Stainless Steel Alloy 430

Stainless steel alloy 430 is a straight chromium ferritic that resists corrosion and is non-hardenable. It is easily formed and resists nitric acid. It is this resistance to nitric acid that promotes it for use where exposure to chemicals is likely. It is also used for appliance components and motor vehicle trim, which are by far the most used applications for this alloy.

There are a couple of other grades of alloy 430, namely the free-machining 430F. This grade in it’s bar form is often used for automatic screw machines. There is a grade that contains molybdenum, stainless steel alloy 434, known for having the same quality as grade 430, but also having a greater resistance to corrosion.

Stainless steel alloy 430 has a great resistance to organic acids such as nitric acid. It is even more resistant to corrosion when it is has been buffed or highly polished. This grade of alloy also has a high degree of resistance to cracking or stress corrosion. Grade 430F, being free machining with a high sulphur content, is more apt to pitting and crevice corrosion.

Oxidation can be resisted during intermittent service to 870 C, however continuous service lowers the oxidation resistance temperature to 815 C. If heated over a prolonged period of time to temperatures of 400 to 600 C, then alloy 430 can become brittle. Annealing will eliminate this tendency towards brittleness.

Grade 430 cannot be hardened by thermal treatment. It is also more likely to scale in high temperatures than is stainless steel alloy 304.

Welding should only be done when the metal has been pre-heated up to 200 C. A post-weld anneal can be used to relieve any embrittlement at the weld and in the area immediately affected by the heat.

The best grade of alloy 430 for machining is grade 430F. While grade 430 is more easily machined that 304 and other standard austenitic grades, it may still gall, however.

During fabrication, it will bend and form a little easier than stainless steel alloy 304 due to the lower work hardening rate. An intermediate anneal may be required when severe cold working is done.

Some of the applications for stainless steel alloy 430 are as outer panels for refrigerators, liners for dishwashers. It can also be found in motor vehicle trim and stove trim rings and element supports.

For more information about the actual chemical composition of Stainless Steel Alloy 430.

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