Development Of High Capacity Steam Turbine Generator Rotor Slot Wedge Copper Alloy And Its High-temperature Properties

With the rapid development of the national economy, China's electricity demands have rapid growth, while the (ultra) supercritical turbine generator unit for high thermal efficiency, lower coal consumption, less pollution has been given great attention and been developed in China. Copper alloy slot wedge is one of the important structural components of turbine rotor, long-term continuous work at high temperature, in order to ensure safe and reliable operation of generating units, developing a good overall performance with (ultra) supercritical turbine-generator wedge of copper alloy, to replace imported products, to achieve localization has important engineering application value.This paper manufactured a series of slot wedge copper alloys with rich in natural resources, not or less of precious elements and elements of less pollution to the environment, universal testing machines, hardness machines and means of eddy current conductivity meter are used to study the copper alloys the mechanical and electrical properties in different heat treatment process, investigated impact of the microstructure when alloy elements added through metallographic microscope, SEM, XRD, and other equipments, and then analzyed and explained in theory. At the same time, taking into account the practical engineering application, it made a preliminary study about high temperature properties of some alloys. The results are shown as follows:(1) The new developed nine kinds of alloys got a better overall performance after solid solution at (950±10℃)×1.5 h and 30⁴0 % cold deformation and ageing at (480±20℃)×3⁴ h. 2# alloy of CuNiCrSiBeZr series, 4#, 5# and 6# alloys of CuNiCoCrBeZr series all reached a performance index 0# alloy in the performance test of room temperature, and the values of hardness and electrical conductivity of 2# alloy are HB 225 and 47.24 %IACS, it's tensile strength, yield strength and elongation can reach 831 MPa, 765 Mpa and 16.09 %; 4#, 5# and 6# alloys of CuNiCoCrBeZr series all reached a performance index 0# alloy in the high temperature tensile test at 427℃, thereinto, tensile strength, yield strength and elongation of 6# alloy can reach 596 MPa, 590 Mpa and 10.2 %.(2) Tensile fracture of room temperature analysis show that 3# and 6# alloys are ductile rupture, and 7# alloy is tough quasi-cleavage rupture; Tensile fracture of high temperature analysis show that 6# alloy has a mixed fracture with plenty of microvoid accumulation dimples and less quasi-cleavage rupture; Moreover softening temperature of 5# and 6# alloys reached 616℃and 606℃, and has a high resistance to softening performance.(3) The analysis show that, precipitates in alloys of CuNiCrSiBeZr series are Cr, Cr2Zr, Cu3Zr and Ni5Si2, may contain CuBe, NiBe, ZrBe and other small particles; Precipitates in alloys of CuNiCoCrBeZr series are Cr, Cr2Zr, Ni11Zr9 and Co0.52Cu0.48, may contain CuBe, NiBe, ZrBe, CoBe and other small particles; Precipitates in alloys of CuNiCrBeSiZr series are Cr, Cr2Zr, Cu3Cr, Ni10Zr7 and NiSi, may contain CuBe, NiBe, ZrBe and other small particles; Because interaction of multiple trace elements in the alloys result in various precipitation of second phase compounds, and gain good strengthening effect.(4) High temperature hardness of 4#, 5# and 6# alloys are higher than 0# alloy, and high temperature hardness of 4#, 5# and 6# alloys increase in turn; 6# alloy of CuNiCoCrBeZr series compared with 0# CuCo2BeZr alloy has good creep resistance, fracture time of 6# alloy is up to 149.7 h, steady-state creep rate is 4.96×10^-5 h^-1, cracks are mixed fracture modes with mainly intergranular fracture and partial transgranular fracture.(5) We only researched high temperature creep of 6# alloy of the new developed CuNiCoCrBeZr series, but 4#, 5# and 6# alloys of CuNiCoCrBeZr series can meet the turbine generator rotor at high temperature using requirement under bad conditions, in the performance test of room temperature, and the values of hardness and electrical conductivity of 6# alloy are HB 247 and 52.93 %IACS, it's tensile strength, yield strength and elongation can reach 861 MPa, 805 Mpa and 15.08 %; in the high temperature tensile test at 427℃, tensile strength, yield strength and elongation of 6# alloy can reach 596 MPa, 590 Mpa and 10.2 %.