热交换器换热管内壁涡流检测显示判定方法

针对在热交换器换热管涡流检测过程中遇到的内壁附着物、磁导率变化等涡流信号与真实的内壁缺陷信号特征基本一致,且用常规的分析方法难以辨别的问题,通过在实验室条件下利用实际缺陷换热管和人工缺陷试验管相结合的方法,得出了内壁缺陷与伪缺陷的判定方法,对Bobbin和旋转探头内壁缺陷的检测能力进行了验证,并通过对内壁缺陷的涡流检测深度与金相检验深度进行对比分析,得出其定量检测偏差的范围,为涡流检测内壁显示的定性和内壁缺陷的定量检测提供技术支持。     

电梯导轨开裂分析

采用金相检验、力学性能测试、化学成分分析等方法对某电梯导轨开裂的原因进行了分析。结果表明,导轨内壁R角处开裂与导轨在成形过程中产生的折叠类缺陷有关,这类缺陷在外力作用下形成了应力集中区,诱发在折叠处起始的疲劳裂纹,并向外壁扩展,导致导轨发生早期失效。     

油气管内壁缺陷的微磁检测技术

针对油气管内壁在服役过程中可能出现的裂纹、腐蚀等影响油气管安全运行的缺陷,提出了一种基于地磁场环境下的微磁检测技术。通过对试验样管的内壁制作人工刻槽,根据油气管的现场环境,设计了油气管微磁检测仪,并对油气管内壁进行试验验证。通过对磁传感器采集到的磁场强度进行差分处理分析,并实现了二维成像。试验结果表明,微磁检测对管筒内壁具有很好的检测效果。同时,该成像方法能够直观地显示出缺陷的具体位置,为缺陷的判定带来便捷。     

蒸汽发生器传热管制造阶段涡流检测缺陷研究

根据相关要求三代核电蒸汽发生器传热管在出厂前需进行100%全管内涡流检测。制造过程中产生的缺陷会导致管材拒收。为了研究管材制造缺陷,对部分拒收缺陷管进行了补充检测。补充检测主要采用了以下几种方式:bobbin探头复探、旋转探头复探、目视检测、渗透检测。通过补充检测发现制造缺陷主要有以下几类:外壁缺陷、单个内壁点状缺陷、单个内壁周向缺陷、内壁环形缺陷等。产生的主要原因为外壁磕碰、内壁夹杂或气孔、轧制不均匀等。     

30CrMnMo钢管热处理裂纹原因分析

某公司一批30CrMnMo原料钢管在调质热处理后的超声波检验中,发现大部分管体存在热处理裂纹缺陷。对带有缺陷的管体和入厂原料管体分批取样,采用直读光谱仪、金相显微镜、扫描电镜等设备分析缺陷样品的化学成分、金相组织、宏观和微观形貌。分析结果表明:该批原料钢管存在轧管折叠、内壁凹凸不平和P元素偏析缺陷;在热处理淬火时,上述缺陷引起应力集中,产生大量淬火裂纹,导致管体开裂。建议钢管原料厂改善轧制工艺,减少轧制折叠、凹坑缺陷;并且提高钢材冶炼质量,严格控制P等有害元素的含量。     

无缝钢管典型内折叠缺陷分析

烟台鲁宝钢管有限责任公司斜轧生产[Φ]177.8 mm×10.36 mm P110套管过程中出现一种较为典型的螺旋内折叠缺陷,严重影响产品质量。本文从宏观缺陷特征和微观金相特征出发,对该内折叠缺陷的形成原因进行了分析,认为管坯中心疏松、中间裂纹等铸坯缺陷是导致该内折缺陷产生的关键因素。     

45MnCrMo钻铤管内壁裂纹成因分析

在生产45MnCrMo钻铤管时,钢管内壁常出现较多裂纹,影响了钢管质量及成材率。通过采用光学显微镜、扫描电镜和能谱仪、热模拟试验机、低倍热酸浸分析测试手段,分析研究了钻铤管内壁缺陷特征和形成原因。结果表明:45MnCrMo钻铤管的内壁缺陷,是由于管坯穿孔过程中,内壁金属与顶头在摩擦和扭转变形等复杂应力作用下产生了较高的温升,从而导致毛管局部区域过热失塑、晶界弱化所形成,与管坯的冶金质量无关。提出了改进钻铤管内壁质量的有效措施。     

