| For G13Cr4Mo4Ni4V steel has excellent performance of surface hardness and inner toughness after heat treatment such as carburizing and quenching,it is widely used in the field of aviation bearing.But the bearing ring produced by G13 steel will be deformed seriously after heat treatment.In order to explore the cause of G13Cr4Mo4Ni4V bearing ring deformation,this paper studies the temperature field of the ring during heating and cooling from the perspective of heat treatment process.By measuring the temperature of different parts of the ring and combining with the finite element analysis,the distribution law of temperature field under different heating and cooling conditions was explored.Some conjectures and hypotheses were preliminarily verified,And this work provided certain basis for the formulation of technological parameters in production.Four heating rates and three radiation environments were set for the heating experiment.According to the temperature measurement results,the actual temperature of the ring would lag behind the set temperature,and the lag time would gradually shorten during the heating process.What's more,the higher the heating rate,the shorter the lag time,while the greater the lag ratio.In addition,reasonable setting of heat preservation step and heating rate can shorten heating time while ensuring the time to the setting temperature to improve production efficiency.Combined with the finite element calculation results,the final temperature of the ring reaches about 955?.In the heating process,the temperature of the ring is evenly distributed along the circumferential direction,while the upper temperature is higher than the lower's along the height direction.The difference between the maximum temperature and the minimum temperature on the ring first increases and then decreases during the heating process.The greater the heating rate is,the greater the temperature difference is,and the more non-uniform the temperature of the ring is.After a long time of heat preservation,the temperature uniformity of the ring can be well improved.On different radiation environmental conditions,the heating rate of the shielded part of the ring lags behind that of other parts.And the larger the shielding part is,the lower the overall temperature of the ring will be.The uniformity of the temperature distribution on the ring becomes worse with the increase of the shielding area.Similarly,setting the heat preservation step can improve the uniformity of the temperature.In the cooling experiments,three cooling rates and three furnace loading quantities were set.According to the actual measuring temperature,the surface cooling rate of G13 bearing ring was significantly faster than that of the core.Combined with the results of finite element analysis,the cooling rate of the edge of the ring's upper and lower end faces is the fastest.And the greater the cooling rate is,the greater the temperature difference between the surface and the core is,and the more obvious the cooling hysteresis of the core is.Martensite transformation occurs in the ring during gas quenching,and the transformation time of the core lag behind the surface,and and the temperature of the core is higher.The greater the cooling rate is,the lower the martensite transition temperature on the ring surface is,while the temperature change at the core is not significant.In other words,the martensite transformation temperature difference between the surface and the core increases with the increase of the cooling rate.The increase of furnace loading will lead to the decrease of the cooling rate of the ring.It is speculated that the flow field of the cooling medium on the ringsurfacehas changed.And the increase of the load will lead to the increase of the temperature of the medium.By changing the convection heat transfer coefficient and medium temperature in the finite element model,the simulated curve can be consistent with the measured curve.That means the rationality of the conjecture is verified. |
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