SA 193 B8M Cl.1 bolts from SA479 rod_Heat treatment requirement

[GD_P]

Hello forum,

In our current project we are short of very few no. of SA193 B8M Cl.1 bolts (required for piping flanges) and due to current COVID situation bolt supplier will not be able to provide required bolt quantity on time. So we have decided to machine heavy hex bolts of spec SA193 B8M Cl.1 from SA 479 316L rod. SA 193 B8M cl.1 requires HT as carbide solution treated but SA479 rod are in solution annealed condition? So can we use this rod to comply SA193 HT requirement?
If no, What could be the other way to comply with SA 193 spec?

GD_P

 

[GD_P]

For your ready reference, definitions from Sec II part A are as follows:
Solution Annealing: (from SA484, general spec for SA479)
The separate annealing treatment shall consist of heating the material to the minimum annealing temperature for the grade as listed in Table 2, holding for a sufficient time to permit grain boundary carbides to enter into solution, and cooling rapidly enough to prevent unacceptable grain boundary carbide precipitation.
Carbide solution treatment: (from SA 193)
The material shall be heated from ambient temperature and held a sufficient time at a temperature at which the chromium carbide will go into solution and then shall be cooled at a rate sufficient to prevent the precipitation of the carbide.

From definitions & after reading some articles, IMO, the purpose of 'Solution annealing' & 'Carbide solution treatment' are essentially the same i.e., dissolve the carbide into solution & then rapidly cooling to avoid the carbide precipitation which may occur in sensitization zone.

 

[r6155]

Try with stud and 2 nuts. It can be easier.

Regards

 

You can do it following the advice given above, but I am loath to use cut threads for a fastener going anywhere near a critical application.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[GD_P]

Thanks you for your comments.
@r6155
Yes, manufacturing stud instead of bolt will save both material + machining efforts.
@ironic metallurgist
You are right, cut threads are weaker as compared to formed threads. These fasteners will be used in non-critical application (pipe flange which is overrated).


GD_P