1000MW核电汽轮机高压转子耐蚀层堆焊工艺题稿.doc

1000 MW 核电汽轮机高压转子耐蚀层堆焊工艺研究 　　摘 要：核电汽轮机高压转子的耐蚀性一直是影响转子运行寿命的关键问题，本文针对 1000 MW 核电汽轮机高压转子进行了耐蚀层堆焊试验，并对堆焊工艺及堆焊层的性能开展了研究。首先，为了实现母材与堆焊层良好的成分过渡，在核电转子用 NiCrMoV 钢试板上堆焊低合金钢过渡层；而后逐层堆焊马氏体不锈钢耐蚀层，直到堆焊层成分达到马氏体堆焊金属的成分为止；最后进行去应力焊后热处理。对堆焊接头性能分析，结果表明，堆焊接头强度不低于母材，抗拉强度可以达到 783 MPa，同时具有优良的塑性和韧性。堆焊层中 Cr 元素的含量随着堆焊层厚度的增加以指数规律升高，在 15.5 mm 时达到 11.9 %与焊丝成分相当，表明此时的堆焊层已经满足耐蚀性的要求。研究结果进一步表明试验中所采用的堆焊层成分及堆焊工艺所获得的堆焊层具有优良的综合性能，可应用于核电高压转子的表面改性。 ? 　　关键词：核电汽轮机；高压转子；耐蚀性；堆焊工艺；接头性能 ? 　　Research on the Cladding Technology of 1000 MW Nuclear Steam ? 　　Turbine HP Rotor ? 　　Qiao Shangfei, Liu Xia, Shen Hongwei ? 　　（Shanghai Turbine Plant of Shanghai Electric Power Generation Equipment, Shanghai 200240） ? 　　Abstract: The surface corrosion resistance of HP rotor is a big issue in determining the service life. Cladding experiments were carried out on the surface of 1000 MW Nuclear Steam Turbine HP rotor . Low alloy filler metal was welded on a NiCrMoV plate as a transition layer on which the martensitic stainless filler metal was deposited. A post welding heat treatment was performed, the mechanical properties of cladding joint were tested and analyzed. The results show that the welding joint has excellent ductility and toughness, wher the ultimate strength is about 783 MPa which can be compared with the base metal. The chromium content increases with rising the cladding thickness. The chromium content reaches 11.9 % at the thickness of 15.5 mm which can meet the requirement of corrosion resistance. This cladding procedure is proved to be reliable and stable due to the excellent joint properties. And also this method has been applied on several 1000 MW nuclear steam turbine HP rotors. ? 　　Key words: nuclear steam turbine; rotor; cladding 　　序 言 ? 　　1000 MW 核电汽轮机组是当前最为先进的核 电汽轮机组之一，已经为阳江核电站等多个核电厂 所采用。核电高压转子是核电汽轮机组的核心部件， 在机组运行期间一直处于高速转动状态，对其性能 的要求十分严格。高压转子材料为 NiCrMoV 钢， 具有优良的强度和韧性，但在蒸汽温度较低的工作 环境下，转子汽封区域会发生腐蚀现象，危害转子 的性能，进一步影响安全性。为了满足转子汽封区 域表面耐腐蚀性能的要求，表面堆焊成为较好的改 性手段。马氏体不锈钢材料具有优良耐蚀性能，成为堆焊材料的优选材料。 ? 　　但是 NiCrMoV 钢是一种低合