Is ss316 A2 or A4?

SS316 falls under the A4 category of stainless steel grades. The A2 and A4 designations are part of the ISO 3506 standard, which specifies the mechanical and chemical properties of stainless steel fasteners (such as bolts, screws, nuts) for use in different environmental conditions.

Here's a breakdown of the A2 and A4 designations:

1. A2 Stainless Steel: A2 is equivalent to AISI Type 304 stainless steel. It contains chromium (around 18%) and nickel (around 8%) as the primary alloying elements. A2 stainless steel is commonly used in applications where corrosion resistance and general strength are required. It's suitable for use in indoor, rural, and mildly corrosive environments.

2. A4 Stainless Steel: A4 is equivalent to AISI Type 316 stainless steel. It contains chromium (around 17-19%), nickel (around 10-13%), and molybdenum (around 2-3%) as the primary alloying elements. A4 stainless steel offers higher corrosion resistance compared to A2 stainless steel. It's suitable for use in more aggressive environments, including marine and coastal areas, where exposure to chlorides and other corrosive substances is higher.

So, SS316 is classified as A4 stainless steel according to the ISO 3506 standard. If you're working with fasteners and need to ensure the right stainless steel grade for your specific application, it's recommended to refer to the relevant standards or consult with suppliers who can provide accurate information based on your needs.