Best water temperature for quenching steels !

[stanislasdz]

I had a hot discussion with a co-worker about the best temperature of the water for quenching steels parts !

Is it more or less than 30 °C ?

Any help ?

Thanks

 

[manu23]

30C at +/-5C is reasonable although, it will mainly depends on your design. If your design is likely to create crack you might want to go higher temperature or add polymer to the water. Then it also depends of the grade of the steel, the hardness and microstructure you want to get after treatment.

 

[TVP]

As manu23 mentioned, 30 C is reasonable, but the exact temperature usage depends greatly upon the steel grade being used, the hardening process (furnace, induction, etc.), the geometry of the part, and the desired/required microstructure (100% martensite only at the surface or complete, through hardening?). Colder water with extremely high flow rate may be used for quenching simple shafts after induction hardening, with the subsequent distortion corrected by a straightening operation. For a complex part with sharp corners that needs to be through hardened, the water temperature should be higher to prevent cracking, and most likely a polymer addition should be used as well.

 

[arunmrao]

30C is a dream temperature in tropical countries,where ambient temperature hovers over 35C. You should be lucky! You have received good advice from TVP,who has said well enough,that it all depends on how fast you want to cool and how safe it is. You can add ice blocks to to reduce water temperature. This I adopt during summer months to keep my melting furnace from tripping due to high temperature of the D.M cooling water.The heat exchanger and cooling towers are inadequate during the summer months.

I have not failed. I've just found 10,000 ways that won't work." — Thomas Edison
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[redpicker]

There is no "Best" temperature as the optimum temperature depends on many things, as has been mentioned above.

In general, you may find limits of 100-105F in the literature (37-40 C). This is a result of a vapor blanket that forms around the part. At water temperatures below 85 F (30 C) or so, this vapor blanket is not very stable and neucleation boiling occurs, rapidly removing heat. At higher temperatures, however, it can form an insulating barrier around the part, greatly lowering the heat transfer rate. The middle ground (85-105 F or 30-40 C) is usually the range where a water quench will begin to give variable results.

Of course, there are many variables that affect the stability of this vapor blanket, one of which is temperature. With spray quenching, for example, no vapor blanket is formed if the spray is strong enough. Quechant vendors also offer additives that can raise the temperature at which it becomes a problem.

rp