Investigation into Hot Deformation Behavior of Spray Formed Superalloy GH742

In order to evaluate the deformation characteristics of spray formed superalloy GH742 and determine the appropriate forging procedure of the alloy on this basis,the influence of deformation temperature and strain rate on the ductility of spray formed GH742 was investigated by using the Gleeble-3500 thermal-mechanical testing machine. It is shown that the forgeability of spray formed GH742 is better than conventional GH742 by ingot metallurgy because of refined grain structure and enhanced chemical homogeneity of spray formed GH742.In the temperature range of 1020 to 1100℃,the ductility of spray formed GHT742 is dependent on the deformation temperature and is increased linearly in proportion to the increment of deformation temperature, which is more than 40% at 1020℃ and more than 60% at the temperature between 1100 and 1140℃.Furthermore,the results indicate the flow stress is affected considerably by the deformation temperature and strain rate.In the temperature range of 1020 to 1140℃,the maximum flow stress of spray formed GH742 increases with the increment of strain rate and decreases with the increment of the deformation temperature.     

高温多轴比例与非比例循环加载下疲劳寿命预测

利用薄壁圆管和缺口试样,在MTS 809电液伺服材料试验系统上对GH4169合金的高温多轴疲劳特性进行了实验研究．实验采用对称轴向和扭转应变控制、比例与非比例循环加载,轴向与扭转应变的相位差分别为0°,45°,90°．通过对薄壁圆管和缺口试样的高温多轴疲劳寿命特性分析,基于临界面方法提出了一个的多轴疲劳寿命预测模型,在考虑临界面上最大剪应变和正应变对多轴疲劳损伤贡献的同时,还引入了应力状态对多轴疲劳寿命的影响因素．应用新模型对GH4169合金高温多轴疲劳寿命进行预测结果表明,该模型对于缺口试样和薄壁圆管的高温多轴疲劳寿命估算具有较高的准确性．     

Absorption effect of pure nickel on the corrosion behaviors of the GH3535 alloy in tellurium vapor

In this study,pure Ni was demonstrated to pro-tect the GH3535 alloy from Te vapor corrosion because of its strong absorption capacity.Severe Te corrosion of a single GH3535 alloy sample occurred in Te vapor at 700℃,which manifested as complex surface corrosion products and deep intergranular cracks.However,when pure Ni and the GH3535 alloy were put together in the vessel,the GH3535 alloy was completely protected from Te corrosion at the expense of the pure Ni.Thermody-namic calculations proved that the preferential reaction between pure Ni and Te vapor reduced the activity of Te vapor considerably,preventing the corrosion of the GH3535 alloy.Our study reveals one potential approach for protecting the alloys used in molten-salt reactors from Te corrosion.     

GH4169D合金电子束焊接接头显微组织和持久断裂特征

采用金相显微镜和扫描电镜分析了GH4169D合金电子束焊接接头的显微组织,利用显微硬度计测试了母材、热影响区和焊缝的显微硬度,采用体式显微镜和扫描电镜研究了焊接接头持久断裂特征.结果表明,GH4169D 母材中的主要析出相为1～20 μm 长的片层状晶界η相、30～80 nm 的颗粒状γ'相和少量的碳氮化物.热影响区中...     

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异种金属1Cr18Ni9Ti和GH3044在点焊后X光检查时发现裂纹。通过对焊点进行金相检查、断口观察和电镜能谱分析后表面发现:焊缝组织为单相奥氏体组织,裂纹断口为典型焊接热裂纹形貌,焊点中镍含量较高。经过分析验证得出结论:由于焊接过程中GH3044熔入量大,导致焊缝中镍含量增大,形成单相奥氏体组织,产生焊接热裂纹。     

Exposure and effects assessment of persistent organohalogen contaminants in arctic wildlife and fish

