P91 hardness testing

[itzhak1402]

When the normal stress release process and the result of low hardness What could be the reason?

 

[metengr]

You mean after post weld heat treatment you have low hardness. This could be caused by over tempering or improper original heat treatment
of Grade 91.

 

[Mr168]

False low readings can also be the result of inadequate surface preparation.

 

[weldstan]

Failure to remove the decarburized surface layer may also be a contributing factor.

 

[Guest102023]

All of the above are possible, but they assume the tech doing the hardness testing knows what he is doing. There are a dozen ways field hardness testing can go wrong.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[pandithan]

go with metengr because i have experienced this kind of problem lot

 

[itzhak1402]

The whole process of heating fine registration process has nevertheless have low hardness
  Could be a difference between the results from this device EQUOTIP-2 and brinell testing method?

 

[weldstan]

The EQUOTIP hardness values have been shown to be consistently lower than that obtained from Brinell testing. ARAMCO has published studies in this regard. SIA has also shown similar results from tests performed on P91 welds supplied by my company.