Giant Magneto-Impedance Effect in Amorphous and Current Annealed Fe73.5Cu1Nb3Si13.5B9 Wire

The magneto-impedance(MI) effect in amorphous and current annealed Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 wires has been measured to investigate the influence of DC annealing,highcurrent-density electropulsing annealing and tensile stress applied during annealing process.The results showed that the MI of DC annealed sample exhibits a sharp maximum.The Maximum MI ratio of 60%was observed in the sample of high-current-density electropulsing annealed under applied tensile stress.

Microstructures of Ti–Ni–Fe wire after severe cold-drawing and annealing

The microstructures and mechanical properties of Ti–47 at%Ni–3 at%Fe shape memory alloy wire under the condition of severe cold-drawing at room temperature and different postdeformation annealing processes were intensively investigated using transmission electron microscope(TEM),X-ray diffraction(XRD),Vickers microhardness tester and electron tensile tester.It is indicated that the structure of the alloy evolves into a predominant amorphous structure with a trace of nanocrystalline B2 phase after the cold-drawing of 76%areal reduction.Postdeformation annealing process exerted significant influence on the microstructure and mechanical properties.Crystallization occurs when the cold-drawn wire was annealed at 300℃ for 30 min.The ultimate tensile strength and ductility as well as the superelasticity of the wire are improved significantly by cold-drawing plus postdeformation annealing.

Improvement of giant magneto impedance of Co-rich melt extraction wires by stress-current annealing

In order to improve the giant magneto impedance （GMI） of Co-rich wires for high sensitive sensor applications, Co6sFe4.sSilsBlz5 wires were prepared by melt an extraction technique and subjected to Joule stress-current anneal treatments with different tensile slresses applied. And then their GMI response was investigated at a frequency range from 0.1 to 13 MHz. It was found through the comparison of results that the GMI effect of these wires had been improved through stress-current anneal treatments, because the tensile stress applied on these Co-rich wires introduced magnetoelastic energy and increased anisotropy, which improved the circular permeability and GMI effect. Their impedance ratio AZ/Z increased from 244% to 480.9% at 7 MHz and the field sensitivity increased to 0.83%/（A/m） at 5 MHz, when a tensile stress of 244 MPa was applied at an anneal current of 100 mA for 10 min. It was therefore concluded that these annealed wires were suitable for high sensitive sensor applications.

The Inspection of Spheroidized Annealing on SCM435 Cold-Forging Quality Steel Wires with Protective Atmosphere

A cold-forging quality steel rod is usually applied for manufacturing wire which is generally produced by drawing wire coil into wire, followed by spheroidized annealing treatment to achieve the necessary formability for cold forging. The subcritical and intercritical processes are usually used to spheroidize the steel wires. The cold-forging quality SCM435 alloy medium carbon steel wires are widely used to manufacture high tension bolts for mechanical and heavy industry. In this study, the spheroidized annealing experiments on SCM435 alloy steel wires are conducted in a commercial bell furnace with a protective atmosphere of nitrogen or hydrogen. The mechanical properties of annealed steel wires are measured by tensile and Rockwell hardness tests and the process capability is evaluated. It is experimentally revealed that, for SCM435 alloy medium carbon steel wires, the wire quality with intercritical annealing is much better than that with subcritical annealing and is markedly affected by furnace atmospheres. The intercritical annealing quality on SCM435 alloy steel wire in hydrogen atmosphere furnace is better than in nitrogen atmosphere furnace. A comparison between the results obtained using the intercritical annealing with hydrogen atmosphere and the measures using the subcritical annealing shows that the intercritical annealing effectively improves the performance measures of low strength and high ductility over their values at the subcritical annealing. The results presented in this study could be a reference for fasters wire manufacturers.

