Characteristics of LR Grade EH36 Marine Steel

I. Chemical Composition Characteristics

Low-carbon + manganese-based + micro-alloyed with trace amounts of Nb/V/Ti; low carbon equivalent and excellent weldability.

Carbon Equivalent and Weld Cracking Index:

1) Ceq ≤ 0.40%, cold crack sensitivity index Pcm ≤ 0.23;

2) Extremely low carbon equivalent; cold cracks are unlikely to form during welding of thick plates with high heat input.

II. Core Mechanical Property Characteristics

1. Tensile Properties

2. Low-Temperature Impact Toughness

3. Z-Direction Properties (Optional)

Thick, large-scale welded load-bearing structures can be manufactured to Z15/Z25/Z35 specifications to reduce the risk of laminar tearing in thick plate welds.

III. Microstructural Characteristics

Microalloyed grain refinement combined with an interlocking needle-like ferrite structure, balancing high strength, high ductility, and ultra-low-temperature toughness, with outstanding resistance to fatigue and impact loads (such as waves and ice floe impacts).

IV. Delivery Condition Characteristics

1. TMCP (Thermomechanically Controlled Rolling) (Thin/medium plates ≤50 mm thick; most commonly used)

Controlled rolling + ultra-rapid cooling results in a microstructure of polygonal ferrite + pearlite + acicular ferrite/granular bainite with ultra-fine grains; meets the -40°C impact requirement without normalizing, offering optimal cost and a wide welding window.

2. Normalized (N) (Thickness > 50 mm; thick plates; mandatory for icebreakers and polar vessels)

Uniform microstructure, greater low-temperature toughness margin, and higher safety redundancy under extreme low-temperature conditions.

V. Welding Process Characteristics

1) Low carbon, low sulfur and phosphorus, and low carbon equivalent result in low susceptibility to cold cracking; suitable for manual arc welding, submerged arc welding, gas shielded arc welding, and high-heat-input submerged arc welding;

2) For plate thicknesses ≤30 mm, preheating is not required at room temperature; for thicknesses >30 mm, low-temperature preheating at 120 - 150°C is sufficient to suppress hydrogen-induced cracking;

3) TMCP plates exhibit minimal toughness loss in the heat-affected zone and can withstand high-energy welding typical of shipbuilding;

4) Post-weld stress-relief heat treatment is generally unnecessary, simplifying the construction process.

VI. Processing Characteristics

Cutting: Good compatibility with oxy-fuel, plasma, and laser cutting;

Cold Bending: Sufficient elongation ensures that cold forming of ship hull flanges and curved plates is unlikely to result in cracking;

Forming: Suitable for forming curved outer hull plates, bulbous bows, and ice-belt curved plates.

VII. Corrosion Resistance and Marine Service Characteristics

1) Basic resistance to seawater corrosion is superior to that of ordinary Class A/B ship plate steels; When combined with a marine coating system, it can withstand long-term service in open ocean and cold-water environments;

2) Strict control of impurity elements ensures resistance to seawater pitting and fatigue corrosion, making it suitable for alternating load conditions in polar and ice-covered regions;

3) Ice impact resistance: Maintains high impact energy even at -40°C; resistant to brittle fracture from floating ice impacts, making it the primary material for ice-strengthened and polar vessels.

VIII. Characteristics of Typical Application Scenarios

Specifically designed for long-term low-temperature, ice-covered, and polar operating conditions:

Ships: Icebreakers, polar research vessels, Arctic LNG carriers, and ice-class outer plates, high-strength decks, deckhead plates, keels, and hatch coamings for deep-sea container ships and oil tankers operating in cold regions;

Offshore Engineering: Arctic offshore platforms, FPSOs (Floating Production, Storage, and Offloading units), support columns for semi-submersible drilling rigs, and thick plates for jacket structures;

Others: Heavy-duty crane bases in cold-region ports and load-bearing sections of deep-sea wind turbine towers.