含轴向对称裂纹锆合金包壳管断裂行为

作为装载核燃料的密封外壳,锆合金包壳管的断裂性能对于反应堆的安全运行至关重要。基于弹塑性有限元分析建立了TFAC试样的断裂韧度测试方法,完成不同氢含量锆合金TFAC试样的断裂韧性试验。研究结果表明,锆合金包壳管具有优良的抗裂性能,氢含量低于200 mg/kg时,其对包壳管断裂韧度的影响较小;当氢含量达到290 mg/kg时,包壳管的断裂韧度显著提高。研究可为锆合金包壳管在服役过程中的安全性评估提供数据支撑。     

9Ni钢焊接接头的力学性能与失效评定曲线

通过试验获得9Ni钢焊接接头、母材和焊缝在室温20℃和低温-158℃下的拉伸和断裂性能,对比分析了温度对性能的影响;建立了母材和焊缝的近似R6选择2失效评定曲线(FAC)以及9Ni钢焊接接头的FAC,并进行了对比。结果表明：低温下母材的拉伸和断裂性能以及接头和焊缝的拉伸性能均高于室温下,焊缝的断裂韧度几乎不随温度改变;不同温度下焊缝的屈服强度和断裂韧度均低于母材,焊缝是9Ni钢焊接接头的薄弱区域。由室温拉伸性能构建的近似选择2 FAC包络面积均略小于采用低温拉伸性能构建的FAC,故可用室温拉伸性能构建近似选择2 FAC对9Ni钢焊接接头进行安全评定;分段选取室温下母材和焊缝的近似选择2 FAC构建的焊接接头FAC能最保守地对低温9Ni钢含缺陷结构进行安全评定。     

TC11钛合金表面渗锆层组织及其摩擦学性能

为提高TC11钛合金的摩擦磨损性能,对合金表面进行双层辉光等离子渗锆处理,对渗锆层进行了物相分析、组织观察和微区成分分析,并在不同温度下进行了摩擦磨损试验。结果表明：TC11钛合金表面获得了组织致密、厚度为25μm、主要由α-Ti相组成的渗层,锆元素主要固溶在α-Ti相中;在室温和450℃时,渗锆层的摩擦因数均远小于T...     

0Cr18Ni9Ti不锈钢表面渗锆合金层的耐腐蚀性能及抗高温氧化性能

采用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备渗锆合金层,然后将其分别置于在0.5mol·L-1 HCl溶液、3.5%NaCl溶液、0.5mol·L-1 NaOH溶液中进行电化学腐蚀试验,另在静态空气中进行了1 000~1 150℃的高温氧化试验,研究了渗锆合金层的耐腐蚀性能及抗高温氧化性能,并与不锈钢基体进行了对比。结果表明:在三种溶液中,不锈钢基体的相对腐蚀速率分别为渗锆合金层的24.43倍、2.44倍、1.90倍,不锈钢基体表面发生了较为严重的腐蚀,而渗锆合金层只出现了局部腐蚀坑,这是因为在腐蚀过程中其表面形成了一层致密的ZrO2钝化膜;不锈钢基体和渗锆合金层的氧化质量增加曲线都基本遵从抛物线规律;在1 150℃氧化20h后,不锈钢基体表面氧化严重,而渗锆合金层的表面形貌较好,存在少量孔洞,组织相对致密。     

低碳合金钢及焊接接头断裂韧度的温度效应

利用Hopkinson压杆装置对某低碳合金钢及焊接接头不同温度下动态断裂韧度进行了测试,给出了试验温度控制方程,分析了温度对断裂韧度的影响.结果表明:在应力波加载(K≈106 MPa·m1/2/s)条件下,母材和焊缝断裂韧度降低;但是同一温度下母材的断裂韧度高于焊缝,原因主要是组织状态对应变速率敏感性不同;同时在分析该钢母材和焊缝断裂韧度温度效应的基础上,建立了应力波加载下母材和焊缝的断裂特征分析图,给出了温度、板厚和断裂韧度之间的关系.     

第二级时效工艺对7050铝合金厚板组织及性能的影响

研究了第二级时效工艺对7050铝合金厚板拉伸性能、断裂韧度及电导率的影响，并采用透射电镜及扫描电镜分析其强韧化机理。结果表明：该合金厚板在双级时效的第一级时效条件相同时，随第二级时效温度的升高或时效时间的延长，合金中沉淀相的尺寸和间距增大，合金强度下降，断裂韧度和抗应力腐蚀能力提高，切变和穿晶韧窝混合型断裂方式中的韧窝...     

熔体中氢含量对ZL114A合金冲击韧度的影响

通过测试铝合金熔体中的氢含量和合金的冲击韧度,分析材料显微组织和断口微观断裂特征,研究了铝合金熔体中氢含量对铸件冲击韧度的影响.结果表明:试验条件下合金中的气孔呈球形弥散分布,合金的冲击韧度随着氢含量的增多而增大.     

