27 Materials & Heat Treatment questions from the Mechanical Design bank, written for Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd.
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A.reheating quenched martensite to 150–650 °C to trade some hardness for toughness, always done immediately after hardening
B.rapid surface austenitising by eddy currents followed by spray quench, giving hard crankshaft journals and gear teeth with compressive residual stress
C.structural steel with 250 MPa minimum yield, the default plate and section grade for machine frames, bases and fabricated structures in India
D.composite of about 60% fibre volume in epoxy with specific stiffness several times that of steel but strongly anisotropic, needing ply-by-ply layup design
Answer + AI explanation with Pro
2. Which term means: "structural steel with 250 MPa minimum yield, the default plate and section grade for machine frames, bases and fabricated structures in India"?
Junior
A.Carbon fibre laminate
B.IS 2062 E250
C.Induction hardening
D.Aluminium 6061-T6
Answer + AI explanation with Pro
3. Which statement is correct?
Junior
A.IS 2062 E250 — medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed
B.IS 2062 E250 — precipitation-hardened Al-Mg-Si alloy of about 275 MPa yield that is weldable and extrudable, the default for light structural parts
C.IS 2062 E250 — case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion
D.IS 2062 E250 — structural steel with 250 MPa minimum yield, the default plate and section grade for machine frames, bases and fabricated structures in India
Answer + AI explanation with Pro
4. What is EN8 steel?
Junior
A.nickel-chromium-molybdenum steel (817M40) hardened and tempered to about 850–1000 MPa for highly stressed gears, shafts and crankshafts
B.diffusing carbon into low-carbon steel at 900–950 °C to form a hard 0.5–2 mm case over a tough core, used for gears and camshafts
C.case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion
D.medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed
Answer + AI explanation with Pro
5. Which term means: "medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed"?
Junior
A.Carbon fibre laminate
B.Aluminium 6061-T6
C.EN8 steel
D.Carburising
Answer + AI explanation with Pro
6. Which statement is correct?
Junior
A.EN8 steel — structural steel with 250 MPa minimum yield, the default plate and section grade for machine frames, bases and fabricated structures in India
B.EN8 steel — medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed
C.EN8 steel — rapid surface austenitising by eddy currents followed by spray quench, giving hard crankshaft journals and gear teeth with compressive residual stress
D.EN8 steel — reheating quenched martensite to 150–650 °C to trade some hardness for toughness, always done immediately after hardening
Answer + AI explanation with Pro
7. What is EN24 steel?
Junior
A.case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion
B.rapid surface austenitising by eddy currents followed by spray quench, giving hard crankshaft journals and gear teeth with compressive residual stress
C.nickel-chromium-molybdenum steel (817M40) hardened and tempered to about 850–1000 MPa for highly stressed gears, shafts and crankshafts
D.diffusing carbon into low-carbon steel at 900–950 °C to form a hard 0.5–2 mm case over a tough core, used for gears and camshafts
Answer + AI explanation with Pro
8. Which term means: "nickel-chromium-molybdenum steel (817M40) hardened and tempered to about 850–1000 MPa for highly stressed gears, shafts and crankshafts"?
Junior
A.Carburising
B.Carbon fibre laminate
C.Nitriding
D.EN24 steel
Answer + AI explanation with Pro
9. Which statement is correct?
Junior
A.EN24 steel — medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed
B.EN24 steel — nickel-chromium-molybdenum steel (817M40) hardened and tempered to about 850–1000 MPa for highly stressed gears, shafts and crankshafts
C.EN24 steel — precipitation-hardened Al-Mg-Si alloy of about 275 MPa yield that is weldable and extrudable, the default for light structural parts
D.EN24 steel — diffusing carbon into low-carbon steel at 900–950 °C to form a hard 0.5–2 mm case over a tough core, used for gears and camshafts
Answer + AI explanation with Pro
10. What is Tempering?
Junior
A.medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed
B.case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion
C.reheating quenched martensite to 150–650 °C to trade some hardness for toughness, always done immediately after hardening
D.rapid surface austenitising by eddy currents followed by spray quench, giving hard crankshaft journals and gear teeth with compressive residual stress
Answer + AI explanation with Pro
11. Which term means: "reheating quenched martensite to 150–650 °C to trade some hardness for toughness, always done immediately after hardening"?
