Welcome to you, Bushrat. Try searching this forum for "file steel". You should find plenty of info with that. Sometimes the search function is a pain here, so I'll give a quick rundown of what I know about file steel.
Somebody (I think it was Ed Caffrey) had a bunch of files tested a couple of years ago. All Nicholsen files came back as 1095, old Black Diamond files came back as 1.23-1.27% C and basicly a 10xx. None of the other brands were consistent as to content. I have used files quite a bit, and here is how I test them. Before I do anything else, I put the tip of each file on my anvil (not flat, at a slight angle) and give it a good whack. I haven't had one that wouldn't break, yet, but this ensures that I'm not wasting my time with case hardened material. Then I normalize it to make grinding easier and grind all of the teeth off the edges. Then I forge/grind just like I would 10xx steel. I quench just like I would 1095, but start tempering at lower temps and adjust according to the brass rod.
I think everyone would agree that it's best to use a known steel to achieve a known result, but I enjoy working with salvaged material from time to time. Just make sure your customers know where it came from.
Good Luck!
Todd