- Split into two
Different materials, different equipment, different process parameters, heat treatment after the organization and quality are also different
Even if the material grade, equipment, process parameters are the same, due to the chemical composition content of the upper and lower limit, the lower limit of the heat treatment temperature, insulation time limit is different, the heat treatment of the organization and quality will also be different
Even if the content of chemical components of upper and lower, upper and lower temperature heat treatment, heat preservation time limit are the same, because the process of heat treatment, hot and cold processing stage of quality, organization, organization and quality after heat treatment is also different.
Therefore, after the problem, specific problems should be analyzed, that is to say, to divide into two parts
- Two graphs
Fe-C phase diagram and C curve
Fe-C phase diagram is the necessary knowledge to deal with iron and steel, C curve of heating and cooling steel microstructure transformation diagram, the two figure is the foundation of heat treatment foundation. Only grasp the two figure, in-depth understanding of the two diagrams, is likely to dry heat treatment, heat treatment can be started.
That is, heating, insulation, cooling of these three processes
These three processes run through all the heat treatment processes, and the quality of these three processes determines the quality of the final heat treatment. These three processes are well understood, and heat treatment is the first step
- Four fires
That is annealing, normalizing, quenching and tempering
The four fire is the most conventional heat treatment, the four fire is good or bad, to a certain extent reflects the level of heat treatment. If the four burning good, is a heat treatment technician
- Five organizations
They are austenite, cementite, martensite, bainite and pearlite
The characteristics, morphology, precipitation (formation) conditions and properties of the five tissues are deeply understood, and the heat treatment technology level can be improved
The six major defects are oxidation, decarburization, overheating, over burning, deformation and cracking
Among them, in the work of the most taboo had a burning and cracking defect, because these two defects are irreparable, the other four should also try to avoid, although can make up for, but obviously increased the workload and the cost of production.
Heat treatment can avoid or reduce these six defects, is a qualified heat treatment engineer
- Seven phase transitions
(1) pearlite transforms to austenite (P to A);
(2) austenite transforms into pearlite (A to P);
(3) austenite transforms into bainite (A = S);
(4) austenite transforms into bent (A) T;
(5) austenite transforms to martensite (A to M);
(6) austenite transforms into bainite (A = B);
(7) martensite transforms into tempered martensite (M = M)
Grasp these seven phase transitions, heat treatment is high level
- Eight arts and crafts
Namely: annealing process, normalizing process, quenching process, tempering process, surface hardening process, chemical heat treatment process, vacuum heat treatment process, special heat treatment process (laser, ion nitriding, PVD, CVD, ion plating, etc.)
Be able to grasp the eight processes, heat treatment is expert!