Dear friend,
ASME code is silent for normalising but you can see the stress relieving temperature in ASME section -VII part-1 under UCS-56 .It is not clear in ASME that, what is normalising?,And what are the temperature for normalising .Instead of normalising,they use austenizing temperature which is 768 deg celcius to 910 deg celcius .what we do in company or any other fabrication company we take a Mill test certificate from our client and in that MTC we know the normalising temperature of particular material only we change the soaking time which 1 mm/min or 1 hour for 25.4 mm or as per client requirement and rate of heating 80 to 150 degree celcius according to thickness generally soaking time and rate of heating is very high in MTC because they do hot rolling but when material reached to us it is room temperature so we use this type of temperature for metal forming.
Now as per your question and according to my knowlegde,when we do PWHT of material in normalising range the grain of material are more uniformly arranged and they having good ductility and when we cool that material in still air it become moderate tough and hardness of a material is good means it is under range and this material is also used and rectifies after heat treatment.so cooling in still air is best as compared to forced air cooling.if hardness is increased after forced air cooling then you should do tempering to remove the hardness ,it will increase your cost.
Normalising temperature-910-920 deg C
anealing temperature is same as that of normalising temperature only it require furnace cooling
tempering - 750-780 degree C
stress releiving- 630-650 degree C
And Sorry i dont have any reference of this it is according to experience.
On Saturday, October 28, 2017 at 10:55:26 AM UTC+5:30, pankaj kolhe wrote:
-- ASME code is silent for normalising but you can see the stress relieving temperature in ASME section -VII part-1 under UCS-56 .It is not clear in ASME that, what is normalising?,And what are the temperature for normalising .Instead of normalising,they use austenizing temperature which is 768 deg celcius to 910 deg celcius .what we do in company or any other fabrication company we take a Mill test certificate from our client and in that MTC we know the normalising temperature of particular material only we change the soaking time which 1 mm/min or 1 hour for 25.4 mm or as per client requirement and rate of heating 80 to 150 degree celcius according to thickness generally soaking time and rate of heating is very high in MTC because they do hot rolling but when material reached to us it is room temperature so we use this type of temperature for metal forming.
Now as per your question and according to my knowlegde,when we do PWHT of material in normalising range the grain of material are more uniformly arranged and they having good ductility and when we cool that material in still air it become moderate tough and hardness of a material is good means it is under range and this material is also used and rectifies after heat treatment.so cooling in still air is best as compared to forced air cooling.if hardness is increased after forced air cooling then you should do tempering to remove the hardness ,it will increase your cost.
Normalising temperature-910-920 deg C
anealing temperature is same as that of normalising temperature only it require furnace cooling
tempering - 750-780 degree C
stress releiving- 630-650 degree C
And Sorry i dont have any reference of this it is according to experience.
On Saturday, October 28, 2017 at 10:55:26 AM UTC+5:30, pankaj kolhe wrote:
please guidewhere is the reference?temperingstress relievingnormalizingannealingwhat is the heat treatment cycle forDear Experts,Why force air cooling is not allowed for normalizing instead of cooling in still air.
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