A4-80 Frequently Asked Questions

A4-80 stainless steel, “A” for Austenitic (non-magnetic), “4” for Grade 4 stainless steel (corrosion-resistant/acid-proof), Class 80 (considered high strength for stainless steel)
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304 is A2 stainless steel, whereas 316 is A4 stainless steel. The higher grade indicates a higher level of corrosion resistance.

Yield Stress (Rp0.2) ≥ 600 MPa

Tensile Strength (Rm) ≥ 800 MPa

Elongation (A) = 0.3xd

Carbon steel is usually going to be stronger. A4-80 is among the strongest non-proprietary stainless steels and approaches the mechanical strength of a class 8.8 fastener, whereas class 10.9 and 12.9 steels will have significantly stronger mechanical properties. Generally, people go with stainless steel for the corrosion resistance. A4-80 starts approaching carbon steel strength, but with corrosion resistance throughout the fastener, whereas steels can be plated, but once corrosion breaches the plating, the fastener can corrode quite quickly.

Austenitic stainless steel has a different crystalline structure which imparts relatively non-magnetic properties to this steel type. This steel type contains more grades and is used in many more product lines than any of the other steel types. Austenitic stainless steel provides corrosion resistance that is superior to martensitic or ferritic.

Austenitic stainless steel provides great formability and possess high toughness in cryogenic temperatures. They also higher thermal expansion and heat capacity, with less thermal conductivity than the other types of stainless steels and alloy steels.

A4-80 stainless steel is considered a 300 series austenitic stainless steel, therefore there is a chance carbide precipitation at high temperatures (such as welding).

Check out this chart.