The heat treatment of spring steel is treated by ( ). A: quenching and low tempering B: quenching and tempering C: quenching and middle tempering D: quenching and high tempering

The heat treatment process after carburization is () A: Quenching + high temperature tempering B: Quenching + medium temperature tempering C: Quenching + low temperature tempering D: normalizing

The common heat treatment on steels such as 65Mn and 60Si2Mn is . A: quenching + low temperature tempering B: quenching + medium temperature tempering C: quenching + high temperature tempering D: normalizing

For tool steel, the heat treatment is usually: () A: spheroidizing followed by quenching and low temperature tempering B: carburizing followed by quenching and low temperature tempering C: Quenching and high temperature tempering D: normalizing

History is littered with examples of people______ , tempering and then tumbling.

The final structure obtained from tempering a fully hardened steel is called tempered .

The cutting force of 45 steel after normalizing is ( ) that of 45 steel after quenching and tempering. A: smaller than B: larger than C: equal to D: uncertain

Boron is added to structural steel to increase its ( ). A: tempering stability B: toughness C: hardenability D: hardening capacity

To improve the machinability of low carbon steel, the heat treatment process usually used is ( ) . A: quenching B: tempering C: annealing D: normalizing

In following temperatures ( ) is not in the range of high, medium and low temperature tempering temperatures of steel. A: 200℃ B: 350℃ C: 400℃ D: 500℃