welding s.s to a-36

Date 05-10-2009 15:00

I failed a tensile pull welding 304 to a-36 with .045 309L, 90He, 7.5 Co2, 2.5 O2. I passed the RT but not the bends and tesile test. The material is 3/8, the position, 2-g. I am qualifying the job so when i say I failed, i'm actually administering the test. Inner pass temp never exceeded 190 f. The cool down was done unaidded. Should i have wrapped it in asbestos blanket to slow cool? From what i know of welding 304 with 309L, no pre or post heat is required. Is this correct? I value the advice of "the Forum" and look forward to reading your advice. Thanks!

By ibeweldingsum (***)

Date 05-11-2009 03:39

Preheat will help you alot when welding ss to carbon alloys. I know threre is a published procedure for this but just from personal experience preheating seems to be the best recourse when tensil strenght is needed. Sounds to me like you had all the other perameters right. Just my two cents.

By weldhawk71 (**)

Date 05-11-2009 14:09

Is there a min/max temp?

By ibeweldingsum (***)

Date 05-11-2009 17:02

400 deg. to no more than 500 deg. preheat has shown in real world practices that the tensile was retained in the parent metal on this procedure. I helped the local Weatherford facility qualify welders on this. Of course it was 304 to A-106. Not the perticular procedure afor mentioned.

By darren

Date 05-11-2009 05:34

what was your volts/amps at?
what part of the weld failed, haz, middle biased to one side?

By RonG

Date 05-11-2009 13:18

You didn't say what Tensile it failed at or where.

By weldhawk71 (**)

Date 05-11-2009 14:08

I don't have all the numbers on hand. recieved the news as i was heading out the door friday. will be meeting with the engineer wednesday so hope to have tensile number. I guess i thought i could for go the preheat since it was 304 but the dissimilar metals are (i assume) the problem with the test. It was gmaw-s and i've passes this many times on carbon to carbon as i've qualified to it having ran multiple coupons but........ In 18 years of welding with numerous certs this is my first failure.....AAAARRRGGHH!!!! I know it could be my fault completley, and make no excuse for the failure, i just want to figure out where i failed for sure so i can learn from this and move on. I'll post more as i know more and thanks for all the help!!
ps- the speciman passed RT.

By DaveBoyer (*****)

Date 05-12-2009 03:54

In Your first post You mention 309L & tri mix. Isn't that usually used in thinner materials with short circut transfer?

By weldhawk71 (**)

Date 05-13-2009 00:24

90 percent helium, not argon.

By RonG

Date 05-12-2009 19:08

Maybe I am reading too much in to it. Are you qualifying a PQR or yourself?

I ask because of the difference in the mechanicals of the 2 metals is considerable.

By weldhawk71 (**)

Date 05-13-2009 00:25

pqr

By RonG

Date 05-13-2009 03:34 Edited 05-13-2009 03:41

I am just curiious what was expected. In reallity the PQR test results for Tensile and Yield points and defines the limits of the procedure.

The Bends would define the quality of the weld (or Welder).

A36 has very low Tensile compared to something like 309. Also A36 is not the best choice for testing because it generally will have Laminations that make for problems in testing.

Oh and by the way, you are correct about the Preheat of 309, very little required, just enough to get the moisture out---uh what was that???? Did I hear some one scream???? Okay,,, Okay minimum preheat 100 F and just forget about the moisture. I sure didn't mean to open the can of worms :-)