Firstly. The effect of titanium on the microstructure and heat treatment of steel
1, titanium and nitrogen, oxygen, carbon have a strong affinity, is a good deoxidizing degassing agent and fixed nitrogen, carbon effective elements.
2, titanium and carbon compounds (TiC) combining force is very 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 coarsening effect.
3, 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 is to reduce the hardenability of steel.
4, titanium content reaches a certain value, due to diffuse precipitation of TiFe2, precipitation hardening effect can be produced.
Second. 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 influence of titanium on the mechanical properties of steel depends on the existence of its form, Ti and C content ratio and heat treatment methods. Titanium mass fraction of 0.03% to 0.1% of the yield strength can be improved, but when the Ti and C content ratio of more than 4, its strength and toughness decreased sharply.
3, titanium can improve the enduring strength and creep resistance.
4, titanium on the toughness of steel, especially low-temperature impact toughness has improved.
Thirdly. Titanium on the physical and chemical properties of steel and the impact of process performance
1,Improve the stability of steel in high temperature, high pressure, hydrogen.
2, titanium can improve the corrosion resistance of stainless acid-resistant steel, especially the resistance to intergranular corrosion.
3, low carbon steel, when the ratio of Ti and C content reaches 4.5 or more, due to oxygen, nitrogen and carbon are all fixed, with good resistance to stress corrosion and alkali embrittlement resistance.
4, in the chromium mass fraction of 4% -6% of the steel to add titanium, can improve the oxidation resistance of steel at high temperatures.
5, the addition of titanium in steel can promote the formation of nitriding layer, can be more quickly to obtain the required surface hardness. Titanium-containing steel is called "fast nitriding steel", which can be used to manufacture high-precision screws.
6,Improve the weldability of low carbon manganese steel and high alloy stainless steel.
Fourth. Titanium in steel applications
1,Titanium 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.
3, titanium has been used as a variety of advanced materials, become an important strategic materials, in the aerospace industry accounted for more than half of the use, such as aviation spacecraft, power machinery and so on.
