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Up Topic Welding Industry / Welding Fundamentals / pwht for alloy steels
- - By pradeep4u (*) Date 02-10-2016 15:15
Hello
            I have a doubt that why alloy steels require stress relieving  and carbon steel do not require stress relieving.

regards
pradeep
Parent - - By Lawrence (*****) Date 02-10-2016 16:31
Here are a couple of articles for you to read.  These might help you refine your questions.

http://www.jflf.org/pdfs/papers/keyconcepts4.pdf

http://www.heat-treat-doctor.com/documents/Stress%20Relief.pdf
Parent - - By pradeep4u (*) Date 02-12-2016 16:19
Dear Sir
                   I read  the articles  but still i didnot got my answers that why alloy steels require stress relieving
Parent - - By js55 (*****) Date 02-12-2016 17:06
Alloy steels, whos microstructures are bainite, martensite, or mixes within ferrite thereof, are generally stronger and demonstrate what is called greater hardenability. In other they harden to a greater extent at any given cooling rate. This will make them more susceptible to cracking. Therefore these microstructures need to be stress relieved to a greater extent than carbon steels.
They are also more susceptible in some instances to stress corrosion cracking as well.
Parent - - By pradeep4u (*) Date 02-13-2016 14:10
Thanks for ur answer. One more thing  why stress relieving done for thickness greater than 18mm incase of carbon steel.
Parent - - By js55 (*****) Date 02-15-2016 14:26
Fracture mechanisms change with increasing thickness thereby becoming more crack prone.
Parent - - By pradeep4u (*) Date 02-21-2016 08:42
Sir can u explain in details about fracture mechanism
Parent - - By js55 (*****) Date 02-22-2016 13:33
Fracture has a tendency to be more ductile with thinner materials. This is the metallurgical mechanical basis of ASME Section IX's and III's exemption on CVN's below 5/8".
These things could be said much better, and more accurate, than I have said them but it gets the general jist.
Parent - By pradeep4u (*) Date 03-02-2016 06:42
thanks sir   for ur answer
- - By mohanramkumar.n Date 05-29-2017 11:44
Dear Sir,
          What is required PWHT cycle to Stress Relieving. SS410 materials......? Please reply me urgently to n.mohanramkumar@gmail.com. Request your needful help.

With Regards
Mohan
Parent - By Tyrone (***) Date 05-30-2017 11:17
Hi Mohanramkumar,
Welcome to the Original AWS Forum,

Please start a new post instead of adding to someone else's question.

There's lots of information on the web.  Google is your friend.
A 2 minute search found this on a steel supplier's website:

Heat Treatment

Annealing – Heat slowly to 1500 – 1650°F (816 – 899°C), cool to 1100oF (593°C) in furnace, air cool
Process Annealing – Heat to 1350 – 1450°F (732 – 788°C), air cool
Hardening – Heat to 1700 – 1850°F (927 – 1010°C), air cool or oil quench. Follow by stress-relief or temper
Stress Relieving – Heat to 300 – 800°F (149 – 427°C) for 1 to 2 hours, air cool
Tempering – Heat to 1100 – 1400°F (593 – 760°C) for 1 to 4 hours, air cool
Up Topic Welding Industry / Welding Fundamentals / pwht for alloy steels

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