Welding 4140 to T-1 high tensile steel 1

[kroppkaka]

We have received intstructions to weld 6.5" diameter to a couple of T-1 1" and 1.5" plates.
The problem we are having is no weld procedures to weld heat treated 4140 to T-1.
The joint is very heavily stressed and has to made of these steels.
I am trying to work out the preheat for and what I have found is I need a lot higher preheat for 4140 than what the maximum interpass temperature is for the T-1 plates.
Is it possible to weld these steels together with the conflicting preheat and interpass temperatures?
What happens to the properties of T-1 plates if I pick the higher preheat temperature?
What should these preheats be?
We can't reheat treat this joint after welding.
Appreciate your help.

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[metengr]

kroppkaka;
What is the heat treatment condition of the 4140? The T1 steel is a high strength low alloy and you need to watch heat input to avoid altering bulk mechanical properties.

The preheat for 4140 can be as low as 250 deg F, which fits well within the preheat range for T1 steel. The interpass temperature should be less than 400 deg F, period.

Can you come back with your filler metal selection and type of weld joint detail?

 

[stanweld]

Additional to metengr, is the 6.5 "diameter refer to a bar or a pipe shape and if so what is its wall thickness? Do you intend to use fillet weld attachment?

 

[kroppkaka]

metengr & stanweld

First I will let you know I am in Australia and some of the units, materials are metric and available Australian steels.
T1 is equivalent to Bisalloy 80 and 4140 is also called 4140 in Australia.
the 25mm (1") Bisalloy 80 (T1) is running along the center axis of the 67" long 4140 (170mm diameter or 6.69" diameter).
There are 6 plates welded perpendicular to the 4140 axis made of 40mm (1.5") Bisalloy 80 (T1) plate with a hole for the round bar to go through at about 10" centres.
The 4140 is solid round bar. Here is the link I just found for the material

http://www.interlloy.com.au/data_sheets/high_tensile_steels/4140.html

. We planned to use a Mig wire called ESD2-GM-W559AH with a yield/tensile strength of 570/660MPa (83000/96000psi)

http://www.welding.com.au/Uploads/.../Austmig ESD2 PDS AA.pdf

.
I planned GMAW or should we use something else?
Thanks.

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[metengr]

kroppkaka;
Thanks for the specifics. The Bisalloy 80 in the 25mm thickness has a carbon equivalent of 0.50, which is indicates good weldability with moderate preheat.

The GMAW process is fine for this application, and the filler metal strength you posted looks acceptable.

From your description above, it would appear you are using fillet welds to join the Bisalloy 80 (T1) to the 4140. If this is the case, use the preheat recommendation and interpass temperature I provided above and use continuous fillet welds (wrap the welds around the entire plate) for the Bisalloy 80 plates.

I would suggest you wrap the T1 plates after welding to slow cool (if necessary), and I would have nondestructive testing (NDT) performed, like magnetic particle or liquid penetrant to ensure defect free welds.

 

[kroppkaka]

The end of the 4140 solid round will have a 0.6" (16mm) weld chamfer but the others will be fillet weld of about 0.6" (16mm). We have to have a few runs to get to 0.6" but I guess that is not going to change anything to the preheat?
You suggest to wrap the T-1 plates.
Do you have a link to a good material to use for a wrapping material?

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[unclesyd]

The first choice is would be flexible ceramic non-woven needled blanket and the second would a woven cloth, glass or ceramic, lagging or insulation covering.

You can get these material at any industrial insulation supply house or any industrial contractor. Mention Cerawool or Kaowool. The blankets come in 25 ft rolls and cloth in larger rolls 100 ft +.

metengr and myself would reach for the A cloth

 

[EdDanzer]

Another suggestion is to use maximum of ¼” beads in a multiple pass skip around arrangement to reduce weld bead stress and help control heat.

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com