常化退火处理对无取向硅钢组织和织构的影响

采用光学显微镜和X射线衍射仪研究了常化退火处理对无取向硅钢热轧板和成品退火板显微组织和织构的影响。结果表明:常化退火处理消除了热轧板中的变形组织,促使变形晶粒完成再结晶;常化退火处理使高斯织构和立方织构易通过再结晶在变形带内形核和长大,可显著降低成品退火板的{111}和{112}不利织构组分的占有率,提高{100}和{110}有利织构组分的占有率,从而有利于提高无取向硅钢成品板的磁性能。     

超快速退火对Nb+Ti-IF钢组织和织构的影响

研究了超快速退火对一种冷轧变形量为94.2%的Nb+Ti-IF钢的微观组织和织构的影响。结果表明:超快速退火(升温速度为300℃/s)提高了钢的再结晶完成温度,整个再结晶退火可在短至0.41 s内完成。与普通退火(升温速度为20℃/s)后钢的再结晶组织相比,超快速退火处理后晶粒平均尺寸由12.98μm细化到10.12μm,晶粒长大速度由～3μm/s提高到～23μm/s,且再结晶晶粒内存在大量缠结位错。在极短时间内,超快速退火再结晶织构仍以均匀、锋锐的{111}//ND有利深冲性能的γ织构为主,且避免了其它α织构的生成,有利于使退火板具有良好的成形性能。     

罩式退火无间隙原子钢的最优冷轧压下率的确定

以工业生产的含钛、铌和含钛的两种无间隙原子(IF)钢热轧钢板为试验材料,在实验室研究了冷轧压下率对两种IF钢的显微组织、力学性能和再结晶织构的影响。结果表明:在试验条件下,两种试验钢经不同冷轧压下率冷轧和720℃×5 h罩式退火后,再结晶完成,随着冷轧压下率的增加,晶粒变得细小均匀,退火后得到的织构也增强,并且织构类型有转向{111}织构的趋势;塑性应变比r90在压下率为70%时达到最大值,随着冷轧压下率的进一步增大,r90值减小;应变硬化指数n90值逐渐降低。最后提出工业生产中冷轧压下率最佳范围为70%~80%,可获得良好的深冲性能。     

热轧后退火对超纯Cr17钢成形性能的影响

为了揭示热轧后退火对超纯Cr17铁素体不锈钢冷轧退火板成形性能的影响,以1种铌、钛双稳定化超纯Cr17铁素体不锈钢的热轧板和热轧退火板为实验材料,分别进行相同的冷轧及退火处理,对其组织、织构演变和成形性能进行了对比研究.研究结果表明,热轧后退火对冷轧退火板的组织、织构和成形性能影响很大.与不退火相比,退火能够使冷轧退火...     

碳含量对超低碳含钛冷轧搪瓷钢性能的影响

使用透射电子显微镜(TEM)、电子背散射衍射(EBSD)检测和电化学氢渗透等手段研究了碳含量对超低碳搪瓷钢微观组织、退火板织构和氢渗透行为的影响。结果表明:随着碳含量的提高超低碳搪瓷钢的强度提高而n值的变化不大,断后伸长率和r值都呈减小的趋势;与r值相对应,退火板的γ织构随着碳含量的提高逐渐减弱。实验钢的氢扩散系数DL随着碳含量的提高而减小,碳含量低于0.004%时钢板的DL低于临界值,不能保证搪瓷板的抗鳞爆性能。     

800MPa冷轧热镀锌双相钢组织性能及其织构演变

对800MPa级热镀锌双相钢热轧、冷轧及退火后的显微组织进行了观察,分析比较了热轧和退火后的力学性能,并考察了其织构演变过程.结果表明:实验用钢经820℃保温140s热镀锌退火后,可获得抗拉强度819MPa,伸长率为17%的铁素体+马氏体双相钢,铁素体晶粒尺寸在1.5~4μm之间,马氏体体积分数为34%左右;热轧织构密度较弱,但已呈现出γ织构的雏形;冷轧后α织构和γ织构密度显著增长;热镀锌退火后α织构变化不大,不利织构{001}〈110〉织构密度有较大程度地攀升,γ织构取向密度值波动很大,最大织构组分为{112}〈110〉织构;快冷过程中形成的马氏体阻碍了有利织构{111}的发展,使得不利织构{001}〈110〉得到一定程度的发展.     

67%变形量纯钨轧板在1250 ℃退火过程中的再结晶行为

目的 研究轧制压下量为67％的纯钨板在退火过程中的再结晶行为.方法 对67％变形量纯钨板在1250℃下进行等温退火实验,运用电子背散射衍射技术获得了变形态和退火态的显微组织与织构,量化了其晶粒尺寸、纵横比以及主要纤维织构的体积分数,分析了变形态组织中潜在晶核的信息.在此基础上,对再结晶前后的显微组织和织构进行了对比分析.结果 温轧后纯钨板的组织中包含了潜在的再结晶晶核,W67在1250℃下退火过程中以较快速度发生了不连续静态再结晶.结论 随着退火时间的增加,再结晶晶粒的尺寸逐渐增大,但其纵横比基本保持不变.在再结晶过程中,θ纤维织构和α纤维织构有所增加,而γ纤维织构明显减少.     

