Mechanical Metallurgy Mid - II, November - 2014

1.The temperature at which the fracture becomes 100% cleavage is ……….
  • FTP
  • FATT
  • NDT
  • DBTT
Answer: C
2.Blue brittleness occurs on heating in the range of ………….
  • 0°C to 50°C
  • 50°C to 100°C
  • 150°C to 230°C
  • 230°C to 370°C
Answer: D
3.Toughness is measured by …………… test.
  • Creep
  • Compression
  • Impact
  • Fatigue
Answer: C
4.Barreling and buckling defects are observed in …………… test.
  • Creep
  • Compression
  • Impact
  • Fatigue
Answer: B
5.Slip band extrusions and intrusions are observed in …………… test.
  • Creep
  • Compression
  • Impact
  • Fatigue
Answer: D
6.In a compression test at constant cross head speed, the true strain rate ---------- with deformation.
  • Continuously decreases
  • Follow sine curve
  • Continuously increases
  • None of them
Answer: C
7.Pre-cracked specimens are used in the Instrumented Charpy test to measure
  • Toughness
  • Dynamic fracture toughness
  • Transition temperature
  • Compressive strength
Answer: B
8.The notch-toughness of low - and medium - strength bcc metals, as well as Be, Zn and ceramic materials is strongly dependent on
  • Temperature
  • Strain rate
  • Size of the specimen
  • None of them
Answer: A
9.The crack propagation rate is indicated by
  • dσ/dt
  • dε/dt
  • dτ/dt
  • da/dN
Answer: D
10.Grain-boundary sliding is promoted by --------- and/or --------
  • increasing the temperature, strain rate
  • decreasing the temperature, strain rate
  • increasing the temperature, decreasing the strain rate
  • decreasing the temperature, increasing strain rate
Answer: C
11.The time dependent deformation is called ___________
Answer: Creep
12.The stress below which a material can be stressed cyclically for an infinite number of times without failure is known as _____________
Answer: Endurance limit
13.Theoretical stress – concentration factor is the ratio of ____________
Answer: The maximum stress to the nominal stress
14.The standard dimensions of the specimen used for Charpy impact test is ____________
Answer: 10 x 10 x 50 mm
15.__________is the ability of a material to withstand very large deformation in tension without necking.
Answer: Super plasticity
16.Based on metallographic examination, fractures in polycrystalline materials are classified as either ____________ or __________.
Answer: Transgranular or intergranular
17.The first explanation of the discrepancy between the observed fracture strength of crystals and the theoretical cohesive strength was proposed by _____________.
Answer: Griffith
18.The expression for fracture stress for a brittle material is σmax = _____________.
Answer: (E γs/a0)½
19.Failures occurring under dynamic loading are called _____________.
Answer: Fatigue failures
20.An important structural feature which appears to be unique to fatigue deformation is the formation of _____ and __________.
Answer: Slip-band extrusions and slip-band intrusio ridges and grooves