فعالية المعالجة الحرارية المتكررة في جودة فولاذ النوابض CK85

Abstract EN

In this work Ck85 carbon steel was subjected to repeated heat treatment.

The Process consisted of repeated short-duration (3.4 minutes) holding at 800Cْ (above Ac3 temperature) followed by forced air cooling.

After 8 cycles (about a total 1 hour duration of repeated heating and cooling), the microstructure mostly contained fine ferrite grains and spheroidzed cementite.

This microstructure possessed an excellent combination of strength and ductility.

The disintegration of lamellar pearlite through dissolution of cementite at boundaries lamellar during short-duration holding above Ac3 temperature, and the generation of lamellar defects during non-equilibrium forced air cooling were the main reasons of accelerated spheroidization.

The strength initially increased mainly due to the presence of finer microconstituents (ferrite and pearlite) and then marginally decreased with the elimination of lamellar pearlite and appearance of spheroid cementite in the microstructure