79) The cutting tools are made from

Answer is:

high speed steel

Engineering Materials MCQ with Answers

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80) which of the following gives the correct order of increasing hot hardness of cutting tool materials?

Answer is:

High speed steel, Carbide, Diamond

81) Killed steels

Answer is:

are free from oxygen

Explanation:

When steel has been fully deoxidized before casting and no gas was evolved during solidification, the resultant steel is known as killed steel. It is combined with an agent like casting before use. This steel is called "killed" because it quietly solidifies in the mold and no gas evolves.