stress relieving structural steel

huangyhg

stress relieving structural steel
hi
i am designing a steel structure that will be a welded construction using hot rolled square hollow section steel to bs en 10025 s275joh.
i need to know the following:
1) what is a suitable stress relieving process?
2) will the stess relieving have any effect on the strength of the stucture?
(apologies, this request has also been posted in the metal and metalury engineering section, wasnt sure which section was best)
thanks
rich
is your application one that involves static loading or dynamic? if its static, you won't get any benefit from stress relieving.
something to consider when stress reliveing is that your structure may distort after the process.
is your particular steel quenched & tempered? (i'm not familiar with uk steel types). if its q&t, you don't want to use thermal stress relieving.
can you elaborate some more on your particular application?
if the thickness of steel section is less than 38mm, we generally do not go for stress relief.
ciao.
generally, the type and extent of stress relieving is mandated by some code, not an optional item.  is there not any specific requirement here?
i would think you do get a benefit from stress relieving for static structures- it is required in cases where loading is not considered cyclic.
thanks all for your replies, much appreciated. the framework is made from 150x150x8mm square hollow section. it is part of a test rig used to structurally test components and will be subjected to cyclic loading. allowances have been made for machining mounting surfaces after any heat treatment should it be required.
i am really trying to gauge whether stress relieving is required and if so what is a suitable process?
thanks
rich
is the dimensional stability of your test rig required, or at least, desirable, to allow your test rig to function affectively?  in its early life (perhaps 30 - 180 days), depending on how "live" the structure is, and what it will be subjected to mechanically, it could well undergo a migration to a different shape, eventually stabilizing.  a vibratory stress relief treatment would hasten this migration, and likely minimize the amount of distortion.  
an effective vibration treatment can be performed by documenting the resonance pattern prior to treatment, and monitoring changes to the resonance pattern (chiefly growth of the resonance peaks, often accompanied by minimal shifting of the resonance peaks to lower frequencies).  these changes will be quick in the beginning of the treatment, but subside as stability is approached.
bk
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