Effect Of The Temperature Sensitive Characteristic On High-temperature Mechanical Properties Of Inconel 625 Alloy

Profit from the excellent corrosion resistance,oxidation resistance and high temperature mechanical properties of Inconel 625 alloy,it was used in nuclear power,chemical industry,military and marine fields.Due to the variety of alloying and complex composition,the mechanical properties of nickel base superalloys would be changed in a narrow temperature range under the condition of high temperature and load.In this research,the above characteristics were defined as the Temperature Sensitive Characteristic.Aim to the temperature sensitive characteristic of Inconel 625 alloy,the high-temperature tensile tests at different parameters were carried to investigate the effect of temperature on high-temperature mechanical properties of Inconel 625 alloy.The effect of creep temperature on creep resistance and microstructure evolution of Inconel 625 alloy was studied by high temperature creep tests at different temperatures.In high-temperature tensile tests under different tensile temperatures,it was found that the tensile strength of Inconel 625 alloy increased with increasing of temperature at 650~700?,which was different from the general evolution rule of tensile strength.In subsequent observation of the microstructure,it was found that the Cr rich M23C6 carbides and the Nb rich MC carbides decomposed at 700?.The morphology of the Cr rich M23C6 carbides changed form large cubes into small cubes and the morphology of the Nb rich MC carbides changed form irregular block into lamellar block.Due to the decomposition of the carbides,the particle dispersion strengthening effect was obtained,and the tensile strength of the alloy wereimproved at 700?.The reason for the decomposition of carbides is deduced as the stress induced in a certain temperature range.In high-temperature tensile tests under different strain rates,it was found that the correlation between mechanical parameters of the Inconel 625 alloy is not significant.In subsequent observation of the microstructure,it was found that with increasing of strain rates,the morphology of Cr rich M23C6 carbides which precipitated form grain boundaries changed form discontinuous ball block into continuous granular.In high-temperature tensile tests under different solid solution treatments,it was found that when the solution temperature reached 1170?,the average grain size increased and the average grain size was about 79?m.The elongation of the samples decreased with the increase of solution temperatures,which was contrary to the results of tensile tests at room temperature.The tensile strength of the specimens decreased with increasing of solid solution treatment temperatures,Except for the tensile strength of the specimens at 1130?,it was found that the ? phase precipitated at 700?.With increasing of the solid solution treatment temperatures,the content of the ? phase increased and led to the high-temperature strength decreased.In high-temperature creep tests under different temperatures,it was found that the Inconel 625 alloy exhibited obvious temperature sensitivity characteristic when it is subjected to creep tests in the temperature range of 650-800?.When the creep temperature was below 750?,the creep curves of the specimens was in the initial creep stage for a long time.When the creep temperature was higher than 750?,the specimens showed complete three stage of creep.When the creep temperature rose to 800?,the steady creep stage of the creep curves was shortened sharply.In the observation of the microstructure,it was found that with increasing of the creep temperatures,the precipitation of the ? phase increased,and the ? phase growth from grain boundaries to crystal in needle like form.The precipitation and growth of the ? phase reduced the high temperature creep resistance of the alloy,which resulted in the decrease of the creep resistance of the alloy at 800?.