高能球磨法对TiAl基合金表面的纳米化改性

采用常规高能球磨机对TiAl基合金进行表面纳米化改性。利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)和X射线衍射分析仪(XRD)对试样表层的微观结构和相组成进行观察分析,研究表面纳米化过程中表层晶粒细化的机制;并采用纳米压痕仪测定试样表层的显微硬度,研究表面纳米化改性对合金表面性能产生的影响。结果表明:高能球磨技术能够实现TiAl基合金表面的纳米化改性。改性后试样表层晶粒尺寸约为10 nm。晶粒主要通过孪晶交割和位错缠结重组进行细化;表面显微硬度提高至920 HV,约为未处理试样的2.8倍。     

连铸机拉矫辊辊面激光重熔纳米ZrO2基涂层性能

 为了提高连铸机拉矫辊的使用寿命,在H13钢表面等离子喷涂常规级和纳米级两种规格的ZrO2涂层,并对其进行激光重熔处理。利用有限元软件ABAQUS分析热障涂层对拉矫辊温度场的影响,利用激光共焦显微镜观察涂层表面和断面的组织结构,利用场发射扫描电子显微镜（SEM）测量涂层断面的元素分布,采用Gleeble-3800热模拟试验机考查涂层的抗热冲击性,结果发现,经激光重熔之后纳米级ZrO2涂层的孔隙率和微裂纹数量都明显少于常规级ZrO2涂层,并且纳米级ZrO2涂层的抗热冲击性都优于常规级涂层。     

冷轧IF钢表面纳米化后的组织与性能

利用机械研磨处理（SMAT）在冷轧IF钢表面制备出具有纳米晶体结构特征的表面层．利用金相观察和透射电镜分析研究了表面纳米层的结构特征,测定了硬度沿厚度的变化,并分析了表面纳米化（SNC）对力学性能的影响．结果表明：（1）表面机械研磨处理后,冷轧（CR）IF钢表面形成了平均晶粒尺寸为7～9nm、晶粒取向呈随机分布的纳米晶组织;（2）表面层附近的硬度显著提高;（3）纳米表层的存在使得材料强化的同时成形极限也得到提高．     

Ti-6Al-4V钛合金表面纳米化机制研究

借助X射线衍射仪、透射电镜及显微硬度仪等先进仪器,研究了经超音速微粒轰击( SFPB)形变热处理Ti-6Al-4V合金表面自身纳米化晶粒尺寸演化及纳米化机制.研究结果表明:超音速微粒轰击使Ti-6Al-4V合金表面获得了纳米组织,并发生显著的加工硬化,表面显微硬度比基体硬度提高了1倍多;随着SFPB处理时间的延长,纳米结构层厚度不断增加,晶粒尺寸逐步细化,当SFPB处理30 min后晶粒尺寸趋于稳定,在表层形成了晶粒尺寸约为20 nm具有随机取向的纳米等轴晶.Ti-6Al-4V合金表面自身纳米化是由于位错运动、孪晶的形成及交割共同作用的结果;在多方向载荷的重复作用下,在塑性变形区产生了大量的由位错线和高密度位错缠结分割的位错胞,并在位错寨集处产生应力集中,进而形成孪晶;孪晶自身相互交割和位错的滑移相互协调,形成了细小的孪晶和胞状组织;晶胞组织转变为细小多边形亚晶;当孪晶尺寸细化到亚纳米级时,位错的滑移起主导作用,最终通过位锗的湮灭和重组形成了具有随机取向的等轴状纳米晶粒.     

时效时间对表面机械研磨处理Cu-4.5Ti合金组织和硬度的影响

采用表面机械研磨法使Cu-4.5Ti合金表面形成纳米晶,利用X射线衍射分析,透射电子显微镜观察和显微硬度测量等手段研究时效时间对表面机械研磨处理Cu-4.5Ti合金组织和硬度的影响。结果表明:经过表面机械研磨处理后的Cu-4.5Ti合金发生了塑性变形,表层塑性变形明显,试样中出现了纳米晶结构,形成大量交割状态的机械孪晶;经过8 h时效处理后,试样中形成了更加致密的孪晶组织,并产生了更多孪晶区域。经表面机械研磨处理合金试样的显微硬度由表层向基体内部表现为先增大后减小的趋势,并最终达到稳定状态;经过8 h时效处理后试样到达峰值硬度,此时合金表层硬度增大至HV 213,并在离表层深度约50μm处获得HV 278的峰值硬度。     

