Welding Ferrous Investment Castings

Date 05-13-2002 15:34

Bill,

Investment casting is a process, it does not tell us anything about the material type. However, most of the castings used for equipment/machinery are some sort of alloy steel, and can be welded. However, with out knowing the type, there are too many variables to be addressed adequately. The components may even be cast iron or other relatively unweldable/hard to weld alloy. Is there any way you can find out more about the casting?

By Bill Hendrick Date 05-13-2002 17:18

The material is going to be either 8620 or 4140. My customer is looking to weld angle iron to the casting made out of 8620 or 4140. We are in the development stages of this snow plow application. The function of the part I am inquiring about is a bracket that attaches the plow to the truck. Any suggestions regarding the elements of the enlarged grain structure of the casting and the loads and stresses that the part will be subjected to that I should need to know. I want to be able to weld the angle to the casting in a way that will ensure the weld will hold.

Bill

By GRoberts (***)

Date 05-14-2002 01:44

Bill,
If you have procedures for welidng 8620 or 4140 in wrought material, it will generally work for castings also. The large grain structure of castings that forms during solidification is refined when they are austenized, water quenched and tempered. Properly melted, poured and heat treated castings can be easier to weld than wrought material in some cases, as you won't run into lammelar tearing, or directional property problems. You can run into other problems though, like micro-shring, hot tears, or gas. Proper NDT can elimiate these problems though, if they will cause a problem for the end user. We don't make a 4140, but we do make a 8620, and most of your variables will depend on the temper of the base material. Generally, we use 300F preheat min. Weld metal from 80-120 ksi, and PWHT is usually mandatory. We temper from 1050-1150F, but you generally want to temper at 25-50F min. below the previous tempering temperature.

Good luck with your project.

G Roberts

By Bill Hendrick Date 05-14-2002 12:31

Procedures are in place for welding, looking for evidence or proof that welding wrought materials to 4140 or 8620 casting will work. I don't want to try this and find out it doesn't hold. Do you know of any cases where wrought materials are welded to castings of 4140, 17-4 or 8620?
thanks,
Bill