Effect Of Pouring Process On Microstructure And Endurance Mechanical Properties Of Investment Casting K417G Alloy

Ni-based superalloy materials are widely used in today's spacecraft,aerospace and rocket motors as well as key hot-end components for ships and industrial gas turbines,such as engine turbine blades,engine guide vanes and integral turbine disks.The main characteristics of the alloy include good plasticity and excellent high-temperature strength.In this paper,the researches and tests were performed to K417 G alloy,and multiple K417 G alloy samples were prepared by different casting parameters;the microstructure of the samples was observed;the tensile and endurance mechanical properties of different alloy samples were measured;the effects of different pouring temperatures and insulation ways on the phase constitution and mechanical properties of alloys were studied;the fracture characteristics of K417 G alloy were also analyzed.Pouring temperatures of 1400?,1410 ? and 1420 ? were used to cast several K417 G alloy test bars by investment casting method in single-shell preheating and thermal insulation preheating modes.All the creep rupture life of the alloys on the condition of 760?/645 MPa met the standard requirements,their life was not less than 23 h.The creep rupture life of the alloys increased with the increase of pouring temperature.The elongation of the alloys also increased with the pouring temperature,all the elongation of the alloys met the standard requirements of more than 2%.The creep rupture life of the alloys on the condition of 950 ? /235 MPa met the standard requirements of more than40 h,and with the increase of pouring temperatures,the creep rupture life of the alloys gradually increased.The elongation of the alloys also increased with the pouring temperature.By using investment casting method,under the mode of sand filling heat preservation,K417 G alloy samples were casted with different pouring temperatures of 1390?,1400?,1410? and 1420?,respectively.All the creep rupture life of the alloys at 760?/645 MPa met the standard requirements of more than 23h;the creep rupture life of the alloy with the pouring temperature of 1390? was 178.72h;the creep rupture life of the alloy with the pouring temperature of 1400 ? was 60.88h;with the pouring temperaturefurther improved,the creep rupture life of the alloys decreased to 39.07 h and25.23 h.The creep rupture life of the alloys on the condition of 950 ? /235 MPa was all greater than the standard value of 40h;when the pouring temperature was 1390?,the creep rupture life reached the maximum of 70.57 h.When the pouring temperature was 1420?,the creep rupture life achieved the minimum of 56.15 h.Under the condition of 950?/235 MPa,the elongation of the alloys first decreased and then increased with the increase of the pouring temperature,with the lowest elongation of 7.76%.