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I need some help from experts related to heat treatment.

1) Material like C60 has high carbon & gives good hardness & micro structure, free from ferrite, after polymer quench but also gives cracks. 

2) Same material i.e. C60 results in poor micro structure i.e. has free ferrite, even after high agitation and oil quenching, though hardness is ok. 

What are the best methods to reduce cracks and improve microstructure.

Dear Deepak,

The polymer has different cooling speed than oil. The material should be normalizaing condition. And also your polymer constratition value is important and your material desing.

I need some help from experts related to heat treatment.

1) Material like C60 has high carbon & gives good hardness & micro structure, free from ferrite, after polymer quench but also gives cracks. 

2) Same material i.e. C60 results in poor micro structure i.e. has free ferrite, even after high agitation and oil quenching, though hardness is ok. 

What are the best methods to reduce cracks and improve microstructure.

I need some help from experts related to heat treatment.

1) Material like C60 has high carbon & gives good hardness & micro structure, free from ferrite, after polymer quench but also gives cracks. 

2) Same material i.e. C60 results in poor micro structure i.e. has free ferrite, even after high agitation and oil quenching, though hardness is ok. 

What are the best methods to reduce cracks and improve microstructure.

Hi Deepak,

The bad news is that this is one of the harder materials to heat treat without cracking, particularly in large sections. However, the good news is that there is a lot of literature on heat treatment related issues on this material. Here are some general suggestions:

1. Look up the T-T-T Diagrams for this material from the Metals Handbook or other sources and determine the minimum cooling rate for the transformation to take place. Select appropriate cooling media and quenching temperature. You may want to increase the quenching media temperature to reduce the severity of quench. Beyond a certain section thickness this material would be hard to heat treat without cracking.
2. Reduce the austenitizing temperature before quenching. This can be accomplished by reducing temperature from "normal" hardening temperature and holding just above the eutectoid temperature. 
3. Another way to reduce cracking will entail normalizing this material first and surface hardening via different processes. This gives a tough core and hard surface. This is widely used in gear production. 
4. You may look at austempering, a process designed for reducing cracking during quenching, if all things fail. This process adds to the cost.
5. Obviously, you may change the composition to steels that are less prone to cracking.

Good Luck!

I need some help from experts related to heat treatment.

1) Material like C60 has high carbon & gives good hardness & micro structure, free from ferrite, after polymer quench but also gives cracks. 

2) Same material i.e. C60 results in poor micro structure i.e. has free ferrite, even after high agitation and oil quenching, though hardness is ok. 

What are the best methods to reduce cracks and improve microstructure.