强流脉冲电子束能量密度对TiAlN涂层微观组织和硬度的影响

采用不同能量密度的电子束对硬质合金刀具Ti Al N涂层进行轰击处理,研究了电子束能量密度对Ti Al N涂层表面改性后的微观组织和硬度的影响。利用扫描电镜(SEM)、能谱分析(EDS)、X射线衍射仪(XRD)分别对Ti Al N涂层进行表面形貌观察、元素分析和物相分析,并对涂层表面进行粗糙度和显微硬度测试。结果表明,随着能量密度的增加,涂层表面更趋于致密。在相同的能量密度1.75 J·cm~(-2)下,采用相对较低的阴极加速电压7 k V和较高电流强度130 A轰击时,涂层表面粗糙度最低达0.15μm。经电子束轰击后的Ti Al N相衍射峰相对强度有所提高;涂层相衍射峰不同程度地向高角度偏移,并且同样能量密度条件下加速电压越高,偏移角度越大;同时涂层相衍射峰有一定宽化趋势。表明电子束轰击后Ti Al N涂层产生较大的压应力和热应力,使晶粒细化,并且在一定的热应力驱动下有利于原子扩散,形成较宽的过渡层,从而提高涂层和基体间结合力。显微硬度随着能量密度的增加呈上升趋势,而相同的能量密度条件,加速电压的提高有助于涂层表面硬化。     

表面纳米化工业纯钛组织性能研究

采用表面机械研磨处理(SMAT)实现工业纯钛的表面纳米化,利用金相显微镜(OM)、显微硬度计对其微观组织及显微硬度进行表征、测定;利用动电位极化曲线和电化学阻抗谱(EIS),结合X射线光电子能谱分析(XPS)技术,研究了表面纳米化工业纯钛在Hank's人工模拟体液中的腐蚀行为。结果表明:SMAT处理工业纯钛表层晶粒尺寸达到纳米级,从表层到基体晶粒尺寸由小到大呈梯度分布,其表层显微硬度明显提高,并由表层逐步降低至基体硬度。SMAT处理工业纯钛的自腐蚀电位较原始工业纯钛正移,腐蚀电流密度较原始工业纯钛低,其EIS高频容抗弧半径较原始试样大,表现出更稳定的钝化现象。表面纳米化过程中产生的高密度晶界和位错为Ti~(4+)提供了更多的扩散通道,有助于表面产生稳定的保护钝化膜,提高其耐蚀性。XPS分析结果表明,SMAT处理工业纯钛钝化膜的主要成分为Ti O_2。     

超声滚压处理7B85合金的显微组织和力学性能

采用不同压下量（0、0.1、0.2、0.3、0.4 mm）对7B85合金进行超声滚压处理，利用光学显微镜、表面粗糙度测量仪、显微维氏硬度计、拉伸实验、扫描电镜、X射线衍射和电子背散射衍射对经过超声滚压处理的7B85合金的微观组织和力学性能进行研究。结果表明，当下压量为0.2 mm时，超声表面滚压处理后7B85合金的表面粗糙度、显微硬度以及抗拉强度达到较优值。滚压处理后合金的断口形貌呈现出大量较深的韧窝，其主要以韧性断裂形式为主。同时，超声表面滚压处理后合金中大部分η析出相溶解到铝基体中，其表层晶粒的平均晶粒尺寸约为（25.22 ± 6.46）nm。滚压后合金力学性能的提高主要归因于合金表面细晶强化和应力强化的共同作用。      

连铸机拉矫辊等离子喷涂WC-20Cr-7Ni涂层性能

 连铸机拉矫辊作为连铸机的重要组件,工作环境恶劣、磨损严重。为了降低连铸机拉矫辊工作过程中的辊面磨损,利用等离子喷涂技术在拉矫辊及H13钢板表面制备了厚度为0.2 mm的WC-20Cr-7Ni涂层。通过水淬热冲击及轧制试验探究了WC-20Cr-7Ni涂层的抗热冲击性能及耐磨性,并对热冲击前后试样进行了金相分析及硬度测试。结果表明,WC-20Cr-7Ni涂层孔隙率较低,并具有较高的耐磨性及优异的抗热冲击性能,可以有效提升连铸机拉矫辊的使用寿命。     

