1. The heating time is longer than the steel parts, generally should be in a few seconds, and should be insulated for a period of time, so that the difficulty tissue is dissolved into the austenites, and the heating speed will lead to excessive thermal stress, which is easy to produce cracks.

2. The heating temperature cannot be too high, the upper limit is 950 ° C, generally at 900 ~ 930 ° C, with a different grade has an optimal temperature, when the heating temperature reaches 950 ° C, the surface of the part will have a phosphorus eutectic, and there will be a thick residual Hit.

3. In order to cause the temperature to be slowly transition to the heart, it is best not to quench immediately after heating, and pre-cooling 0.5 to 2.0 s is best.

4. Cast iron parts induction quenching generally use a polymer aqueous solution or oil as a quenching cooling medium, and some pieces such as cylinder lines are directly quenched and cooling medium, and the cylinder valve seat is used for self-cooling.

5. After the gray cast iron is quenched, it is low-temperature tempering to eliminate stress, for example, the cylinder sleeve is turned back, 220 ° C * 1H.

The basic ferrite cast iron is basically ferrite and graphite carbon, in order to dissolve in the austenite, it is necessary to increase the heating temperature (up to 1050 ° C), but also extend the heating time (more than 1 min), so that small Some graphite carbon is integrated into the austenite and high surface hardness can be obtained after quenching.