SA 517 Gr F - forming

[amol gengaje]

we have to make a sphere from crown petal construction.Material SA 517 Gr F. UTS 790-820MPa. cold forming will be done
whether this will require intermediate heat treatment to avoid formation of cracking?
If so when/at which stage of forming it has to be carried out?

[pgoswami]

 

Hi Amol,

 

Please seethe requirements of UHT-79(Sec-VIII, DIV-1) for HT after forming.You may perform PWHT on completion. However there's no harm,( in fact a good engineering practice) to perform intermediate HT after forming. SA-517 (all grades) are not very fabrication friendly material. Hence some extra caution would be always good for follow.

 

Thanks.

 

Pradip Goswami, P.Eng,IWE

Welding & Metallurgical Specialist

Ontario, Canada

pgos...@quickclic.net

pradip....@gmail.com

http://ca.linkedin.com/pub/pradip-goswami/5/985/299

 

UHT-79 FORMING SHELL SECTIONS AND HEADS

(a)

The selected thickness of material shall be such that the forming processes will not reduce the thickness of the material at any point below the minimum value required by the rules.

(1)

Pieces that are formed after heat treatment at a temperature lower than the final tempering shall be heat treated in accordance with Table UHT-56 when the extreme fiber elongation from forming exceeds 5%as determined by the formulas in UCS-79(d).

(2)

Pieces that are formed at temperatures equal to or higher than the original tempering shall be reheat treated in accordance with the applicable material specification,either before or after welding into the vessel.

---

From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of amol gengaje
Sent: Thursday, January 01, 2015 11:26 PM
To: material...@googlegroups.com
Subject: [MW:22665] SA 517 Gr F - forming

we have to make a sphere from crown petal construction.Material SA 517 Gr F. UTS 790-820MPa. cold forming will be done
whether this will require intermediate heat treatment to avoid formation of cracking?
If so when/at which stage of forming it has to be carried out?

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[amol gengaje]

sir,
thanks a lot for your guidance.
but i m worried if the crack gets developed during the forming as material is very hard.
then in that case heat treatment is of hardly any use.precisely i want to know during forming at what stage intermediate heat treatment should be carried out.
or we should continuously check hardness during forming & if hardness gets increased above particular value say value of hardness which was before forming & then carry out stress releiving.Is this appriach ok?
Kindly let me have your valued opinion.

On Jan 2, 2015 6:19 PM, "pgoswami" <pgos...@quickclic.net> wrote:

[Zola Dlodlo]

Hi Amol,

answering the cold forming intermidiate HT question, it depends on the determined fibre elongation. If your sphere fibre elongation is 5% and less, only cold forming is required before welding and if your fibre elongation is above 5% cold forming and intermidiate HT shall be applied. It is also advised to determine if PWHT is required since you are dealing with critical material (SA 517 Gr. F). I recommend that you consult ASME code to determine the fibre elongation.