核燃料包壳锆合金表面吸氢开裂行为的研究进展

锆(Zr)及其合金因其在高压/高温水环境中的力学和化学性能、高剂量中子辐射下的结构稳定性和中子透明度,而被广泛用于核燃料包壳材料及其他核反应堆的重要结构材料.福岛核事故后,锆合金的腐蚀和吸氢行为成为耐事故核燃料包壳材料的重点研究方向之一.文中概述了锆合金氢化物的形成,并综述了3个因素对氢在锆合金中固溶度的影响,以及锆合...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

IC10合金的高温拉伸性能

利用力学测试与模拟试验机测得了IC10合金在很宽的温度范围(25～900℃)和不同应变速率(10-5～10-2S-1)下的应力一应变曲线,对曲线进行了分析;用扫描电子显微镜对试样的断口进行了分析.结果表明:室温下IC10合金的流变应力对应变速率不太敏感,而在900℃下对应变速率非常敏感;比较各温度下材料的屈服强度可以发现,当温度低于(含)800℃时,IC10合金的力学性能与室温下相当,而在更高的温度(900℃)下力学性能有所下降;在低于(含)800℃时断口主要以穿晶断裂为主,在900℃下主要为韧窝聚集型断裂,随着温度的增加,断口上韧窝更大、更深、更多.     

焊缝合金化对稀土铝锂合金焊缝组织及韧性的影响

通过焊缝合金化手段，探讨了合金元素锆和铈对不同含铈量的２０９０铝锂合金焊缝组织及断裂韧性的影响机制，并对焊后人工时效处理的影响进行了分析讨论。结果表明，采用所研制的新型焊丝焊接２０９０Ｃｅ铝锂合金，其焊缝组织明显细化．焊缝金属的裂纹扩展阻力显著增加．而焊后热处理将导致焊缝断裂韧性下降．     

铸态奥氏体-贝氏体球墨铸铁的研究

本文较系统地研究了在不同模数下,合金加入量对铸态奥氏体-贝氏体球墨铸铁的组织和性能的影响。研究结果表明,通过合金化获得铸态奥-贝球铁是可行的。它的抗拉强度可达9×10{sup}8N/m{sup}2以上,延伸率可达3%以上。并且它具有较高的低温冲击韧性,在-40℃时,冲击韧性（V型缺口）达4.6J。常温断裂韧性可达5.4×10{sup}7N/m{sup}(3/2),经325℃回火后可再提高20%,研究表明,残余奥氏体对于机械性能有良好的作用。     

Residual stresses in aluminium alloy friction stir welds

Residual stresses are detrimental to the fatigue, fracture and corrosion resistance of welds. The literature on residual stress measurements in aluminium alloy friction stir welds is reviewed. The results of a large number of longitudinal residual stress measurements performed by the slitting method on friction stir welds in 2024-T3, 6082-T6 and 5754-H111 aluminium alloys are compared and their origin discussed. From the current investigation, it can be derived that the type of machine used for welding has only little influence on the residual stress profile. The influence of alloy type and welding parameters on the magnitude of the residual stresses and the shape of their distribution across the weld is investigated. Their magnitude is far below the room temperature yield strength of the base material. A distribution with an ??M-shape?? is always found on age hardenable structural alloys (albeit more pronounced in 6082-T6 alloy than in 2024-T3 alloy), while a ??plateau?? is found in the case of the strain hardenable 5754 H111 alloy. The low magnitude and the differences in distribution of the longitudinal residual stress are attributed mainly to the microstructural changes in the weld centre and are discussed based on the hardness profiles performed across the welds. The paper also discusses the reasons why those results are in disagreement with a number of numerical simulations from the literature that do not account for the influence of the welding thermomechanical history on the material microstructure and properties.     

The erosion of heat-treated steels

The erosion behavior of a plain carbon steel (AISI-SAE 1020), an austenitic stainless steel (type 304) and a low alloy steel (AISI-SAE 4340) in various heat-treated conditions was determined. The testing was conducted at room temperature using aluminum oxide particles with an average size of 140 μm in an air stream. An attempt was made to characterize the erosion behavior as it relates to the mechanical properties obtainable in these alloys by conventional heat treatments. It was found that the ductility of the steels had a significant effect on their erosion resistance which increased with increasing ductility and that hardness, strength, fracture toughness and impact strength had little effect on erosion behavior. The platelet mechanism of erosion occurred in all the steels tested at all conditions.     

