27 real Engineering Materials questions from the Mechanical Core bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is Eutectoid reaction?
Junior
A.depth to which a steel hardens on quenching, measured by the Jominy end-quench test and raised by chromium, molybdenum and manganese
B.brittle crack growth from the combined action of tensile stress and a specific corrosive environment, such as chlorides on austenitic stainless steel
C.austenite of 0.8% carbon transforming on slow cooling to pearlite, a lamellar mix of ferrite and cementite, at 727 °C
D.loss of ductility in high-strength steels when hydrogen absorbed during pickling or plating collects at stress raisers, prevented by baking after plating
A.Eutectoid reaction — microscopic ridges on a fracture surface each marking one cycle of crack advance, the signature that confirms a fatigue failure
B.Eutectoid reaction — austenite of 0.8% carbon transforming on slow cooling to pearlite, a lamellar mix of ferrite and cementite, at 727 °C
C.Eutectoid reaction — brittle crack growth from the combined action of tensile stress and a specific corrosive environment, such as chlorides on austenitic stainless steel
D.Eutectoid reaction — chromium above about 11–12% forms an adherent, self-healing Cr₂O₃ film that provides the corrosion resistance
A.temperature below which BCC steels fracture by brittle cleavage, found from Charpy impact tests at falling temperatures
B.depth to which a steel hardens on quenching, measured by the Jominy end-quench test and raised by chromium, molybdenum and manganese
C.loss of ductility in high-strength steels when hydrogen absorbed during pickling or plating collects at stress raisers, prevented by baking after plating
D.hard, brittle body-centred tetragonal phase formed by diffusionless shear transformation when austenite is quenched
A.Martensite — austenite of 0.8% carbon transforming on slow cooling to pearlite, a lamellar mix of ferrite and cementite, at 727 °C
B.Martensite — temperature below which BCC steels fracture by brittle cleavage, found from Charpy impact tests at falling temperatures
C.Martensite — brittle crack growth from the combined action of tensile stress and a specific corrosive environment, such as chlorides on austenitic stainless steel
D.Martensite — hard, brittle body-centred tetragonal phase formed by diffusionless shear transformation when austenite is quenched
7. What is Ductile-brittle transition temperature?
Junior
A.brittle crack growth from the combined action of tensile stress and a specific corrosive environment, such as chlorides on austenitic stainless steel
B.depth to which a steel hardens on quenching, measured by the Jominy end-quench test and raised by chromium, molybdenum and manganese
C.temperature below which BCC steels fracture by brittle cleavage, found from Charpy impact tests at falling temperatures
D.hard, brittle body-centred tetragonal phase formed by diffusionless shear transformation when austenite is quenched
A.Ductile-brittle transition temperature — loss of ductility in high-strength steels when hydrogen absorbed during pickling or plating collects at stress raisers, prevented by baking after plating
B.Ductile-brittle transition temperature — chromium above about 11–12% forms an adherent, self-healing Cr₂O₃ film that provides the corrosion resistance
C.Ductile-brittle transition temperature — temperature below which BCC steels fracture by brittle cleavage, found from Charpy impact tests at falling temperatures
D.Ductile-brittle transition temperature — time-dependent plastic deformation under constant stress, significant above about 0.4 of the absolute melting temperature
11. Which term means: "depth to which a steel hardens on quenching, measured by the Jominy end-quench test and raised by chromium, molybdenum and manganese"?
