In the research, the author found that (a4.5mm67CrVA spring steel wire after lead quenching at different temperatures, the lead quenching temperature is between 520540e, the tensile strength is the lowest; at 580e, the tensile strength is the highest; at 540560e, the cross section The shrinkage rate is the lowest; below 540e, the lower the lead quenching temperature, the larger the area shrinkage rate. When the temperature is higher than 600e, the area shrinkage rate does not change much. The metallographic structure observed under the optical metallographic microscope cannot explain this phenomenon. To this end, a representative sample of 500e, 540e and 600e3 at the lead quenching temperature was selected and studied by means of TEM and SEM. SEM photo @20001.2 test equipment was a pickled and phosphatized a5.5mm67CrVA hot rolled wire. After drying, cold-drawn to a4.5mm, cut a few samples of length 1.2m, and straighten by hand. The austenitizing heating equipment is a self-made electric heating tube furnace, and the austempering equipment is also a self-made lead bath. Furnace, the temperature control accuracy of both is 1e; the tensile test is carried out on the WE-5B hydraulic universal testing machine from the Changchun Test Machine Factory; the MM-6 metallographic microscope of the Leitz company in Germany is observed. Pu Company's CM -200 type transmission electron microscope and XL20 type scanning electron microscope.
TEM sample preparation was carried out by wire cutting method from a4.5mm lead quenched steel wire sample to take 0.3mm thin film, sanded to 100Lm, and then double-sprayed in 10% perchloric acid alcohol solution to reduce perforation to the perforation. The film was further thinned by an LGB-1 ion thinning machine to prepare a film sample for observation under a transmission electron microscope. SEM photo of the SEM photo @4000a4.5mm67CrVA spring wire after lead quenching is seen after 540e lead quenching. It can be seen that in addition to most of the sorbite and a small amount of upper bainite, some strange structural structures appear in the microstructure: ferrite is distributed in strips or blocks in steel, ferrite Cementite carbides are distributed between the steel and the sorbite. The cementite carbides are distributed along the strip ferrite boundary and are connected to one end of the sheet-like cementite in the sorbite and at an angle, observed at a lower magnification, which are distributed on the ferrite boundary. The cementites appear to be connected together in a strip shape, but after partial enlargement, the cementite carbides are not all connected together, and some parts are broken. It can be seen that the morphology of cementite carbide distribution around the massive ferrite and the morphology of cementite carbide around the ferrite are basically the same, and will not be described here. Partial enlargement of dc dark field phase @38000b upper bainite + sorbite @6600cb @38000a metamorphic pearlite @38000c massive ferrite + sorbite + carbide distributed along the boundary of bulk ferrite @ Partially enlarged photo of 15000dc @30000 micro-organization see. It can be seen that in addition to most of the sorbite and a small amount of ferrite, the microstructure has a certain amount of metamorphic pearlite and the upper bainite. The arrangement of ferrite slabs in the upper bainite is approximate. Parallel, some of the cementite carbides are distributed in a long strip between the ferrite slabs. There are spindles or short rods distributed between the ferrite slabs. The material is distributed not only in the form of short rods between the ferrite slats but also in the form of beads in the interior of each ferrite slab.
When the 67CrVA spring steel wire 500e is quenched, the diffusion coefficient of carbon atoms is smaller due to the lower phase transition temperature, and the carbon atoms are decomposed from the ferrite and diffused into the austenite through the interface of ferrite and austenite. Insufficient, as a result, carbides are precipitated in the form of strips, spindles or short rods between the ferrite slabs. The mechanism for the precipitation of carbides inside the ferrite slabs in a bead shape remains to be studied.
Conclusion (1) After the lead steel quenching of a4.5mm67CrVA spring steel wire between 500660e, the microstructure is extremely complicated and varies with the lead quenching temperature. (2) The reason for the trough shrinkage of the a4.5mm67CrVA spring steel wire after 500600e lead quenching is that strips or chain-like cementite carbides are distributed around the steel strip and the block ferrite.
Brushless DC fans are usually available at three nominal voltages: 12V, 24V and 48V. If the system has regulated power supply in one of these, then a brushless DC Fan may be selected which will give the exact performance required, regardless of the AC input variables which plague AC fans.
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Product description
Feature:
1.energy saving
2.stepless speed regulation
3.quiet and long life
Specification:
Model
Bearing
Rated voltage(v)
Rated current
(A)
Rated
Nominal speed
(RPM)
Air flow
(CFM)/(m^3/min)
Air pressure
Noise
(dB)
Weight(g)
FS5015
sleeve/ball
5/12/24
0.08~0.35
0.75~3.60
3500~5000
3.75~5.55
0.10~0.15
5.15~7.35
0.20~0.28
28~33
30
FS5020
sleeve/ball
5 /12
0.09~0.35
0.65~2.64
3500~5500
3.5~6.5
0.09~0.18
11.85~23.56
0.46~0.92
32~43
33
FS6015
sleeve/ball
5 /12
0.09~0.35
1.08~2.64
3800~5500
3.8~6.8
0.10~0.19
12.35~24.50
0.48~0.96
35~45
32
FS7530
sleeve/ball
12/24
0.2~0.45
2.40~8
2500~3500
9.18~12.55
0
7.55~10.03
0
33~42
85
FS9733
sleeve/ball
12/24
0.25~0.8
4.20~13.2
2000~3200
15.05~26.33
0.42~0.73
6.23~10.88
0.24~0.43
35~52
95
FS12032
sleeve/ball
12/24
0.28~1.0
5.88~19.2
1600~2300
18.88~33.01
0
8.82~15.41
0
45~55
198
Imput
power(W)
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