Tool wear in turning of titanium alloy after thermohydrogen treatment

The influence of hydrogen contents on the tool wear has been mainly focused on the flank wear of the common tool,and the influence of hydrogen contents on the rake crater wear(main wear type) of the tool,particularly for the fine granular material tool,has been less investigated comprehensively.In this paper,for the purpose of researching the influence of hydrogen contents on tool wear,the titanium alloy Ti-6Al-4V is hydrogenated at 800 ℃ by thermohydrogen treatment technology and the turning experiments are carried out by applying uncoated WC-Co cemented carbide tool.The three-dimensional video microscope is used to take photos and measure tool wear.The results show that both of crater wear depth(KT) and average flank wear width(VB) firstly decreases and then increases with the increasing of hydrogen content.The maximum reducing amplitude of KT and VB is about 50% and 55%,respectively.Under the given conditions,the optimum hydrogen content is 0.26%.It is considered that the reduction of cutting temperature is an important factor for improving tool wear after the Ti-6Al-4V alloy is properly hydrogenated.Furthermore,the reasons of hydrogen effect on the tool wear are chiefly attributed to comprehensive effect of hydrogen contents on microstructure,physical properties and dynamic mechanical properties of the Ti-6Al-4V alloy.The proposed research provides the basic data for evaluating the machinability of hydrogenation Ti-6Al-4V alloy,and promotes practical application of thermohydrogen treatment technology in titanium alloys.     

Effect of root pass filler metal on microstructure and mechanical properties in the multi-pass welding of duplex stainless steels

This paper is focused on the estimation of the effect of root pass chemical composition, in multi-pass GTA Weldments, on microstructure and mechanical properties of duplex stainless steel welds. We used two different filler metals, the super duplex ER 2594 and duplex ER 2209. Microstructures of different passes of welded joints are investigated using optical microscope and scanning electron microscope. The relationship between mechanical properties, corrosion resistance, and microstructure of welded joints is evaluated. It is found that the tensile and toughness properties of the first weldment, employing the combination of ER 2594 in the root pass and ER 2209 in the remaining, are better than that of the second weldment employing ER 2209 all passes, due to the root pass grains refinement and its alloy elements content as chromium Cr and nitrogen N. The microstructure indicates the presence of austenite in different forms on the weld zone of ER 2209, same in the case of ER 2594, but with higher content and finer grains size, in particular Widmanstätten austenite WA. Potentiodynamic polarization tests of the first weld metal evaluated in 3.5% NaCl solution at room temperature have been demonstrated a corrosion resistance higher than that of the second weld metal. This work addressed the improvement of the corrosion resistance using appropriate filler metal without getting any structural heterogeneity and detrimental changes in the mechanical properties.     

硼含量对铅镁铝合金组织与力学性能的影响

采用真空熔炼法制备了含硼的铅镁铝合金,通过扫描电子显微镜、X射线衍射仪、能谱仪和力学性能试验机等研究了硼含量对合金组织与力学性能的影响。结果表明:添加硼后,合金中出现了黑色的颗粒状AlB2相,且与Mg-Mg17Al12共晶组织相伴生;随着硼含量的增加,AlB2相分布趋于均匀化,Mg-Mg17Al12共晶相增多;当硼的质量分数为1%时,合金的力学性能最好,抗拉强度、硬度和伸长率分别为105MPa,160MPa和6.87%,室温拉伸断口主要为韧性断裂和准解理断裂的混合特征。     

硅锰钼钒钢低温回火脆性问题的研究

本文利用冲击韧性试验、断裂韧性试验、显微断口形貌观察及离子探针等分析方法研究了硅锰钼钒钢的低温回火脆性。试验结果表明,不含钼的硅锰钢,有明显的低温回火脆性,这个脆性出现在360℃（以下简称360℃脆性）,加入钼（＞0.33%）能使360℃脆性大大减弱,甚至完全被抑制。但钒含水量量从0.05到0.33%对于60℃脆性无显著影响。钼和钒对断裂韧性的影响具有与冲击韧性相似的规律。离子探针的分析结果表明,硅锰钢360℃脆性的出现是与磷沿奥氏体晶界的偏析有关。     

镍对高铝锌合金组织和性能的影响

着重研究了金属元素镍对高铝锌合金ZA-27的结晶组织、枝晶成分偏析以及常温和高温机械性能和耐蚀性能的影响。试验结果表明,金属元素镍可以改善ZA-27合金在常温与高温下的机械性能,并且对其耐磨性能和耐热性能均有利。     

EFFECT OF DYNAMIC LOADING ON FRACTURE BEHAVIOR OF WELDED JOINTS OF STRUCTURAL STEEL

To investigate the effect of dynamic loading on fracture behavior of welded joints of structural steel Q23SB and 16Mn in common use and compare the earthquake resistances of the two kinds of materials, dynamic tension and fracture toughness tests are carried out at room temperature. On the basis of the tests, the stress-strain fields near the crack tip of the compact specimens are analyzed by three-dimensional finite element model. The test results and finite element analysis results show that, the fracture toughness of welds and base metal of 16Mn steel increases with the increment of loading rate. Compared with 16Mn steel, Q235B steel is more sensitive to dynamic loading. The fracture toughness of welds of Q235B is comparatively low under static loading and dynamic loading at room temperature. Compared with the static loading, the fracture toughness of Q235B parent metal under dynamic loading decreases by about four times. Therefore, it can be concluded that compared with 16Mn steel, the earthquake re