Thank you for your inputs.
Our parts are very tiny and we have been using material from same heat lot with same grinding supplier for over two years. We start having this issue 6 months ago.
If it is the MnS inclusion, how does it lead to pitting or rusting? Time sitting in inventory? Specific...
Parts are made of SS 316L. We found about 1% of parts with brown marks, look like rust.
The OD surface go through grinding and cleaned with Alconox and Oakite 31, rinse with DI water.
What could be the cause? Is it from the material? A lab told us they found Manganese Sulfur inclusion in these...
