Which alloying element fails to contribute high strength at elevated operating temperatures__________________?
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Answer: B. magnesium
Explanation
Alloying elements added to steel generally improve mechanical properties, but magnesium fails to provide useful high-temperature strength. Magnesium has a low melting point and oxidizes readily, making it completely unsuitable for high-temperature alloy steel applications. Transition metals like nickel, manganese, and silicon form stable solid solutions that effectively resist high-temperature creep. High-temperature structural applications require alloying elements that prevent grain boundary sliding and high-temperature oxidation. Magnesium is primarily used as a lightweight alloying addition in aluminum alloys and ductile iron production rather than high-temp steel. Creep resistance is achieved by adding refractory metals such as chromium, molybdenum, tungsten, and nickel to the iron matrix.
Manganese contributes effectively to steel hardenability, tensile strength, and high-temperature performance when alloyed correctly. Nickel is a premier alloying element that provides excellent high-temperature strength, toughness, and corrosion resistance. Silicon improves high-temperature oxidation resistance and strength, making it a valuable addition unlike magnesium.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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