Classification Of Stainless Steel Seamless Pipe

Stainless steel is a low-cost and corrosion-resistant material with a high level of durability. Not only is it durable and long-lasting with a perfect surface finish, but it also has excellent strength. Stainless Steel Seamless Pipes / Tubes are widely used in commercial and industrial fields, especially fluid transportation.

Types of Stainless Steel Seamless Pipes

According to metallographic structures of stainless steel, stainless steel seamless pipes can be divided into:

1. Austenitic Stainless Steel Seamless Pipes

Austenitic stainless steel is the most popular and widely used stainless steel in the world. Through increasing the percentage of chromium, moly and nitrogen to the base alloy, austenitic SS's corrosion resistance can be further enhanced . The addition of these chemical elements makes the steel nonmagnetic and make it to be bend, drawn, or formed. Austenitic stainless steel cannot be hardened by heat treatment. Generally, austenitic stainless steel can be classified into 200 series and 300 series, and grade 304/304L is the most familiar stainless steel, which is widely used in food industry.

2. Ferritic Stainless Steel Seamless Pipes

Ferritic stainless steel has high chromium content but low carbon content (usually below 0.1 percent). Ferritic SS is based on the body-centred cubic crystal structure of iron combined with a small percentage of chromium, which can be cold worked, but can not be heat treated. Except for low welding resistance, ferritic stainless steel has exceptional resistance to cracking corrosion stress. Ferritic SS is similarly magnetic to martensitic steels. 430 and 409 are the most common ferritic grades, mostly used in the automotive sector.

3. Martensitic Stainless Steel Seamless Pipes

Martensitic stainless steel is a specific type of stainless steel, whose nickel content is small, whereas its carbon content can up to 1 percent. High carbon content enables martensitic SS to be hardened and tempered to make it become extremely hard, and be ideal for applications where strength, hardness and wear resistance are essential. Unlike typical austenitic stainless steel, martensite stainless steel is magnetic.  Common grades of martensite stainless steel are 410, 420, and 440C.

4. Duplex and Super Duplex Stainless Steel Seamless Pipes

Duplex and super duplex stainless steel are the combination form of ferritic and austenitic stainless steels, which can only be hardened only by cold working. The most frequently used grades are 904L and 2205 which contain higher chromium, nickel and other alloying elements such as nitrogen or copper to enhance its structure or performance. Duplex and super duplex stainless steel is widely used in applications that require high strength as duplex and super duplex SS feature high corrosion resistance, excellent mechanical strength and good weldability.

Depending on the manufacturing method, there are:

- Hot rolled

- Cold worked(cold-rolled and cold-drawn)