Q235, SS400, St37, and S235JR are all commonly used low-carbon structural steel grades worldwide, widely applied in construction, machinery manufacturing, bridges, and other fields. Their chemical compositions and mechanical properties are similar, with the main differences lying in their respective standards and regional usage habits. Here is a detailed comparative analysis:

1. Core Performance Commonality

Low-Carbon Characteristics: Carbon content typically ranges from 0.12% to 0.20%, ensuring excellent weldability and ease of processing (rolling, stamping, cutting, etc.).

Mechanical Properties: Yield strength is approximately 235–250 MPa, tensile strength ranges from 375–500 MPa, and elongation is ≥25%, making them suitable for structural components bearing static loads.

Application Scenarios: Generally used in building steel structures, mechanical equipment housings, pipelines, angle/channel steel manufacturing, and general engineering projects that do not require high strength or special environments (e.g., low temperatures, corrosion).

2. Detailed Description of Each Grade

Q235 (Chinese Standard: GB/T 700)

Standard Affiliation: Chinese national standard, the most widely used low-carbon structural steel in China.

Grade Subdivision: Divided into four grades: Q235A, Q235B, Q235C, and Q235D. The differences mainly lie in impact toughness requirements:

Grade A: No impact test required;

Grade B: Requires impact test at room temperature (20°C);

Grade C: Requires impact test at 0°C;

Grade D: Requires impact test at -20°C (better low-temperature toughness).

Typical Applications: Building frames, factory structures, general mechanical parts, welded components, etc.

SS400 (Japanese Standard: JIS G3101)

Standard Affiliation: Japanese Industrial Standard. "SS" stands for "Structural Steel," and "400" refers to a minimum tensile strength of approximately 400 MPa.

Performance Characteristics: Similar to Q235B, with a yield strength ≥235 MPa, tensile strength of 400–510 MPa, and qualified room-temperature impact toughness.

Application Scenarios: Commonly used in Japan and Southeast Asia for bridges, building components, vehicle manufacturing, etc., and can be interchangeably used with Q235B.

 

 

 

 

 

 

 

 

 

St37 (German Standard: DIN 17100, now superseded by EN standards)

Standard Affiliation: Former German industrial standard. "St" stands for "Structural Steel," and "37" originally referred to a yield strength of approximately 37 kgf/mm² (equivalent to 235 MPa).

Current Status: Germany now primarily adopts the European EN 10025 standard, with St37 corresponding to S235JR (see below).

Performance: Yield strength ≥235 MPa, tensile strength of 360–510 MPa, excellent weldability and ductility, suitable for general structures.

S235JR (European Standard: EN 10025-2)

Standard Affiliation: European universal structural steel standard. "S" stands for "Structural Steel," "235" indicates a yield strength ≥235 MPa, and "JR" denotes room-temperature impact toughness (impact energy ≥27 J at 20°C).

Correspondence: It is the updated replacement grade for St37, with properties essentially consistent with Q235B and SS400, and is the mainstream low-carbon structural steel in the European market.

Applications: Building steel structures, bridges, mechanical components, etc., often regarded as the "benchmark grade for general low-carbon steel" in international engineering.

 

 

 

 

 

 

 

 

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