800 MPa高强焊丝用盘条退火工艺研究

针对热轧800 MPa高强焊丝用盘条组织中存在较多淬火组织,在拉拔过程中不变形,深度拉拔时发生断裂问题,研究盘条退火工艺。利用马弗炉对盘条试样进行不同的退火工艺处理,研究退火工艺对盘条金相组织和力学性能的影响。结果表明:采用650℃退火并保温2 h,然后在炉内冷却至300℃后再空冷至室温,能得到铁素体和颗粒状的渗碳体,这种组织的抗拉强度低,对盘条的后续拉拔生产更有利。

ER69-3盘条退火过程晶界氧化问题分析与改进

ER69-3作为工程机械用70 kg级焊丝钢的代表牌号,其热轧盘条在720℃保温3.5 h退火后,经过机械除鳞和拉拔、镀铜等工序加工的焊丝表面出现“发黑”现象,“发黑”的焊丝表面存在较多裂纹缺陷,对应的退火盘条存在明显晶界氧化现象。通过单变量试验,确认退火盘条的晶界氧化主要是因为退火温度设定较高,在720℃时氧化铁皮中的氧从晶界向基体扩散,产生晶界氧化。试验通过降低退火温度至670℃或酸洗去除氧化铁皮后再进行720℃退火处理两种措施,均可保证退火后消除马氏体和贝氏体组织,同时确保退火盘条几乎不产生晶界氧化,解决了退火盘条加工过程中焊丝表面“发黑”的问题。

贯通地线用护套盘管失效分析

某电缆制造厂在贯通地线制造过程中发现护套盘管开裂,采用宏观形貌分析、化学成分分析、金相显微镜分析、残余应力分析等手段分析了贯通地线护套盘管开裂原因。结果表明:贯通地线在线退火时,退火炉的电源功率存在不稳定性,电源功率骤升,使得护套盘管产生晶粒长大,甚至局部点熔化产生裂纹源;随着热应力、护套盘管变形应力及缆芯应力释放的共同作用,护套盘管裂纹扩展,甚至断裂。

Influence of the distance between two voltage contacts on giant magneto-impedance of Co-based amorphous wires

The Co75Fe4.2Si8B12Nb0.8 amorphous wires of 30μm in diameter are produced by melt extraction and annealing at 450℃ for 20 min in vacuum with a longitudinal or transverse field of 40 kA/m. Distances between the two voltage contacts of 6, 5, 4 and 2 mm are obtained by moving the two voltage contacts towards the centre of the sample at the same time. Results indicate that magneto-impedance response is dependent on the distance significantly. As distance decreases from 6 to 2 mm, AZ/Z reduces from 609% to 95% and giant magneto-impedance （GMI） profiles change from two-peak to single-peak. Besides, field sensitivity improves from 0.47%/（A/m） to 0.76%/（A/m） when the single-peak GMI just appears. It is therefore concluded that actual measurements can be made comparable only by taking into account the influence of distance between two voltage contacts for a magneto-impedance measurement.

Giant Stress-Impedance Effect in Co_(71.8)Fe_( 4.9)Nb_(0.8)Si_(7.5)B_(15) Glass-Covered Amorphous Wires

The giant stress-impedance （GSI） effect in as-cast and DC current annealed Co71.8Fe4.9 Nb0.8Si7.5 B15 amorphous glass-covered wires is presented. The SI ratio of the as-cast sample exhibits negative GSI effect. For the sample annealed by 60 mA DC current, the SI ratio first increases with applied tensile stress, then decreases. The maximum ΔZ/Z ratio of 304% is obtained. Frequency dependence in the range from 1 to 110 MHz of the GSI effect is investigated. Experimental results show that the real part R and the imaginary part X of impedance play an important role at high frequency and low frequency, respectively. At 1 MHz, the maximum AX/X ratio of 1448% is obtained. At 110 MHz, the maximum AR/R ratio of 648% is obtained.

退火及变形工艺对5056铝合金丝材组织性能的影响

研究了中间退火、冷轧变形量以及成品退火对5056铝合金丝材组织和性能的影响。结果表明:Φ1.1 mm的5056铝合金圆丝经85%的轧制变形和400℃2 h中间退火后,组织发生了完全再结晶,晶粒形貌由拉长状转变为等轴状,丝材强度明显下降,抗拉强度由423 MPa降低至376 MPa,降低了11%。随着冷轧变形量增大,丝材强度逐渐升高,当变形量由79%提高至87%,抗拉强度由420 MPa升高到432 MPa,屈服强度由382 MPa升高到388 MPa。随着成品退火温度升高,成品丝材强度逐渐降低;当退火温度低于120℃时,丝材抗拉强度不小于400 MPa。

