Materials & Corrosion Basics interview questions

1. A.localised attack forming small deep holes, typically on stainless steel in chloride environments where the passive film breaks down locally
2. B.brittle cracking under combined tensile stress and a specific environment, such as austenitic stainless steel in hot chlorides above about 60 °C
3. C.accelerated attack of the less noble metal when two dissimilar metals are electrically connected in an electrolyte, as with carbon steel bolted to stainless
4. D.combined mechanical wear and corrosion at high-velocity or impingement points such as elbows and impellers, controlled by velocity limits and harder alloys

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1. A.Galvanic corrosion
2. B.Sacrificial anode
3. C.Stress corrosion cracking
4. D.Hydrogen embrittlement

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1. A.Galvanic corrosion — cathodic protection using a more active metal such as zinc or magnesium that corrodes in place of the protected steel structure
2. B.Galvanic corrosion — localised attack forming small deep holes, typically on stainless steel in chloride environments where the passive film breaks down locally
3. C.Galvanic corrosion — accelerated attack of the less noble metal when two dissimilar metals are electrically connected in an electrolyte, as with carbon steel bolted to stainless
4. D.Galvanic corrosion — combined mechanical wear and corrosion at high-velocity or impingement points such as elbows and impellers, controlled by velocity limits and harder alloys

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1. A.chromium carbide precipitation at grain boundaries of stainless steel held at 450–850 °C, causing intergranular attack; prevented by L-grade or Ti/Nb-stabilised steel
2. B.cathodic protection using a more active metal such as zinc or magnesium that corrodes in place of the protected steel structure
3. C.formation of a thin adherent chromium oxide film on stainless steel containing at least about 11% chromium, which stops further oxidation
4. D.pitting resistance equivalent number, %Cr + 3.3 × %Mo + 16 × %N, ranking stainless steels; duplex 2205 scores about 35 against about 25 for 316L

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1. A.Pitting corrosion
2. B.Passivation
3. C.Galvanic corrosion
4. D.PREN

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1. A.Passivation — pitting resistance equivalent number, %Cr + 3.3 × %Mo + 16 × %N, ranking stainless steels; duplex 2205 scores about 35 against about 25 for 316L
2. B.Passivation — formation of a thin adherent chromium oxide film on stainless steel containing at least about 11% chromium, which stops further oxidation
3. C.Passivation — loss of ductility when atomic hydrogen diffuses into high-strength steel from pickling, plating or wet H2S service
4. D.Passivation — cathodic protection using a more active metal such as zinc or magnesium that corrodes in place of the protected steel structure

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1. A.localised attack forming small deep holes, typically on stainless steel in chloride environments where the passive film breaks down locally
2. B.pitting resistance equivalent number, %Cr + 3.3 × %Mo + 16 × %N, ranking stainless steels; duplex 2205 scores about 35 against about 25 for 316L
3. C.accelerated attack of the less noble metal when two dissimilar metals are electrically connected in an electrolyte, as with carbon steel bolted to stainless
4. D.chromium carbide precipitation at grain boundaries of stainless steel held at 450–850 °C, causing intergranular attack; prevented by L-grade or Ti/Nb-stabilised steel

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1. A.PREN
2. B.Stress corrosion cracking
3. C.Pitting corrosion
4. D.Passivation

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1. A.Pitting corrosion — formation of a thin adherent chromium oxide film on stainless steel containing at least about 11% chromium, which stops further oxidation
2. B.Pitting corrosion — pitting resistance equivalent number, %Cr + 3.3 × %Mo + 16 × %N, ranking stainless steels; duplex 2205 scores about 35 against about 25 for 316L
3. C.Pitting corrosion — localised attack forming small deep holes, typically on stainless steel in chloride environments where the passive film breaks down locally
4. D.Pitting corrosion — brittle cracking under combined tensile stress and a specific environment, such as austenitic stainless steel in hot chlorides above about 60 °C

