Cast Iron Stove Repair Question - Rust/degradation at joint

So, my yurt, where we used to live, has a lovely little cast iron woodstove that served us perfectly for 5 years.   Now, as it's about 15 years old and not used regularly, I went to check on the 'guest yurt' and saw that the joint where the chimney fitting comes out of the top is rusted(??) away.

How does one fix that?  Do I simply try and buy another top?   Can I stuff something in there?   Should I bother?  it doesn't seem to hurt the functionality so that I can tell.

Here's an image attached.

Tys

I dunno, maybe caulk with wire-wool daubed with stove cement.

You have a lot of options to fix this.

(1) It is just the chimney to stove connection so smoke will go up the chimney anyway, and by the looks of it, it looks like a Vogelzang Boxwood Stove which is not an airtight stove either. So stove cement applied a few times a heating season would work.

(2) You could make a longer lasting patch by using fiberglass stove rope and stove gasket cement together.

(3) You could also try finding a part to fix the stovetop. There are woodstove parts places throughout the country. I have one in my town and in 10 minutes found legs for a 1893 Woods and Bishop Pot Bellied Stove, so there is always hope for parts.

(4) You could also weld it. They make cast iron welding rod, and I have used it, but I just use standard 6011 1/8 welding rod instead. In welding, it pulls enough cast iron base material in the weld to hold. The key to welding cast iron is to apply heat PRIOR to welding, then welding it, then adding heat after welding to SLOWLYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY cool it off. If you do not do that, it will crack for sure. And I mean slowly let it cool.

yes, Vogelsang, well done. thanks for the options.  I will NOT be welding.