Letter 29081

Phosphating of tool steel [India]  

++++

We use a casting of CH13 (hot worked tool steel investment casting)for our component making. This casting undergoes heat treatment (spherodising, machining, gas carburising, hardening and tempering, Hardness = 60 HRC) followed by sand blasting for surface cleaning.

While performing manganize phosphating, we find white patches. We are looking for a unifirm black colour. Can some one help to avoid white patches. Phosphating is followed by tectyl 272 oiling. Corrosion test (as per ASTM B-117 [link is to info about spec at TechStreet]) on the component with white patches show a good corrosion resistance.

G R Patel
Manufacturer, Power Equipments - Vadodara, Gujarat, India

I want to answer or follow-up on this subject publicly (in non-commercial fashion).

 

My company is a supporting advertiser at finishing.com and we want the contact information to reach the inquirer privately.

 

I want to post a new question or inquiry of my own on a different subject.