SUS 304 is the Japanese JIS standard designation for the most common austenitic stainless steel, equivalent to AISI 304 or 18/8 stainless (18% Chromium, 8% Nickel). When it is cold rolled, it means the final shaping process at the mill was done at or near room temperature, resulting in a superior surface finish, tighter dimensional tolerances, and increased strength through work-hardening.

304L: This is a low-carbon variation of the classic 18/8 (18% Chromium, 8% Nickel) austenitic stainless steel. The "L" stands for "Low Carbon" (max 0.03% vs. 0.08% in standard 304). This reduction in carbon minimizes the risk of sensitization (carbide precipitation at grain boundaries) during welding, which can lead to intergranular corrosion in harsh environments.
Cold Rolled (CR): This refers to the manufacturing process. The steel is rolled at room temperature, below its recrystallization temperature. This process hardens the steel, improves its surface finish, and allows for tighter dimensional tolerances compared to hot-rolled (HR) sheet.

Hot-rolled carbon steel sheet is a flat steel product made from carbon steel at a recrystallization temperature (usually above 900°C). It has a carbon content of ≤0.25% (low-carbon steel). Its thickness ranges from 0.35-200mm. While it has an oxide scale on the surface, it possesses high ductility and is widely used in structural components for automobiles, bridges, etc.

Main Characteristics

Processing Advantages: High-temperature rolling reduces energy consumption, suitable for large-size production.

Performance Characteristics: Compressive strength 390-422MPa, high temperature resistance, and excellent weldability.

Surface Treatment: Requires pickling to remove oxide scale; surface finish is lower than cold-rolled sheet.

Cold-rolled carbon steel sheets are steel products made from hot-rolled steel coils, which are pickled to remove oxide scale and then rolled at room temperature. They are characterized by a smooth surface, high dimensional accuracy, and high strength and hardness.

Key Properties of SS400 Steel:
Good Strength: Its 400 MPa minimum tensile strength makes it suitable for structural applications.
Excellent Weldability: Its low carbon content makes it very easy to weld using all common methods (SMAW, GMAW, FCAW, etc.) without requiring pre-heating in most cases.
Good Formability: It can be bent and shaped relatively easily, though this becomes more difficult with increasing thickness.
High Ductility: It can undergo significant deformation before fracturing, which is a key safety feature in structures.
Low Cost: It is an economical choice for large-scale construction projects.
No Corrosion Resistance: It will rust quickly if exposed to moisture.

A36 hot-rolled plate is the backbone of modern construction and heavy industry.
Building and Bridge Construction: I-beams, columns, base plates, gusset plates, and girders.
Heavy Equipment and Machinery: Frames, booms, buckets, and supports for agricultural, mining, and construction machinery.
Shipbuilding and Barge Construction: Hull plates, decks, and structural members.
Truck Frames and Trailers: Long members and crossmembers.
General Fabrication: For any project requiring a strong, weldable, and affordable steel. This includes everything from custom machine bases and welding tables to sculpture and architectural features (where the rustic "hot-rolled" look is desired).

Q195: This is the grade designation, following the Chinese GB standard (very common internationally).
Key Characteristic: Its primary advantage is low cost and high strength. Its main drawback is that it will rust (corrode) readily when exposed to moisture and oxygen unless it is protected (e.g., by painting, galvanizing, or coating).
Q195 1.2mm sheet is ubiquitous in manufacturing due to its low cost and ease of use. It is almost always used as a base material that will be painted, coated, or galvanized.
General Fabrication: Brackets, boxes, enclosures, and frames.
Automotive: Non-structural body panels, brackets, and interior parts (before rust-proofing and painting).
Furniture: Bed frames, cabinet bodies, shelving brackets.
Appliances: Housings for dryers, washing machines, and other white goods that are subsequently painted.
Ductwork and Ventilation: For HVAC systems.
Base Material for Galvanizing: This sheet is often sent through a hot-dip or electro-galvanizing process to become

Cold-rolled carbon steel plate is primarily made of two types of materials: low-carbon steel and high-quality carbon structural steel. Common grades include Q195, Q235, SPCC, and ST12. Thickness is typically less than 4 mm.
Common Materials
‌Q195/Q235‌: Common carbon structural steel with excellent cold bending and welding properties, suitable for mechanical parts, containers, and more.
‌SPCC/ST12‌: Cold-rolled carbon steel plate according to the Japanese JIS standard. SPCC is commercial steel, while ST12 is a common steel grade with similar mechanical properties.
‌DC01-DC06‌: Indicates stamping-grade steel plates of varying hardness. DC03 and above are suitable for deep drawing (e.g., automotive fuel tanks).

