Steel plates, as the basic materials of modern industry, have highly specialized definitions, classifications, applications and standard systems. The following is a systematic interpretation from five aspects: core concepts, manufacturing processes, application scenarios, standard systems, and cutting-edge trends:
I. Definitions and Basic Characteristics
1. Essence and Form
Steel plate is a flat steel material made by pouring molten steel, cooling it and then rolling it. Its core feature is that the ratio of width to thickness is extremely large (usually > 100:1). It is classified into flat plate (steel plate) and coil (steel strip) according to its form.
2. Composition and Properties
- Composition: Mainly iron and carbon (0.2% - 2.1%), with the addition of alloying elements such as manganese, silicon, nickel, and molybdenum to optimize performance.
Core features:
- High strength: The yield strength ranges from 195 to 1000 MPa, for instance, Q690E can reach up to 690 MPa.
- Corrosion resistance: Achieved through coating (zinc, aluminum) or alloying (stainless steel);
- Plasticity: Supports forming processes such as cold rolling, hot rolling, and stamping.
II. Classification and Manufacturing Process
1.Classified by thickness
| Type | Thickness Range | Typical Process |
|----------------|--------------------|--------------------|
| Thin plate | < 4mm | Cold-rolled/hot-rolled |
| Medium plate | 4-25 mm | Mainly hot-rolled |
| Thick plate | 25-60 mm | Hot rolling |
| Extra-thick plate | > 60mm (up to 150mm) | New technology of mold casting + rolling/continuous casting.
2. Classification by rolling process
Hot-rolled steel plate:
- Process: The steel billet is heated to 1200℃ for rolling. The cost is low but the surface is rough.
- Applications: Building structures, ship decks, pressure vessels.
Cold-rolled steel plate
- Process: Secondary rolling of hot-rolled plates at room temperature, with smooth surface and high precision;
- Applications: Automotive bodies, precision instruments, coated substrates.
3. Breakthroughs in special processes
- Extra-thick plate production: The traditional mold casting has a low yield rate. Taiyuan Iron & Steel (Group) Co., Ltd. has innovated the continuous casting billet rolling technology, achieving uniform performance throughout the entire thickness of 150mm extra-thick plates (such as meeting the impact toughness standard at -196℃), breaking the 70mm thickness limit.
- Refined steel processing: The Xichuang system achieves "zero deformation" of 15-meter super-long components through mortise and tenon welding and mirror polishing, which is used in the artistic structure of curtain walls.
III. Main Application Fields
- Architecture and Bridges
Heavy-duty structures: For high-rise building frames (such as the Shanghai Tower) and large-span Bridges (the Hong Kong-Zhuhai-Macao Bridge), high-strength steel plates like Q690E are used, reducing weight by 30% and enhancing seismic resistance.
- Enclosure system: Color-coated thin plates (0.3-0.6mm) are used for roofs and walls, featuring both anti-corrosion and aesthetic appeal.
2. Transportation
- Automobile manufacturing: Cold-rolled deep-drawn sheet (08Al) is used for car doors and hoods; The fuel tank is made of lead-plated plates.
- Marine engineering: EH36 grade ship plates (thickness 12-50mm) are resistant to seawater corrosion and meet the strength requirements of the hull.
3. Energy and Chemical Engineering
- Pressure vessels: 14Cr1MoR alloy steel plates resistant to 450℃ high temperature, used in hydrogenation reactors.
LNG storage tanks: 9% nickel steel plates (with toughness at -196℃) ensure the safety of liquefied natural gas storage.
4. Special requirements field
- Food packaging: Tinplate (tinplate) is non-toxic and corrosion-resistant, and is used for can packaging.
- Military and aerospace industry: Bulletproof steel plates (hardness HB500) and low-magnetic steel plates are used in special equipment.
IV. International Standards
1. General standard system
- ISO standards: ISO 630 (Structural steel), ISO 9328 (Pressure vessel steel);
- European standards: EN 10025 (Structural steel), EN 10028 (Pressure vessel steel);
- American standards: ASTM A36 (Carbon structural steel), ASTM A240 (Stainless steel).