表面机械研磨处理工业纯锆的组织和拉伸性能研究

对退火态工业纯锆试样分别进行了5,15,30和45 min的表面机械研磨处理,利用光学显微镜和扫描电子显微镜观察了试样的微观组织,对其表层晶粒尺寸进行了X射线衍射分析、采用维氏显微硬度仪测量了沿层厚方向的硬度,并进行了室温拉伸性能测试。实验表明,经过表面机械研磨处理,在强烈塑性变形作用下试样表层晶粒尺寸能够细化到纳米尺度,而且随处理时间增加而进一步降低,经过45 min处理后试样表层晶粒尺寸可以达到25 nm左右;处理后在试样的次表层形成了一定深度的变形层,具有较高的孪晶密度,并且变形层厚度随处理时间延长而提高。试样表层形成的纳米结构使其显微硬度获得了显著提高,并随处理时间增加而进一步提高;沿层厚方向试样显微硬度逐渐降低,与微观组织的变化一致。拉伸试验表明,表面机械研磨能够使试样得到强化。随处理时间的增加,试样屈服强度和抗拉强度能够得到明显改善,而试样的延伸率则随处理时间的增加而降低。对经过45 min处理的试样,其屈服强度和抗拉强度分别为324和414 MPa,相对于原始试样分别提高了11.7%和8.7%,延伸率为23%,降低了30.9%,拉伸断口主要形貌特征为韧窝,处理层和中心层呈现不同的组织特征。     

浅析连续热镀锌机组的涂层控制

热镀锌板的镀后涂层处理是镀锌产品生产的关键环节.涂层控制涉及多方面技术,要控制好膜层均匀性、膜重及固化效果,必须对辊涂机蘸液辊和涂辊表面粗糙度、蘸液辊与涂辊接触压力、涂辊与带钢的压力和带钢包角、烘干温度、带钢冷却、镀层表面状况方面施行良好的控制.文章对卧式辊涂和立式辊涂工艺进行对比,分析两种工艺的优点和缺点,然后依据膜...     

3D surface microtopography of cold-rolled and galvanized strip

The switch from 2D filtration to 3D filtration of surface microtopography is described. Important new surface parameters in the metallurgical industry are considered. The use of 3D parameters reveals new aspects of working-roller wear and the development of roughness at the surface of cold-rolled and galvanized auto-industry steel sheet and permits comparison of the surface roughness of coated and uncoated sheet. On that basis, the development of roughness on auto-industry steel sheet in temper rolling may be reassessed; the surface texturing of the rollers may be further improved; and the quantity of rolled metal obtained from a single pair of working rollers may be considerably increased.     

Influence of roller treatment on the surface topography of cold-rolled sheet

The surface microtopography of auto-industry sheet passed through rollers whose surface has undergone various kinds of treatment—shot blasting, electric-discharge texturing, electron-beam texturing, and TOPOCROM treatment—is compared. The amplitude and frequency parameters of the surface roughness are also compared, as well as the correlational, spectral, and fractal characteristics of the surface microprofile. It is shown that the microrelief of the sheet is best after TOPOCROM treatment and electron-beam texturing of the rollers.     

Numerical simulation of the gas-solid two-phase flow inside the multi-channel nozzle for the surface nanocrystallization induced by the ultrasonic particulate peening

Using a gas-solid two-phase model(a discrete phase model),the authors investigated the flow field inside the multi-channel nozzle for surface nanocrystallization(SNC)induced by the ultrasonic particulate peening(USPP).By computation,the velocity fields of both the gas and the solid phases were simulated and the track of the solid phase was analyzed in detail.It can be found that the velocities of the two phases are able to reach an ultrasonic level;meanwhile,the dispersion width of the solid phase at the nozzle exit is less than that of the gas phase.When particle diameters are less than 5 μm,there is a decreasing trend in the dispersion width of the solid phase with an increase in particle diameters.The trend becomes stable as the particle diameters are greater than 5 μm;in the meantime,the distribution of solid particles is near the axis of the jet flow.The optimal standoff distance between the nozzle and the substrate in the process of USPP is about 120 mm.Simulation results can help improve the design of mass-production-oriented multi-channel nozzles for SNC induced by USPP.     

