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Eastern Steel Manufacturing Co.,Ltd is a leading manufacturer and distributor of seamless steel pipe, welded steel pipe, OCTG products and fittings. We supply first-step processing, semi-finished parts and finished parts to help our clients meet fabrication requirements beyond their capacity or to improve operations by moving forward the pre-production processing.
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In this column you can find the steel pipe related articles you need, including industry trends, product standards and materials, and some technical guidelines.
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Eastern Steel Manufacturing Co.,Ltd not only improve product production and sales services, but also provide additional value-added services. As long as you need, we can complete your specific needs together.
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Many years of large-scale project experience in various fields（Oil & Gas, Construction, Power Energy, Marine & Offshore, Water Treatment, Exploration & Drilling Services, Pipeline & Petrochemical etc.）, professional project team is responsible from receiving until the end of the project.
RHS steel stands rectangular tubes. As an important form of structural steel pipe, are widely used in building structures, machinery manufacturing, vehicle industry, furniture, bridge engineering, and other fields. Their performance and service life largely depend on the material used; therefore, understanding the common material classifications and characteristics of rectangular tubes is crucial for material selection in engineering projects.
Rectangular tubes, as a common type of steel pipe, are mainly made of the following materials:
1. Carbon Steel
2. Alloy Steel
3. Stainless Steel
4. Aluminum Alloy
Ordinary carbon steel is the most widely used material for RHS steel. Its main components are iron and carbon. It has high tensile and bending strength, and high hardness, but poor corrosion resistance. It is inexpensive, easy to process, and suitable for most general structures.
Q195: Lower strength, often used in light-load structures.
Q215: Slightly higher strength than Q195, suitable for general structural components.
Q235: The most common carbon structural steel, with a yield strength of 235 MPa, widely used in construction, machinery, and other fields.
SS400: A general structural steel in Japanese standards, similar to Q235.
20# steel, 45# steel: Medium carbon steel, with higher strength, suitable for applications with high requirements such as mechanical parts.
Low price, large supply; strong weldability and formability; suitable for most conventional load-bearing applications.
Moderate corrosion resistance, requiring painting or galvanizing protection.
Building frames, machinery supports, vehicle frames, fences, door and window structures.
Alloy steel rectangular tubes have added alloying elements such as chromium, nickel, and molybdenum, resulting in superior mechanical properties and corrosion resistance.
Q345B: Low-alloy high-strength steel, with superior comprehensive performance compared to Q235, commonly used in heavy-duty structures such as bridges and ships.
16Mn: Similar in performance to Q345B, belonging to low-alloy steel.
Q390, ST52-3: Higher-strength low-alloy steels, used for special heavy-duty structures.
Yield strength 30-100% higher than ordinary carbon steel; More suitable for high load-bearing and heavy-duty structures; Better impact toughness.
Higher cost than ordinary carbon steel; Higher welding process requirements.
Bridge engineering, construction machinery, shipbuilding, automobile beams, hydraulic equipment.
Stainless steel rectangular tubes are mainly composed of iron, chromium, nickel, and other elements, possessing excellent corrosion resistance and aesthetic appeal, making them the preferred material for special industries.
304 (0Cr18Ni9): Austenitic stainless steel, highly corrosion-resistant, suitable for chemical and food industries.
316/316L: Contains molybdenum, resistant to chloride corrosion, used in marine or highly corrosive environments.
2205 Duplex Stainless Steel: Combines strength and corrosion resistance, used in specialized industrial equipment.
Optimal corrosion resistance;
Clean and hygienic, smooth and aesthetically pleasing;
Long service life (30-50 years).
High price;
Difficult to form and process.
Food processing, marine environments, petrochemical industry, medical equipment, decorative engineering.
The main components of aluminum alloy rectangular tubes are aluminum and other alloying elements. They are lighter and stronger than other materials, but have poorer acid and alkali resistance and corrosion resistance.
6061-T6: Medium strength, good weldability, excellent corrosion resistance, suitable for aerospace, automotive, and sporting goods.
6063-T5: Lower strength, smooth surface, suitable for extrusion, suitable for architectural and decorative profiles.
7075-T6: High-strength aluminum alloy, strength close to steel, but high cost, suitable for aerospace and military equipment.
Lightweight (suitable for lightweight applications);
Good corrosion resistance; High formability.
Poor high-temperature performance;
Lower strength than carbon steel and alloy steel;
High price.
Aerospace, automotive, light industrial equipment, sporting goods, architectural decoration.
|
Material Type |
Yield Strength (MPa) |
Tensile Strength (MPa) |
Corrosion Resistance Grade |
Density (g/cm³) |
Weldability |
|
Ordinary Carbon Steel（Q195） |
195 |
315–430 |
2 |
7.85 |
10 |
|
Ordinary Carbon Steel（Q235 / SS400） |
235 |
375–500 |
3 |
7.85 |
9 |
|
Medium Carbon Steel（45#） |
355 |
600–750 |
3 |
7.85 |
5 |
|
Low Alloy High Strength Steel（Q345B） |
345 |
470–660 |
4 |
7.85 |
8 |
|
High Strength Steel（Q390–Q460） |
390–460 |
550–780 |
4 |
7.85 |
7 |
|
ST52-3（DIN） |
≥355 |
490–630 |
4 |
7.85 |
8 |
|
Stainless Steel 201 |
275 |
520–750 |
5 |
7.93 |
7 |
|
Stainless Steel 304 |
210 |
520–720 |
8 |
7.93 |
9 |
|
Stainless Steel 316 / 316L |
170–300 |
530–750 |
10 |
7.99 |
9 |
|
Duplex Steel 2205 |
450 |
620–880 |
9 |
7.80 |
7 |
|
Aluminum Alloy 6061-T6 |
240–275 |
290–310 |
6 |
2.70 |
8 |
|
Aluminum Alloy 6063-T5 |
160–180 |
205–240 |
6 |
2.70 |
8 |
|
High-Strength Aluminum Alloy 7075-T6 |
480–540 |
520–600 |
5 |
2.81 |
6 |
Note:
Corrosion resistance rating (1–10): Higher numbers indicate better corrosion resistance; 316 = best rating (10).
Weldability (1–10): Higher numbers indicate easier welding; carbon steel is best.
By environment: Indoor = carbon steel; Outdoor = Q345; Marine = 316; Chemical = 2205.
By strength: Choose materials with higher strength for greater stress.
By budget: Cost from low to high is: Q345 → 304 → 316/2205.
The most commonly used is Q235 carbon steel rectangular tube, which has a high cost-performance ratio, good weldability, and is suitable for most building and structural applications.
RHS (rectangular steel) is generally stronger because it has a higher moment of inertia when bent in one direction. SHS (square tube) is more balanced and more stable when subjected to forces in multiple directions (such as columns).
Read more: What Does RHS Steel Mean?
E-mail: sales@eastern-steels.com
