I have some parts made from 17-4PH cond H1025 stainless steel that require a black surface finish for cosmetic purposes only. I have been using MIL-DTL-13924 class 4 black oxide, but this black oxide coating is very easy to damage. I appreciate that black oxide coating is not intended to provide corrosion protection or wear resistance, but this black oxide comes off just from the rubbing contact experienced during routine handling. I did a comparison test with the black oxide coating on some commercial alloy steel fasteners I had. I rubbed both samples with fine steel wool (dry) and the black oxide coating on the fasteners was significantly more durable than the black oxide on my stainless parts.
Can anyone think of a reason for this situation? Am I using the proper type of black oxide process for my 17-4PH material? Or does this particular type of black oxide just have very poor durability?
Thanks for any help.
Can anyone think of a reason for this situation? Am I using the proper type of black oxide process for my 17-4PH material? Or does this particular type of black oxide just have very poor durability?
Thanks for any help.