Performance Comparison and Selection Guide for LR AH32/DH32/EH32 Marine Steel Plates

1. Identical Basic Strength Parameters

LR AH32, DH32, and EH32 share the same core mechanical properties:

The fundamental differences among these three grades lie not in load-bearing capacity, but in low-temperature impact performance, steel purity, microstructural stability, and adaptability to extreme environments. These differences determine their respective applicable temperature ranges and engineering safety grades.

2. Key Differences: Low-Temperature Impact Test Temperatures and Suitable Environments

The most significant technical distinction among the three grades lies in the Charpy V-notch impact test temperature:

This impact toughness temperature tier serves as the primary basis for material selection.

3. Chemical Composition and Process Control Gradients

Impurity Control:

1) AH32 adheres to the standard impurity limits for conventional high-strength steel;

2) DH32 further reduces sulfur and phosphorus content;

3) EH32 achieves the highest purity and ultra-low impurity levels.

Production Processes:

1) AH32 employs a controlled rolling process;

2) DH32 incorporates additional low-temperature microstructural stabilization treatment;

3) EH32 utilizes vacuum degassing, secondary refining, and a graded tempering process.

These process gradients directly determine the performance differences among the three grades in low-temperature environments.

4. Typical Engineering Applications

AH32: Tropical/subtropical deep-sea container ships, bulk carriers, conventional coastal workboats, and general offshore platform auxiliary structures.

DH32: Vessels operating in cold-temperate waters, engineering vessels in seasonal ice zones, and low-temperature-resistant offshore structures.

EH32: Polar icebreakers, cryogenic offshore load-bearing structures, and core offshore engineering projects in extremely cold regions.

5. Selection Based on the Balance Between Performance and Cost

AH32: Lowest market unit price and best cost-performance ratio; suitable for conventional, non-low-temperature marine engineering projects.

DH32: Moderate cost; suitable for projects in cold-temperate waters.

EH32: Highest production cost due to complex manufacturing processes; suitable only for extremely cold environments.

Selection Principles:

a) Blindly selecting DH32 or EH32 for conventional projects in non-extremely cold environments will result in unnecessary cost overruns;

b) Replacing high-grade steel grades with AH32 in seasonally cold or polar projects will pose safety risks due to low-temperature brittle fracture;

c) It is recommended to make a comprehensive decision based on the project’s minimum ambient temperature, structural safety grade, and life-cycle costs.