GATE MT 2011 Q39. Match the heat treatment processes in group 1 with resultant microstructure of steel in group 2.
GATE MT 2011 Q39. Match the heat treatment processes in group 1 with resultant microstructure of steel in group 2.
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Correct answer is option D. Martempering is also known as stepped quenching or interrupted quenching. In this process, steel is heated above the upper critical point (above the transformation range) and then quenched in a salt, oil, or lead bath kept at a temperature of 150-300 °C. The workpiece iRead more
Correct answer is option D.
- Martempering is also known as stepped quenching or interrupted quenching. In this process, steel is heated above the upper critical point (above the transformation range) and then quenched in a salt, oil, or lead bath kept at a temperature of 150-300 °C. The workpiece is held at this temperature above martensite start (Ms) point until the temperature becomes uniform throughout the cross-section of workpiece. After that it is cooled in air or oil to room temperature. The steel is then tempered. In this process, austenite is transformed to martensite by step quenching , at a rate fast enough to avoid the formation of ferrite, pearlite or bainite.
- Normalizing is a heat treatment used on steel so as to refine its crystal structure and produces a more uniform and desired grain size distribution. The final microstructure consists of fine pearlite.
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