Recommendations Welding 8740 ? 2

[weldeng32]

We build construction equip. What experience/recommendations do you have in welding 8740 material? I don't have a thickness yet. Still early in design.

 

[metengr]

The information I have regarding 8740 is that it is a Ni-Cr-Mo alloy steel

0.55% Ni - 0.5% Cr - 0.25% Mo with about 0.4% C

This material should be weldable using a preheat requirement of about 300 deg F minimum. The thickness of the base metal will dictate specific (possibly higher) preheat requirements. Also, what is the heat treatment condition of this material?

 

[weldeng32]

I do not have this info at this time. I am investigating a material usage for a design engineer. The weld will need structural and probably impact integrity. I see that the CE (carbon equivalent) is about 0.75%. Quite hardenable?

 

[TVP]

Yes, quite hardenable. This grade will attain a hardness of > 54 HRC in a 25 mm section that has been oil quenched, which makes it useful for making large diameter, high strength bolts.

 

[metengr]

Not sure why you would want to use this alloy in a structural application. How about a
T-1 steel? This is a low alloy steel that is supplied in a quenched and tempered heat treatment for use in structural applications. It is hardenable, and also exhibits good toughness. The weldability of this material is good, as well. However, strict interpass temperature requirements must be followed when welding with T-1 material.