高碳钢中珠光体在温楔横轧过程中的组织演变

采用温楔横轧方法制备出表层具有超微细复相组织的高碳珠光体钢棒件,研究了珠光体组织在温变形过程中的演变.结果表明,珠光体组织中的渗碳体片层主要以弯曲扭折的形式协调塑性变形,表现出较强的塑性变形能力;剧烈塑性变形促进了渗碳体片层的球化,表层球化完全的渗碳体颗粒粒径均小于0.2μm;温楔横轧后铁素体基体发生了动态连续再结晶,等轴铁素体平均晶粒尺寸为0.3～0.4 μm,0.5R处和心部的渗碳体球化不完全,铁素体再结晶也不完全;铁素体晶粒的超细化和渗碳体片层的球化明显改善高碳珠光体钢棒件的塑性,温变形过程中应变、应变速率及温度分布的不均匀是引起组织性能差异的根本原因.     

回火工艺对连轧10MnNiCr钢板组织性能的影响

研究了热轧态及热轧后回火两种状态下10MnNiCr钢板的性能。通过光学显微镜、扫描电镜、透射电镜分析了回火工艺对材料组织及性能的影响。试验结果表明,轧态钢板回火后韧性提高,钢板断口分层撕裂现象得到改善。微观组织分析表明,钢板回火后珠光体中渗碳体由片层状转变为短棒状或粒状,另外,晶界转变物发生球化,位错发生回复。微观组织结构的变化及位错回复是回火后钢板性能改善的主要原因。     

过冷对共析钢动态相变和组织演变的影响

将共析钢在600-700℃的过冷奥氏体状态下进行单轴热压缩,获得了亚微米级别等轴铁素体 纳米级别弥散分布球化渗碳体的复相组织,其组织演变经历动态相变、片层渗碳体球化、铁素体动态再结晶和纳米级别渗碳体颗粒析出等过程.随着形变温度的降低,过冷度增加,相变动力学过程加快.片层渗碳体的球化程度由球化时间和球化速度控制,形变温度升高使渗碳体球化速度加快,但是相变开始时间及动力学延迟使得用于渗碳体球化和熟化的时间相应缩短,导致球化程度降低.铁素体再结晶和等轴化过程则主要受位错迁移、渗碳体颗粒钉扎的影响,形变温度升高导致较高的等轴化发展速度.     

球化退火后的深冷处理对9SiCr钢强韧性的影响

目的 针对9SiCr钢加热脱碳倾向大、加工性较差的问题,研究能够提高9SiCr钢的强韧度与耐磨性的热处理工艺。方法 设计一种球化退火后进行深冷处理的新热处理工艺路线来实现对9SiCr钢强度与耐磨性的改良。对比9SiCr钢的等温球化退火与循环球化退火后的组织与性能,确定最适合的球化退火工艺;对退火后的9SiCr钢进行淬火,之后按照淬火后是否进行深冷处理、深冷处理前是否进行预回火进行分组对照试验。结果 对于热轧态9SiCr钢,800～750℃往复循环球化退火的强化效果优于各温度下等温球化退火的强化效果;深冷处理12 h后,9SiCr钢循环退火组织中的马氏体基体析出了大量超微细碳化物,增强了9SiCr钢的耐磨性与刚性。并且,进行深冷处理前在160℃（9SiCr钢Ms点附近）下保温1 h可以增大碳化物的形核率,之后再进行深冷工艺,可以进一步促进碳化物析出,有利于改善9SiCr钢的退火组织,增强材料强度与韧性。结论 循环球化退火后预回火并进行深冷处理可以显著提高9SiCr钢的强韧性与耐磨性。     

