Bend tests -Use of correct mandrel size

By BGM dharan Date 02-17-2005 10:34

As per QW 466.1 of ASME Sec IX (Test Jig dimensions of ASME Sec IX), the 4t bend tests (t is the bend specimen thickness) are applicable to base materials with % elongation equal to or greater than 20%.

But if the welding consumable has a lower ductility (inspite of a right PWHT), say 15%, and is used to weld a base material which is having an elongation of 20%, what should be the correct mandrel size for carrying out bend tests? We feel 4t bend tests, based on base material elongation, can be harsh and may lead to failure. In this situation, can one use a mandrel size based on the elongation of the welding consumable?

Thanks

By gerold

Date 02-17-2005 13:53

In the General Notes from the table, note (b) states: "The dimensions of the test jig shall be such as to give the bend test specimen a calculated percent outer fiber elongaion equal to at least that of the base material with the lower minimum elongation as specified in the base material specification."
My feeling is that the bend tests ensure that the base and weld metal are compatable and able to meet the minimum requirements of the Code.
Make sure to use the formulas under General Note (b) to ensure that you have the proper jig dimensions.
Hope this helps and doesn't just say what you already know.

Chris

By jwright650 (*****)

Date 02-17-2005 17:04

Not sure about ASME, so take that for what it's worth, but in D1.1 the bend test jig has specific dimns for the radius of the plunger/dies depending on the material yeilds. I'll look it up and furnish the exact figure number in Section 4, if you are interested.
John Wright

edit:
Figure 4.15 for guided bend
Figure 4.16 for wrap around guided bend
Figure 4.17 an alternative roller equipped guided bend

By BGM dharan Date 02-18-2005 10:40

Thanks for the reply.

I presume you are referring to Fig A-4 - Nomogram for selecting minimum bend radius of AWS 4.0 Mechanical Testing of Welds.

Regards

By jwright650 (*****)

Date 02-18-2005 12:19

No actually the Figures listed are from AWS D1.1:2004 Structural Welding code--Steel.

The three catagories listed in these Figures are(gives dimns for plunger/die)

1) Specified or Actual yields of 50ksi and under
2) over 50ksi to 90ksi
3) 90ksi and over

John Wright

By HgTX

Date 03-14-2005 21:37

If you want to pick and choose your elongations the nomograph (AWS B4.0 Fig. A4) is the way to go. Looks like the D1.1 & D1.5 requirements corrspond to 20% for Gr. 36 & 50, 16% for Gr. 70, and 13 % for over Gr. 70. Am I off by much?

Hg