1) High strength for titanium alloy? Quality ratio, better strength, toughness and ductility. In addition, titanium alloy also has good oxidation resistance and corrosion resistance, and can maintain good strength at high temperature. These performance advantages make titanium alloys widely used in aerospace, automobile, chemical industry and medical devices [1]. However, in addition to the above advantages, its machinability is a difficult problem in production. The machinability of titanium alloy is mainly reflected in the following points [2,3]: (1) Low thermal conductivity. The low thermal conductivity of titanium alloy causes a lot of cutting heat during machining, and most of it remains in the tool, which makes the tool wear faster [4], and in rare cases, the cutting heat even causes sparks; (2) Severe work hardening. During the cutting process, the surface of titanium alloy parts will undergo work hardening, which will affect the fatigue strength and geometric dimension accuracy of the parts. (3) Low elastic modulus. In heavy-load cutting, the low elastic modulus of titanium alloy will lead to deformation and vibration; (4) High chemical activity. Titanium alloy has high chemical activity. At high temperature, titanium easily reacts with tool materials, which will accelerate tool wear [4] and shorten tool life. The machinability of titanium alloy directly affects its processing efficiency. Therefore, choosing a reasonable tool material is an effective way to improve the machining efficiency of titanium alloy. In the processing of titanium alloy, cemented carbide is mostly used as tool material, but because of its short life. Minimum or smaller. Cubic boron nitride (CBN) tool materials have high hardness, wear resistance, high thermal stability, excellent chemical stability, good thermal conductivity and low friction coefficient, which are exactly what titanium alloy tool materials should have. Researchers and engineers have begun to try to use CBN tools to cut titanium alloys. . Nabhani found that PCBN tool has a lower wear rate when cutting titanium alloy TA48, and can obtain a better machined surface quality [5]. Z.A. Zoya and R. Krishnamurthy studied the cutting performance of CBN tool when cutting titanium alloy at high speed, and proved that the cutting performance of titanium alloy was mainly affected by cutting heat. The increase of friction heat at tool-chip interface and tool-tool interface will lead to the aggravation of tool wear, and the wear reason of CBN tool depends on the properties of titanium alloy, tool material and cutting medium. [6].E.O. Ezugwu et al. studied the machinability of different CBN tools when cutting titanium alloy TC4 under different coolant conditions [7]. Bhaumik et al. used CBN composite blade to cut titanium alloy TC4. X-ray analysis shows that there is titanium in the crescent region of the tool, and the bonding layer also contains some titanium compounds, such as titanium boride and titanium nitride [8]. Titanium alloy TC4 is the most widely used titanium alloy in industry. Aiming at the machinability of titanium alloy TC4 processed by PCBN tool, the experimental research and theoretical analysis were carried out from the aspects of cutting force, surface quality, tool damage form and damage mechanism, tool life and so on, in order to provide reasonable cutting parameters for titanium alloy processing.
2) For superalloys, the integral CBN tool is the most ideal tool. We have many things that our customers are using now, and the effect is very good.
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How to eliminate work hardening? It is eliminated by metal recrystallization.
The general theory is this:
Work hardening refers to the destruction of internal crystals of metal at room temperature, which leads to the increase of hardness and the decrease of plasticity.
Recrystallization refers to heating the metal, at which time the crystal will recrystallize, so the original properties of the metal can be partially restored. The specific recrystallization temperature varies from metal to metal.
How to eliminate the work hardening of stainless steel generally has the following methods to eliminate the work hardening:
1 ... recrystallization annealing: heat treatment process of heating cold deformed metal above recrystallization temperature for a certain time, and then cooling for recrystallization. Recrystallization annealing is adopted in production to eliminate work hardening of processed products, improve plasticity and completely eliminate residual stress. Recrystallization annealing is sometimes carried out in the middle of cold deformation processing in order to restore plasticity and facilitate continuous processing.
2. Solution annealing (a common method for Cr-Ni stainless steel): carbide solution annealing, which is a process of heating the finished product to above 10 10 degrees Celsius, removing carbide precipitates (that is, carbon escapes from the solid solution of stainless steel), and then rapidly cooling, usually quenching with water. Carbides contained in alloy steel return to the solid solution of stainless steel. Solution annealing can be applied to a series of alloy steel and stainless steel parts. Solution annealing of 300 series stainless steel castings can produce uniform microstructure without carbide impurities. Solution annealing of precipitation hardening alloy castings and forgings can produce soft microstructure.
