Hard Chromium Plating on Nitrided Steels
Q. We chromium plate a flash thickness of 500 microinches on mandrel bending dies. We are having difficulty with nitrided-hardened dies. If we do not get them activated properly the first time for plate, we have mis-plating worse each time they are stripped and re-plated. We are using HCl to strip, and it appears we are adversely affecting the part each time. Any suggestions for stripping/reactivating the part for hard chroming would be appreciated.Ron Schmitt
metal finishers - Colorado Springs, Colorado
A. I would try two things:
1st - I would try to strip the chrome in caustic solution with reverse current i.e., electrocleaner;
2nd - with either process I would bake @ 375 °F for 4 hours for hydrogen embrittlement relief.
plater - Charlotte, North Carolina
Q. Chris is right about stripping any carbon steel with reverse current in caustic. What I want to know is how are you activating the nitrided surface? I haven't had much luck at this.
plating shop - Oxnard, California
October 25, 2010 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
I have a job shop unit, doing Hard chrome (SRHS and new technology Organic base) and Electroless nickel plating (mid phosphorous). I am facing two problems.
1) To plate Hard Chrome Plating 25-35 microns on hardened metals above 65 HRC such as nitriding: Rejection rate is 50%. I normally do 1 minute reverse etching at same current. Some portion of job remains unplated.
2) Hard Chrome Plating on electroless nickel plated jobs: No reverse etching, job is already hot so I put it in live current in hard chrome plating bath. What is the bonding strength of chrome on nickel?
Please suggest me process to ensure minimum rejection. Which is the best metal to plate Hard chrome (bonding)?
Plating Shop - Ahmedabad, Gujarat, India
August 19, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread
Q. Has anyone found a way to successfully hard chrome a steel part that has been nitrided? The parts have an ion nitride 2 - 3 thousands thick.David Peck
Plating shop employee - Leslie, Michigan, USA
A. Hi David. I am not a plater myself, but on some related threads several knowledgable people have suggested starting with a Wood's Nickel Strike for carbonitrided parts -- and it sounds right to me. Good luck.
Ted Mooney, P.E.
Pine Beach, New Jersey
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