S355JR Alloy Carbon Steel Plate Core Parameters

Standard: European Standard EN10025-2, corresponding to Chinese Standard Q355B

Strength: Yield strength ≥355MPa, tensile strength 470-630MPa

Chemical Composition: Carbon ≤0.22%, Manganese ≤1.60%, Phosphorus/Sulfur ≤0.025%

Impact Toughness: Impact energy at 20℃ ≥27J (JR grade)

Application Areas: Building structures, bridges, engineering machinery, and shipbuilding

S275 is a European standard non-alloy structural steel with a yield strength ≥275MPa, conforming to standard EN10025-.

Strength: Yield strength 275MPa, tensile strength 410-560MPa

Process: Hot-rolled/thermomechanically rolled, thickness 0.3-500mm

Applications: Building structures, shipbuilding, boilers, and other applications.

ASTM A572 Grade 50 is a high-strength low-alloy niobium-vanadium structural steel plate, conforming to the standard ASTM A572/A572M.

Strength Grade: Gr50 indicates a minimum yield strength of 50 ksi (approximately 345 MPa) and a tensile strength of 490-600 MPa.

Chemical Composition: Carbon ≤0.20%, Manganese ≤1.50%, Niobium (Nb) 0.005-0.05%.

Elongation: ≥22%-35% (for thickness ≤16 mm).

ASTM A36 is an American standard carbon structural steel with a yield strength ≥250 MPa, tensile strength 400-550 MPa, and elongation ≥20%. It contains ≤0.25% carbon and possesses good weldability, machinability, and low-temperature toughness. It is widely used in construction, bridge building, and machinery manufacturing.

Q345 is a Chinese low-alloy high-strength structural steel (GB/T 1591-2018 standard) widely used in construction, bridges, and heavy machinery due to its good strength, weldability, and toughness. It is equivalent to European S355 and ASTM A572 Grade 50.
Advantages
✅ Higher strength than Q235 (similar to ASTM A36).
✅ Good weldability & formability (low carbon content).
✅ Cost-effective for structural applications.
Applications
Construction: High-rise buildings, stadiums, bridges.
Heavy Machinery: Cranes, mining equipment, truck frames.
Pressure Vessels & Pipelines (Q345R variant).
Shipbuilding & Offshore Structures (higher grades like Q345D/E).

S355 is a European standard structural steel with a minimum yield strength of 355 MPa (51,500 psi). It is part of the EN 10025 series and is widely used in construction, heavy machinery, and engineering due to its high strength, weldability, and toughness.
Key Mechanical Properties
Property Value
Yield Strength (ReH) ≥355 MPa (varies by thickness)
Tensile Strength (Rm) 470–630 MPa
Elongation (A₅) 20–22% (depends on grade)
Impact Toughness Tested at +20°C to –40°C (based on subgrade)
Carbon Content (C) ≤0.24% (low carbon for weldability)
Note: Thinner plates have higher yield strength (e.g., 355 MPa at ≤16mm, decreases to 325 MPa at >40mm).
Applications of S355 Steel Plate
Construction: Bridges, high-rise buildings, stadiums.
Heavy Equipment: Cranes, mining machinery, bulldozers.
Offshore & Wind Energy: Platforms, turbine towers (S355NL).
Transportation: Shipbuilding, rail cars, truck chassis.

321 (UNS S32100) is a titanium-stabilized austenitic stainless steel offering:
Excellent intergranular corrosion resistance
Good high-temperature strength
Oxidation resistance up to 900°C (1650°F)
Non-magnetic properties
Key standards: ASTM A240, EN 1.4541, JIS SUS321
Corrosion Resistance
Excellent intergranular corrosion resistance
Good oxidation resistance up to 900°C
Similar to 304 in most environments
Pitting Resistance Equivalent (PRE): ~19
Common Applications
Aircraft exhaust systems
Heat exchangers and boiler components
Chemical processing equipment
Pressure vessels
Welded components for high-temperature service