E410 overlay on carbon steel

By - Date 03-18-2005 22:48

410 stainless steel is a martensitic type of steel. The preheat of this grade depends on the carbon content. A carbon content of <0.05 requires a preheat of 250 deg. F.. Carbon content of 0.05-0.15 requires a preheat of 400 deg. F.. The 410 with the lower carbon content, PWHT is optional. 410 of the mid range of carbon, PWHT is recommended. Overlaying with a butter pass of 309 or 309L will definitely give you a better chemistry balance on the initial pass than welding straight to the carbon steel, but it is done every day. Since the thermal conductivity of a carbon steel and a stainless steel are quite different, I would suggest a 300 deg. F. interpass temperature. Also, a 75/25 (argon/CO2) gas would help keep the carbon content within a safe limit moreso than straight CO2.

By GRoberts (***)

Date 03-19-2005 05:31

I would reccommend against using the 309 before the 410. If you weld the 410 to the 1020 directly, your first pass will be a low alloy martensitic steel, then your second pass will be a martensitic stainless. All 3 of these are compatible from the preheat, PWHT, and coefficient of expansion standpoint. If you do the 309 first, you will have a mild steel coated with an austinitic stainless steel, followed by a mix of austinitic/ferritic/martensitic stainless steel on the second layer, and martensitic stainless on the 3rd layer. This mix is a lot trickier, and any ferrite present could form brittle intermetallics duirng PWHT depending on the temperature. You would also have different coefficient of thermal expansion, which if it has heating/cooling cycles could contribute to problems.
Also, with FCAW, using 100% CO2 will not adversely affect the carbon content since all the droplets are slag covered absorption of CO2 does not occur in any significant amount.

By - Date 03-19-2005 13:53

GRoberts,
I think the author stated he would not be doing a PWHT. We a manufacturer of stainless steel welding consumables and produce FCAW. Our research lab, while agreeing that each droplet of FCAW is encased by slag, has proven that a CO2 increase of up to 0.02% is very likely, depending on the heat input. That is why when welding a 2205 base metal (an ELC material) with a 2209 FCW is not recommended for a CO2 shielding. The same applies to any stainless, 410 included.

By dasimonds (**)

Date 03-20-2005 00:58

ELC?

By - Date 03-20-2005 14:04

Extra Low Carbon (ELC) I'm sorry... I was only trying to show that certain materials that are ELC's (C=0.02% max.) cannot afford to allow ANY carbon pick-up from the shielding gas. In the case of 2205 (although this is getting away from the forum's original question) this can present a problem. Although 100% CO2 is certainly a compatible shielding for FCW, it is not always recommended. An example is when welding an ELC (2205 duplex and 2507 Super Duplex are just 2 examples), or when the carbon content determines the recommended preheat and PWHT requirements. (410 for example)

Peace B2U

CM <><

By Bill Mc (**)

Date 03-21-2005 19:17

thanks to all for the great assistance and comments!

By GRoberts (***)

Date 03-22-2005 00:29

While we do not try to maintain carbon below .02%. We do get carbon content below .02% sometimes when using 2209T0-1 on 100% CO2 sheilding gas. While there may be carbon pickup while welding FCAW using 100% CO2, in most cases it is not enough to affect the weld, if it is able to be detected at all. With 410 filler metal, and a max carbon of .12%, anything picked up from the shielding gas would be negligable. You are right about the PWHT, but the part may see some heat cycles due to its service conditions. The only reason I made the comment, is that sometimes people get confused and assume that the carbon pickup they get with GMAW applies to FCAW in the same way, but I can see you are well educated on that matter.

By - Date 03-22-2005 02:44

Thank you, Sir, for your comments. They are very well taken and very true. I guess that since I work for the company that developed and manufactures both the 2205 and 2507 (UNS 31803 and 32250 duplex and UNS 32750 Super Duplex) I try to be very cognisent of the levels of carbon. Since the max. carbon content of a duplex material is 0.02%, both Duplex and Super Duplex, and the max. carbon content for FCW filler metal is 0.04% for 2209, then you can see why the carbon has to be monitored so closely. Naturally, the 2507 Super Duplex filler metal is a propritary product so it is not addressed in A5.22-95, only 2209T0-1 or 2209T0-4. As far as the 410 was concerned, I was only trying to make the author aware that the carbon content of the base metal he was using, especially with no formal PWHT. is very critical when determining a preheat temperature. Of course, we did not all the facts of service conditions and other critical conditions the part might experience, so you and I both tried to give good practical advice based on the limited information we were given. As we discussed earlier, although the carbon pick up might be very little when using FCW, sometime ANY is too much. So, to take that totally out of the equation, 75/25 is normally recommended when welding Duplex or any stainless steel where the carbon content is right near the maximum limits. Thank you for your response as it was most interesting and true. I really enjoyed our discussion. You, too, seemed very knowledgable in stainless steel welding. Maybe soome time we can discuss other corossion related items. Thanks again...

Peace B2U

CM <><