Junior
A.Aluminium 6061-T6
B.EN8 steel
C.Tempering
D.EN24 steel
Answer + AI explanation with Pro
12. Which statement is correct?
Junior
A.Tempering — precipitation-hardened Al-Mg-Si alloy of about 275 MPa yield that is weldable and extrudable, the default for light structural parts
B.Tempering — rapid surface austenitising by eddy currents followed by spray quench, giving hard crankshaft journals and gear teeth with compressive residual stress
C.Tempering — reheating quenched martensite to 150–650 °C to trade some hardness for toughness, always done immediately after hardening
D.Tempering — case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion
Answer + AI explanation with Pro
13. What is Carburising?
Junior
A.medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed
B.case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion
C.diffusing carbon into low-carbon steel at 900–950 °C to form a hard 0.5–2 mm case over a tough core, used for gears and camshafts
D.rapid surface austenitising by eddy currents followed by spray quench, giving hard crankshaft journals and gear teeth with compressive residual stress
Answer + AI explanation with Pro
14. Which term means: "diffusing carbon into low-carbon steel at 900–950 °C to form a hard 0.5–2 mm case over a tough core, used for gears and camshafts"?
Junior
A.EN24 steel
B.EN8 steel
C.Carburising
D.Aluminium 6061-T6
Answer + AI explanation with Pro
15. Which statement is correct?
Junior
A.Carburising — case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion
B.Carburising — composite of about 60% fibre volume in epoxy with specific stiffness several times that of steel but strongly anisotropic, needing ply-by-ply layup design
C.Carburising — medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed
D.Carburising — diffusing carbon into low-carbon steel at 900–950 °C to form a hard 0.5–2 mm case over a tough core, used for gears and camshafts
Answer + AI explanation with Pro
16. What is Nitriding?
Mid
A.nickel-chromium-molybdenum steel (817M40) hardened and tempered to about 850–1000 MPa for highly stressed gears, shafts and crankshafts
B.case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion
C.precipitation-hardened Al-Mg-Si alloy of about 275 MPa yield that is weldable and extrudable, the default for light structural parts
D.composite of about 60% fibre volume in epoxy with specific stiffness several times that of steel but strongly anisotropic, needing ply-by-ply layup design
Answer + AI explanation with Pro
17. Which term means: "case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion"?
Mid
A.Carbon fibre laminate
B.Nitriding
C.Carburising
D.Induction hardening
Answer + AI explanation with Pro
18. Which statement is correct?
Mid
A.Nitriding — medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed
B.Nitriding — reheating quenched martensite to 150–650 °C to trade some hardness for toughness, always done immediately after hardening
C.Nitriding — case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion
D.Nitriding — composite of about 60% fibre volume in epoxy with specific stiffness several times that of steel but strongly anisotropic, needing ply-by-ply layup design
Answer + AI explanation with Pro
19. What is Induction hardening?
Mid
A.structural steel with 250 MPa minimum yield, the default plate and section grade for machine frames, bases and fabricated structures in India
B.medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed
C.precipitation-hardened Al-Mg-Si alloy of about 275 MPa yield that is weldable and extrudable, the default for light structural parts
D.rapid surface austenitising by eddy currents followed by spray quench, giving hard crankshaft journals and gear teeth with compressive residual stress
Answer + AI explanation with Pro
20. Which term means: "rapid surface austenitising by eddy currents followed by spray quench, giving hard crankshaft journals and gear teeth with compressive residual stress"?