二氧化硅喷雾造粒粉体的热处理工艺研究

研制了一种以SiO2为基体的高温可磨耗封严涂层,为了改善二氧化硅喷雾造粒粉体的性能,研究了热处理工艺对粉体松装密度、流动速度及粒度分布的影响。结果表明,热处理过程中伴随着SiO2颗粒的烧结,热处理温度对粉体性能的影响较热处理时间更为显著,随着温度的升高,喷雾造粒SiO2球逐渐烧结,粉体粒度减小,松装密度增加,流动性提高,采用1000～1050℃、30～60min的工艺对粉体进行热处理能够获得最优的粉体性能。     

钢的热处理组织分析：第四讲 钢的热处理组织分析实例（二）

5 40Cr球化退火组织 图6为40Cr球化退火组织。从显微观察可见,该组织由两部分组成:白亮块和分布着小颗粒的白亮块。40Cr钢球化退火后只能由铁素体与渗碳体两相组成。所以白色颗粒状物为渗碳体,白亮块及分布有渗碳体颗粒的白亮块(基体)均为铁素体。从形态看也可判断它是铁素体块及分布有渗碳体的铁素体。形成这种组织完全决定于退火工艺。球化前原始组织为大块状铁素体与珠光体的混合组织,经750℃加热时,组织为铁素体块+(奥氏体和少量的渗碳体);缓冷后,铁素体块不变,而奥氏体分解为球状珠光体,致使缓冷后组织中碳化物分布极不均匀,     

细珠光体在变形中的行为

用喷射成形工艺制备的细珠光体超高碳钢在共析转变温度以下变形时,呈现强烈而持续的加工软化.组织检测表明,渗碳体片表现出与相邻铁素体协凋变形的能力;随着应变增大,渗碳体片发生局部溶解而碎化;在应变足够大时,珠光体逐步转变为细小碳化物颗粒弥散分布的球化组织.细珠光体的这种特性使得这种材料无需预先球化处理,即可具有伸长率达300%的超塑变形能力.     

超快冷对碳素钢中渗碳体析出强化行为的影响*

用超快速冷却技术并控制轧后冷却温度, 研究了3种碳含量不同的碳素钢热轧后组织中渗碳体的析出行为和强化机制。结果表明, 在超快速冷却条件下0.04%C和0.5%C(质量分数, 下同)实验钢的主要强化方式分别是细化晶粒和细化珠光体片层间距, 没有纳米级渗碳体颗粒析出, 而在0.17%C实验钢的组织中则有大量弥散的纳米级渗碳体析出, 颗粒直径范围为10-100 nm, 通过超快速冷却技术实现了在不添加微合金元素的条件下纳米级渗碳体的析出。随着超快速冷却终冷温度的降低纳米渗碳体的析出强化作用使0.17%C钢的屈服强度提高110 MPa, 强化效果明显。在超快速冷却的工艺基础上若继续采用形变热处理工艺, 可进一步提高0.17%C实验钢的位错密度, 促进渗碳体均匀形核, 实现纳米级渗碳体颗粒在整个组织中更加均匀弥散的分布, 达到更好的均匀强化效果。在超快速冷却和形变热处理工艺条件下0.17%C钢的屈服强度可达到650 MPa以上, 强化效果提高300 MPa以上。     

超声波搅拌及等温热处理对ZL101合金半固态组织的影响

采用超声波搅拌和等温热处理制备ZL101合金半固态坯料,研究了超声波搅拌处理和等温热处理中等温温度、等温时间等工艺参数对ZL101半固态组织形貌的影响。研究结果表明:超声波搅拌可有效细化和球化组织,消除组织缺陷;适当的等温处理可以明显改善半固态ZL101的凝固组织;当等温温度为590℃、等温时间为30min时,半固态ZL101合金中初生α-Al相细化和球化效果最明显;初生α-Al相的平均等积圆尺寸达到157μm,形状因子达到0.87。     