基于模拟退火算法优化增益的车辆传动比算法设计

针对线控转向(SBW)系统车辆进行研究,基于定横摆角速度增益法设计变传动比算法,并依照系统结构与设计目的对算法改进修正。采用模拟退火算法,以郭孔辉院士提出的操纵稳定性综合评价指标函数作为优化算法目标函数,对经验选取的定增益值进行优化,得到全局最优定增益值。以全局最优增益值作为最终传动比算法设计依据。对所设计传动比算法进行仿真分析,结果表明,采用优化后增益值传动比算法的SBW车辆具有更好的转向性能,并有效减轻驾驶员的操作负担。

退火对黄铜包覆纯铜绞线组织和力学性能的影响

黄铜包覆纯铜绞线是电气化铁路综合接地系统的关键地线材料,目前主要采用套管拉拔法加工。本文采用连铸复合-拉拔加工新工艺制备了黄铜包覆纯铜绞线,研究了退火温度和时间对拉拔态复合线材微观组织、性能、界面和拉伸断裂行为的影响。结果表明:当退火时间固定为1 h时,随着退火温度的升高,纯铜芯线和黄铜包覆层再结晶程度增大,二者分别在275℃和300℃完成再结晶。在退火温度200~300℃、退火时间0.5~1 h的范围内,随退火温度升高和退火时间的延长,复合线材的硬度和抗拉强度快速下降,断后伸长率快速提高。随退火温度的提高和退火时间的延长,黄铜/纯铜界面的扩散层厚度增厚,从(250℃, 1 h)退火条件下的4.0μm增加至(400℃, 1 h)的7.2μm,或从(300℃, 0.5 h)时的4.3μm增加至(300℃, 2 h)时的8.1μm。综合考虑各种因素,推荐的合理退火条件为(300~350℃, 1 h)。在该条件下退火后,线材的断后伸长率由拉拔态的3%大幅度升高至约40%;黄铜包覆层的拉伸断裂模式由退火前的解理断裂转变为韧性断裂,有利于提升贯通地线的服役安全性和延长服役寿命。

900MPa高强焊丝用盘条拉拔退火工艺的研究

900 MPa高强实心焊丝使用的原材料为低碳合金钢盘条,在拉拔过程中由于加工硬化、塑性降低而无法进行。通过对粗拉拔后盘条采用不同退火工艺热处理,研究了退火工艺对盘条组织及力学性能的影响。结果表明:退火温度过高会导致盘条在随后冷却过程中发生过冷奥氏体转变,生成硬化相贝氏体组织,抗拉强度及硬度偏高,塑性较差。采用690℃加热,保温6 h,随炉冷却至300℃,再空冷至室温的退火工艺,会得到均匀细小的铁素体和球状珠光体,这种组织抗拉强度及硬度低、塑性好,更有利于盘条后续的拉拔生产。

电弧熔丝增材制造船用低合金高强钢组织与性能研究

采用电弧熔丝增材制造技术,填充自制的船用低合金高强度钢丝材,制备了多道多层的钢墙体,并对其沉积态和退火态试样的组织与力学性能进行了研究。结果表明,采用电弧熔丝增材制造技术制备的低合金高强度钢墙体成形质量良好,层间实现了有效的冶金结合。沉积态试样的微观组织主要由粒状贝氏体和不规则的多边形铁素体组成,具有较高的强度、塑性和低温冲击韧性。经过400℃和600℃退火热处理后,马氏体-奥氏体组元不断发生分解,形成铁素体和许多细小的碳化物,使粒状贝氏体的数量减少,铁素体的数量增加,导致强度降低,塑性和低温韧性提高。

高强度螺栓用35CrMo免退火冷镦钢热轧盘条的研制

通过入减定径温度780℃,入减定径减面率42%(Φ18.4 mm→Φ14 mm),冷却速度0.42℃/s,35CrMo钢热轧材显微组织为F+P,铁素体含量≥40%,实际晶粒度10~11级,抗拉强度≤750 MPa,断面收缩率≥60%,硬度值214~225HV,实现免退火直接进行大减面率拉拔。

