Some of them are carbon steel and some are stainless. The common work shop variety are CS. Long length flat blade versions, esp ones for outdoor use, are often stainless.
The stainless strip is made to ASTM A666 and is usually "1/4 hard". In most alloys this will give you 75ksi min yield and 120ksi min tensile.
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Corrosion never sleeps, but it can be managed.