Titanium alloy valve material selection
At present, with the advancement of science and technology and the increasing application of new materials by all trades and professions, titanium valve has been extensively used as an indispensable product for various special environments and special fluid medium delivery systems. However, different fields and industries of liquefied medium and environmental conditions vary, the performance requirements of titanium valve materials used are different. At the same time, due to differences in the performance requirements of different components of titanium valve, molding process is different, as well as to reduce the cost of some components need to be used alternative materials and other factors, the selection of titanium valve design and manufacture must be the primary consideration of one of the technical issues.
2, commonly used titanium and titanium
2.1, industrial titanium
Industrial pure titanium refers to several distinct Fe, C, N, O and other impurities of non-alloyed titanium. Industrial titanium cannot be heat strengthened, molding performance, easy welding and brazing. Industrial pure titanium widely used in practice. The vacuum network found that the typical deformation of industrial grade titanium with TA1, TA2 and TA3; typical cast industrial grade titanium grades ZTA1, ZTA2 and ZTA3.
2.2, titanium alloys
Α-type titanium alloy has good weldability, casting performance, pressure processability, organizational stability and non-cold brittleness, the disadvantage is the lower plastic and hydrogen embrittlement sensitivity. Α-type titanium alloy is widely used in practice, a typical α-type titanium alloy grades TA5, TA7, TA9 and so on.
The main component of β-type titanium alloy is the alloy of Cr, Mo, V and other elements added to Ti. These alloys are hardened to obtain β solid solution structure, which has high strength and impact toughness, and has decent pressure processability and welding performance. However, the β-type titanium alloy structure and performance instability, the melting process is complex, less application. The stable β-type titanium alloy with TB7 and Ti40.
The α + β-type titanium alloy has α + β microstructure at room temperature and contains 5% to 25% of β phase in a stable state and α + β titanium alloy of α-type martensite precipitated rapidly from β region Can be quenched by heat treatment plus aging treatment. Α + β titanium alloy mechanical properties of a wide range of wide temperature range have better overall performance, suitable for a variety of different uses. Typical α + β-type titanium alloy deformation TC4, TC11 and TC16 and so on. Typical α + β cast titanium grades are ZTC3, ZTC4 and ZTC5.
3, titanium mechanical properties
Casting titanium metal must have good fluidity and processability, forging titanium metal must have good plasticity,
Titanium O, C, N and other impurities often have a significant influence on the mechanical properties of titanium, they can increase the strength of titanium and reduce its plasticity, its greater impact on the N, C less impact, O of the middle. In addition, B, Be and Al and other elements have a greater impact on the increase of titanium strength, while Cr, Mo, Mn, Fe, V and Sn have little effect on the strength of titanium. Al is often utilized as α-stabilizing element and an important alloying element in α-type and α-type β-type titanium alloys. Al is characterized by grain refinement of the alloy, enhancement of recrystallization temperature and transformation temperature, significant strengthening effect, and reduction of alloy density, increase the alloy elastic modulus. Mo is often used as a β-stable element and an essential alloying element in β-type and α + β-type titanium alloys. Mo is designed to have a greater strengthening effect without significantly reducing the plasticity of the material and can simultaneously improve the fracture toughness of the material. Erosion, decreasing its stress corrosion sensitivity.
H has a good influence on the mechanical properties of titanium and titanium alloys. When the content of H reaches a certain value, the sensitivity of titanium and titanium alloy to the notches will be significantly improved, so that the impact toughness and other properties of the notched specimens will be reduced. It is generally accepted that the hydrogen content should be less than 0.007% to 0.008% (mass fraction) and not more than 0.0125% to 0.015% (mass fraction), above which the hydride will precipitate out and significant hydrogen Crisp phenomenon. Hydrogen embrittlement is an essential issue for titanium and titanium alloys. Titanium absorbs hydrogen easily from pickling liquids, corrosives, and hot working hot atmospheres. Hydrogen embrittlement of titanium and its alloys often have two manifestations. First, a slight increase in strength, plasticity and impact toughness decreased. Another form is similar to the embrittlement of steel, under a constant load or sustained load, slow embossing occurs when a lengthy stretch.
