Oil vs Air Quenching AISI A6 Steel during heat treatment

[mwe3051]

I am looking for information on the affects of oil quenching AISI A6 material during heat treatment rather than using air to quench. I would like to know just how negatively this will affect the mechanical properties of this steel?
By using an oil quench, has this completely destroyed the mechanical properties of this steel or only reduced it's fracture resistance to that of an O-series materail rather than that of and A series steel?
We have heat treated many parts using an oil quench and the metallurgist for the steel supply company is recommending we scrap all part. However, this is the a rep from the company we will buy the replacement steel.

 

[redpicker]

The problem with oil quenching A6 is the danger of distoriton or cracking the parts. If the parts did not crack and the dimensions are OK, their mechanical properties will be comparable to air cooled material. If you have parts in inventory, I would do a mag partical inspection to identify any cracked pieces.

rp

 

[TVP]

I agree with redpicker-- the problem is cracking and distortion, not poor microstructure or fracture toughness.

 

[mwe3051]

Thanks Guys.
So if I mag partical inspect these and there are no cracks, after the manufacturing processes are complete (Grinding), I should be able to put them into their end-use applications and they should perform as air quenched A6 would have performed. Is this correct?

 

[TVP]

Yes.

 

[dhan12]

Dear Friend,
Please check the possibility of Polymer Quenching. This will help you to reduce the crack as well distortion due to quenching process.

 

[1toolsteelguy]

Agree,... Oil quenched parts are fine if they do not have quench cracks. The whole point of quenching is to cool fast enough to hit the martensite start temp and avoid the "nose" of the cooling curve. An oil quench or polymer can in fact be even more consistent in actual practice. Parts can also be "interupted" quench to below the curve and then slowed cooled through the martensite range to avoid quench cracking from un-uniform cooling.