ISO 7539-10:2013 pdf free
ISO 7539-10:2013 pdf free.Corrosion of metals and alloys一Stress corrosion testing
RUB specimens are prepared from pieces of production tubing, piping, and other hollow cylindrical products cut into half longitudinally or from plate, bar or other products formed into a semicircular shape along the axial direction. In this case, forming of the specimen should be followed by a heat treatment to relieve residual stresses before undertaking the reversed U-bending process.
A variety of tube dimensions and specimen sizes can be employed. The tube is cut to selected specimen lengths and then sectioned axially to produce specimens with a semi-circular section.
The tubing shall retain its original surface finish.
During bending, deformation of the tube half may be constrained by the forming jig to force it to maintain its semicircular cross-section or its sides may be allowed to deform freely in which case it may tend to flatten at the apex. Both methods may be used. The latter procedure results in lower stresses, but has the advantage of avoiding cracking at the edges. The former type specimen is named as “Half tube RUB specimen”, and the latter type specimen is named as”RUB specimen with a gauge section”, in this standard.
When testing RUB specimens with a gauge section (in which the stresses generated during reverse bending are lower because of reduced constraint), pre-straining can be used to achieve the desired stress level.
Examples of preparation of half tube RUB specimens are shown in Annex A. Examples of preparation of non-pre-strained and pre-strained RUB specimens with a gauge section are shown in Annex B.
Final heat treatment shall be performed before bending (and pre-straining if this is adopted).
Either single-stage or two-stage stressing may be performed. In single-stage stressing the specimen is not allowed to spring back after bending before final stressing. In two-stage stressing the specimen is allowed to spring back after bending before final re-stressing.
When stressing specimens with a loading bolt after forming, care should be taken to ensure that the deflection is restored beyond that pertaining at the end of the forming operation. The final distance between the specimen legs at the loading bolt shall be at least 1 mm less than that at the end of the forming operation. The final separation of the legs should be the same for all specimens in a given series; overloading should be avoided. To obtain consistency a micrometer measuring device should be used.ISO 7539-10 pdf download.