Answer + AI explanation with Pro

1. A.formation of a thin adherent chromium oxide film on stainless steel containing at least about 11% chromium, which stops further oxidation
2. B.localised attack forming small deep holes, typically on stainless steel in chloride environments where the passive film breaks down locally
3. C.loss of ductility when atomic hydrogen diffuses into high-strength steel from pickling, plating or wet H2S service
4. D.cathodic protection using a more active metal such as zinc or magnesium that corrodes in place of the protected steel structure

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1. A.Pitting corrosion
2. B.Galvanic corrosion
3. C.Sacrificial anode
4. D.Passivation

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1. A.Sacrificial anode — pitting resistance equivalent number, %Cr + 3.3 × %Mo + 16 × %N, ranking stainless steels; duplex 2205 scores about 35 against about 25 for 316L
2. B.Sacrificial anode — cathodic protection using a more active metal such as zinc or magnesium that corrodes in place of the protected steel structure
3. C.Sacrificial anode — combined mechanical wear and corrosion at high-velocity or impingement points such as elbows and impellers, controlled by velocity limits and harder alloys
4. D.Sacrificial anode — localised attack forming small deep holes, typically on stainless steel in chloride environments where the passive film breaks down locally

Answer + AI explanation with Pro

1. A.formation of a thin adherent chromium oxide film on stainless steel containing at least about 11% chromium, which stops further oxidation
2. B.chromium carbide precipitation at grain boundaries of stainless steel held at 450–850 °C, causing intergranular attack; prevented by L-grade or Ti/Nb-stabilised steel
3. C.brittle cracking under combined tensile stress and a specific environment, such as austenitic stainless steel in hot chlorides above about 60 °C
4. D.combined mechanical wear and corrosion at high-velocity or impingement points such as elbows and impellers, controlled by velocity limits and harder alloys

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1. A.Pitting corrosion
2. B.Sacrificial anode
3. C.Stress corrosion cracking
4. D.Erosion-corrosion

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1. A.Stress corrosion cracking — localised attack forming small deep holes, typically on stainless steel in chloride environments where the passive film breaks down locally
2. B.Stress corrosion cracking — chromium carbide precipitation at grain boundaries of stainless steel held at 450–850 °C, causing intergranular attack; prevented by L-grade or Ti/Nb-stabilised steel
3. C.Stress corrosion cracking — combined mechanical wear and corrosion at high-velocity or impingement points such as elbows and impellers, controlled by velocity limits and harder alloys
4. D.Stress corrosion cracking — brittle cracking under combined tensile stress and a specific environment, such as austenitic stainless steel in hot chlorides above about 60 °C

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1. A.accelerated attack of the less noble metal when two dissimilar metals are electrically connected in an electrolyte, as with carbon steel bolted to stainless
2. B.pitting resistance equivalent number, %Cr + 3.3 × %Mo + 16 × %N, ranking stainless steels; duplex 2205 scores about 35 against about 25 for 316L
3. C.formation of a thin adherent chromium oxide film on stainless steel containing at least about 11% chromium, which stops further oxidation
4. D.loss of ductility when atomic hydrogen diffuses into high-strength steel from pickling, plating or wet H2S service

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1. A.PREN
2. B.Erosion-corrosion
3. C.Galvanic corrosion
4. D.Hydrogen embrittlement

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1. A.Hydrogen embrittlement — combined mechanical wear and corrosion at high-velocity or impingement points such as elbows and impellers, controlled by velocity limits and harder alloys
2. B.Hydrogen embrittlement — localised attack forming small deep holes, typically on stainless steel in chloride environments where the passive film breaks down locally
3. C.Hydrogen embrittlement — brittle cracking under combined tensile stress and a specific environment, such as austenitic stainless steel in hot chlorides above about 60 °C
4. D.Hydrogen embrittlement — loss of ductility when atomic hydrogen diffuses into high-strength steel from pickling, plating or wet H2S service