拉丝断面压缩率对10B30钢球化退火组织及力学性能的影响

研究了拉丝断面压缩率(5%~35%)对Φ9.67~11.69 mm 10B30钢丝(/%:0.28~0.34C,0.0005~0.0030B)球化退火组织及力学性能的影响。结果表明:随着球化退火前拉丝断面压缩率的增加,球化退火组织级别提高,抗拉强度降低,断面收缩率提高,这是因为拉丝促进了球化退火过程中的自发球化和碳化物的ostwald熟化;当拉丝断面压缩率达到25%以上,球化组织和相应的抗拉强度和断面收缩率趋于稳定;实际生产中,退火前拉丝断面压缩率不应低于25%。

旋锻复合铜包铍铜线材的组织性能

采用热旋锻-拉拔方法制备了直径为1.4 mm、包覆铜层厚度均匀、界面结合良好的铜包铍铜复合线材,研究了热旋锻、拉拔、中间退火和固溶形变时效对复合线材组织性能的影响。结果表明:合理的旋锻制度为旋锻温度700℃,单道次变形量50%,旋锻两道次,可获得良好的复合界面结合质量。线材拉拔过程中的合理中间退火工艺为(600℃,1 h),此时铍铜基本完成再结晶,界面层没有发生明显增厚,线材塑性相对较好,断后伸长率为38.5%。线材合理的固溶-形变-时效工艺为经780℃固溶10 min后变形拉拔40%,然后再经320℃时效2 h。此时线材综合力电性能较好,抗拉强度为896 MPa,导电率为50.5%IACS。

冷拉拔纯铁丝在退火过程中的显微组织与织构演变

对截面减小率为80%的冷拉拔纯铁丝分别在723,823,923 K进行退火处理,采用精确线材织构测定方法测定了纯铁丝在退火前后的织构组成,并研究了纯铁丝在退火过程中的显微组织与织构演变。结果表明:退火前纯铁丝的主要织构组分为〈110〉丝织构,取向分布函数(ODF)分析发现〈110〉丝织构主要包括{001}〈110〉,{113}〈110〉,{112}〈110〉,{111}〈011〉,{233}〈011〉等织构类型;退火后,纯铁丝的织构类型与拉拔织构相同,主要织构组分仍为〈110〉丝织构;随着退火温度的升高,织构强度有增加趋势,同时织构强度沿着线材径向分布呈现一定规律的变化;在退火处理过程中,纯铁丝的显微组织由纤维状逐渐向多边形块状转变。

退火温度对单向纤维晶纯铜线材组织性能影响

对退火前后单向纤维晶纯铜线材组织进行了观察,测试了其力学与导电性能,结果表明:在300℃以下退火时,线材的金相显微组织与退火前相比没有明显变化,仍然保持为连续纤维晶,其抗拉强度有所下降,延伸率有所增加;在400℃退火时,线材发生完全再结晶,且有孪晶生成;500℃退火时,再结晶晶粒长大;在400℃以上退火时,抗拉强度大幅度下降,延伸率显著增加;在200～400℃的范围退火时,电导率增加,但增幅较小.

钽丝的拉拔及退火织构

对不同拉拔变形程度及不同温度退火后的钽丝织构， 借助极图与现代ＯＤＦ 分析术进行了研究。结果表明钽丝的拉拔织构主要聚集在α取向线上，形成〈１１０〉丝织构，织构组分主要有｛４４１｝〈１１０〉，｛３３２｝〈１１０〉，｛３３４｝〈１１０〉及｛１１５｝〈１１０〉。丝织构的形成与发展的主要特征可用｛１１０｝〈１１１〉位错滑移和轴对称变形的Ｔａｙｌｏｒ 完全限制模型进行解释。两种不同减面率的钽丝具有明显不同的退火织构组分。７７ ％ 冷拉减面率的钽丝退火后具有与拉拔丝基本相同的织构组分， 钽丝发生了原位再结晶。９０ ％ 冷拉减面率的钽丝低温退火后产生同样的效果， 然而经高温退火后出现新的织构组分｛１１１｝〈１１０〉和｛１１１｝〈１１２〉随退火温度的升高而增强， 其形成由定向长大机制控制。