Analysis of the Core Technical Advantages of LR Grade DH32 Marine Steel
- Jul 22, 2026
Knowledge
Technical Specifications for LR DH32 Shipbuilding Steel Plates
1. Chemical Composition
LR DH32 is a fine-grained, killed, low-alloy marine steel. Its chemical composition strictly complies with LR specifications, with the following control ranges (wt%):
| Element | C | Si | Mn | P | S | Cu |
|---|---|---|---|---|---|---|
| Content (wt %) | ≤ 0.18 | ≤ 0.50 | 0.90 - 1.60 | ≤ 0.025 | ≤ 0.025 | ≤ 0.35 |
| Cr | Ni | Nb | V | Ti | Mo | Als |
| ≤ 0.20 | ≤ 0.40 | 0.02 - 0.05 | 0.05 - 0.10 | ≤ 0.02 | ≤ 0.08 | ≥ 0.015 |
LR DH32 incorporates aluminum to refine the grain structure and enforces stricter impurity limits to eliminate the risk of low-temperature brittle fracture.
Carbon equivalent (CEV) limits:
| Thickness | 5 - 50 mm | 50 - 150 mm |
|---|---|---|
| CEV | ≤ 0.36 % | ≤ 0.38 % |
Ensure excellent cold formability and weldability while maintaining structural stability under long-term low-temperature cyclic loading.
2. Mechanical Properties
LR DH32 shipbuilding steel plates must pass official LR inspection. The key mechanical property parameters are as follows:
| Yield Strength (ReH) | Tensile Strength (Rm) | Elongation (A) |
|---|---|---|
| ≥ 315 MPa | 450 - 570 MPa | ≥ 22 % |
3. Impact Properties
| Thickness | Temperature | Impact Energy | |
|---|---|---|---|
| Longitudinal | Transverse | ||
| ≤ 50 mm | - 20 ℃ | ≥ 31 J | ≥ 22 J |
| > 50 - 70 mm | - 20 ℃ | ≥ 38 J | ≥ 26 J |
| > 70 - 150 mm | - 20 ℃ | ≥ 46 J | ≥ 31 J |
Key property: -20°C Charpy V-notch impact test, ensuring the material possesses stable toughness and resistance to brittle fracture in seasonal sub-zero marine environments; it is the mainstream low-temperature-resistant high-strength steel for shipbuilding in cold-water regions.
4. Full-Process LR Certification Requirements
a) LR DH32 shipbuilding steel plates comply with LR’s specialized full-process production and inspection specifications for low-temperature marine steel, covering processes such as refining, vacuum degassing, low-temperature controlled rolling, microstructural homogenization, and precision finishing. The entire production chain must conform to LR’s Rules for the Construction of Merchant Ships and Offshore Structures.
b) Each batch of products must undergo 100% sampling inspection for chemical composition and mechanical properties, with low-temperature impact toughness at -20°C serving as the core acceptance criterion.
c) Qualified finished products must be accompanied by an EN 10204 Class 3.2 certificate and an official LR inspection report, which serve as the basic admission documents for LR-classed vessels and offshore engineering projects in cold regions worldwide.
5. Dimensions and Specifications
LR DH32 shipbuilding steel plates are available in a wide range of specifications to meet the diverse needs of shipbuilding and offshore engineering:
| Thickness | Width | Length | Delivery Conditions |
|---|---|---|---|
| 3 - 120 mm | ≤ 4,500 mm | ≤ 22,000 mm | HR / TMCP / N |
6. Tolerance Standards
Dimensional tolerances comply with LR’s high-precision standards for cryogenic marine steel:
| Thickness Tolerance | Flatness Deviation | Edge Perpendicularity and Flatness |
|---|---|---|
| ≤ ±0.25 mm | ≤ 1.8 mm/m | Meet zero-deviation requirements |
Strict dimensional control prevents structural stress concentrations caused by assembly errors, ensuring the structural stability and operational safety of offshore facilities in seasonal low-temperature environments.
Recent Article
Customer Cooperation
Customers choose to engage in long-term cooperation with Yuxin Steel not only because of our high-quality products and services, as well as our strong reputation in the international market, but also due to our experienced one-stop raw material supply and further steel processing capabilities!
