Category: Corrosion Testing
Iron contamination and rust staining on stainless steel
Rust staining can occur and has been reported as anything from a slight brown 'bloom' on the surface to severe surface pitting or rusty scour marks on items such as handrails. These effects are usually due to surface contamination from contact with non-stainless steel items. Iron contamination can be costly to remedy, and is avoidable. The ferroxyl test can be used to detect 'free' iron contamination. (108)
On-site methods for stainless steel grade product sorting
Guidance on methods for sorting stainless steels from low alloy and carbon steels is shown. These include physical (colour, density, magnetic) and mechanical (hardness) properties and chemical tests (copper sulphate, copper chloride, nitric acid and sulphur tests). A suggested approach to a step-by-step procedure for differentiating stainless steels from carbon steels is tabulated. These methods have not been verified by the BSSA, who take no responsibility for their accuracy of the conclusions reached on steel types.
Salt spray testing of stainless steels
Salt spray testing is an accepted method for assessing the suitability of stainless steel parts and fabrications that are likely to encounter chloride environments in service. The test outcome is sensitive to the shape of the parts (designed-in crevices), surface finish and the test conditions and so specific results for 'hours to failure' for steel grades alone is not appropriate. Specified test methods are shown.
Selection of stainless steels for surgical instruments
Steel grades A (410 1.4006), B (1.4021), C (1.4028), D (1.4034), E (1.4116), F , G, H, I, K (1.4122), R, L (1.4105), M (304 1.4301), N (303 1.4305), O (301 1.4310), and P (316 1.4401) of BSENISO 7153-1:2001 (BS 5194-1:1991) are shown. The surgical and dental applications for these grades are outlined. These include cutting and non-cutting instruments and fitting parts and assemblies. (Body implants are NOT covered here.) Corrosion resistance, corrosion testing and the affects on these surgical steels of sterilization practices are covered.
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