At present, with the advancement of science and technology and the increasing application of new materials by all trades and professions, titanium valve has been extensively used as an indispensable product for various special environments and special fluid medium delivery systems. However, different fields and industries of liquefied medium and environmental conditions vary, the performance requirements of titanium valve materials used are different. At the same time, due to differences in the performance requirements of different components of titanium valve, molding process is different, as well as to reduce the cost of some components need to be used alternative materials and other factors, the selection of titanium valve design and manufacture must be the primary consideration of one of the technical issues.
2, commonly used titanium and titanium
2.1, industrial titanium
Industrial pure titanium refers to several distinct Fe, C, N, O and other impurities of non-alloyed titanium. Industrial titanium cannot be heat strengthened, molding performance, easy welding and brazing. Industrial pure titanium widely used in practice. The vacuum network found that the typical deformation of industrial grade titanium with TA1, TA2 and TA3; typical cast industrial grade titanium grades ZTA1, ZTA2 and ZTA3.
2.2, titanium alloys
Α-type titanium alloy has good weldability, casting performance, pressure processability, organizational stability and non-cold brittleness, the disadvantage is the lower plastic and hydrogen embrittlement sensitivity. Α-type titanium alloy is widely used in practice, a typical α-type titanium alloy grades TA5, TA7, TA9 and so on.
The main component of β-type titanium alloy is the alloy of Cr, Mo, V and other elements added to Ti. These alloys are hardened to obtain β solid solution structure, which has high strength and impact toughness, and has decent pressure processability and welding performance. However, the β-type titanium alloy structure and performance instability, the melting process is complex, less application. The stable β-type titanium alloy with TB7 and Ti40.
The α + β-type titanium alloy has α + β microstructure at room temperature and contains 5% to 25% of β phase in a stable state and α + β titanium alloy of α-type martensite precipitated rapidly from β region Can be quenched by heat treatment plus aging treatment. Α + β titanium alloy mechanical properties of a wide range of wide temperature range have better overall performance, suitable for a variety of different uses. Typical α + β-type titanium alloy deformation TC4, TC11 and TC16 and so on. Typical α + β cast titanium grades are ZTC3, ZTC4 and ZTC5.
3, titanium mechanical properties
Casting titanium metal must have good fluidity and processability, forging titanium metal must have good plasticity,
Titanium O, C, N and other impurities often have a significant influence on the mechanical properties of titanium, they can increase the strength of titanium and reduce its plasticity, its greater impact on the N, C less impact, O of the middle. In addition, B, Be and Al and other elements have a greater impact on the increase of titanium strength, while Cr, Mo, Mn, Fe, V and Sn have little effect on the strength of titanium. Al is often utilized as α-stabilizing element and an important alloying element in α-type and α-type β-type titanium alloys. Al is characterized by grain refinement of the alloy, enhancement of recrystallization temperature and transformation temperature, significant strengthening effect, and reduction of alloy density, increase the alloy elastic modulus. Mo is often used as a β-stable element and an essential alloying element in β-type and α + β-type titanium alloys. Mo is designed to have a greater strengthening effect without significantly reducing the plasticity of the material and can simultaneously improve the fracture toughness of the material. Erosion, decreasing its stress corrosion sensitivity.
H has a good influence on the mechanical properties of titanium and titanium alloys. When the content of H reaches a certain value, the sensitivity of titanium and titanium alloy to the notches will be significantly improved, so that the impact toughness and other properties of the notched specimens will be reduced. It is generally accepted that the hydrogen content should be less than 0.007% to 0.008% (mass fraction) and not more than 0.0125% to 0.015% (mass fraction), above which the hydride will precipitate out and significant hydrogen Crisp phenomenon. Hydrogen embrittlement is an essential issue for titanium and titanium alloys. Titanium absorbs hydrogen easily from pickling liquids, corrosives, and hot working hot atmospheres. Hydrogen embrittlement of titanium and its alloys often have two manifestations. First, a slight increase in strength, plasticity and impact toughness decreased. Another form is similar to the embrittlement of steel, under a constant load or sustained load, slow embossing occurs when a lengthy stretch.
