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Roughness vs Tensile Strength

I'm a student of Sriwijaya University, South Sumatera Indonesia, Majoring Mechanical Engineering.
Right now I'm doing my research about The Relation Between Roughness Surface and Tensile Strength on Stainless Steel, Copper, Brass, and Low Carbon Steel. In lapping process I use sandpaper to finishing. Right now I need your help to give me information about table contents of Surface Finish of Stainless Steel, Copper, Brass, and Low Carbon Steel; Ra vs US Grit (60, 220, 400, 800).
Beside of that would you give me information or literature by Web Address which containing relation between Roughness and Tensile Strength.
I look forward your information soon.

Yours sincerely,

Erick Parlindungan Morgan
Sriwijaya University - Inderalaya, South Sumatera, Indonesia
2006

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Hi,

I think there is no numerical data for your request, but basically the roughness is inversely proportional to tensile strength, as the finish become worst then the strength will ultimately low.

I have studied this relation in cast iron tensile strength specimen. At first we have machined the sample in conventional machine it results low tensile finally we have gone for CNC machining, it works better.

I would like to know in which method you are predicting this tensile strength.

By lapping the tensile strength would go much higher.

Ganesh Marudhamuthu
- Coimbatore, TN, INDIA
2006

The method for lapping we use sandpaper with grit 60, 220, 400, 800; but to make symmetric surface of specimen we use conventional machine tools with 900 rpm. And the method to get tensile strength we use conventional universal testing machine and digital universal testing machine. Thank you very much.

Erick P Morgan
Sriwijaya University - Palembang, South Sumatera, Indonesia
2006