Advanced shipbuilding materials

 1. A new class of ship steels

he CRISM Prometey State Research Center works on development, pilot production and practical introduction of new nitrided steels for design and construction of modern and future ships featuring high reliability and long service lives.

In these nitrided chrome steels, the nitrogen is the main alloying component that forms the specified set of mechanical properties. The material strength becomes 3-4 times better whereas the ductility, the fracture toughness, the weldability. the corrosion resistance and the workability remain on their high levels. These steels cost no more than the conventional ones thanks to rejection or minimization of expensive alloying elements like nickel, molybdenum, tungsten, etc.

Apart from shipbuilding, these steels will surely find applications in oil and gas production, power, chemical and petroleum engineering, in mining, in medicine, etc.

  2. Grade 15Õ2Â2ÔÀ-À low-activating steel and welding consumables

The CRISM Prometey has developed and patented in Russia new low-activating radiation-resistant parent and welding materials with the Fe-Cr-W-V basic composition for vessels of future water-water reactors that will have higher radiation lives and better environmental safety features.

These materials offer high mechanical properties in both as-produced and irradiated states, which are as good and in some aspects even better (e.g. in the resistance to radiation-induced embrittlement) than the presently used ones. Their main advantage is the faster induced radiation decay rate. This will enable one to save repair time and personnel radiation doses, as well as to reduce expenses associated with nuclear power plant decommissioning and disposal.

The application of low-activating steels in non-faced advanced water-water reactor vessels for both marine and land applications will allow sizeable savings in valuable nickel and chrome used today for corrosion-protection surfacing.

At the moment, the new materials are with the industry for production familiarisation and are undergoing certification.

  3. Composite materials Polymer-based composites

Composite materials based on polyester and epoxy resins reinforced with glass or carbon fibres are finding more and more applications in shipbuilding.

Their high specific strength, corrosion resistance, non-magnetic properties and production simplicity have defined the choice of reinforced-plastic materials for countermine ships and electromagnetic sweeps. High radiotransparency and strength properties of pressed reinforced-plastic materials have made them the best option for radar domes enabling one to do without retractable devices that are expensive and tricky in service.

Good sound transparency and resistance to interference have defined the success of these materials in sonar domes on both surface ships and submarines while their low friction factors and high wear resistance allow applying water lubrication in friction details, thus making ships both less observable and less polluting.

Superstructures and deck houses on fast ships, armour, vibration and sound proofing, pressure vessels and piping, propellers and lift fan blades, air propeller nozzles, deepwater submersible buoyancy modules, missile transportation/launch containers, safety and guard rails - these are just some items on the very long list of naval applications of the polymer-based composites.

The CRISM Prometey is working on optimisation of physical, mechanical and service properties of metals, glass- and carbon-reinforced plastics.

  Metal-&-polymer materials

The design of competitive ships requires developing light-weight hull structures capable of enduring high service loads at the same time effectively reducing noise, vibration, and temperature gradients while maintaining good mechanical strength properties.

The CRISM Prometey has developed a sandwich metal-&-polymer damping material consisting of alternating layers of a high-tensile corrosion-resistant

aluminium alloy and a low-epoxy-number bonding material, which has high mechanical and damping characteristics.

Such materials may be used for soundproofing in internal spaces, for building high-stress components (decks, hulls, etc.) with noise reduction and damping features, for shells, casings, screens of various noisy instruments and machines, and for details of sound-absorbing structures subjected to short-time exposures to high temperatures (up to 300 C).

  4. Function-designed materials

Due to their chemistry, phase compositions and structures, new function-designed materials with amorphous, nano-phase and intermetallic structures have significantly enhanced structure-sensitive properties:

- anomalous magnetic permeability and low magnetostriction;

- catalytic activity;

- corrosion-erosion properties and wear resistance.

The CRISM Prometey has developed priority technologies for utilising these materials in functional-gradient coatings. 3D porous and composite structures, which served to fabricate experimental prototypes of various products for the needs of the modern naval architecture.

Tasks associated with function-designed materials involve unique technologies: supersonic plasma spraying, ion-plasma, magnetron and atom-ion sputtering, plasma-chemical synthesis, hypersonic cold gas jet spraying, the universal disintegration-activation mechanic chemistry method, tribosynthesis and tribospraying.

We have expanded future applications of function-designed materials, primarily in naval low-observability techniques, in the development of high-capacity high-temperature fuel cells and emergency/life-saving packages that utilise seawater-activated chemical generators for power sources.

  5. Advanced welding process

Laser welding. One of the promising avenues in modern ship design and construction is to more extensively apply light three-dimensional honeycomb structures, which enable one to save 20-30% of the weight compared to other kinds of structures with similar performances. The fabrication of such structures largely requires laser welding that ensures high productivity and accuracy at minimum residual stress and deformation levels.

The CRISM Prometey has developed a laser welding process for triple-layer 3D panels of common ship and stainless steels, and titanium alloys. The process enables one to achieve high-quality full-strength welds at rates of up to 90 m/h.

We have also developed laser-welding techniques for sophisticated-shape honeycomb structures, butt joints of corrugated plates, components of cylindrical and spherical shells. The welds can be made at different 3D directions and different angles of the welded structural components.

For the sake of still better productivity and metal fusing efficiency in the fabrication of 3D ship structures, we have developed a combined laser-and-arc welding process, which combines the highly concentrated energy available in the laser beam with the economic benefits of the arc welding.

Electron-beam welding in vacuum characteristically involves a powerful source of concentrated heat and virtually complete absence of gases in way of the weld. Vacuum-shielded electron-beam welding • guarantees preventing weld contamination with gases and ensures achieving the best possible ductility and fracture toughness of the welded joints.

With the electron-beam welding, the welds are narrow and the amount of the fused metal is much less

than with other welding processes. The width of the heat-affected zone is also much smaller, and that means a significant reduction in welding-induced stresses and strains.

Thanks to the high concentration of the energy, even thick details can be welded in a single pass without bevelling. At the same time, the weld forms of the fused parent material, and the joint becomes full-strength without any geometric reinforcements of the weld.

The highest efficiency of the electron-beam welding manifests itself in the joints of thick-walled structures, refractory and reactive metals.

The CRISM Prometey has developed a welding process for thick details made of high-tensile titanium alloys and intended for special-application structures operating under high loads.