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Up Topic Welding Industry / ASME Codes / ASME Sect. IX QW-451.1 == Side Bend vs Face Bend&Root Bend
- - By maxilimiano (**) Date 02-16-2015 04:32
Dear All,
I am confuse about note 5.
"Note (5) in QW-451.1" is vice verse or not?..Face Bend & Root Bend may substituted too for side bend?

Thanks, Regard.
Parent - - By 803056 (*****) Date 02-16-2015 13:56
The standard guided bend fixture using a 1 1/2 inch diameter mandrel is intended to bend carbon steel specimens that are 3/8 inch thick and results in elongating the specimen 20% along the convex surface. When the welded coupon is thicker than 3/8 inch thick, the code allows the side bend in lieu of the standard face and root bend.

Think about the clearance between the plunger and the die of the typical guided bend testing machine. If one tried to perform a face bend on a 1 inch thick specimen, it simply would not work, i.e., there isn't sufficient clearance between the plunger and the die. The side bend allows the laboratory to cut 3/8 inch wide specimens from the welded coupon to eliminate the need for time consuming, expensive machining. If the laboratory prefers, they can machine each bend specimen to the required 3/8 inch thickness so the specimen can be bent as a face of root bend. It that route is taken, the laboratory must machine the face bend specimen to a thickness of 3/8 inch by removing material from the root surface. If the root bend is performed, the face surface must be machined to reduce the thickness to 3/8 inch.

It is easier and more efficient to simply cut side bend specimens and eliminate all the machining discussed in the preceding paragraph.

Be aware that the bend diameters used to evaluate the welded coupon is dependent on the base metal properties, the filler metal properties, and the thickness of the welded coupon. For example, a welded coupon consisting of 6061-T6 base metal welded with 4043 filler metal must be machined to 1/8 inch thick and bent with a mandrel that is about 16 times the thickness of the coupon. The reason is that the welded specimen has very poor properties of elongation. The very large bend diameter is needed to prevent breaking the specimen. As a matter of fact, because the HAZ is overaged, it is recommended that a wrap-around bending machine be used instead of a standard plunger and die bending fixture. 

In a similar manner, high strength steels require a larger bend diameter because the high strength steel has lower elongation properties than the lower strength steel. The applicable code with dictate the proper bend diameter to be used.

There is a potential for a laboratory to use the incorrect bend diameter if they do not pay close attention to the code requirements and the material properties of the welded coupon. It is for that reason I always include the bend diameter used when the test results are reported. It allows the client to "audit" the bend test to ensure the proper test was performed.

Best regards - Al
Parent - - By maxilimiano (**) Date 03-04-2015 04:35
Thanks a lot Mr. AI...
Parent - By 803056 (*****) Date 03-04-2015 18:16
Glad to help.

- - By greggianin (*) Date 08-12-2015 09:17
recently i'm preparing a procedure welding qualification to material incoloy 800HT piping. I choose the 3 types of bending test to check the material: side, root and face.
to my surprise the face bend test cracking and the others no!
as the asme IX permit change face and root by side test, what was wrong!?
Attachment: 20150807_154326.jpg - surface of bend samples (101k)
Parent - - By 803056 (*****) Date 08-12-2015 12:43
It could have been the preparation of the samples. Any grinding marks should be transverse to the weld and the corners should have been filed to form a radius.

Since you didn't include a description of the failure, it could have been a defect in the weld. There is nothing saying every coupon is defect free and is going to pass the bend test. Welding is a fickle mistress.

Who can tell based on the limited information you provided.

A photograph would be very useful in this situation. We all like a good high res. photograph to help determine causes of failures.

Best regards - Al
Parent - - By jon20013 (*****) Date 08-12-2015 23:09
Al, too bad AWS hasn't put "Like" options on its Forum emoticons because I "like" most of your responses. :cool:
Parent - By welderbrent (*****) Date 08-12-2015 23:23
Here Jon,

Just use one of these:

Attachment: LIKE.jpg (4k)
Attachment: icon_that.gif (576B)
Parent - By 803056 (*****) Date 08-12-2015 23:41
Thanks for the compliment.

Parent - - By greggianin (*) Date 08-13-2015 08:34
i just attached a photo. the cracking accurred in the heat affected zone of face bend test
Attachment: 20150807_154326.jpg (101k)
Parent - By 803056 (*****) Date 08-14-2015 01:53
Difficult to determine the dimensions from the photograph, but are the specimens 3/8 inch thick or are they thicker? If they are thicker, and you use too small a bend radius, you are causing the samples to elongate too much.

From the photograph it appears the failure is in the base metal, not in the weld or HAZ. I also noticed the corners were not rounded, but again, the failure is not in the weld.

Check the sample thickness and the bend radius to verify they comply with the requirements of ASME Section IX.

- - By QA Ronzo Date 03-02-2017 12:00
ASME IX table QW-452.1(a) states that a root & face bend may be substituted for two side bends on mat’l from 3/8” to less than 3/4” (see note 3). If you then go to Figure QW-466.1 you have jig dimensions for mat’l up to 3/8” in thickness.  My question is where do you get the jig dimensions for material over 3/8” in thickness?
Parent - By 803056 (*****) Date 03-02-2017 22:47
3/8 inch is the thickest specimen tested. Anything over 3/8 inch thick must be evaluated using side bends.

Up Topic Welding Industry / ASME Codes / ASME Sect. IX QW-451.1 == Side Bend vs Face Bend&Root Bend

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