Mid
A.Tempering
B.EN8 steel
C.EN24 steel
D.Induction hardening
Answer + AI explanation with Pro
21. Which statement is correct?
Mid
A.Induction hardening — composite of about 60% fibre volume in epoxy with specific stiffness several times that of steel but strongly anisotropic, needing ply-by-ply layup design
B.Induction hardening — medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed
C.Induction hardening — diffusing carbon into low-carbon steel at 900–950 °C to form a hard 0.5–2 mm case over a tough core, used for gears and camshafts
D.Induction hardening — rapid surface austenitising by eddy currents followed by spray quench, giving hard crankshaft journals and gear teeth with compressive residual stress
Answer + AI explanation with Pro
22. What is Aluminium 6061-T6?
Mid
A.rapid surface austenitising by eddy currents followed by spray quench, giving hard crankshaft journals and gear teeth with compressive residual stress
B.case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion
C.precipitation-hardened Al-Mg-Si alloy of about 275 MPa yield that is weldable and extrudable, the default for light structural parts
D.structural steel with 250 MPa minimum yield, the default plate and section grade for machine frames, bases and fabricated structures in India
Answer + AI explanation with Pro
23. Which term means: "precipitation-hardened Al-Mg-Si alloy of about 275 MPa yield that is weldable and extrudable, the default for light structural parts"?
Mid
A.EN8 steel
B.Tempering
C.Carbon fibre laminate
D.Aluminium 6061-T6
Answer + AI explanation with Pro
24. Which statement is correct?
Mid
A.Aluminium 6061-T6 — composite of about 60% fibre volume in epoxy with specific stiffness several times that of steel but strongly anisotropic, needing ply-by-ply layup design
B.Aluminium 6061-T6 — nickel-chromium-molybdenum steel (817M40) hardened and tempered to about 850–1000 MPa for highly stressed gears, shafts and crankshafts
C.Aluminium 6061-T6 — diffusing carbon into low-carbon steel at 900–950 °C to form a hard 0.5–2 mm case over a tough core, used for gears and camshafts
D.Aluminium 6061-T6 — precipitation-hardened Al-Mg-Si alloy of about 275 MPa yield that is weldable and extrudable, the default for light structural parts
Answer + AI explanation with Pro
25. What is Carbon fibre laminate?
Senior
A.case hardening at 500–570 °C by nitrogen diffusion into alloy steels such as EN40B, giving over 1000 HV without a quench and hence little distortion
B.precipitation-hardened Al-Mg-Si alloy of about 275 MPa yield that is weldable and extrudable, the default for light structural parts
C.composite of about 60% fibre volume in epoxy with specific stiffness several times that of steel but strongly anisotropic, needing ply-by-ply layup design
D.nickel-chromium-molybdenum steel (817M40) hardened and tempered to about 850–1000 MPa for highly stressed gears, shafts and crankshafts
Answer + AI explanation with Pro
26. Which term means: "composite of about 60% fibre volume in epoxy with specific stiffness several times that of steel but strongly anisotropic, needing ply-by-ply layup design"?
Senior
A.Carbon fibre laminate
B.Tempering
C.EN24 steel
D.Nitriding
Answer + AI explanation with Pro
27. Which statement is correct?
Senior
A.Carbon fibre laminate — diffusing carbon into low-carbon steel at 900–950 °C to form a hard 0.5–2 mm case over a tough core, used for gears and camshafts
B.Carbon fibre laminate — structural steel with 250 MPa minimum yield, the default plate and section grade for machine frames, bases and fabricated structures in India
C.Carbon fibre laminate — medium-carbon 0.4% C steel (080M40) supplied normalised, used for shafts, studs and axles where through-hardening is not needed
D.Carbon fibre laminate — composite of about 60% fibre volume in epoxy with specific stiffness several times that of steel but strongly anisotropic, needing ply-by-ply layup design
Answer + AI explanation with Pro
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