Electroless Nickel-Plated Steel vs. Stainless Steel
Corrosion resistance comparisons and cost savings of EN-plated mild steel versus 400 series stainless steel.
Corrosion resistant steels have been in existence for well over a thousand years. One of the earliest examples is the Iron Pillar of Delhi, a Hindu monument constructed around A.D. 400 from an iron-, and interestingly enough, phosphorus alloy. Its longevity and corrosion resistance are due to the formation of a phosphate film. After 1,600 years in the open air, it has barely corroded, and the film has grown by just 1/20 of a millimeter.
There are many other instances of historic corrosion resistant steels, but commercial, large production practicality has come only in the last 100 years with the development of the electric arc furnace, in which most of today’s stainless steels are produced.
Most stainless steels today owe their stain and corrosion resistance to high levels of chromium and nickel in the alloy. There are more than 150 grades of stainless steel available on the market, classified in five groups: austenitic, martensitic, ferritic, precipitation-hardened and duplex. This study only considers the austenitic alloys 303 and 304, and the martensitic alloy 416R.
Austenitic stainless steels (200 and 300 series) are generally more corrosion resistant than the martensitic stainless alloys, but as a rule, cannot be hardened by heat treatment. Martensitic alloys (400 series) can be hardened by heat treatment, but usually are not as corrosion resistant as the austenitic alloys. Composition comparisons are shown in Table 1.