Research On New Induction Boronizing Treatment Technology

In China,high-performance special control valves as the key core equipment of the process industry are all dependent on imports.These imported special control valves are expensive and the service is not timely,which seriously affects the long cycle operation of the device and becomes a "stuck neck" product.The purpose of this study is to enhance the surface corrosion resistance and wear resistance of axial concave valve core under high temperature,high pressure and high corrosion conditions,and to increase its surface hardness.A new induction boronizing technology based on high frequency boronizing combined with solid boronizing technology is created.The boronizing agent and sample temperature are simultaneously controlled to achieve the effect of rapid temperature rise of boronizing agent and sample simultaneously in a short time.Boronizing rate,boron concentration and boronizing path have great influence on the boronizing effect,among which boronizing temperature plays a decisive role.First of all to the structure design of inside the sealed container,the spiral structure and temperature measuring thermocouple to join,as well as the boronizing agent temperature and sample temperature monitoring and achieve in a short period of time to improve both the effect of heating temperature,and use simulation software to discuss the spiral structure of the sample temperature,magnetic field intensity and the influence of the temperature of boronizing agent.The simulation results are further verified by experimental study on H13 steel.At the same time,H13 steel and 45 steel matrix materials were boronized to explore the influence of different materials on boronizing.It is found that the addition of rare earth makes the thickness of boronizing layer change obviously,and 0.3%is the most suitable.This is because rare earth accelerates the decomposition rate of boron atoms by boronizing agent,which increases the concentration of boron elements on the sample surface.However,excessive rare earth elements will result in excessive rare earth elements on the sample surface and inhibit the infiltration of boron atoms.The induction magnetic field generated by the addition of spiral structure is in the same direction as the magnetic field of the sample,which increases the strength of the magnetic field around the sample,and then increases the temperature of the sample and the temperature of boriding agent.The sample temperature increased about 150℃ in 2 minutes,and the boriding agent temperature increased 200℃.It is observed that the addition of spiral structure causes the deviation of grain boundary and increases the penetration of boron atoms.At the same time,the boronizing layer thickness increased to 360μm,hardness up to 2100HV.The boronizing of alloy steel is more difficult than that of medium carbon steel because alloying elements can inhibit the penetration of boron atoms into the matrix.Under the same conditions,the boronizing layer of medium carbon steel is 80μm thicker than that of alloy steel and penetrates more tightly,which is not easy to fall off.