It looks like very poor stick welding by a 'hobbyist' for the most part... Not pretty or in any way strong, most of it would fall off with a hit as it is only held in place by the inclusions!
For the record, anyone trying to weld Chinese so called steel would be presented with a similar outcome until you learn that you need to wash over it with weld first to get some decent steel on the surface then try and weld it!
The date of this shell would be early bake hard steel and it was awful stuff to work with at the best of time and tin worm had an easy job...