BS ISO 3506‑6:2020 pdf download.Fasteners — Mechanical properties of corrosion-resistant stainless steel fasteners.
4.2.2 Grade Al
Stainless steels of grade Al are specially designed for machining. Due to high sulfur content, this grade has lower resistance to corrosion than corresponding stainless steels with normal sulfur content. This grade is neither suitable for use in non-oxidizing acids and agents, nor in an environment with chloride (e.g. in swimming pools using chloride as a cleaning agent, or marine environments).
4.2.3 Grade A2
Stainless steels of grade A2 are the most frequently used stainless steel. This grade is not suitable for use in non-oxidizing acids and agents, or in an environment with chloride (e.g. in swimming pools using chloride as a cleaning agent, or marine environments).
4.2.4 Grade A3
Stainless steels of grade A3 have properties similar to grade A2, but with increased resistance to temperature (typically up to 350 °C). They are stabilized by addition of titanium or niobium that combines with carbon and nitrogen. This grade is neither suitable for use in non-oxidizing acids and agents, nor in an environment with chloride (e.g. in swimming pools using chloride as a cleaning agent, or marine environments).
4.2.S Grade A4
Stainless steels of grade A4, often known as “acid proof steels”, are molybdenum alloyed which gives a considerably better resistance to corrosion. This grade may be used in some environments where chloride is present; however, it is still not suitable in swimming pools using chloride as a cleaning agent, or many marine environments.
4.2.6 Grade AS
Stainless steels of grade A5 are stabilized stainless steels with properties of grade A4, hut with increased resistance to temperature (typically up to 350 °C). Stainless steels of grade AS have properties similar to grade A4 and are resistant to many acids. They are stabilized by addition of titanium or niobium that combines with carbon and nitrogen. This grade may be used in some environments where chloride is present; however, it is still not suitable in swimming pools using chloride as a cleaning agent, or many marine environments.
4.2.7 Grade A8
Stainless steels of grade A8 are known as “6% Mo” stainless steels. They have a high level of resistance to all forms of corrosion including pitting, crevice and stress corrosion cracking. They are suitable for use in swimming pools using chloride as a cleaning agent. However, there can be specific requirements and/or regulations for buildings and construction. Grade A8 is also suitable for applications in marine environments.BS ISO 3506‑6 pdf download.