Seamless stainless steel pipe vs Seamless carbon steel pipe

The main difference between seamless stainless steel pipe and seamless carbon steel pipe is that carbon steel seamless pipe has no artificial addition of other alloy elements except carbon content. Carbon steel seamless pipe is mainly composed of carbon, iron and other elements, while stainless steel pipe contains alloy elements such as chromium and nickel, which makes seamless stainless steel pipe have better corrosion resistance.

Seamless stainless steel pipe and seamless carbon steel pipe have significant differences in many aspects, including composition, corrosion resistance, price, mechanical properties, manufacturing process and use. The following is a detailed analysis of these differences:

1. Material composition

Seamless stainless steel pipe: mainly made of stainless steel material (304, 316 stainless steel), which usually contains chromium (Cr content greater than or equal to 12.5%), which makes it have excellent corrosion resistance. In addition, according to different needs, stainless steel seamless pipe may also contain other alloy elements such as nickel and molybdenum. Seamless stainless steel pipe can be divided into austenitic stainless steel seamless pipe, ferritic stainless steel seamless pipe, martensitic stainless steel seamless pipe, etc. Stainless steel seamless pipes are generally not magnetic, but this is not entirely true. Austenite is not magnetic, but ferrite is, but it is also relatively weak.

Seamless carbon steel pipe: Mainly composed of carbon and iron elements, carbon steel is a relatively common metal material, referring to an iron-carbon alloy with a carbon content of less than 2.11%. Carbon steel is much harder than stainless steel, but it is heavier, less plastic, and easy to rust. According to the carbon content, it is divided into low-carbon steel seamless pipes (mild steel seamless pipe), medium-carbon steel seamless pipes and cast iron. Generally, those with a carbon content of less than 0.2% are called low-carbon steel seamless pipes, commonly known as wrought iron or pure iron; those with a content of 0.2-1.7% are called steel; and those with a content of more than 1.7% are called pig iron. Compared with stainless steel, its corrosion resistance is poor.

2. Corrosion resistance

Seamless stainless steel pipe: Due to its special material composition, stainless steel seamless pipes have excellent corrosion resistance, especially in corrosive media such as acidic and alkaline. Stainless steel seamless pipes of different materials have different corrosion resistance and different corrosion resistance to different media.

Seamless carbon steel pipe: Seamless carbon steel pipe has relatively poor corrosion resistance and is easily corroded by corrosive media. Stainless steel pipes can resist corrosion from weak corrosive media such as air, steam, and water, and chemically corrosive media such as acids, alkalis, and salts. Carbon steel pipes are prone to rust when exposed to corrosive media, while stainless steel pipes can form a dense oxide film to prevent further corrosion.

3. Price

Seamless stainless steel pipe: Due to the use of stainless steel materials, its cost is relatively high.
Seamless carbon steel pipe: The price is relatively low and it is a more economical choice.

4. Specifications and appearance

Seamless stainless steel pipe: Various specifications, including hot rolling, hot extrusion and cold drawing (rolling) types, length, diameter and wall thickness and other parameters can be produced according to demand. The appearance quality requirements are high, and there must be no defects such as cracks, folds, and cracks.

Seamless carbon steel pipe: It also has a variety of specifications and is widely used in various fields. Its appearance quality must also meet relevant standards.

5. Mechanical properties

Seamless stainless steel pipe: In addition to corrosion resistance, it also has good mechanical properties and processing properties, which can adapt to various complex process requirements. In addition, stainless steel pipes will undergo work hardening during cold processing, that is, they have anisotropy when bent, and the transverse and longitudinal properties are different. The stress/strain curve of stainless steel is different in shape and there is no yield point.

Seamless carbon steel pipe: It has excellent mechanical properties and light weight. It is an economical cross-section steel that is widely used in various fields.

6. Manufacturing process

Seamless stainless steel pipe: Seamless stainless steel pipe and seamless carbon steel pipe have similar production processes, including hot rolling (extruded seamless steel pipe), cold drawing (rolling) and other steps. The production process of hot rolling (extruded seamless steel pipe) includes round tube billet heating, perforation, three-roller oblique rolling or continuous rolling, tube removal, sizing (or reducing), cooling, straightening, hydraulic pressure test (or flaw detection), etc.

Seamless carbon steel pipe: The production process may vary depending on specific needs and material properties, but in general it is also produced through a series of processing steps.

7. Application field

Seamless stainless steel pipe: Mainly used in chemical equipment, pharmaceutical equipment, sewage treatment equipment, etc. in industrial sites, as well as fields with high requirements for corrosion resistance, such as food, medical, aviation, etc.

Seamless carbon steel pipe: More used in industries such as oil and gas, chemicals, construction, automotive industry, energy, etc., for conveying fluid media such as water and gas, as well as manufacturing structural parts and mechanical parts.

In general, carbon steel pipes (CS pipe) are suitable for a variety of industrial fields due to their strength and durability, while stainless steel pipes are suitable for fields that require high hygiene standards, such as food processing and medical equipment, due to their corrosion resistance and lightweight properties.

Read more: Stainless Steel ERW vs Seamless Pipe or American Standard Seamless Steel Pipe