welding different grades of steel? 1

[hobbs101]

Hi. What are the limitations in welding different grades of carbon steel? For instance, can I weld grades 1045 and 4140 together?

If I use SMAW, can I just specify electrode E60 and not worry about the grades of steel that I'm welding?

Thanks

 

[metengr]

Welding different grades or compositions of carbon and low alloy steel is common. The information/precautions you would need to be concerned about are;

1. Material thickness and weld joint detail.
2. Preheat.
3. Selection of filler metal - one size does not fit all applications. The selection of filler metal is based on matching one or more of the two base materials you intend to join. The filler metal can be under or overmatched in terms o composition and strength properties.
4. Need for post weld heat treatment to achieve certain properties of the weld region.

I am not going to get into any further detail than above. My suggestion is to hire the services of a welding engineer.

 

[hobbs101]

Thanks for the information.

I'm a mechanical designer. I'm trying to understand what materials/welds I can specify on fabrication drawings, especially when the grades of material differ, which is likely if say I'm welding a RHS to plate. I guess the welding shops will always recommend alternative materials/weld types when they quote for the parts.

 

[jwhit]

Before designing with the referenced materials, I would suggest doing a little research into the weldability of them and what is required to make a safe sound weld in the field. Hint, these aren't materials you just start welding away at. The advice to get a welding expert involved is a good one.

 

[Guest102023]

The good folks in the weld shop are almost the last ones to ask welding engineering and materials questions. As metengr advised, seek out a welding engineer.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[berkshire]

When you are welding 4140, make sure to ask your engineer about " Under bead Cracking."
B.E.

You are judged not by what you know, but by what you can do.

 

[weldstan]

hobbs101,
1. Yes you can weld 1045 to 4140.
2. You should not indicate electrode E60. The fabricator may well take you at your word and you will end up with a weld with inadequate strength and will very likely crack. A Change Order may be required to correct the problem and you will pay dearly for the Change.

 

[hobbs101]

Thanks. What electrode should I specify?

 

[Duwe6]

SMAW would be E7018 [you want this for the ductility that 7018 exhibits]
GTAW I would use ER70-S6

These are extremely common fillers, and a slight overmatch for the 1045. Not hardenable, and an undermatch for the 4160. Thus the cautions you are getting on the welding of these two wildly dissimilar steels.

 

[weldstan]

It depends on the minimum strength needed for the design. Low hydrogen electrodes and processes similar to that provided by Duwe6. Higher strength filler metals (E8018-XX, E9018 may be required depending on design and PWHT conditions.

 

[hobbs101]

Thanks everyone for your posts. Slowly by slowly I'm learning more about welding .