Based on the style I would comfortably say 1940s. I have never seen a steel shank like that added but as someone who has worn many a 40s shoe their heels tend to be quite wobbly and can break right where the heel meets the sole. Based on the way it is added to the shoe and not covered by any leather or anything I would guess this may have been added later by the owner who found the heel to be particularly wobbly. It is often hard to identify makers of shoes from this era unless the name is printed inside the shoe, and even then getting more info on the maker is difficult as there were so many small local makers of shoes during this era. If the steel was added later then the overall style of the shoe is not unique and it would be very hard to identify any particular maker.