Complete Technical Specifications for BV Grade E Shipbuilding Steel Plates

1. Chemical Composition

BV Grade E shipbuilding steel is a fully killed, ultra-low-carbon structural steel for marine applications that strictly complies with the BV Polar Marine Code and utilizes an ultra-pure formulation optimized for extreme cold environments down to -40°C. Its chemical composition (mass fraction) is specified as follows:

Compared to BV Grade D steel, Grade E steel further tightens the limits for sulfur and phosphorus impurities, raises the lower limit for manganese content to enhance grain refinement, and lowers the upper limit for carbon content to improve low-temperature toughness.

* CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15

The carbon equivalent (CEV) for all thickness grades is strictly controlled at ≤0.40%, providing the foundation for excellent ultra-low-temperature weldability and microstructural density.

The ultra-low levels of harmful impurities eliminate the risk of low-temperature microcrack propagation, ensuring long-term structural stability under polar ultra-low-temperature conditions and ice-wave coupling scenarios.

2. Mechanical Properties

All BV Grade E steels must meet the following core mechanical property requirements:

The above specifications fully meet the requirements of polar structures for ultimate load-bearing capacity, deformation resistance, and fatigue resistance.

3. Impact Properties

All BV Grade E steels must meet the ultra-low-temperature impact toughness requirement at -40°C. The core impact test requirements are as follows:

For the mandatory -40°C Charpy V-notch impact test, the impact energy absorption must reach the values specified in the BV Code to ensure effective suppression of brittle fracture and crack propagation under long-term sub-zero freezing conditions, ice load impacts, and alternating loads from polar storms.

4. Size Specifications

BV Grade E steel plate specifications cover the diverse requirements of polar cargo ships, icebreakers, and high-latitude extreme cold projects:

Thickness range: 5.0 - 150.0 mm

Width range: 1,500.0 - 4,000.0 mm

Length range: 6,000.0 - 18,000.0 mm

These specifications comprehensively cover ice-breaking outer plates for polar vessels, cryogenic decks, heavy-duty bulkheads, and primary load-bearing components for polar platforms.

5. Dimensional Tolerance Ranges

Dimensional tolerances comply with the stringent BV Polar Cryogenic Steel Standard:

Thickness tolerance: ≤ ±0.18 mm

Flatness error: ≤ 1.5 mm/m

Edge perpendicularity and flatness: Meet assembly requirements

High-precision dimensional control effectively eliminates stress concentration during cryogenic assembly, ensures structural tightness, and prevents localized cracking in extremely cold operating environments.

6. Delivery Conditions

BV Grade E steel plates are available in a variety of delivery conditions based on thickness and customer requirements:

Normalized (N): The most common delivery condition, particularly suitable for thick plates with a thickness greater than 25 mm. Normalizing refines the grain structure, ensuring consistent compliance with low-temperature impact toughness requirements at -40°C.

TMCP (Thermomechanical Control Process): Suitable for certain thin-gauge steel plates; excellent comprehensive mechanical properties are achieved through controlled rolling and cooling processes.

Quenched and Tempered (QT): Quenched and tempered.