Weldability of dissimilar steels

[SteveyB]

Hi,

I was wondering if someone could offer some advice on welding two dissimilar steels together and the possibilty of the process. Basically I have a component made from E460N mechanical tube and I need a steel of similar yield that can be welded to the tube. Due to the in service conditions I was wondering if it would be posdible to weld EN24t to the E460 and provide a weld which is at least as strong as the lesser base material.

Any advice would be greatly appreciated.

Thanks

 

[metengr]

There is more information required. What is the heat treat conditions of the EN24t? The E460N is basically high strength, structural steel tubing material. The selection of filler metal should support the strength level of the lower yield strength base material, as a minimum. Yes, they can be welded but you will need to qualify a welding procedure to ensure minimum mechanical properties are met, as you require.

 

[SteveyB]

Hi metengr,

Thanks for the response. I was looking to use the EN24 in the T condition. My understanding is that stainless fillers may be used to help reduce hydrogen cracking. Is this likely to be the best approach?

Thanks

 

[metengr]

No, I would not use a austenitic-based (stainless or Ni-base) filler metal because of the coefficient of expansion difference and significant alloy mismatch. The filler metal should be a low alloy steel with low hydrogen suffix designation. In addition, a preheat of 230 deg C is recommended, and I would post weld heat treat at 650-660 deg C to stress relieve and to temper the heat affected zone in the E24tn base material. PWHT will also reduce susceptibility to hydrogen cracking.

 

[SteveyB]

Thanks thats good info. How do you actually go about determining this, in terms of heat treatment and filler selection?

 

[metengr]

First you need to understand materials and welding, which means conversing with a welding or materials engineer. Second, you need to have experience to know where to look for information on material properties, recognizing that welding will locally alter material properties and you need to compensate for this in your approach for welding - preheat, filler metal and post weld heat treatment selections.