表面纳米化处理对IF钢电化学析氢行为的影响

利用阴极极化曲线、交流阻抗谱,对超音速微粒轰击（USPP）表面纳米化处理（SNC）的IF钢在30%NaOH溶液中的析氢行为进行了研究,同时利用XRD和SEM分析了表面纳米化前后IF钢的晶粒度和表面形貌。试验证明,经SNC处理后,IF钢析氢过电位比基材降低200 mV;SNC＋1%平整的IF钢比基材析氢过电位低300 mV以上;经处理后IF钢真实表面积比原IF钢板分别增大18倍和21倍,其表观析氢活化自由能分别由51.7 kJ/mol降低为26.5 kJ/mol和21.7 kJ/mol,仅为原IF钢板的50%。     

超音速微粒轰击表面纳米强化多通道喷嘴气固双相流的数值模拟

采用气固双相流模型（离散相模型）研究了超音速微粒轰击表面纳米强化多通道耦合喷嘴的流场,通过计算,分析了气固两相速度场以及固体颗粒在气体流场中的轨迹。模拟结果发现,气体—颗粒双相射流中,气固两相射流速度均可以达到超音速,而且颗粒相的分散度小于气体,粒径小于5μm的颗粒相其分散度随颗粒粒径增大而减小,大于5μm的颗粒相其射流分散度基本稳定,颗粒相粒子集中在各通道射流中心线附近。最佳表面纳米强化处理距离在120 mm附近。模拟结果有助于设计面向大规模表面纳米强化处理应用的多通道耦合喷嘴。     

冷轧钢带表面清洁度的研究

对影响冷轧后钢带表面清洁度因素的分析,通过调整辊表面粗糙度和油品润滑,清洗性能,优化酸洗及轧制工艺参数,控制乳化液浓度,皂化值等主要工艺技术指标,使得冷轧后钢带表面清洁度提高了12%。     

Cold rolling on textured rollers to obtain regulated surface roughness

At OAO MMK, a new production technology has been developed for cold-rolled steel sheet with regulated surface roughness, used in the auto industry. This technology relies on regulation of the tension in the cold-rolling mills, a special textured barrel surface of the working rollers, new roller profiles, and the use of a wetting liquid in the temper mill.     

Heat treatment of rollers in the ShPS 30-80 ball-rolling mill at JSC DMPZ

In the production of steel rollers, surface decarburization may occur in the course of heating before quenching. Means of more effective protection against such decarburization are considered in the case of the 35X CA steel barrel of wrapped rollers for the ShPS 30-80 ball-rolling mill. A technological protocol for the heat treatment of the rollers is developed. It is shown that protection by means of nitrogen + a carburizing agent + a muffle increases the likelihood of the desired outcome (no decarburized surface layer and hardness no less than 45 HRC) by 31.9% in comparison with protection by means of Barier protective compound + a carburizing agent + a muffle. On average, 450–470 t of grinding balls (diameter 40 mm; hardness groups III and IV) may be rolled in a complete run (to regrinding) on rollers heat-treated by the proposed protocol.     

Roller temperature in metallurgical machines with scale formation

When hard water is used to cool the rollers of metallurgical machines, scale forms on the inner surface of the cooling channel. Predictions of the roller temperature usually fail to take into account that, in the initial period of roller operation, the cooling channel is scale-free and operates in conditions very different from those in the final period. With continuing growth of the scale layer, which has good mechanical properties and poor heat conduction, the working surface is heated to the temperatures at which the rollers in the machine are tempered. In the present work, the working temperature of the rollers is investigated when scale forms on the surface of the cooling channel. A method is proposed for estimating the working temperature of the rollers in those conditions. For the example of rollers in a continuous-casting machine, it is shown that, for the selected operating conditions, the maximum temperature of the roller’s external surface reaches its critical value after operation for half a year. By the proposed method, different approaches may be taken in determining the mean and maximum surface temperature of the rollers for different thermal loads, different cooling conditions, and different quality of the cooling water. The method provides the basis for determining the roller life and setting standards for the content of reagents in the cooling water.