The titanium alloy plate, due to its unique physical and chemical properties, has gradually demonstrated significant advantages in various fields such as coastal thermal power plants and nuclear power plants, and has become an indispensable key material in the power industry.
Condenser: The preferred choice for corrosion resistance and long service life
Thermal power plants and nuclear power plants in coastal areas usually use seawater as the cooling water for their condensers, whose core function is to condense steam into water. Traditionally, the condensers mostly adopted aluminum brass tubes. However, with the rapid deterioration of the seawater environment, seawater containing hydrogen sulfide will cause severe corrosion to aluminum brass tubes, leading to frequent leaks and affecting the normal operation of the power plants.
The titanium alloy plate condenser stands out for its outstanding corrosion resistance and long service life. Titanium alloy has excellent resistance to chemical and electrochemical corrosion, and it has strong resistance to corrosion caused by seawater, sulfides, chlorides, as well as point corrosion caused by marine organisms and sediments. At the same time, it can also resist accelerated corrosion caused by high-speed seawater and local vortices. This is because the titanium surface can quickly repair the damaged protective oxide film. Even in seawater containing sand and diamond dust, with a 2 m/s flow velocity, the corrosion rate on the titanium surface is extremely low. Therefore, the condenser made of titanium alloy can increase the flow rate of seawater to enhance the cooling effect, and significantly reduce maintenance costs and downtime risks to ensure the stable operation of the power station.
Steam turbine blades: A model of lightweight and corrosion-resistant materials
The blades of steam turbines, especially those in the low-pressure sections, have extremely high requirements for the material's properties. Traditionally, steam turbine blades are made of martensitic chromium stainless steel, but this material has obvious drawbacks. Steel has a high density, and in high-speed rotating steam turbines, steel blades need to withstand tremendous centrifugal forces, increasing the burden on the equipment and the risk of failure. Moreover, water vapor often contains chlorides and sulfides mixed in due to leakage from the condenser, and these media can cause pitting corrosion on the surface of the steel blades, forming crevice corrosion between the root and tip of the blades or at the tension ribs, and becoming a source of cracks. Additionally, the fatigue performance of Cr13 steel is not ideal. In a corrosive environment with saturated sodium chloride solution, especially in a low pH value and oxygen-containing solution, its fatigue strength will significantly decrease.
In contrast, titanium alloy plates have become the ideal choice for steam turbine blades. Titanium blades are lightweight, and at the same rotational speed, the centrifugal force at the blade root can be reduced by 40%, significantly reducing the equipment's energy consumption and wear. At the same time, titanium blades have much better corrosion resistance to salt-containing steam than steel, effectively avoiding problems such as pitting corrosion and crevice corrosion. Moreover, the fatigue performance of titanium alloys is significantly higher than that of stainless steel. In air, the fatigue strength of Ti-6A1-4V alloy is approximately 30% higher than that of Cr13 steel; while in sodium chloride solution, the fatigue strength of Cr13 steel will decrease by 2/3 - 4/5, while the fatigue performance of titanium alloys is basically unaffected. Therefore, considering the fatigue performance in corrosive conditions, titanium alloy plates have become an important material to replace steel blades, helping to improve the efficiency and reliability of steam turbines.
Generator guard ring: The ideal material with high strength and no magnetism
In the entire turbine generator system, the guard ring is one of the key components. Large generators have extremely strict requirements for the guard ring, which must have high strength, good anti-fracture performance, be insensitive to stress corrosion cracking in water media, and be non-magnetic. Currently, the guard rings are mostly made of austenitic Fe-Mn-Cr alloys, but this alloy has a strong tendency for stress corrosion cracking and there are certain issues regarding the reliability of achieving high strength.
Titanium alloy plate guard rings can well meet these requirements. Their specific strength can easily reach the design standards, and they are non-magnetic, insensitive to stress corrosion, and have excellent comprehensive performance. Therefore, using titanium alloy plates to manufacture guard rings is a more suitable choice. Currently, in the field of generator guard ring manufacturing, some countries have made significant progress, demonstrating the broad application prospects of titanium alloy plates in this field.