弹壳打凹-平底成形微折叠缺陷分析及改进措施

以某型号弹壳为研究对象,针对初始设计方案中弹壳底部成形后底火室侧壁微折叠的问题,通过微观组织观察和数值模拟确定微折叠产生于打凹成形,而导致微折叠产生的原因为：打凹成形过程中,隔板处金属的径向和轴向流动明显快于内侧壁,导致隔板与内壁连接处圆角的曲率半径持续变小,直至出现微折叠缺陷。同时,该微折叠缺陷在平底成形时保留并随着侧壁金属的轴向流动向下移动,与实际观测到的微折叠缺陷位置相吻合。为提高弹壳成形质量和避免该缺陷问题,提出一种修改打凹成形模具尺寸以改善打凹成形金属流动的改进方案,数值模拟和工艺试验结果均表明,采用改进方案后,打凹壳、平底壳均无微折叠缺陷,其他尺寸达到设计要求,改进工艺方案能够满足实际生产需求,提高了弹壳底部成形质量。     

止推轴承座挤压成形过程中产生折叠缺陷的原因及解决方案

针对止推轴承座挤压成形过程中在内壁上产生的折叠缺陷,采用MSC/superform软件进行数值模拟,分析金属的流动规律,找出了缺陷形成的原因;提出了解决方案,采取在凸模上相应位置增加凸起,按照节约材料的原则求得了最佳的凸起大小.最终通过物理实验对结论进行了验证.     

核电站钛管内壁缺陷判伤曲线

核电站热交换器钛管中缺陷大多产生于内壁,因此对内壁缺陷的定量研究是一个重要的问题。将涡流试验相似律应用到钛管内壁判伤曲线研究,通过试验解决了内壁缺陷定量问题,弥补了涡流检测标准的不足。     

低压铸造升液管优化的水模拟

用水模拟低压铸造中的合金液，研究了升液速度、升液管结构尺寸对充型流动形态的影响。结果表明，型腔有效截面积S4一定时，升液管内径D1较大有利于低压铸造实现快速平稳充型。当D1〈5．0cm时，升液管内截面积S1与升液管出口截面积S2比值应小于1．6；型腔有效截面积S4与升液管出口截面积S2比值对充型流动形态的影响比升液管结构的影响显著，S4：S2应小于40。当Dt〉5．0cm时，S1：S2应小于3，升液管结构的影响变得重要，可采用适当锥度的锥形口来优化升液管的结构。一般S4：S2应小于25。     

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文章就27SiMn液压支架用无缝钢管内壁镀镍后,在使用过程中内壁出现的起泡和剥落等缺陷进行了检测分析,经分析其原因为无缝管内壁镀镍前未完全清洗干净,导致镀镍层与内壁局部结合不好,在使用中起泡并剥落。     

The growth of nanophases in the clean room inside single-wall carbon nanotubes

The interior of single-wall carbon nanotubes is studied by filling fullerenes into the one-dimensional nanospace inside the tubes using different filling methods. Filling from solution is demonstrated as efficient as filling from the vapor phase. Evidence for successful filling comes from a transformation of the encapsulated carbon atoms to a secondary tube centered inside the primary tube. Isotope-labeled fullerenes are used to disentangle the Raman response from the two shells in double-wall carbon nanotubes.     

水下气动发射装置内弹道仿真和参数影响分析

对某水下气动发射装置进行了理论分析,研究了其内弹道特性。利用数学建模方法对发射过程进行了建模并对内弹道性质进行了计算。对影响内弹道性能的3个主要参数:武器运动的初始阻力、发射阀最大开启面积和发射气瓶初始充气压强进行了分析。计算结果表明:发射管最大膛压的主要影响参数为武器运动初始阻力;而武器出管速度的主要影响参数为发射气瓶初始充气压强和发射阀的最大开启面积。     

Plasma immersion ion implantation into cylindrical bore using internal inductively-coupled radio-frequency discharge

