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text c: «methods of steel heat treatment»
quenching is a heat treatment when metal at a high temperature is rapidly cooled by immersion in water or oil. quenching makes steel harder and more brittle, with small grains structure. tempering is a heat treatment applied to steel and certain alloys. hardened steel after quenching from a high temperature is too hard and brittle for many appli- cations and is also brittle. tempering, thatis re-heating to an intermediate temperature and cooling slowly, re- duces this hardness and brittleness. tempering tempera tures depend on the composition of the steel but are fre- quently between 100 and 650 °c. higher temperatures usually give a softer, tougher product. the colour of the oxide film produced on the surface of the heated metal often serves as the indicator of its temperature.
annealing is a heat treatment in which a material at high temperature is cooled slowly. after cooling the metal again becomes malleable and ductile (capable of being bent many times without cracking).
all these methods of steel heat treatment are used to obtain steels with certain mechanical properties for cer- tain needs.
1. what can be done to obtain harder steel?
2. what makes steel more soft and tough?
3. what makes steel more malleable and ductile?
4. what can serve as the indicator of metal tempera-
ture while heating it?
5. what temperature range is used for tempering?
6. what are the methods of steel heat treatment
used for?
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