On the seal, the word "Tiejun" is the seal of Yang Wen.
Judging from the impression given by the original picture, the original author's calligraphy level is not high, and it is not a masterpiece if he has never seen it. I don't think he is a famous artist. At most, celebrity calligraphy or a leading figure in calligraphy. So the value should not be too high.
As for the name Tiejun, there should be many names. Calligraphy has no characteristics, and I'm not sure which one it is. I suggest you click on Baidu to search for "calligrapher's iron army" or you can find the information you want. Wish you success!