I have a Question concerning Cryo/deep Freeze Treatment.
When I use Stainless I work with Sandvik Steels like AEB-L, 13C26, 12C27. I do a Dry Ice/Acetone treatment immediately after HT.
According to the Sandvik HT manual there is no holding time at cryo temperature necessary, you only have to make sure the whole blade reaches the deep freeze temp.
AFAIK the process of converting the retained Austenite is instantaneous once the Freeze Temperature is reached.
Sometimes I read about prolonged holding time in cryo (about up to 6h). Why? Is there another benefit from longer holding time?
Other than sandvik HT Regime of AEBL I have states a 3x cryo treatment with intermediate snap temper
AEB L
For normal HT this steel
1. Preheat stage 1 550 -600C soak for 3-5min
2. Preheat stage 2 900- 1000C soak for 3-5 min
3. Austenizing 1050-1080°C equalize for 3-5 min,, soak 8 min
4. Quench in preheated in Oil 60-80°C (For Vak. Furnace min 4Bar N2)
5. Cryo minimum -70°C or more soak for 1h (Cyo. has to be done immediately after Quench to be efficient, maximum time for delay is 2h)
6. Temper 1 150°C for 2h
7. Quench in Cold Water
8. Cryo minimum -70°C or more soak for 1h immediately after Quench
9. Temper 2 150°C for 2h
10.Quench in Cold Water
11.Cryo minimum -70°C or more soak for 1h immediately after Quench
12.Final temper 150°C-200°C for 2h depending on the job that has to be done you select the final temper temp.
This will lead you in the range between 63 - 59HRC
Why 3x cryo? I know the reason for multiple tempering cycles, - after the first temper , some retained austenite converts to some fresh untempered martensite which is then tempered in the following temper cycle - but whats the benefit of the multiple cryo cycles?
Is it because not all the retained austenite converted in the first Cryo cycle? tempering first and then cryo is usually not recommended because tempering more or less stabilizes the retained austenite.
The blades I have made so far are good and I am satisfied but I do not want to simply follow some instructions but understand the reason behind it.
Best Regards
rolynd
When I use Stainless I work with Sandvik Steels like AEB-L, 13C26, 12C27. I do a Dry Ice/Acetone treatment immediately after HT.
According to the Sandvik HT manual there is no holding time at cryo temperature necessary, you only have to make sure the whole blade reaches the deep freeze temp.
AFAIK the process of converting the retained Austenite is instantaneous once the Freeze Temperature is reached.
Sometimes I read about prolonged holding time in cryo (about up to 6h). Why? Is there another benefit from longer holding time?
Other than sandvik HT Regime of AEBL I have states a 3x cryo treatment with intermediate snap temper
AEB L
For normal HT this steel
1. Preheat stage 1 550 -600C soak for 3-5min
2. Preheat stage 2 900- 1000C soak for 3-5 min
3. Austenizing 1050-1080°C equalize for 3-5 min,, soak 8 min
4. Quench in preheated in Oil 60-80°C (For Vak. Furnace min 4Bar N2)
5. Cryo minimum -70°C or more soak for 1h (Cyo. has to be done immediately after Quench to be efficient, maximum time for delay is 2h)
6. Temper 1 150°C for 2h
7. Quench in Cold Water
8. Cryo minimum -70°C or more soak for 1h immediately after Quench
9. Temper 2 150°C for 2h
10.Quench in Cold Water
11.Cryo minimum -70°C or more soak for 1h immediately after Quench
12.Final temper 150°C-200°C for 2h depending on the job that has to be done you select the final temper temp.
This will lead you in the range between 63 - 59HRC
Why 3x cryo? I know the reason for multiple tempering cycles, - after the first temper , some retained austenite converts to some fresh untempered martensite which is then tempered in the following temper cycle - but whats the benefit of the multiple cryo cycles?
Is it because not all the retained austenite converted in the first Cryo cycle? tempering first and then cryo is usually not recommended because tempering more or less stabilizes the retained austenite.
The blades I have made so far are good and I am satisfied but I do not want to simply follow some instructions but understand the reason behind it.
Best Regards
rolynd