Study On Thermal Deformation Behavior Of 15Cr-30Ni-Fe Alloy For Internal Combustion Engine Valve

In recent years,with the development of automotive internal combustion engine cylinder direct injection,turbo charge and so on to improve the efficiency of combustion technology is widely used,the exhaust valve material need better corrosion resistance and oxidation resistance and high strength under high temperature.With the future of the automobile emission requirements continuously improve,traditional automotive exhaust valve steel 21-4N and 21-4NWNb has been unable to meet the design requirements of the future,but the traditional nickel based valve alloy for example GH4080 and GH4751 are too expensive.So it is need to develop a new kind of economical iron-nickel base alloy.In this paper,the thermal deformation behavior and heat treatment process of 15Cr-30Ni-Fe valve are analyzed and studied.The results would help to guide the actual production.The main research contents are as follows:1.Using Thermo-Calc numerical simulation technology,the phase diagram of 15Cr-30Ni-Fe alloy is calculated,which provides referenceprocess parameters for smelting and hot working.2.The thermal simulating tests were carried out on the Thermecmastor-Z thermal simulation test machine.The hot compression test temperature was 900,950,1000,1030 and 1050?.The strain rate was1,5,10 and 20s^-11 respectively.The maximum strain capacity was 40%.The stress-strain curves of different test temperatures were obtained.The fluid curve,microstructure and hot working processing map was discussed.The results show that the deformation temperature and strain rate have obvious influence on the thermal deformation behavior of the 15Cr-30Ni-Fe alloy.With the increase of deformation temperature and deformation rate,the material is changed to dynamic recrystallization.The best deformation temperature is 1050¹000?,and the best strain rate is 10²0s^-1.3.The heat treatment process was studied,the 15Cr-30Ni-Fe alloy can be obtained good performance after 980?solution and 760?aging treatment.4.The high temperature strength and the high temperature endurance of 15Cr-30Ni-Fe alloy was studied.The alloy has better high temperature strength below 700?temperature and 230Mpa stress.