How to improve lifetime of Cr12MoV mould
How to improve lifetime of Cr12MoV mould
1.1 Improve the annealing process
Cr12MoV After forging, spherical annealing is often used to obtain fine spherical carbide tissue, reduce the hardness, improve the cutting performance, and prepare for the subsequent quenching. The improved spherization annealing process is 860-880℃, heating for 3-4h, cold to 740-760℃ for 4-6h, and furnace to 500-550℃. The evaluation of carbide grade must be strict, precision mold 1-3, general mold 1-4. The poor performance of many molds is not the poor quenching process, but the forging and spherical annealing process can not meet the requirements.
1.2 Improve the quenching and tempering process
Cr12MoV Steel, the final hardening treatment is divided into primary hardening treatment and secondary hardening treatment. The primary hardening treatment refers to high temperature quenching (about 1000℃) and low temperature tempering (about 200℃), and the secondary hardening treatment refers to high temperature quenching (about 1100℃) and high temperature tempering (about 500℃). Research and practice show that Cr12MoV steel after a hardening treatment, high hardness (60-62 HRC), wear resistance, fine grain, good toughness, small quenching deformation, moderate residual austenite amount, is a better conventional strong toughness treatment process. In addition, Cr12MoV steel by 800-850℃ preheating, 102-1050℃ heating quenching, two 160-180℃ low temperature tempering, the use effect is also good.
Processing small size round hole punch often use rolled round steel, this kind of unmodified forging can use 500℃ and 800℃ secondary preheating, 1100-1150℃ solid solution treatment, quenched into hot oil or isothermal quenching, 750℃ high temperature tempering, machining 960℃ heating oil cooling for final heat treatment, can also make carbide refinement, angular rounding, grain refinement.
Research data, the use of 850℃ preheating, 1030℃ heating, 280℃ isothermal quenching, 200℃ tempering, isothermal can get 7% -10% of bainite and martensite, with the best wear resistance and impact toughness, can make the self, driving head cold heading die life from conventional grading quenching less than 40,000 to 120,000 times.In short, if the quenching temperature is high, Cr12MoV steel will have large austenite grains, which makes the martensite thick and toughness is insufficient; if the quenching temperature is too low, the effect of carbide is obvious, and the strength, toughness and wear resistance will be greatly reduced. Because the heat treatment of Cr12MoV steel needs good technology, the process should be strictly controlled in the operation process, so as to ensure the quality of the mold.
1.3Add deep cooling treatment
Deep cooling treatment can not only improve the strength and toughness of steel, stabilize the mold size, but also improve the processing accuracy and save some parts with super tolerance. The deep cooling treatment process is as follows: first, Cr12MoV steel by 1030℃ quenching, 100℃ tempering, -160℃ deep cooling treatment for 2h, 500℃ tempering twice, or using 1060℃ quenching, -196℃ deep cooling treatment and 400℃ tempering, the wear resistance is greatly improved. Experience shows that the service life of the M12 nuts treated by this method is increased by about 5 times. Second, Cr12MoV steel after 1100℃ quenching, liquid nitrogen deep cold treatment, 520℃ tempering, wear resistance can also be greatly improved.
1.4 Surface reinforcement treatment
In addition to the matrix with high enough strong toughness, the mold also requires the surface to have high hardness, wear resistance, corrosion resistance and low friction coefficient, fatigue resistance, etc. The improvement of these properties, the overall heat treatment effect of the material alone is not obvious, also not economic, and through the surface treatment technology, change the chemical composition, tissue structure and stress state of the mold surface, often can get twice the result with half the effort. There are many surface treatment methods of molds, and new treatment technologies are constantly emerging, but for Cr12MoV steel molds, the main applications are nitrogen infiltration and multiple composite infiltration, hardening membrane deposition technology.
