Not logged inAmerican Welding Society Forum
Forum AWS Website Help Search Login
Up Topic Welding Industry / Technical Discussions / Cast Stainless Weldability & Strength
- - By BPI1 (*) Date 12-06-2007 14:13
Subject says it all!  How does cast stainless weld (using pulse mig)?  How strong is the weld?  We will be using a filler material appropriate for the application, of course.  Finally, how strong is the base material itself?

These parts need to withstand a minimum of 2500 pounds.  Knowing how brittle cast iron is, I am concerned about cast stainless's strength.  If anyone has experience with this, or can direct me to information about it, I would appreciate it.

If you need any further information, please let me know.  I am assuming that these parts will be cast out of 304.
Parent - - By aevald (*****) Date 12-06-2007 14:40
Hello Josh, it is very likely that you will find these parts very weldable. When comparing cast iron and it's weldability to steel there are profound differences, in fact completely different. In this case if the parts are cast from 304 grade stainless the only real weldability issues may come from the "skin" on the outside of the casting. Once you have properly cleaned and prepped any welded areas they should weld as well as most sheet or plate grades of the same alloy. The only other types of issues may stem from internal voids or trapped casting medium that may be internally present dependent on the specific casting process and the attention paid by the manufacturer. My $.02. Best regards, aevald
Parent - - By BPI1 (*) Date 12-06-2007 15:24
Thanks for your fast response! 

Would you happen to know if this part would withstand a 2500 lb load?  Specifically, this is a 3/4" stainless round bar shaped into a U.  The U-bar is then inset into a carbon steel round plate with holes (the bar passes through the plate via the holes).  A 1/4" fillet is all the way around the "top" connecting the u-bar to the plate on both legs of the u-bar, then a 1/4" fillet is half way around the other side of the u-bar to plate, where the legs of the u-bar extend through the plate.

What type of cleaning would you recommend?  We are manufacturing thousands of these items, so grinding may not be the best way.  Will acetone cut the "skin", or a similar solution?
Parent - By aevald (*****) Date 12-06-2007 16:28
Hello again BPI1, if you believe that grinding might be overly burdensome in the preparation of these parts I believe I would consider welding a few test pieces in the "as received condition" and then doing some testing of the resulting welds. Possibly sectioning the piece so that you can view the fillet and it's interface with the round bar and the through plate, will tell you whether there are any issues with cleaning and preparation. Possibly a polish and etch of this section would further reveal issues. Even the visual inspection of the weld itself will give you some pretty good clues as to whether the interface of the weld metal to the base metal has any issues.
     The "skin" that I was referring to is typically not of quite the same composition as the rest of the casting due to it being the contact and release point from the mold. Depending on the particular casting process and the care exhibited by the manufacturer, this may or may not have a great impact on welding to this surface. Not having specific knowledge of this, or the condition of the parts that you are working with, is the reason for my mention of it. Also, the intended purpose of these parts can impact the level of acceptable weld performance that is expected and would determine to what degree you would need to go with part preparation. Best regards, aevald
Parent - - By js55 (*****) Date 12-06-2007 15:32
Though there are inherent mechanical differences between cast and wrought materials (due to cooling time, chemistry adjustments, Si content, microstructural orientation, grain size, etc) cast iron is not brittle because of the casting process but because of the carbon content.
Thousands upon thousands of cast steel, cast alloy steel, and cast stainless steel valves are welded everyday with standard procedures used for wrought products.
Parent - - By js55 (*****) Date 12-06-2007 15:34
Cast SS round bar?
Whats the material spec?
Parent - By DaveBoyer (*****) Date 12-07-2007 05:20
My guess is that rather than "a 3/4" stainless round bar shaped into a U" He means "a U shaped stainless casting with a 3/4" round cross section" if that helps any, and as You note without an actual material spec. You cant determine strength. Another guess on My part, if the castings are sound and made from 304 as He guesses, they should easily hold 2500# if welded as mentioned provided the plate is strong enough to carry the load PROVIDED IT IS TENSILE AND PARALLELL TO THE LEGS OF THE U. Make the legs of the U long and pull perpendicular to them, and that is another story... Holding 2500# and having enough safety factor for overhead lifting are 2 different situations as well.
Parent - By CWI555 (*****) Date 12-06-2007 16:37
To answer most of your questions, the exact spec would be needed. This could be round bar, valve body castings, or other. Different cast stainless parts have different values. Whats the service of the part? Whats the spec? etc
Up Topic Welding Industry / Technical Discussions / Cast Stainless Weldability & Strength

Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill