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Stainless is kinda soft. Your better off using steel rod for that application.
I have used 318 stainless rod for welding large cast iron castings in the past. Since the stainless is soft material it gives some and also the chemistry of how it combines with the iron, it works good for crack problems where a lot of strength isn't important. Just remember if you weld steel with it you can not use a torch to cut it, as the stainless will not oxidize. So its good for an application where you don't want someone using a torch to cut something.
Stainless rods are great with cast due to the nickel content.
To add to the above- Make absolutely sure all combustible materials are away from the area, and if you like your clothing and skin don't use this rod overhead- It splatters like you would not believe. Also heats up really quick, and at the correct amp settings for your application, the rod will be glowing and possibly even soften before it's completely used.