After I cleaning the washing machine by using
Citric acid and then using white vinegar.
The Drum coating was peeling or it's a hard calcium ?
how i can rid from that ?
Maybe because it's really hard to tell from the pics. I wonder what the outer tub looks like? Maybe make the room dark, shine a flashlight by putting the bulb of the light direction on the drum and look through the hole to see if you can see the outer tub? I can see my heating element in my duet doing this. I once wanted to see what my outer tub looked like and someone gave this tip. If you see buildup it might be from that? Maybe the first treatment was eating away at the buildup but wasn't able to get quite all of it?
My water is hard too, but laundry detergent has things in it to keep that from building up.
Vinegar dissolves the carbonate bond (crusty stuff) but calcium is still an insoluble powdery metal that has to be encouraged by surfactancy and light abrasion to let go of the surface.
It looks as if the tub sat full of water for a long spell. If you can't rub/scratch it off with a thumb nail then it is just some sort of haze on the surface of the stainless.
You could polish it off with a little metal polish but that could be a lot of work. It won't hurt anything and using the washer will slowly polish it off. I'd say it isn't worth worrying about.
I agree with Phil, I wouldn't worry about it. The steel can handle way higher temperatures than your washer can achieve. So no problem there. And it's not stainless steel itself either.
BTW, did you use the citric acid with the highest temperature available on your washer?