What is work hardening? Work hardening
With the increase of cold deformation, the strength and hardness of metal materials increase, but the plasticity and toughness decrease.
brief introduction
When metal materials are plastically deformed below recrystallization temperature, the strength and hardness increase, while the plasticity and toughness decrease. Also known as cold work hardening. The reason is that when the metal is plastically deformed, the grain slips, dislocations entangle, the grain elongates, breaks and fiberizes, resulting in residual stress in the metal. The degree of work hardening is usually expressed by the ratio of microhardness of surface layer after processing to microhardness of surface layer before processing and the depth of hardened layer.
Nanomaterials will also undergo work hardening, and the hardening behavior at this time is considered to be closely related to dislocation movement.
Work hardening brings difficulties to the further processing of metal parts. For example, in the process of cold rolling steel plate, it will become more and more difficult to roll, so it is necessary to arrange intermediate annealing during the processing to eliminate its work hardening by heating. Another example is to make the surface of the workpiece brittle and hard during cutting, thus accelerating tool wear and increasing cutting force.
On the one hand, it can improve the strength, hardness and wear resistance of metals, especially for pure metals and some alloys that cannot be improved by heat treatment. For example, cold-drawn high-strength steel wire and cold-rolled spring are deformed by cold working to improve their strength and elastic limit. For example, the tracks of tanks and tractors, jaws of crushers and turnouts of railways are also hardened by work to improve their hardness and wear resistance.
When a metal material undergoes plastic deformation below the recrystallization temperature, it is called work hardening or cold working hardening, because the grains slip and entangle, which makes the grains elongate, break and fiberize, which increases the strength and hardness of the metal and reduces the plasticity and toughness.
The color of titanium alloy will change after wire cutting. How to eliminate this phenomenon? The discoloration of titanium material after wire cutting is caused by poor heat dissipation control. Color changes generally do not affect the use. If you must eliminate it, you can cut it again and pay attention to cooling. Cut off the colored parts.
How to prevent cold rolling hardening? Cold rolling is bound to work hardening and can't stop!
Generally, after cold working, annealing and other heat treatment processes will be carried out to eliminate work hardening!
If the hardening of the first cold working is too great to reach the target degree, an annealing process can be added in the middle, and then the second cold working can be carried out to achieve the goal!
Are ta2 and tc4 compatible? Can pure titanium and titanium alloy be melted by argon arc welding? Pure titanium series welding wire can be melted and welded, and Viodin 30 1 pure titanium series can be selected.
Can titanium alloy be machined by wire cutting? Of course.
It is more difficult to process than ordinary steel.
FYI
What is the high temperature resistance and hardness of TC4 titanium alloy? Poor stamping performance and good thermoplasticity. Parts that work for a long time below 400℃.
What factors should be guaranteed, such as melting point, thermal conductivity, thermal expansion, surface tension, elastic modulus and so on. . .
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How to eliminate the red eye phenomenon caused by taking pictures with flash? In the past, red eyes appeared when taking pictures with a flash in the dark. After that, the red eye phenomenon was almost completely eliminated. Step 1: Open the image with red eye phenomenon Step 2: Zoom in and center one eye Step 3: Select the red eye control point Step 4: Apply the red eye control point for enhancement Step 5: Drag the image to display the other eye Step 6: Apply the red eye control point. Step 2: Enlarge the display screen, center one eye and select Zoom Tool. Click an eye, or drag the zoom tool on one eye to enlarge the display to 100-200%. The eye part of the image is enlarged. Step 3: Select "Red-eye Control Point" Select "Red-eye Control Point" Step 4: Apply "Red-eye Control Point" to enhance the click on the eyeball center and add a "red-eye control point". The phenomenon of red eye is reduced or eliminated. The Red Eye Control Point dialog box will be displayed. Drag the size slider left or right to adjust the area of the red-eye control point effect until the best effect is obtained. The area size of the red-eye control point effect can also be specified in the Size box of the Red-eye Control Point dialog box. Step 5: Drag the image to display the other eye and select the hand tool. Use the hand tool to drag the image until the other eye is displayed. Step 6: Apply the "red-eye control point" enhancement, re-select the red-eye control point to reduce the red-eye phenomenon in the other eye. According to step 4, set the red-eye control point and adjust the size of the effective area to reduce or eliminate the red-eye phenomenon. In the Red Eye Control Point dialog box, click OK. The red-eye control point step is added to the edit list, and the enhancement is completed.