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Chemical blacking query [UK] 

May 2, 2007

Does anyone know if you can sucessfully chemi black EN31 Carbon Steel?

Louise Boyle
Production engineer - Glos, UK

EN 31 = DIN 100Cr6 = SAE 52100. A high carbon, high chrome steel with high hardness and wear resistance. Commonly quenched & tempered to HRC 62. Composition is
C 0.98-1.1, Cr 1.30-1.60, Mn 0.25-0.45, P 0.025 max, S 0.025 max, Si 0.15-0.30, bal Fe.

It likely can be blackened by either the conventional hot black oxide or room temperature chemical processes. I haven't any experience treating this alloy. Due to the levels of C & Cr, it is perhaps treated as a 400-series stainless steel. Anyone with more info?

Chemical suppliers may be able to refer you to local jobshops having the appropriate treatment solutions.

Ken Vlach - Goleta, California

The EN31 (400) series material can be treated with a low temperature chemi black system that operates at ambient temperature.

Barry Clements
- Coventry Warks, UK