1. split into two

The

Different materials, different equipment, different process parameters, heat treatment after the organization and quality are also different.

Even if the material grade, equipment, and process parameters are the same, the organization and quality of the heat treatment will be different because of the upper and lower limits of the chemical composition, the upper and lower limits of the heat treatment temperature, and the upper and lower limits of the holding time.

Even if the upper and lower limits of the chemical composition, the upper and lower limits of the heat treatment temperature, and the upper and lower limits of the holding time are the same, the heat treatment after the heat treatment has different structures and qualities due to the difference in the process, quality, and organization of the heat and cold processing in the early stage of the heat treatment.

Therefore, after a problem arises, a specific analysis of the specific issue must be divided into two parts.

2. Two figures (Fe-C phase diagram and C curve)

The Fe-C phase diagram is an indispensable knowledge for dealing with steel. The C-curve is an organizational transformation diagram for steel cooling after heating. These two diagrams form the basis of the heat treatment foundation. Only by grasping these two diagrams and understanding the two figures in depth, it is possible to dry heat treatment before the heat treatment can be started.

3. Three processes

That is, the three processes of heating, heat preservation, and cooling. These three processes run through all the heat treatment processes. The quality of these three processes determines the quality of the final heat treatment. The three processes are well understood and the heat treatment is even easier.

4. Four fires

That is, annealing, normalizing, quenching, and tempering. These four fires are the most common heat treatments. The four fires reflect the heat treatment level to some extent. If these four fires are well, it is a heat treatment technician.

5. Five organizations

That is, austenite, cementite, martensite, bainite, pearlite. A deep understanding of the characteristics, organizational forms, precipitation (formation) conditions, and performance of the five organizations can improve the level of heat treatment technology.

6. Six major flaws

The six major defects are oxidation, decarburization, overheating, overheating, deformation, and cracking. Among them, in the work of the most taboo has been burned and cracking defects, because these two defects are irreparable defects, the other four should also be avoided as much as possible, although they can make up, but significantly increased the workload and production costs. Heat treatment can avoid or reduce these six major defects. It is a qualified heat treatment engineer.

7. Seven phase transitions

(1) Pearlite transforms to austenite (P → A)

(2) Austenite transforms into pearlite (A→P)

(3) Austenite transforms to sorbite (A→S)

(4) Transformation from austenite to flexo (T →)

(5) Austenite transforms to martensite (A→M)

(6) Austenite transforms into bainite (A→B)

(7) Martensite transformation to tempered martensite (M→back M)

 Grasping these seven phase changes, heat treatment is a high level.

8. Eight processes

That is: annealing process, normalizing process, quenching process, tempering process, surface quenching process, chemical heat treatment process, vacuum heat treatment process, special heat treatment process (laser, ion nitriding, PVD, CVD, ion plating, etc.).