Shaanxi Yunzhong Industry Development Co.,Ltd
Address: NO.128 Gaoxin Road, Baoji City, Shaanxi Province of China
Titanium alloy has low density, high specific strength, good corrosion resistance, no magnetic excellent performance, in the aviation, aerospace, chemical industry, shipbuilding, automobile, weapons, sports, medical and other fields is an important structure material.
However, higher costs limit its scope of application. Therefore, the research and development of low cost titanium alloy and low cost preparation technology of titanium alloy is still the most important research hotspot at present .
Reducing the cost of raw materials and shortening the processing flow is an effective way to reduce the cost of titanium alloy......
This work studied electron beam cold hearth (EBCHM) melting of TC4 titanium alloy flat ingot rolling plate in the process of deformation and annealing microstructure and properties, reveals the variation of the plate microstructure evolution and mechanical properties at room temperature, get plate strength and elongation of the best matching annealing system, to for the industrialization of the alloy sheet batch production provides the basis.
1 test materials and methods
Use sponge titanium, titanium alloy return raw materials, such as in the electron beam cold hearth melting slab 270 x 1085 x 5 000 mmTC4 titanium alloy and its chemical composition conform to GB / T 3620.1-2007 standards and metallographic method measured the beta transition temperature of 974 DEG C. By ingot after treatment in the 1200 mm four roller hot rolling mill on the column at the phase transition point below 20 ~ 50 DEG c......
2 test results and discussion
Microstructure and properties of the plate during the 2.1 deformation
Fig. 1 microstructure of TC4 titanium alloy sheet after different fire deformation. From Figure 1 (a) of TC4 titanium alloy electron beam cold hearth melting visible flat ingot coarse grain, grain for dendritic structure. After a fire deformation, the cast dendrite structure is broken, the formation of columnar structure, see Figure 1 (B). After two fire deformation, coarse grains are broken into small grains......
2.2 the microstructure and properties of the plate after annealing treatment
Figure 2 for the plate after 720 to 950 degrees C /1h, AC after annealing microstructure. From the figure can be seen when the annealing temperature is low (720 - 820) C, although some changes in the microstructure, but still to rod like or equiaxed alpha + beta microstructure transformation mainly, grain size and morphology is very similar to (see Figure 2A ~ d). As the annealing temperature increased from 820 to C, the microstructure of the plate was significantly changed at low temperature......
1) along with the increase of fire of rolling deformation, electron beam cold hearth melting TC4 titanium alloy flat ingot thick cast state grain is crushed, the dendrite microstructure change organization * *, and the mechanical properties of sheet at room temperature increased significantly;
2) of TC4 titanium alloy sheets after annealing, the organization is more uniform equiaxed, with the increase of temperature, precipitation of secondary lamellar alpha phase, primary alpha content * *; tensile strength of the plate presented to * * * * of the trend, yield strength and cross section shrinkage rate showing an overall trend of * *, while the elongation change little;
3) the best matching of strength and plasticity can be obtained after annealing treatment.