制备工艺对氧化钨电致变色薄膜性能的影响

采用WO3陶瓷靶,运用射频反应磁控溅射工艺,通过正交试验方法优化实验参数,制备出性能优异的WO3电致变色薄膜,通过对薄膜进行真空热处理,提高了薄膜变色存储能力。结果表明,氧分量为60%、压强为2.5Pa、功率为145W时制备的薄膜,对光调制幅度(ΔT)达89.3%。适度温度真空热处理可改善薄膜性能,着色率略有提高,变色存储时间增加(达32h),离子存储能力增大(达3.96mC/cm2),循环稳定性能良好,同时热处理使薄膜晶化,密度增加,变色响应时间增加。     

Effect of Nb on Structure and Mechanical Properties of Chilled Cast Iron at Room and Elevated Temperatures

Effect of Nb on microstructure and mechanical properties of chilled cast iron at room and elevated temperatures isstudied in this research. The results demonstrate that the cast structure and mechanical properties of chilled castiron at room and elevated temperatures are improved with the addition of trace amount of Nb. However, if Nb wasadded too much, the cast structure and mechanical properties of chilled cast iron would deteriorate. The suitablecontent of Nb in chilled cast iron is about 0.05% (mass fraction). Except the dissolution in the matrix of cast ironthe excessive Nb will form Nb-rich phases in three morphologies. Those are lumpy NbC, complicated strip-like phaseand compound with pearlite structure.     

奥氏体铸体和18—8不锈钢在烧碱中的腐蚀行为

用失重法和电化学方法研究了奥氏体铸铁的１８－８不锈钢在高温烧碱中的腐蚀行为。用扫描电镜观察了两种材料泵件表面的腐蚀形貌,分析了奥氏体铸铁耐碱腐蚀性能优于１８－８不锈钢的原因。     

Direct chill casting of magnesium alloy under pulsed magnetic field

To refine the grain size and improve the hot workability, the billets of AZ80 magnesium alloy were cast by a new process of the pulsed magnetic field-direct chill casting. The effect of pulsed magnetic field on the grain size, segregation and mechanical properties of cast billet were investigated by experiments. The results indicate that the grain size of cast billet with pulsed magnetic field was greatly refined, and the homogeneity of microstructure was improved significantly. Meanwhile, the macrosegregation and microsegregation of main alloying elements in the cast billet with pulsed magnetic field were suppressed. Compared with the conventional cast billet, the yield strength, ultimate tensile strength and elongation of the cast billet with pulsed magnetic field were increased obviously.     

基于图像分析的色偏检测算法

针对传统色偏检测算法存在的局限性,提出一种新的基于图像分析的色偏检测算法。该算法采用图像的色彩度指标对色偏因子的计算方法进行优化,通过色彩度加权,将含有大块单一颜色的图像"转化"为色彩丰富的图像,从而消除图像主色调对色偏检测的影响,降低色偏图像的误判率。与传统的基于图像分析的色偏检测算法进行实验比较,结果表明,该算法能够准确、高效地检测出色偏图像,提高色偏检测的准确率和可靠性;将检测结果与人眼主观评价结果进行对比,结果表明,该算法不仅能消除主色调的影响,降低色偏图像的误判率,还能准确判别色偏图像和主色调图像。     

铬系白口铸铁的热塑性及其锻前加热新工艺研究

对不同铬含量白口铸铁的热塑性，铬对白口铸铁热塑性的影响规律以及铬影响白口铸铁热塑性的机理进行了探讨，通过试验提出了可明显提高铬系白口铸铁热塑性的锻前加热新工艺。     

中锰合金耐磨铸铁闸瓦的研究与应用

本文以中锰合金铸铁闸瓦为研究对象,并与中磷铸铁、高磷铸铁进行了对比研究。结果表明,中锰合金铸铁机械性能与摩擦磨损性能优于中磷、高磷铸铁。经现场装车试用,实际效果较好。     

Microstructure,mechanical properties and high stress abrasive wear behavior of air-cooled MnCrB cast steels