Answer + AI explanation with Pro

1. A.formation of a thin adherent chromium oxide film on stainless steel containing at least about 11% chromium, which stops further oxidation
2. B.chromium carbide precipitation at grain boundaries of stainless steel held at 450–850 °C, causing intergranular attack; prevented by L-grade or Ti/Nb-stabilised steel
3. C.cathodic protection using a more active metal such as zinc or magnesium that corrodes in place of the protected steel structure
4. D.pitting resistance equivalent number, %Cr + 3.3 × %Mo + 16 × %N, ranking stainless steels; duplex 2205 scores about 35 against about 25 for 316L

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1. A.Sensitisation
2. B.PREN
3. C.Galvanic corrosion
4. D.Erosion-corrosion

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1. A.Sensitisation — combined mechanical wear and corrosion at high-velocity or impingement points such as elbows and impellers, controlled by velocity limits and harder alloys
2. B.Sensitisation — chromium carbide precipitation at grain boundaries of stainless steel held at 450–850 °C, causing intergranular attack; prevented by L-grade or Ti/Nb-stabilised steel
3. C.Sensitisation — cathodic protection using a more active metal such as zinc or magnesium that corrodes in place of the protected steel structure
4. D.Sensitisation — localised attack forming small deep holes, typically on stainless steel in chloride environments where the passive film breaks down locally

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1. A.cathodic protection using a more active metal such as zinc or magnesium that corrodes in place of the protected steel structure
2. B.accelerated attack of the less noble metal when two dissimilar metals are electrically connected in an electrolyte, as with carbon steel bolted to stainless
3. C.localised attack forming small deep holes, typically on stainless steel in chloride environments where the passive film breaks down locally
4. D.pitting resistance equivalent number, %Cr + 3.3 × %Mo + 16 × %N, ranking stainless steels; duplex 2205 scores about 35 against about 25 for 316L

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1. A.Passivation
2. B.Galvanic corrosion
3. C.Hydrogen embrittlement
4. D.PREN

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1. A.PREN — localised attack forming small deep holes, typically on stainless steel in chloride environments where the passive film breaks down locally
2. B.PREN — pitting resistance equivalent number, %Cr + 3.3 × %Mo + 16 × %N, ranking stainless steels; duplex 2205 scores about 35 against about 25 for 316L
3. C.PREN — chromium carbide precipitation at grain boundaries of stainless steel held at 450–850 °C, causing intergranular attack; prevented by L-grade or Ti/Nb-stabilised steel
4. D.PREN — brittle cracking under combined tensile stress and a specific environment, such as austenitic stainless steel in hot chlorides above about 60 °C

Answer + AI explanation with Pro

1. A.loss of ductility when atomic hydrogen diffuses into high-strength steel from pickling, plating or wet H2S service
2. B.chromium carbide precipitation at grain boundaries of stainless steel held at 450–850 °C, causing intergranular attack; prevented by L-grade or Ti/Nb-stabilised steel
3. C.combined mechanical wear and corrosion at high-velocity or impingement points such as elbows and impellers, controlled by velocity limits and harder alloys
4. D.cathodic protection using a more active metal such as zinc or magnesium that corrodes in place of the protected steel structure

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1. A.Galvanic corrosion
2. B.Erosion-corrosion
3. C.Sacrificial anode
4. D.Sensitisation

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1. A.Erosion-corrosion — pitting resistance equivalent number, %Cr + 3.3 × %Mo + 16 × %N, ranking stainless steels; duplex 2205 scores about 35 against about 25 for 316L
2. B.Erosion-corrosion — formation of a thin adherent chromium oxide film on stainless steel containing at least about 11% chromium, which stops further oxidation
3. C.Erosion-corrosion — loss of ductility when atomic hydrogen diffuses into high-strength steel from pickling, plating or wet H2S service
4. D.Erosion-corrosion — combined mechanical wear and corrosion at high-velocity or impingement points such as elbows and impellers, controlled by velocity limits and harder alloys

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