【作者】 杨小垒；

【导师】 邓德伟；

【作者基本信息】 大连理工大学 ， 材料连接技术， 2011， 硕士

【摘要】 锆合金因其具有优秀的耐腐蚀性能和机械性能而被广泛地应用于化工和核电工业。随着核电以及化工行业的迅猛发展,锆合金及其研究越来越受到人们的重视,其中锆合金的腐蚀过程和腐蚀机理的研究成为关注的焦点。本文对不同热处理条件下Zr-Nb合金(Zr705)的力学和耐腐蚀性能进行了研究,结果显示：首先,热处理工艺条件对Zr-Nb合金力学和耐腐蚀性能有着显著的影响；其次,在Tcq(在850℃-870℃之间的某个温度或温度区间)以下对合金进行淬火处理,可以得到较为优良的耐腐蚀性能,而在Tcq以上对合金进行淬火处理,可以使合金获得较高的强度,但合金抗腐蚀性能会下降；再次,870℃淬火并时效后的Zr705合金在力学和耐腐蚀性能方面均表现良好。采用金相、扫描电镜、透射电镜和电子探针等实验手段对热处理条件影响Zr-Nb合金力学和耐腐蚀性能的机理进行了分析,发现热处理对Zr-Nb合金性能的影响主要是通过改变Nb元素的分布,晶粒显微结构形态以及第二相粒子的形态来完成的。FV520B不锈钢是风机叶片用钢,属马氏体沉淀硬化型不锈钢,其机械以及耐腐蚀性能优良,焊接性能好且易于加工,因此被广泛应用于风机行业,尤其是风机叶片材料。叶片疲劳性能的好坏是风机安全运行的重要保障。本次研究FV520B不锈钢角焊缝接头疲劳性能,测试结果：481MPa的名义平均应力下,对应5×106疲劳寿命的名义疲劳极限为56MPa。首先根据疲劳实验断口,对疲劳试件断裂分为两种类型,之后通过SEM对断口进行微观形貌分析,并结合宏观金相和微观焊缝与母材组织结果,发现：焊接之后的热处理工艺消除了热影响区的不利影响；实验中两类疲劳断裂分别是由焊缝与母材的组织差异以及焊缝中焊道之间存在的夹杂导致的。最后对疲劳断裂机理进行了阐述。更多还原

【Abstract】 Zr alloys have been widely used in chemical and nuclear industries owing to the excellent corrosion resistance and mechanical properties. With the rapid development of nuclear power and chemical industry, the corrosion mechanism of Zr alloys has been paid more and more attention. The mechanical performance and corrosion resistance of Zr-Nb alloy (Zr705) after being treated in different ways is tested. It is found that the properties of Zr-Nb alloy are significantly affected by heat treatment. The most important parameter during the heat treatment is quenching temperature. The Zr-Nb alloy, quenched below the critical quenching temperature Tcq (a temperature or a range of temperature between 850℃-870℃), shows good corrosion resistance performance. However, alloy quenched above the Tcq, gets a high strength and a decrease on corrosion resistance. Zr705 quenched 870℃and tempered can get both high strength and good corrosion resistance. Through the study on the basis of the evidences gotten by means of metallographic, SEM, EPMA and TEM, the conclusion can be drawn as that the effect of heat treatment on the performances of Zr-Nb alloy is primarily because of the mechanism of the changing of the distribution of Nb, the quantity of (3-Zr, and the morphology of grains.FV520B stainless steel is a new type of martensitic stainless steel. Due to the excellent mechanical properties, high corrosion resistance and good welding performance, the steel is widely used in blade material of wind turbine industry. The fatigue performance of leaves is an important factor in the running of wind turbine. Therefore, the fatigue performance of fillet weld of FV520B stainless steel was tested. Under the applied nominal average stress of 481MPa, the nominal fatigue limit 56MPa with fatigue life 5×106 was obtained. The fractures, separated into two types, were observed by SEM. Combined SEM results with macro and micro metallographic of base metal and weld, it was found that the heat treatment after welding eliminated the adverse effects of the heat-affected zone; two types of fractures were caused by, respectively, differences between the microstructures of the welding and base metal as well as the inclusions existed between the weld heads. Furthermore, the fatigue mechanism was also researched here.更多还原