustain in mode I is: (round off to nearest integer). Assume: Linear elastic fracture mechanics is validGiven: Fracture toughness, 𝑲𝑰𝑪= 20 MPa m1/2
GATE MT 2021 Q46. Two dislocation lines parallel to z-axis lying in the x-z plane are shown in the figure. The glide force (in Newton) exerted by the edge dislocation on the screw dislocation is:(round off to nearest integer). For the edge, the shear stress component is given by: 𝛕xy = 𝐆𝐛. x. 𝐱2(𝐱 −𝐲 )2 / 𝟐p(𝟏−n) (𝐱𝟐+𝐲𝟐) 𝟐 Given: Shear modulus, G = 28 GPa Poisson’s ratio, n = 0.3 Burgers vector, b = 0.29 nmDistance between the two dislocations = 0.5 nm.
GATE MT 2021 Q43. For the equilibrium reaction: 𝟐𝑪𝒖 (𝒔) + 𝑺𝑶𝟐(𝒈) = 𝑪𝒖𝟐𝑺 (𝒔) + 𝑶𝟐 (𝒈), the value of 𝒍𝒏 ( 𝑷𝑶𝟐/ 𝑷𝑺𝑶𝟐 ) at 973 K is: _ (round off to 2 decimal places).𝑷𝑶𝟐value of 𝒍𝒏 ( ) at 973 K is: _ (round off to 2 decimal places) Given: 𝟐𝑪𝒖 (𝒔) + 𝟎. 𝟓𝑺𝟐(𝒈) = 𝑪𝒖𝟐𝑺 (𝒔) ΔGo at 973 K = -100 kJ 𝑺𝑶𝟐(𝒈) = 𝟎. 𝟓𝑺𝟐(𝒈) + 𝑶𝟐(𝒈) ΔGo at 973 K = 292 kJ R = 8.314 J mol-1 K-1Assume: Cu and Cu2S are pure solids.
GATE MT 2021 Q40. A continuous fillet weld is made using a 3000 W welding machine. At a travel speed of 6 mm s-1, the cross-sectional area (in mm2) of the weld is: (round off to nearest integer). Given: The unit energy required to melt the metal is 6 J mm-3.Heat transfer factor = 0.6 Melting factor = 0.5
Consider the function 𝒇(𝒙) = 𝒙 − 𝐜𝐨𝐬 𝒙. Using Newton-Raphson method, the estimated root of 𝒇(𝒙) after the first iteration is: (round off to 3 decimal places).Assume: Initial guess of the root = 0.5 radians.
Consider the function 𝒇(𝒙) = 𝒙 − 𝐜𝐨𝐬 𝒙. Using Newton-Raphson method, the estimated root of 𝒇(𝒙) after the first iteration is: (round off to 3 decimal places).Assume: Initial guess of the root = 0.5 radians.Read less