Разликата между титанова сплав и неръждаема стомана
The density of titanium and titanium alloy is only 4.51, which is smaller than steel and only half the weight of steel, but its strength is similar to that of ordinary carbon steel. Titanium belongs to thermodynamically unstable metals and is very active. Titanium metal can form a natural oxide film (titanium dioxide) with air. This stable, highly adhesive and protective oxide film determines the corrosion resistance of titanium, so titanium has excellent corrosion resistance. Secondly, light texture, high tensile strength and good mechanical properties are another excellent feature of titanium alloy.
Titanium alloys can be divided into corrosion-resistant titanium alloys, structural titanium alloys, heat-resistant titanium alloys and low-temperature titanium alloys according to their uses.
1. It can be distinguished by color. Titanium is a little dark, exuding a cold color, which feels very cool. Titanium is a little darker than steel. Steel is white, the kind of pale white. The two colors are very obvious and can be seen.
2. There is also a chemical method to distinguish, that is, soak it in nitric acid. Titanium does not react, and stainless steel will react strongly as soon as it is put down. The distinction between pure titanium and titanium alloy is difficult to see from the appearance.
3. Titanium can leave a gray-black mark on tiles, but stainless steel cannot.
4. Titanium has good corrosion resistance: below 550℃, a dense oxide film is easily formed on the surface of titanium alloy, so it is not easy to be further oxidized, and it has high corrosion resistance to the atmosphere, seawater, steam, and some acids, alkalis, and soft media.
5. Titanium has good thermal strength: the melting point of titanium alloy is 1660℃, which is higher than that of iron. It has high thermal strength and can work below 550℃. At the same time, it exhibits good toughness at low temperatures.
6. Titanium processing is difficult: welding, electroplating, and cold drawing are very difficult. Welding and electroplating must be carried out in a vacuum or in an inert gas atmosphere (vacuum ion plating)
1. Different composition:
(1) Titanium alloy is an alloy composed of titanium and other elements. Titanium has two isomorphous crystals: below 882℃ is a close-packed hexagonal structure α titanium, and above 882℃ is a body-centered cubic β titanium.
(2) Stainless steel refers to steel that is resistant to corrosion by weak corrosive media such as air, steam, and water, and chemically corrosive media such as acids, alkalis, and salts. It is also called stainless acid-resistant steel. In practical applications, steel that is resistant to corrosion by weak corrosive media is often called stainless steel, while steel that is resistant to corrosion by chemical media is called acid-resistant steel.
2. Different properties:
(1) Titanium is a new type of metal. The properties of titanium are related to the content of impurities such as carbon, nitrogen, hydrogen, and oxygen. The purest titanium iodide has an impurity content of no more than 0.1%, but its strength is low and its plasticity is high.
(2) Stainless steel: weldability; corrosion resistance: most stainless steel products require good corrosion resistance; polishing performance: in today's society, stainless steel products are generally polished during production. Only a few products such as water heaters and water dispenser tanks do not require polishing.
3. Different functions:
(1) Titanium alloys are mainly used to make aircraft engine compressor components, followed by rockets, missiles, and high-speed aircraft structural parts.
(2) 304 stainless steel is widely used in curtain walls, side walls, roofs and other building purposes, but in severely corrosive industrial or marine atmospheres, 316 stainless steel is used.
Classification of titanium alloys:
At room temperature, titanium alloys have three matrix structures, and titanium alloys are divided into the following three categories: α alloy, (α+β) alloy and β alloy.
1. α titanium alloy
It is a single-phase alloy composed of α phase solid solution. Whether at normal temperature or at a higher actual application temperature, it is α phase. It has stable structure, higher wear resistance than pure titanium, and strong oxidation resistance.
2. β titanium alloy
It is a single-phase alloy composed of β phase solid solution. It has high strength without heat treatment. After quenching and aging, the alloy is further strengthened, and the room temperature strength can reach 1372~1666 MPa.
3. α+β titanium alloy
It is a two-phase alloy with good comprehensive properties, good structural stability, good toughness, plasticity and high temperature deformation performance, can be well processed by hot pressure, and can be quenched and aged to strengthen the alloy.
Performance differences
Strength and density: The density of titanium alloy is generally 4.51 grams per cubic centimeter, which is only 60% of that of steel, and the density of pure titanium is close to that of ordinary steel. Some high-strength titanium alloys are lighter than many steel structures.
Corrosion resistance: Titanium alloys work in humid atmospheres and seawater media, and their corrosion resistance is far better than stainless steel; they are particularly resistant to pitting, acid corrosion, and stress corrosion; they have excellent corrosion resistance to alkali, chloride, chlorine organic substances, nitric acid, sulfuric acid, etc. However, titanium has poor corrosion resistance to reducing oxygen and chromium salt media.
Price difference: Titanium alloys are relatively expensive and suitable for families with better economic conditions. Stainless steel is more economical and affordable, and it is also more affordable for daily use.
Processing difficulty: Titanium alloy welding, electroplating, and cold drawing are very difficult. Welding and electroplating must be carried out in a vacuum or under a condition filled with inert gas.
Application field differences
Aerospace field: Titanium powers are concentrated in Western countries, especially the United States, and 60% of titanium materials are used in this field. The use of titanium alloys in military aircraft has stabilized at more than 20%, and the proportion of titanium used in new models is increasing significantly.
Automobile field: For every 10% reduction in the weight of the car, fuel consumption can be saved by 8%-10%, and exhaust emissions can be reduced by 10%. The preferred way to lightweight cars is to replace traditional automotive materials (steel) with lightweight materials with high specific strength, such as aluminum, magnesium, and titanium.
Medical field: Titanium is close to human bones, has good biocompatibility with human tissues, and has no toxic side effects. Therefore, titanium and titanium alloys are widely used in the medical field.
Differences in appearance and physical properties
Color: Titanium is a bit dark, exuding a cold color, which feels very cool. Titanium is a little darker than steel. Steel is white, the kind of pale white. The two colors are very obvious and can be seen 1.
Chemical properties: Titanium has high chemical activity and produces strong chemical reactions with O, N, H, CO, CO2, water vapor, ammonia, etc. in the atmosphere. When the carbon content is greater than 0.2%, hard TiC will be formed in the titanium alloy; when the temperature is high, a hard TiN surface layer will also be formed by the reaction with N.
Conclusion
Titanium alloys and stainless steel each have their own advantages and applicable scenarios. Titanium alloys are often used in aerospace, automotive, medical and other fields due to their light weight, high strength and excellent corrosion resistance. Stainless steel is widely used in various products in daily life due to its affordable price, easy processing and good corrosion resistance. Which material to choose depends on the specific application requirements and budget.