Three medium carbon low alloyed MnCrB cast steels containing different Cr contents (0.3%, 0.6%, and 1.2%) were designed and the effect of Cr contents on the microstructure, mechanical properties and high stress abrasive wear behavior of the cast steels after 850 °C air-cooling and 220 °C tempering was studied. The results show that the hardenability of the MnCrB cast steels was excellent. The microstructure of the cast steels with low Cr contents (0.3% or 0.6%) consists of granular bainite and lower bainite/martensite multiphase. With increasing of Cr content, the formability of martensite was improved, the hardness and wear-resistance increased, but the impact toughness decreased in that more bainite was replaced by martensite. The air-cooled MnCrB cast steel containing 0.6% Cr, with granular bainite and lower bainite/martensite multiphase, exhibited excellent combination of strength, hardness, ductility, and impact toughness. In addition, its abrasive wear-resistance was 30% more than that of Hadfield cast steel in the high stress abrasive wear condition. This air-cooled MnCrB cast steel by simple alloying scheme and heat treatment has the advantages of high-performance, low cost, and environmentally friendly. It is a potential advanced wear-resistant cast steel for low- or even medium-impact abrasive conditions.     

蠕墨铸铁发动机缸体噪声辐射测试分析

为准确分析蠕墨铸铁发动机缸体噪声辐射特性,基于LMS Test.Lab软件,使用力锤冲击激励法分别对灰铸铁和蠕墨铸铁铸成的发动机缸体进行振动噪声测试,基于理论推导出的力能量和声能量计算公式,使用激励力加权系数法进行加权分析。分析结果表明,被测的蠕墨铸铁发动机缸体力-声能量转换效率比灰铸铁发动机缸体力-声能量转换效率低35.43%,降噪性能优于灰铸铁发动机缸体。此研究表明力-声能量转换效率分析方法可以很好地分析不同材料发动机缸体的噪声辐射性能,为改善发动机缸体的噪声辐射性能提供理论基础。     

铸造针孔和钠变质对ZL101铸铝合金组织和性能的影响

采用宏观检查和金相检验的方法，研究了铸造针孔和钠变质对ZL101铸铝合金组织和性能的影响。试验结果表明，在浇铸ZL101铸铝合金时，提高冷却速度，增加凝固压力，降低浇铸温度，同时进行钠变质处理，有利于铸造针孔的减少和组织的细化及力学性能的提高。     

Effect of refinement of grains and icosahedral phase on hot compressive deformation and processing maps of Mg-Zn-Y magnesium alloys with different volume fractions of icosahedral phase

The effect of the volume fraction of I-phase on the hot compressive behavior and processing maps of the extruded Mg-Zn-Y alloys was examined, and the obtained results were compared with those of the cast alloys in a previous work. The average grain sizes, fractions of dynamically recrystallized (DRXed) grains, and sizes of DRXed grains of the extruded alloys after compressive deformation were significantly smaller, higher and smaller, respectively, than those of the cast alloys after compressive deformation under the same experimental conditions. This was because the microstructures of the extruded alloys, having much more grain boundaries and more refined I-phase particles than the cast alloys, provided a larger number of nucleation sites for dynamic recrystallization than those of the cast alloys. The constitutive equations for high-temperature deformation of the extruded and cast alloys could be derived using the same activation energy for plastic flow, which was close to the activation energy for lattice diffusion in magnesium. Compared with the cast alloys, the onset of the power law breakdown (PLB) occurred at larger Zener-Holloman (Z) parameter values in the extruded alloys. This was because the extruded alloys had finer initial grain sizes and higher fractions of finer DRXed grains compared to the cast alloys, such that the onset of PLB caused by creation of excessive concentrations of deformation-induced vacancies was delayed to a higher strain rate and a lower temperature. The flow-stress difference between the extruded alloys and the cast alloys could be attributed to the difference in the fraction of DRXed grains. According to the processing maps, the extruded alloys exhibited higher power dissipation efficiency and flow stability than the cast alloys. This agreed with the microstructural observations.