Bad test plates.

Date 09-04-2015 18:59 Edited 09-04-2015 20:15

My employer buys their test coupons from the major supplier of weld coupons. I am in charge of welder quals for the jobsite.several weeks ago I was bending a test coupon and a large crack developed 1/16" outside of the weld. I noticed that there were grind marks transverse to the bend and that the crack/s were propagating from them. Since then I have been preparing discarded sections and preparing them similarly with similar to extreme results. All cracks are in the base metal outside of the weld. Until today all coupons with the grind marks parallel to the bend have bent cleanly. I hope this finds anyone who has been failing welders and can hopefully clear the names of any welders wrongly failed. These are 1/2" coupons welded both with 7018 and Dualshield. If someone could tell me how to post pictures since there doesn't seem to be an attachment icon available I would appreciate it. Looks like I'll have to reduce the resolution of my cellphone camera to be able to post anything.

By Blaster (***)

Date 09-04-2015 21:25

Do the coupons have the grain oriented in the correct direction?

By thirdeye (***)

Date 09-04-2015 21:59

Proper prep as well as correct grain direction are very important.

For posting photos I use a photo hosting site. My favorite is now Imgur. It's free and each photo is assigned an anonymous URL address. Once uploaded, you can resize and do minor editing. A good size for online viewing is 800 X 600.

By welderbrent (*****)

Date 09-04-2015 22:52

The attachment button doesn't show up until after you post your post. Then you should have a series of buttons along the bottom of your newly posted post; reply, edit, attach, notify, delete. When you hit attach, you can then choose where the pic comes from and how to post it.

Brent

By hvymax

Date 09-08-2015 10:24

Yeah I eventually found the attach icon but need lower resolution pics evidently. Several of the more drastic examples seem to be delaminating away from the weld. I have also since referenced D1 which indicates face and root bent specimens should be 3/8" thick. I have no idea why we have 1/2" but will be addressing that today. I question whether1/2" specimens would be stable enough to side bend with the normal distortion.

By hvymax

Date 09-08-2015 12:41

Blaster. They are pre beveled from the manufacturer. The way they are cut the grain should be properly oriented. I am doing side bends today to see if that helps.

By Blaster (***)

Date 09-08-2015 15:15

I test guys all the time, and have for years, on 8" sch 80 pipe (A53 grade b) which is 1/2 " thick. It side bends fine with a 3/8" wide coupon.

By hvymax

Date 09-12-2015 12:55

Side bends went ok but I will be having the non bend sides reduced by 1/8" so the bend sections are 3/8". Future coupons will be 3/8" solving the problem hopefully. I will probably prepare some reduced thickness specimens as the failed ones and see if the trend continues with 3/8" thick bends.considering that several exhibited severe delamination into the base metal it will be interesting to see. The really interesting part is that the failures are all in the base metal.