Steel types with a high level of corrosion and acid resistance are called stainless. Stainless steel is used in almost all industries for many different applications. However, it would be correct to call these steel products "rust-resistant" or "rustproof", because even stainless steel can rust under adverse conditions. Stainless steel contains more than 10.5% chromium that must be dissolved in the austenitic or ferritic solid solution. Other alloy components such as nickel, molybdenum, manganese or niobium add even better corrosion resistance.
Although the name is commonly used, it is actually incorrect to equate high-grade steel with stainless steel. Not all high-grade steel is stainless, and not all stainless steel types are high-grade steel. The requirements for stainless steel are clearly defined and may be met by some high-grade steel types, even though this isn't always the case.