It is commonly accepted that the drop in mechanical properties of INCONE1718(IN718) after long time exposure at high temperature is a result of coalescence of y", ?/ and the transformation of y" to 8-Ni3Nb p...It is commonly accepted that the drop in mechanical properties of INCONE1718(IN718) after long time exposure at high temperature is a result of coalescence of y", ?/ and the transformation of y" to 8-Ni3Nb phase. Besides the 7", ?/ and , the precipitation of B.C.C. -Cr is another factor that affects the mechanical properties of IN718. In this paper, the Thermal-Calc software is used to reveal the thermodynamic condition of -Cr formation. The calculated sections of the pseudo ternary diagrams of Cr-Nb-IN718 and Cr-Fe-IN718 explain why -Cr particles do not precipitate dispersedly in matrix but in the vicinity of phase. The selected area diffraction (SAD) of TEM confirms the crystallography relationship of -Crwith is (010) g// (-110) a.Cr, [100] s//[Hl] a-cr? In combination of TTT diagram with the Thermal-Calc and TEM results, the mechanism of -Cr formation in IN718 is suggested.展开更多
AISI H13 hot work tool steel is widely used for hot forging, hot-extrusion and die-casting because of its high temperature strength, impact toughness, heat checking resistance and wear resistance, etc. The thermally i...AISI H13 hot work tool steel is widely used for hot forging, hot-extrusion and die-casting because of its high temperature strength, impact toughness, heat checking resistance and wear resistance, etc. The thermally induced surface damage, i. e., thermal fatigne,is believed to be controlled by the magnitude of the imposed cyclic strain. The thermal fatigue on the surface of hot working die, which is responsible to the initiation of the cracks, is reported to result in more than 80 % of the failure of dies.展开更多
文摘It is commonly accepted that the drop in mechanical properties of INCONE1718(IN718) after long time exposure at high temperature is a result of coalescence of y", ?/ and the transformation of y" to 8-Ni3Nb phase. Besides the 7", ?/ and , the precipitation of B.C.C. -Cr is another factor that affects the mechanical properties of IN718. In this paper, the Thermal-Calc software is used to reveal the thermodynamic condition of -Cr formation. The calculated sections of the pseudo ternary diagrams of Cr-Nb-IN718 and Cr-Fe-IN718 explain why -Cr particles do not precipitate dispersedly in matrix but in the vicinity of phase. The selected area diffraction (SAD) of TEM confirms the crystallography relationship of -Crwith is (010) g// (-110) a.Cr, [100] s//[Hl] a-cr? In combination of TTT diagram with the Thermal-Calc and TEM results, the mechanism of -Cr formation in IN718 is suggested.
文摘AISI H13 hot work tool steel is widely used for hot forging, hot-extrusion and die-casting because of its high temperature strength, impact toughness, heat checking resistance and wear resistance, etc. The thermally induced surface damage, i. e., thermal fatigne,is believed to be controlled by the magnitude of the imposed cyclic strain. The thermal fatigue on the surface of hot working die, which is responsible to the initiation of the cracks, is reported to result in more than 80 % of the failure of dies.
