Experimental methods for surface heat treatment and surface cold plastic deformation of titanium plates

Sintering temperature: If the temperature is too high, the growth rate of titanium carbide grains will accelerate. The final sintering temperature of titanium carbide high-manganese steel hard alloy is generally recommended to be 1420℃. Titanium plate manufacturers believe that the sintering temperature should not be too high. Even if it causes the bonding phase to turn into liquid metal and be lost, this will lead to the adjacent, aggregation and growth of the hard phase, forming a fragmentation source. This is the reason for the less bonding phase transformation between the hard phase as analyzed earlier.

Of course, the sintering temperature should not be too low either, otherwise the alloy will be under-sintered. Besides the control of sintering temperature and speed as mentioned earlier, the vacuum degree inside the furnace, during the liquid phase sintering stage, also needs to be controlled. Because an excessively high vacuum degree will cause a large amount of liquid metal to volatilize, resulting in composition segregation. Especially in the three stages of degassing, reduction and liquid phase sintering, the heating rate during sintering should not be too fast for this alloy.

The heating rate and holding time should be strictly controlled. Because in the low-temperature degassing stage, the process of the die being released from the compressive stress and the volatilization of the forming agent, if the heating rate is too fast, due to the insufficient time for the forming agent to volatilize, it will liquefy and turn into steam, causing the die to crack or have micro-cracks; in the reduction stage above 900℃, the die should have enough time to remove the volatile substances and oxygen from the raw materials (such as Mn2Fe intermediate alloy); during the liquid phase sintering stage, the heating rate should be slowed down to allow the die to be fully alloyed.

Under the same conditions, different components of industrial titanium plates will exhibit different decarburization behaviors. For example, Si can increase the elastic limit, strength, temper stability and elastic reduction resistance. Due to the different effects of different alloy elements on the activity and diffusion of carbon. However, the increase of Si in the austenite causing the activity and gradient of carbon in the surface to be severely decarburized must also be given attention.

Titanium plate manufacturers believe that the surface strength of the part is an important factor affecting fatigue strength. Surface heat treatment and surface cold plastic deformation processing are very effective in improving fatigue strength. Reducing the formation of fatigue cracks. Removing the surface decarburized layer produced by heat treatment can significantly improve the fatigue limit; not removing the surface decarburized layer after heat treatment and directly shot peening is more effective than removing the decarburization layer first and then shot peening, such as surface quenching, carburizing, carbon-nitrogen co-sintering, nitriding, shot peening and rolling.