Steel and titanium are commonly used metals in manufacturing due to their excellent strength, hardness and other physical and mechanical properties.
Steel is an alloy of iron and carbon, with carbon content ranging from 0.2% to 2.1% by weight. Although iron and carbon are the main constituents, small amounts of other elements such as manganese, silicon and phosphorus may be present. There are several types of steel, categorized according to carbon content, alloying elements and heat treatment processes. These include mild steel, stainless steel and high-strength low-alloy steel. Steel is known for its strength, durability and versatility, which makes it suitable for a wide range of applications. Its uses cover everything from construction and automobiles to tools and cutlery.
Titanium is a chemical element with the symbol Ti atomic number 22. it is a lustrous transition metal with a silvery color, low density, and high strength. While it is as strong as steel, it is significantly less dense, making it the metal of choice for applications where strength-to-weight ratio is critical. In its unalloyed state, titanium is as strong as some steels but less dense. When alloyed with other elements such as aluminum and vanadium, it can be significantly strengthened. The two main uses of titanium are aerospace (airplanes, spacecraft, and missiles) and industrial applications because it is lightweight, strong, and resistant to corrosion even at high temperatures.
I. Influence of titanium on the microstructure and heat treatment of steel
① Titanium and nitrogen, oxygen, carbon have a very strong affinity, is a good deoxidizing and degassing agent and fixation of nitrogen and carbon effective elements.
② titanium and carbon compounds (TiC) combination is extremely strong, high stability, only heated to more than 1000 ℃ will slowly dissolve into the solid solution of iron, TiC particles have to prevent the steel grain growth and coarsening of the role.
(iii) Titanium is one of the strong ferrite-forming elements, so that the austenite phase region is narrowed. Titanium in solid solution to improve the hardenability of steel, while the presence of TiC particles to reduce the hardenability of steel.
④ When the titanium content reaches a certain value, precipitation hardening can occur due to diffuse precipitation of TiFe2.
Second, the influence of titanium on the mechanical properties of steel
① When titanium exists in solid solution in the ferrite, its strengthening effect is higher than aluminum, manganese, nickel, molybdenum, etc., followed by beryllium, phosphorus, copper, silicon.
② The effect of titanium on the mechanical properties of steel depends on the form in which it exists, the ratio of the content of Ti and C, and the heat treatment method. Titanium mass fraction of 0.03% to 0.1% of the yield strength can be improved, but when the ratio of Ti and C content more than 4, its strength and toughness decline sharply.
(iii) Titanium improves the enduring strength and creep resistance.
(iv) Titanium has an improving effect on the toughness of steel, especially the low-temperature impact toughness.
Third, titanium on the physical, chemical and process properties of steel influence
①Improve the stability of steel in high temperature, high pressure and hydrogen.
② titanium can improve the corrosion resistance of stainless acid-resistant steel, especially the resistance to intergranular corrosion.
③ In low carbon steel, when the ratio of Ti and C content reaches more than 4.5, it has good resistance to stress corrosion and alkali embrittlement because oxygen, nitrogen and carbon are all fixed.
(iv) Adding titanium to steel with a chromium mass fraction of 4%-6% improves the oxidation resistance of steel at high temperatures.
⑤ The addition of titanium to steel can promote the formation of nitriding layer, and the required surface hardness can be obtained more quickly. Titanium-containing steels are called "fast nitriding steels" and can be used to manufacture high-precision screws.
⑥Improve the weldability of low carbon manganese steel and high alloy stainless sodium.
Application of titanium in steel
①Titanium mass fraction of more than 0.025% can be considered as an alloying element.
② titanium as an alloying element in ordinary low-alloy steel, alloy structural steel, alloy tool steel, high-speed tool steel, stainless steel, acid-resistant steel, heat-resistant non-skinning steel, permanent magnet alloys, and cast steel are widely used.
③Titanium has been used as a variety of advanced materials, become an important strategic materials, the use of more than half of the aerospace industry, such as aviation spacecraft, power machinery.