Plasma immersion ion implantation (PIII) is a potentially excellent interior surface treatment technique due to no line-of-sight restriction. However, some problems have been encountered due to the low ion energy and ion fluence non-uniformity especially for treatment of the interior wall of a thin tube. In this paper, a new method for inner surface PIII using internal inductively-coupled radio-frequency (RF) discharge is described. A cylindrical inductive coil inserted inside the tube serves as both the plasma source and grounded electrode to avoid overlapping of the plasma sheath fronts propagating from opposite sides. The effects of the gas species, gas pressure, RF power, and number of coil turns are investigated. Our results demonstrate the feasibility of this novel inner surface treatment method and the number of turns in the coil has a critical influence on the discharge behavior. If the number of turns is little, the plasma density is low and non-uniform inside the tube due to the relatively intense capacitively-coupled RF discharge at the two ends. In contrast, the plasma density and uniformity are evidently improved by using more turns in the coil.     

Equal channel angular extrusion of NiTi shape memory alloy tube

As a new attempt, equal channel angular extrusion (ECAE) of nickel–titanium shape memory alloy (NiTi SMA) tube was investigated by means of process experiment, finite element method (FEM) and microscopy. NiTi SMA tube with the steel core in it was inserted into the steel can during ECAE of NiTi SMA tube. Based on rigid-viscoplastic FEM, multiple coupled boundary conditions and multiple constitutive models were used for finite element simulation of ECAE of NiTi SMA tube, where the effective stress field, the effective strain field and the velocity field were obtained. Finite element simulation results are in good accordance with the experimental ones. Finite element simulation results reveal that the velocity field shows the minimum value in the corner of NiTi SMA tube, where severe shear deformation occurs. Microstructural observation results reveal that severe plastic deformation leads to a certain grain orientation as well as occurrence of substructures in the grain interior and dynamic recovery occurs during ECAE of NiTi SMA tube. ECAE of NiTi SMA tube provides a new approach to manufacturing ultrafine-grained NiTi SMA tube.     

大型渗碳炉用CrNiNRE耐热钢辐射管的失效机理研究

应用SEM电镜、能谱分析及X射线衍射等方法研究了高镍铬含氮和稀土的奥氏体型CrNiNRE耐热钢辐射管在长期高温渗碳中的失效机理和组织特征。结果表明,CrNiNRE钢在长期高温和单边渗碳作用下,使得M7C3碳化物持续长大,并促使奥氏体区域退缩和沿碳化物周边形成裂隙;合金元素的重新分布造成基体贫铬;管内壁氧的侵入形成氧化空洞和疏松;这些因素的综合作用导致构件最终贯通穿孔而失效。     

铜管内部阴极保护电位分布公式探讨

简述了管道内部阴极保护时电位分布公式的推导过程，重点推导和分析了双点阳极时其电位公式，并与文献中的同类公式进行了比较，同时，用该公式检验了试验结果。     

Advanced gas atomization processing for Ti and Ti alloy powder manufacturing

A multi-layer ceramic composite melt pour tube for superheating and pouring of molten Ti-6Al-4V (wt.%) was tested using an existing Ti atomization system. Free fall gas atomization was conducted with the pour tube while liquid metal temperatures were measured in situ using a two-color optical pyrometer. Post-process pour tube erosion was compared with pre-process matching surfaces, and minimal change in interior liner thickness was found. Microstructural analysis, phase identification, and composition determination of the resulting gas-atomized powder indicated minimal contamination from the composite pour tube despite very high liquid superheat, approaching 300° C. Hot isostatic pressing of the powder resulted in mechanical properties exceeding the MIL-T-9047 standard for Ti-6Al-4V.     

Computed tomographic images of soft materials using differential attenuation: interior properties of the materials at optimum energy in terms of attenuation coefficient

Computed tomographic images of soft materials are obtained using differential attenuation and transmission method with a tube source of X-rays, for samples like walnut, brew tooth and peaches in order to know the interior properties of the material at optimum energy in terms of attenuation coefficient. At optimum energy it is possible to calculate the three-dimensional representation of inner and outer surfaces of the object. The interior of the soft material is visualized using the novel soft ware in order to know the distribution of attenuation coefficient in terms of density. The results for walnut, brew tooth and peaches are presented as a set of images from the internal parts of the sample.