Study Of Gradient Performance Hammer Of Multicomponent Alloys

In the work of the hammer,it has different performance requirements in different parts of the hammer.The knock part of hammer is that the material has been violent collision withstand strong impact wear has high hardness;the installation part of the hammer cannot wear the pin shaft,it requires a lower hardness.The middle part of the hammer must have sufficient toughness to ensure the hammer work safety.Therefore,it required the hammer has gradient properties(the change of hardness and toughness).Composite hammer of different materials formed can satisfy requirements of this gradient performance.The composite hammer has a kind of complex process,it is difficult to mass production.Especially the combine of between the two materials is bad,it prone to fracture failure,there is a large potential safety problem.A kind of more reasonable process route is through a partial quenching of a single material hammer to form gradient performance.Because of the comprehensive performance of the low-alloy steel with high hardness and high toughness,it can according to the situation of specific use on the composition and process optimization,in a wide range of hardness and toughness reasonable match(32?60HRC,and ak 10?100J/cm2).This paper is to develop components of the low-alloy steel of a middle carbon,which can form a gradient performance hammer,study the formation of gradient performance influencing factors,discuss the possible formation of gradient performance of the heat treatment process,and it can provide a reference for the actual industrial mass production of large-scale gradient performance car crusher hammer.The paper is based on the requirement of the performance of the car crusher hammer,design alloy composition range:0.4?0.5%C,1.4?2.0%Cr,0.8?1.3%Si,1.4?2.0%Mn,0.5?1.0%Ni,0.2?0.4%Mo.In accordance with the alloy composition,casting,and experiment.The results showed that the experimental steel cast structure is acicular martensite,normalizing and quenching cannot form a change in performance,but this kind of alloy steel hardness and toughness can satisfy the performance requirements of the car-damaged hammerhead.Through studies found is that the content of Mn and Cr in the alloy composition is too high,it make the transition from high temperature area becomes stable,accelerated the time of the bainite change,making the steel in a continuous air-cooled can be obtained bainite structure,and therefore it cannot form a performance change.Therefore,by reducing the content of Mn and Cr,redesigned alloy composition:0.4?0.5%C,0.8?1.2%Cr,0.8?1.3%Si,0.5?1.0%Mn,0.5?1.0%Ni,0.2?0.4%Mo.The alloy get enough change in performance between the quenched and the normalized,it satisfy with the requirements of gradient performance of the car crusher hammer.This paper studies the effects of the cast structure,austenitizing temperature,soak time,the austenite of tempering temperature:The austenitizing temperature and austenizing time in the experimental range(30min?90min)has little effect on the changes in the mechanical properties,it because under the same cooling rate will have similar microstructure;The tempering temperature has great influence on forming gradient performance;And the larger effect of cast structure on the performance of the gradient.The cast structure is martensite or bainite,then it cannot be obtained gradient performance by partial quenching.Only the cast structure is pearlite,it can meet the requirements of gradient performance of the car crusher hammer.The quenching can obtain high hardness(54HRC)and toughness(26J/cm2),the main organization is martensite;Normalizing obtain low hardness(42HRC)and higher toughness(50J/cm2),the main organization is the iron pearlite + ferrite organization.The change of performance between the quenching and the normalizing satisfy with the requirements of the gradient performance of the car crusher hammer.