Research On Failure Mechanism And Organization Performance Control Technology Of Bi-metal Band Saw Blade

The bimetal band saw blade is made of two different metals(high-speed steel is commonly used as the tooth material,and spring steel is used as the back material),and the two are combined by welding and a series of cold and hot processing methods,resulting in high-quality saw blades with high-strength,heat-resistant,high bending and fatigue resistance at high temperatures,it's cutting performance and service life are improved greatly.In the practical use of bimetal band saw blades,their working conditions are harsh,and they are also affected by the cyclic stress,twisting,impact,etc.,so the service life will be greatly affected,its failure form is mainly the wear of the tooth material and the fatigue crack of the back material.In the current mechanical processing background,the teeth material of the bi-metal band saw blade is required to perform high-speed cutting at a high temperature for a long time.In order to improve the service life of the bi-metal band saw blade,the hardness value,wear resistance and high temperature performance of the tooth material needs to be greatly improved.As a composite material,the heat treatment process of the bimetal band saw blade is performed after the tooth material and the back material are welded,that is,the heat treatment process of the tooth material of the bimetal band saw blade and the back material is performed synchronously.The preparation of the heat treatment process of the bimetal band saw blade is based on the premise of satisfying the material properties of the tooth,that is,the heat treatment process of the tooth high speed steel material is used to select the parameters.In this heat treatment process parameters,the heat treatment temperature applied to the back spring steel material is already belongs to ultra-high temperature.In order to take into account the comprehensive performance of the teeth and back of the bimetal band saw blade,it is important to study and formulate a more reasonable heat treatment process to improve the fatigue resistance and sawing life of the back material in the ultra-high temperature quenching and high temperature tempering conditions.In this paper,a variety of bimetal band saw blade samples are tested to focus on the failure mechanism of the bimetal band saw blade and the regulation of the organization and performance.By comparing different performance samples,the main reasons that affect the service life of bi-metal band saw blades are studied,and the effects of various heat treatment processes on the microstructure and performance of bi-metal band saw blades are analyzed in combination with different heat treatment stage samples,and different orthogonal experimental factors are selected.The orthogonal test was designed for the traveling speed,quenching temperature and tempering temperature.The effects of different quenching-tempering processes on carbide precipitation and distribution,grain size,and microstructure hardness change of the bimetal band saw blade were analyzed,and the following conclusions were obtained:(1)When the hardness difference between the tooth material and the back material reaches 437 HV,the bimetal band saw blade has poor cutting performance and short service life compared with the hardness difference of 413 HV.And the carbide size in the tooth material is too large,irregular shapes and carbide cracks can adversely affect its performance;(2)The difference between the hardness of the bimetal band saw blade and the backing material is basically determined after the first tempering,and the hardness difference does not change significantly with the number of tempering times;(3)With the increase of quenching temperature,the grain size and hardness value of the quenched material of the teeth of the bimetal band saw blade are decreasing.The hardness value of the back material after quenching is not sensitive to the quenching temperature.(4)The current best heat treatment process parameters are quenching at 1183°C and tempering at 620°C for three times.Under this process,the hardness value of the tooth material can reach 912 HV,which satisfies the performance requirements of the teeth,and the back material hardness value is 491 HV,increased 29 HV based on the C series samples.The final difference between the hardness of the teeth and backing material from 441 HV effectively reduced to 418 HV.