(i) Cupro-nickel (copper-nickel, e.g. 70/30 or 90/10 Cu/Ni): an alloy of copper and nickel. It has good strength, excellent corrosion resistance, especially to sea water and biofouling, good thermal conductivity, and good resistance to erosion and pitting. It is non-magnetic. Example use: condenser tubes and heat exchanger tubes in sea-water cooling systems, where resistance to sea water corrosion and biofouling is essential; also used for piping in sea-water systems.

(ii) White metal: in marine engineering this usually refers to white bearing metal / tin-base or Babbitt-type bearing liners, or tin-antimony (tow), or white gunmetal. Generally, a soft, low-friction, anti-seizure metal (often a tin or tin-lead base). Practical use: the soft metal bearing liner (e.g. in small end or big-end bearings / crosshead slippers and thrust pads) which gives low friction and embeds hard particles, protecting against seizure; also used for bearing shells (white metal liners) in connecting rod small-end bushes to give good bedding-in and emergency running.

(iii) Titanium and its alloys: low density, very high strength-to-weight ratio, excellent corrosion resistance (passive oxide film), good high-temperature properties and biocompatibility. Practical use: high-performance fasteners, propeller shafts in special craft, sea-water-exposed fittings, exhaust and heat exchanger components, and in desalination/high-temperature condensers where corrosion resistance and high strength at temperature are required.

(i) Nickel aluminium bronze: has high strength, good fatigue resistance, excellent sea-water corrosion and cavitation-erosion resistance, and good casting/ machining properties. It is the standard material for large controllable-pitch and fixed-pitch propellers and is chosen for its combination of strength, corrosion resistance, castability and low susceptibility to stress-corrosion and biofouling.

(ii) Stainless steel: has very high strength and hardness, but for propellers it is less favoured for a large casting because it is more expensive, harder to cast to the thin sections, heavier, prone to galvanic effects with the hull and to stress-corrosion cracking in sea water, and more difficult to machine. Its merit is strength, but bronze is preferred for the general large propeller because of castability, corrosion resistance and fatigue behaviour.

• Tensile test to determine yield strength (proof stress), ultimate tensile strength and percentage elongation, ensuring the plate exceeds the grade minimums.
• Bend (transverse) test to check ductility and freedom from brittleness; plates should bend without cracking.
• Impact/fatigue considerations covered by material grade.
• Chemical analysis for carbon, manganese, sulphur, phosphorus and other elements to meet the classification/grade specification (mild steel, DH36, AH36 etc.).
• Ultrasonic and/or magnetic-particle (non-destructive) testing of the finished plate for laminations, cracks or inclusions.
• Pressure/boiler tests not relevant; instead Charpy impact test for toughness and hardness check may be applied.
• Verification documents: mill certificates and class-approved inspection confirming plate meets grade, dimensions and surface quality.