ステンレス鋼の詳細分析: 原因と性質

導入

Stainless steel is an alloy composed primarily of nickel, クロム, モリブデン, そしてチタン. These elements are adjusted in varying proportions to create different grades. Stainless steel is not completely rust-proof, but it is more resistant to rust compared to regular steel.

Why Is It Called Stainless Steel?

Stainless steel is referred to as “ステンレス” because it is more resistant to rust. Some stainless steels are also acid-resistant, which makes them corrosion-resistant. This resistance is due to a thin, chromium-rich oxide layer, known as a passivation film, that forms on the surface. しかし, this resistance is relative, and under certain conditions, even stainless steel can corrode.

Experiments show that as the chromium content in the steel increases, so does its resistance to corrosion in mild environments, like air and water, and in oxidizing agents such as nitric acid. When the chromium content reaches a certain level, the steel transitions from being prone to rust to becoming rust-resistant and corrosion-resistant.

ステンレス鋼の分類

Stainless steel can be classified in several ways:

By Microstructure at Room Temperature:
- マルテンサイト系
- オーステナイト系
- フェライト
- デュプレックス
By Chemical Composition:
- Chromium Stainless Steel
- Chromium-Nickel Stainless Steel
用途別:
- Nitric Acid-Resistant Stainless Steel
- Sulfuric Acid-Resistant Stainless Steel
- Seawater-Resistant Stainless Steel
By Corrosion Resistance:
- Pitting-Resistant Stainless Steel
- Stress-Corrosion-Resistant Stainless Steel
- Intergranular Corrosion-Resistant Stainless Steel
By Functional Characteristics:
- Non-Magnetic Stainless Steel
- Free-Cutting Stainless Steel
- Low-Temperature Stainless Steel
- High-Strength Stainless Steel