falco
Industrial
- Jul 4, 2001
- 24
This might be unsual and I will appreciate any opinion
We were qualifying a mmanual GTAW WPS to weld stainless steel sheet metal 0.040" thick. We use about 40 A and a travel speed range between 2-4 in/min. Gas flow used was about 20 CFH and we use also backing gas. Electrode used was 0.035" diameter and we use a 1/16 Thorium electrod as well as a size #8 cup, root opening was 0.020"
The weld is done in one single pass, The appearance of the weld was pretty good, fairly o no sign of dicolorations, no crack indications were found inboth sides (root and face). It has a good visually appearance.
When we took the radiograph there was a fine dark line (somtimes straight somtimes a little weavy) indication that appears in the center of the weld. in some coupos it is along the complete weld and in some others no.
We ask the welder to re-weld taking care of its speed as well as of its weaving motion. but the indication continously appears in the radiograph
We decide to test the weld, We cut the coupons and we remove excess reinforcement. Weld succesfully pass bend testing (root and face) and tensile testing it brokes beyon 104 Ksi in the weld but it didn't broke in the center of the weld but almost along its toe within the weld metal
We also cut soem coupons each 10 cm and we polish and perform chemical etch using ferric chloride and nitric acid as specified in AWS b2.1 and no sign of lack of fusions were detected.
So either we are performing an incorrect etching process or it might be some metallurgical condition I am not aware that is deviating the Xrays beam and givig the indication
In case someone has face a similar case, what might be wrong?
Will appreciate a lot any comments
We were qualifying a mmanual GTAW WPS to weld stainless steel sheet metal 0.040" thick. We use about 40 A and a travel speed range between 2-4 in/min. Gas flow used was about 20 CFH and we use also backing gas. Electrode used was 0.035" diameter and we use a 1/16 Thorium electrod as well as a size #8 cup, root opening was 0.020"
The weld is done in one single pass, The appearance of the weld was pretty good, fairly o no sign of dicolorations, no crack indications were found inboth sides (root and face). It has a good visually appearance.
When we took the radiograph there was a fine dark line (somtimes straight somtimes a little weavy) indication that appears in the center of the weld. in some coupos it is along the complete weld and in some others no.
We ask the welder to re-weld taking care of its speed as well as of its weaving motion. but the indication continously appears in the radiograph
We decide to test the weld, We cut the coupons and we remove excess reinforcement. Weld succesfully pass bend testing (root and face) and tensile testing it brokes beyon 104 Ksi in the weld but it didn't broke in the center of the weld but almost along its toe within the weld metal
We also cut soem coupons each 10 cm and we polish and perform chemical etch using ferric chloride and nitric acid as specified in AWS b2.1 and no sign of lack of fusions were detected.
So either we are performing an incorrect etching process or it might be some metallurgical condition I am not aware that is deviating the Xrays beam and givig the indication
In case someone has face a similar case, what might be wrong?
Will appreciate a lot any comments