201 Stainless steel, 201 Seamless stainless steel pipe

What is 201 seamless stainless steel pipe?

201 stainless steel is an austenitic stainless steel whose chemical composition mainly includes C, Cr, Ni, Mn, Si, P, S and other elements. Its characteristics mainly include good acid and alkali resistance, good welding performance and processability, high density, no bubbles in polishing, no pinholes, etc. This material of stainless steel is mainly used to produce various watch cases, watch strap bottom covers, etc. It is also suitable for decorative tubes, industrial tubes and some shallow stretched products. "Seamless tubing" refers to the manufacturing process of stainless steel pipes.

201 stainless steel marking method:

201 stainless steel pipe--S20100 (AISI/ASTM)

AISI (American Iron and Steel Institute) uses three digits to represent various standard grades of wrought stainless steel. Among them:

1. Austenitic stainless steel is marked with numbers in the 200 and 300 series.
2. Ferritic and martensitic stainless steels are represented by 400 series numbers.

For example, some of the more common austenitic stainless steels are marked with 201, 304, 316 and 310, ferritic stainless steels are marked with 430 and 446, and martensitic stainless steels are marked with 410, 420 and 440C. Phase (austenitic-ferritic) stainless steels, precipitation hardened stainless steels and high alloys with an iron content of less than 50% usually have patented or trade names.

201 stainless steel is part of the 200 series, indicating that it belongs to the category of austenitic stainless steel. Although the corrosion resistance of 201 stainless steel is weaker than that of the 300 series, its market potential is huge.

Chemical composition of 201 stainless steel:

The chemical composition of 201 stainless steel seamless pipe includes carbon, silicon, manganese, chromium, nitrogen, phosphorus and sulfur. The content of manganese is relatively high, which makes the 201 stainless steel seamless pipe have a certain hardness, but during the deep drawing and deep drawing process may crack. Nonetheless, after polishing, 201 stainless steel seamless pipe will not rust in a short period of time and is as non-magnetic as 304 stainless steel, which makes it widely used in the decorative welded pipe industry.

C: ≤0.15
Si: ≤1.00
Mn: 5.5～7.50
Cr: 16.0～18.0
N: ≤0.25
P: ≤0.060
S: ≤0.030
Ni: 3.5-5.5

Grades of 201 stainless steel:
The strength grades of 201 stainless steel are usually divided into: S201, S202, S203, S204, S205, etc. These grades represent the tensile strength values of stainless steel, which are 201MPa, 202MPa, 203MPa, 204MPa, and 205MPa respectively.

In the field of stainless steel materials in China, there are many types of 200 series stainless steel, mainly including J1, J3, J4 and the common 201 and 202 steel grades. These steel grades were initially widely used, but later 200 series derivatives with more stringent nickel content controls emerged to meet specific needs.

Among them, 201 steel type is known by its standard number 1Cr17Mn6Ni5N, which is characterized by containing a certain proportion of chromium, manganese and nickel elements. However, with the development of technology, some steel mills in China have further developed special models such as 201C on this basis. The characteristic of 201C is that it appropriately increases the manganese content while reducing the nickel content, which gives it unique advantages in some specific industrial applications.

Production process:
a. Round steel preparation; b. Heating; c. Hot rolling and perforation; d. Cut off the head; e. Pickling; f. grinding; g. Lubrication; h. Cold rolling processing; i. Skim; j. Solid solution heat treatment; k. Straightening; l. Cut the tube; m. Pickling; n. Finished product inspection.

201 stainless steel vs 304 stainless steel:

Compared with 304 stainless steel, the price of 201 seamless stainless steel pipe is usually lower because of its lower nickel content and relatively poor corrosion resistance. However, 201 stainless steel seamless pipes may rust when used for a long time in humid and salty air. Nevertheless, there is also a stainless steel detection solution on the market that can distinguish the type of stainless steel in a few seconds through a simple chemical reaction. This method is convenient, accurate and feasible‌.

In general, 201 stainless steel seamless pipe is an economical and practical choice in specific application scenarios due to its low cost and certain corrosion resistance. Although it is not as corrosion-resistant as 304 stainless steel, 201 stainless steel seamless pipe is a viable alternative in certain applications where extremely high corrosion resistance is not required.

FAQs:

Q1: Will 201 stainless steel seamless pipe rust?

A: Yes, it will rust, especially in certain environments.
While 201 stainless steel has some corrosion resistance, its rust prevention is relatively weak. 201 is suitable for dry indoor environments. For coastal or outdoor applications, it is recommended to upgrade to 304 or 316L stainless steel.

Q2: Can 201 stainless steel seamless pipe be used in contact with drinking water or food?

A: Generally not recommended.
201 stainless steel has limited corrosion resistance and a high manganese content, which does not meet the standards for food-grade stainless steel. For contact with food or drinking water, 304 or higher grade stainless steel conforming to GB 4806.9 food safety standards should be used.

Q3: What precautions should be taken when welding 201 stainless steel seamless pipe?

A: Welding 201 is more sensitive than welding 304, requiring the use of specialized welding materials.
If pickling and passivation treatment is not performed after welding, the corrosion resistance of the weld area may significantly decrease.

Q4: What is the applicable temperature range for 201 stainless steel seamless tubes?

A: The applicable temperature range for 201 stainless steel seamless tubes is -20℃ to 300℃, but it is recommended to keep the long-term operating temperature below 250℃. Performance is unstable at temperatures exceeding 300℃, making it unsuitable for high-temperature applications such as boilers and heat exchangers.

Q5: Is 201 stainless steel good for jewelry?

A: 201 stainless steel is not suitable for jewelry. Although it is inexpensive and has a good polishing effect, its fatal flaw of poor corrosion resistance makes it unsuitable for long-term close-fitting wear—the salt in sweat will gradually corrode the surface, leading to rust, discoloration, and even skin allergies.

If you are purchasing stainless steel jewelry, please look for 316L stainless steel (titanium steel/medical steel). It remains very affordable (far lower than gold and silver), but its durability, safety, and aesthetics far surpass 201, making it the current gold standard for stainless steel jewelry.

Read more: Carbon steel vs Stainless steel or 304 vs. 316 Stainless Steel