Research On The Heat Treatment And Properties Of Cast High-vanadium High-speed Steel/42CrMo Bimetallic Pipe

Bimetal composite pipe were widely used in the electronic and chemistry field because of its outstanding priority.Usually,the wear resistance was the typical priority of that material.The high-speed steel/42 CrMo Bimetallic tube which were newly designed in component was studied in this paper.The profile and micro structure of the raw sample which was accustomed to hot extrusion were analyzed and raw sample had been preliminary treated according to the analysis,then strengthen heat treatment carried on the sample either.OM,SEM,EDS and XRD were taken to detect the effect of preliminary treatment and strengthen treatment on the raw sample.Rockwell hardness,Micro hardness tester,Impact tester,Universal bending test machine were applied to explore the regulation between the treatment and mechanical property.Wear tester,Rotational friction tester and Multifuction surface analyzer studied on the effect of hot treatment on the wear resistance and anti friction.Finally,the structure and property attributed to the diffusion of elements in different phase were explored in detail.The results followed:1)The interface of high-speed steel/42CrMo was fine.High-speed steel were consisted of martensite,retained austenite and amounts of carbide which was seriously banded segregating.Meanwhile,the structure of 42CrMo was typical sorbide.2)The preliminary treatment reduced the segregation in the high-speed steel and decreased the hardness of the bimetal composite either.With the increasing tempering temperature,the hardness of bimetal steel was softened.The banded segregation in the high-speed steel dissolved when the bimetal steel sample tempering at 720 ? after quenching at 1100?.3)The quenching temperature resulted in varied structure of martensite and carbide in high-speed steel.With the increase of the quenching temperature,the martensite became thicker and the content of carbide decrease.The martensite was well-distributed and lessened in the high-speed steel at 1140? strengthen treating while the carbide diffused.4)Repeatedly tempering of strengthen treatment led to the break down of martensite and carbide which contributed to the performance of bimetal steel.And 540 ? repeated tempering after preliminary and strengthen treatment;the bimetal steel had a better anti friction co-efficiency and wear resistance.5)The inner stress in high-speed steel of the raw sample was intensified and the variation of micro hardness ranged significantly in the transition area.With the strengthen treatment,the ranged hardness became stable and transition area was widened.The intensified inner stress in the transition area and high-speed steel was released with 720 ? tempering.Obviously,the temperature of strengthen treatment sufficiently widened the transition area of micro hardness.