A.Hardenability — loss of ductility in high-strength steels when hydrogen absorbed during pickling or plating collects at stress raisers, prevented by baking after plating
B.Hardenability — brittle crack growth from the combined action of tensile stress and a specific corrosive environment, such as chlorides on austenitic stainless steel
C.Hardenability — microscopic ridges on a fracture surface each marking one cycle of crack advance, the signature that confirms a fatigue failure
D.Hardenability — depth to which a steel hardens on quenching, measured by the Jominy end-quench test and raised by chromium, molybdenum and manganese
A.hard, brittle body-centred tetragonal phase formed by diffusionless shear transformation when austenite is quenched
B.loss of ductility in high-strength steels when hydrogen absorbed during pickling or plating collects at stress raisers, prevented by baking after plating
C.temperature below which BCC steels fracture by brittle cleavage, found from Charpy impact tests at falling temperatures
D.time-dependent plastic deformation under constant stress, significant above about 0.4 of the absolute melting temperature
A.Creep — time-dependent plastic deformation under constant stress, significant above about 0.4 of the absolute melting temperature
B.Creep — chromium above about 11–12% forms an adherent, self-healing Cr₂O₃ film that provides the corrosion resistance
C.Creep — brittle crack growth from the combined action of tensile stress and a specific corrosive environment, such as chlorides on austenitic stainless steel
D.Creep — austenite of 0.8% carbon transforming on slow cooling to pearlite, a lamellar mix of ferrite and cementite, at 727 °C
A.loss of ductility in high-strength steels when hydrogen absorbed during pickling or plating collects at stress raisers, prevented by baking after plating
B.time-dependent plastic deformation under constant stress, significant above about 0.4 of the absolute melting temperature
C.chromium above about 11–12% forms an adherent, self-healing Cr₂O₃ film that provides the corrosion resistance
D.microscopic ridges on a fracture surface each marking one cycle of crack advance, the signature that confirms a fatigue failure
A.Stainless steel passivity — chromium above about 11–12% forms an adherent, self-healing Cr₂O₃ film that provides the corrosion resistance
B.Stainless steel passivity — depth to which a steel hardens on quenching, measured by the Jominy end-quench test and raised by chromium, molybdenum and manganese
C.Stainless steel passivity — temperature below which BCC steels fracture by brittle cleavage, found from Charpy impact tests at falling temperatures
D.Stainless steel passivity — austenite of 0.8% carbon transforming on slow cooling to pearlite, a lamellar mix of ferrite and cementite, at 727 °C
A.microscopic ridges on a fracture surface each marking one cycle of crack advance, the signature that confirms a fatigue failure
B.depth to which a steel hardens on quenching, measured by the Jominy end-quench test and raised by chromium, molybdenum and manganese
C.time-dependent plastic deformation under constant stress, significant above about 0.4 of the absolute melting temperature
D.brittle crack growth from the combined action of tensile stress and a specific corrosive environment, such as chlorides on austenitic stainless steel
20. Which term means: "microscopic ridges on a fracture surface each marking one cycle of crack advance, the signature that confirms a fatigue failure"?
A.Fatigue striations — brittle crack growth from the combined action of tensile stress and a specific corrosive environment, such as chlorides on austenitic stainless steel
B.Fatigue striations — chromium above about 11–12% forms an adherent, self-healing Cr₂O₃ film that provides the corrosion resistance
C.Fatigue striations — microscopic ridges on a fracture surface each marking one cycle of crack advance, the signature that confirms a fatigue failure
D.Fatigue striations — time-dependent plastic deformation under constant stress, significant above about 0.4 of the absolute melting temperature
A.loss of ductility in high-strength steels when hydrogen absorbed during pickling or plating collects at stress raisers, prevented by baking after plating
B.depth to which a steel hardens on quenching, measured by the Jominy end-quench test and raised by chromium, molybdenum and manganese
C.microscopic ridges on a fracture surface each marking one cycle of crack advance, the signature that confirms a fatigue failure
D.time-dependent plastic deformation under constant stress, significant above about 0.4 of the absolute melting temperature
23. Which term means: "loss of ductility in high-strength steels when hydrogen absorbed during pickling or plating collects at stress raisers, prevented by baking after plating"?
A.Hydrogen embrittlement — time-dependent plastic deformation under constant stress, significant above about 0.4 of the absolute melting temperature
B.Hydrogen embrittlement — austenite of 0.8% carbon transforming on slow cooling to pearlite, a lamellar mix of ferrite and cementite, at 727 °C
C.Hydrogen embrittlement — chromium above about 11–12% forms an adherent, self-healing Cr₂O₃ film that provides the corrosion resistance
D.Hydrogen embrittlement — loss of ductility in high-strength steels when hydrogen absorbed during pickling or plating collects at stress raisers, prevented by baking after plating
A.brittle crack growth from the combined action of tensile stress and a specific corrosive environment, such as chlorides on austenitic stainless steel
B.time-dependent plastic deformation under constant stress, significant above about 0.4 of the absolute melting temperature
C.hard, brittle body-centred tetragonal phase formed by diffusionless shear transformation when austenite is quenched
D.depth to which a steel hardens on quenching, measured by the Jominy end-quench test and raised by chromium, molybdenum and manganese
26. Which term means: "brittle crack growth from the combined action of tensile stress and a specific corrosive environment, such as chlorides on austenitic stainless steel"?
A.Stress corrosion cracking — brittle crack growth from the combined action of tensile stress and a specific corrosive environment, such as chlorides on austenitic stainless steel
B.Stress corrosion cracking — chromium above about 11–12% forms an adherent, self-healing Cr₂O₃ film that provides the corrosion resistance
C.Stress corrosion cracking — microscopic ridges on a fracture surface each marking one cycle of crack advance, the signature that confirms a fatigue failure
D.Stress corrosion cracking — depth to which a steel hardens on quenching, measured by the Jominy end-quench test and raised by chromium, molybdenum and manganese
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