Residual Stress Measurement NDT

[ashfaqanwer]

Interesting... never heard of such NDT before...
And if its practical and applicable on welds requiring post weld heat treatment then in addition to hardness check, this NDT can provide some key values which would ensure the integrity of weld joints, as if residual stress is within acceptable limit or not. I searched for such NDT some months before as was handling some welds for which PWHT was not sure if carried out in the right manner.
Anyway, follow the link and get yourself known with this technique...
http://www.scribd.com/doc/6067883/New-T ... rement-NDT

[Ahsin]

Really interesting and intriguing....

[ennio curto]

More information about residual stress measurement NDT/NDE

The residual stress in a metal don’t depend from it hardness, but from the module of elasticity or Young module and from its chemical composition (density).
The hardness of a metal indicates its ability to absorb energy elastic, plastic or kinetic energy, but through it not possible to determine the value of residual stress. In a metal with the same hardness we will have a different values of residual stress. Therefore, the problem will be to measure the values that vary so exactly proportional to the residual stress values in a given metal.
The residual stresses tend to equilibrate themselves in the surface of the material.
The measurement made with all the major methods, X-ray, string gauge (destructive), optical etc. the residual stress is determined between the measuring the displacement of the equilibrium point the reticule crystalline.
The method discovered analyzes the value of acceleration vibratory generated by an impulse to constant energy with the subsequent reaction elastic (elastic field) from the metal, The equipment does not recognize the value of compression from that of tensile stress. It gives the value of the space resulting or volume but with the applying of a triaxial accelerometer we can have forces values axis x, y, z.

You will realize the convenience of this system.
1) Portable and easy to use and very rapid, high accuracy.
2) NDT/NDE non-destructive testing.
3) Repeatable in unlimited number of times.
4) Not dangerous (X-ray).
5) Do not expensive. Effective for welding, hardened treatments, vessels control, bridges, pipes line, aeronautics, NDT inspection for every metal types.



p.i Ennio Curto.

[ashfaqanwer]

Dear Curto,
Can this NDT technique provide the information whether the weld joint has been properly post weld heat treated or not? Are there any acceptance values charts for residual stress in different material? Any pass / fail criteria?

[ennio curto]

Dear Ashfaq Anwer,

This system permit to measure the residual stress value in every point of weld surface ad for all metals type, allunimiun
give the residual stress in the metals than have had hardness treatment, but not the superficial hardnenig like induction tempering.or afther peening (only before).Remember the system work in elasic dominio of metals.

Best Regards
Ennio Curto

[ashfaqanwer]

Dear Curto,

Please let me know from where I can get the complete specifications of subject equipment in order to purchase the same.
Also mention if this technique has been accepted under any international standard / code?
Provide some references also as in which industries this technique is being used.