StE355 is a high-strength, fine-grain structural steel plate produced in hot-rolled condition, with its designation following the European (EN) steel naming system. In this nomenclature, "St" stands for "Steel" (from the German word "Stahl"), "E" denotes "Engineering steel," indicating its suitability for engineering applications with emphasis on excellent weldability and formability, and "355" refers to the specified minimum yield strength of 355 MPa at room temperature. Therefore, StE355 is a fine-grain, high-strength structural steel designed for welded load-bearing structures. It is typically manufactured using thermomechanically controlled processing (TMCP), which refines the grain structure to enhance strength, toughness, and fatigue resistance.
The main characteristics of StE355 steel plate include a balanced combination of high strength and superior overall performance. Its tensile strength typically ranges between 490 and 630 MPa, with good elongation and excellent low-temperature impact toughness. The steel is generally required to meet specified Charpy V-notch impact energy values at -20°C. Due to its low carbon equivalent (CEV), StE355 exhibits outstanding weldability and is compatible with various welding methods such as MAG, TIG, and SMAW. It often requires little or no preheating, reducing manufacturing costs and simplifying construction. Additionally, the steel offers good cold-forming capability and resistance to lamellar tearing, making it suitable for fabricating complex-shaped components and critical welded joints.
StE355 is widely used in heavy machinery, cranes, commercial vehicles, construction equipment, bridges, building structures, pressure vessels, and wind turbine towers—applications demanding high strength, safety, and reliability. It is particularly suitable for large structural components where weight reduction, improved load efficiency, and extensive welding are required, making it an ideal high-strength alternative to conventional carbon steels in modern industrial applications.
The current standard for StE355 is EN 10149-2:2023, titled Hot-Rolled Flat Products of High Yield Strength Fine Grain Structural Steels – Part 2: Technical Delivery Conditions. Published in 2023, this latest version supersedes the previous EN 10149-2:2013 and represents the current international technical specification. It provides detailed requirements for chemical composition, mechanical properties, manufacturing processes, test orientations, and inspection criteria. As a key grade in the European high-strength steel system, StE355 is widely adopted globally, especially in advanced manufacturing and infrastructure projects.
Ultrasonic Testing (UT)
A key non-destructive testing technique that uses high-frequency sound waves to detect internal flaws in steel plates. The probe emits sound waves, which reflect when encountering defects such as cracks or inclusions. The receiver captures the echoes, enabling precise determination of defect location and size. With high sensitivity, strong penetration, and fast inspection speed, UT effectively ensures internal quality, widely used in the production of heavy plates, pressure vessel plates, and other high-end products to guarantee safety and reliability.
Magnetic Particle Testing (MT)
A common surface inspection method that magnetizes the workpiece, causing leakage magnetic fields at surface or near-surface defects like cracks or inclusions, which attract magnetic particles to form visible indications. Simple to operate and highly sensitive, MT is suitable for rapid inspection of surface and near-surface flaws in ferromagnetic materials, widely used for online or offline inspection of plate edges, ends, and welds, ensuring product quality and safety.
Penetrant Testing (PT)
A non-destructive method for detecting surface-breaking flaws. A penetrant liquid is applied to the cleaned steel surface, allowing it to seep into defects such as cracks or pores. After removing excess penetrant, a developer is applied, causing the trapped penetrant to bleed out and form visible indications. Simple and cost-effective, PT is suitable for inspecting surface defects in various non-porous materials, commonly used for welds, castings, and complex components, effectively ensuring surface quality of steel plates.