Persistent organic pollutants (POPs) encompass an array of anthropogenic organic and elemental substances and their degradation and metabolic byproducts that have been found in the tissues of exposed animals, especially POPs categorized as organohalogen contaminants (OHCs). OHCs have been of concern in the circumpolar arctic for decades. For example, as a consequence of bioaccumulation and in some cases biomagnification of legacy (e.g., chlorinated PCBs, DDTs and CHLs) and emerging (e.g., brominated flame retardants (BFRs) and in particular polybrominated diphenyl ethers (PBDEs) and perfluorinated compounds (PFCs) including perfluorooctane sulfonate (PFOS) and perfluorooctanic acid (PFOA) found in Arctic biota and humans. Of high concern are the potential biological effects of these contaminants in exposed Arctic wildlife and fish. As concluded in the last review in 2004 for the Arctic Monitoring and Assessment Program (AMAP) on the effects of POPs in Arctic wildlife, prior to 1997, biological effects data were minimal and insufficient at any level of biological organization. The present review summarizes recent studies on biological effects in relation to OHC exposure, and attempts to assess known tissue/body compartment concentration data in the context of possible threshold levels of effects to evaluate the risks. This review concentrates mainly on post-2002, new OHC effects data in Arctic wildlife and fish, and is largely based on recently available effects data for populations of several top trophic level species, including seabirds (e.g., glaucous gull (Larus hyperboreus)), polar bears (Ursus maritimus), polar (Arctic) fox (Vulpes lagopus), and Arctic charr (Salvelinus alpinus), as well as semi-captive studies on sled dogs (Canis familiaris). Regardless, there remains a dearth of data on true contaminant exposure, cause-effect relationships with respect to these contaminant exposures in Arctic wildlife and fish. Indications of exposure effects are largely based on correlations between biomarker endpoints (e.g., biochemical processes related to the immune and endocrine system, pathological changes in tissues and reproduction and development) and tissue residue levels of OHCs (e.g., PCBs, DDTs, CHLs, PBDEs and in a few cases perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonates (PFSAs)). Some exceptions include semi-field studies on comparative contaminant effects of control and exposed cohorts of captive Greenland sled dogs, and performance studies mimicking environmentally relevant PCB concentrations in Arctic charr. Recent tissue concentrations in several arctic marine mammal species and populations exceed a general threshold level of concern of 1 part-per-million (ppm), but a clear evidence of a POP/OHC-related stress in these populations remains to be confirmed. There remains minimal evidence that OHCs are having widespread effects on the health of Arctic organisms, with the possible exception of East Greenland and Svalbard polar bears and Svalbard glaucous gulls. However, the true (if any real) effects of POPs in Arctic wildlife have to be put into the context of other environmental, ecological and physiological stressors (both anthropogenic and natural) that render an overall complex picture. For instance, seasonal changes in food intake and corresponding cycles of fattening and emaciation seen in Arctic animals can modify contaminant tissue distribution and toxicokinetics (contaminant deposition, metabolism and depuration). Also, other factors, including impact of climate change (seasonal ice and temperature changes, and connection to food web changes, nutrition, etc. in exposed biota), disease, species invasion and the connection to disease resistance will impact toxicant exposure. Overall, further research and better understanding of POP/OHC impact on animal performance in Arctic biota are recommended. Regardless, it could be argued that Arctic wildlife and fish at the highest potential risk of POP/OHC exposure and mediated effects are East Greenland, Svalbard and (West and South) Hudson Bay polar bears, Alaskan and Northern Norway killer whales, several species of gulls and other seabirds from the Svalbard area, Northern Norway, East Greenland, the Kara Sea and/or the Canadian central high Arctic, East Greenland ringed seal and a few populations of Arctic charr and Greenland shark.     

GH4169高温合金惯性摩擦焊的有限元模拟

基于Ansys有限元分析软件,建立了GH4169高温合金惯性摩擦焊过程的二维模型,进行了热力耦合分析,得到了焊接过程中的瞬时温度场和应力应变场,获得了焊接缩短量。根据惯性摩擦焊工艺分析了温度场和应力应变场的形成过程。     

GH864合金显微组织与力学性能的关联性

通过对GH864合金进行不同的固溶处理及时效处理,研究合金中g￠相的含量变化规律及碳化物回溶析出规律,及其对合金晶粒度的影响和对拉伸性能、蠕变性能及裂纹扩展性能的影响。结果表明,相同热处理制度下,晶粒越均匀细小,强度越高;晶粒尺寸越大,裂纹扩展速率越低;在960~1080 ℃范围内,g￠相含量随固溶温度的升高而降低,经过时效处理后g￠相含量趋于一致,此过程冷却介质对g￠相含量影响不显著;g￠相和碳化物交互作用影响合金晶粒尺寸长大,在1020 ℃以下固溶处理,晶粒长大十分缓慢。此外,合金的晶粒度尺寸对蠕变性能影响显著,存在最佳晶粒度以使性能发挥最优。     

小型无人机发动机温度监控系统设计

为了实时监控小型油动无人机的发动机工作温度,设计开发了基于K型热电偶的4路温度监控系统;该系统采用模拟开关CD4052作通道切换,选通的热电偶信号经放大调理,由STM32F103控制器片上A/D采集,经DS18B20数字温度传感器作冷端补偿,最终以Modbus RTU协议将温度值发送到485总线上;经调试校准,该温度监控系统在蚊子直升机MZ202型发动机正常工作温度范围内与原机温度仪表相差±3℃,数据刷新率大于2 Hz,且工作稳定抗干扰能力较强,为发动机调校提供了可靠的依据,有效地保障了发动机安全稳定运行;该温度监控系统也可用于Rotax582,Rotax912/914等小型活塞航空发动机缸头及排气温度的采集与监控。     

GH169高温合金主要相分析

用透射电镜对GH169高温合金主要强化相γ′、γ″进行分析观察及稳定相δ的亚结构及有关晶体学的测量计算。结果得出,γ″相具有三种不同位向的变体。利用γ′、γ″在(110)倒易面上超结构斑点重合来同时显现γ′、γ″相。通过迹线分析方法测量得出δ相的亚结构为层错,层错面为。