Preheat & Max Interpass Temperature

Date 10-29-2003 12:05

I am welding a procedure Qualification on 516 Gr. 70 plate 4 inches thick
With ER80S-D2 filler metal using the Gmaw process. This plate will go through Normalizing and Tempering after welding. I find various ranges of preheat and interpass temperatures suggested for this application. I have chosen 350 F preheat and 500 F interpass with a slow cool down after welding. Am in the ball park for the correct temperatures? I have not done a qualification with this thick of plate before. Any feed back would be very much appreciated.

Ron Butler

By bmaas1

Date 10-29-2003 17:06

Just curious where you found your preheat and interpass temps.
ASME?

Brian Maas

By jwright650 (*****)

Date 10-29-2003 17:58

In D1.1:2002 Table 3.2; For A516 Gr 70; Thicknesses of 2"1/2 and Greater requires a Min Preheat and Interpas temp of 225F.
John Wright

By jwright650 (*****)

Date 10-29-2003 18:00

What code are you working to?
John Wright

By GRoberts (***)

Date 10-29-2003 20:40

I ran your cobination on The Lincoln Electric "Welding Preheat and Interpass Temperature Calculator" and came up with a minimum preheat of 185F on for a 4" thick plate using CMTR we had here for 516 Gr 70 plate. I do think that your preheat is conservative. You are using a very low hydrogen process on a low to medium strength material. The thing you have going against you the most is the thickness, which means high joint restraint and high residual stresses. However, since you are normalizing and tempering the joint, as long as you get it to heat treat without cracking, many of the other ill effects that can be caused by too low of a preheat or too high of an interpass temperature are mitigated. (such as high hardness, or grain coarsening) If you are working to a specific code, I would think that the minimum preheat temperature allowed by the code (225F as mentioned by JWright) would be adequate, and it agrees with the Lincoln calculator fairly well.

By jwright650 (*****)

Date 10-29-2003 21:38

Also note that there is a "Guideline on Alternative Methods for Determining Preheat" (Annex XI) in D1.1:2002. Also see the Commentary Section (Annex CXI) that relates to the code writer's scientific data and reasoning. this may be helpful in determining a better preheat/interpass temperature range for your material and thickness based on it's specific chemical make-up.
Just another thought,
John Wright