退火温度对TC4钛合金热轧板材的显微组织、织构和力学性能影响

对用电子束冷床炉(EB炉)熔炼的TC4钛合金热轧板材进行三火轧制变形,研究了退火温度对其显微组织、织构和力学性能的影响。结果表明：TC4钛合金的原始轧态组织为双态组织,由初生α相和β转变组织构成。退火后等轴α相的含量提高,次生α相的含量降低并趋于球化,组织的等轴化程度提高,在900℃退火后合金的显微组织转变为等轴组织。随着退火温度的提高α相晶粒的偏聚方向发生了变化,织构类型由初始的B型织构转变为B型织构与T型织构的混合织构类型,最终再转变为B型织构。在800℃退火后α晶粒的择优取向最弱,其织构类型为B型织构和T型织构组成的混合织构,较强织构的成分为：φ2=0°截面,■;φ2=30°截面,■。对材料进行室温和高温(400℃)拉伸实验,可得到TC4钛合金强度及塑性与退火温度间的关系：退火温度的提高使合金的抗拉强度提高、屈服强度降低、改善了塑性,合金屈强比的降低使其可靠性提高。     

深冲IF钢再结晶{111}纤维织构形成机制探讨

为了探讨深冲IF钢再结晶织构与退火温度之间的关系及{111}再结晶织构形成机制,采用X射线衍射三维取向(ODF)和背散射电子衍射(EBSD)分析技术并结合金相组织观察,利用Gibbs-Thom son方程对冷轧IF钢在不同退火温度下的再结晶织构演变规律及形成机制进行研究.实验结果表明:随着退火温度的增加,再结晶量逐渐增多,γ纤维织构强度亦相应增强,同时,α纤维织构强度则逐渐降低;冷轧IF钢再结晶初期的织构转变主要发生在γ纤维织构之间.研究表明,再结晶核心的形成主要以"显微择优形核"为主,晶核的长大则主要以择优生长为主,而Σ重位点阵晶界在再结晶γ纤维织构形成过程中起着重要作用.     

IF钢铁素体区热轧和退火过程中织构的演变

研究了一种Ti—IF（Interstitial—free）钢在铁素体区热轧和退火过程中织构的变化．由于轧制过程摩擦的影响,热轧织构和退火织构在厚度方向上都有很大的差异．在钢板的表层,热轧织构的主要组分是{110}（001）,退火后表层的铁素体晶粒没有发生再结晶,该组分转变为（001）（110）;在试样的中心和1／4面,热轧织构组分主要是较弱的（111）／／ND（板法向）织构和部分（110）／／RD且在{001}（110）处最强;退火后中心面上的晶粒发生了完全再结晶,{001}组分转变为（111）／／ND组分使（111）／／ND织构成为唯一织构组分且在{111}（112）处最强．     

Effects of External Electric Field on AlN Precipitation and Recrystallization Texture of Deep-drawing 08Al Killed Steel Sheet

The effects of an electric field on AIN precipitation and recrystallization texture were investigated. Cold-rolled 08Al killed steel sheets were annealed at 550℃ according to the two-step processes, for various maintaining times, with and without applying an electric field. It was found that the electric field promotes the precipitation of the second phase （AlN particles）, strengthens the γ-fiber and weakens the α-fiber texture component in the recrystallized specimens. A possible explanation for the reinforcement of γ-fiber texture by the electric field is that the second phase AIN particle promotes the growth of γ-fiber at the expense of differently oriented grains.     

Microstructural evolution during batch annealing of boron containing aluminum-killed steel

Role of boron in low carbon aluminum-killed cold rolled batch annealed steels has been critically examined. It was found that it is not the absolute boron but B/N ratio that controls the forming properties. Pancake shaped grains (high grain shape anisotropy) are highly desirable for improving the desirable {111} texture, normal anisotropy, and draw ability of the steel sheets. Microstructural analysis showed that the extent of pancaking decreases with increase in B/N atomic ratio and reaches ultimately to formation of equiaxed grains. Low B/N ratio (upto 0.3) resulted in improved mean plastic anisotropy ratio (r _m) value and high grain shape anisotropy, which has been characterized through grain aspect ratio. The desirable orientation in steel with low B/N ratio is attributed to sufficient availability of Al and N to precipitate during batch annealing. Optimum amount of boron, aluminum, and nitrogen in steel has resulted in coarse pancake structure, which is ideally suited for improved formability.     

Warm rolling behaviour of low carbon steels

Abstract

Warm (ferritic) rolling can be a low cost method of producing sheet steel products. However, for steels containing solute carbon, microstructural development during processing is affected by dynamic strain aging (DSA). This can significantly weaken the {111} texture formed during annealing, thus resulting in products with poor formabilities. It is known that the DSA behaviour can be modified by the addition of elements such as boron and chromium. Experimental low carbon (LC) steels with various additions of chromium, boron and phosphorus were warm rolled and their behaviour compared with that of a standard LC material. It was found that these additions promote the formation of shear bands under warm rolling conditions, thus resulting in a stronger {111} recrystallisation texture than that of the unmodified LC steel.     

低收缩耐热耐油聚氯乙烯/氮化硼复合材料的制备及其性能研究

首先使用退火处理的方法使六方氮化硼(hBN)带上羟基,并与硅烷偶联剂混合,得到表面处理后的氮化硼(BN)。然后用熔融共混的方式制备出不同浓度的聚氯乙烯/氮化硼(PVC/BN)及聚氯乙烯/氮化硼/聚酰胺(PVC/BN/PA)复合材料。通过维卡软化点温度测定仪,动态力学分析仪和游标卡尺、耐油性能测试对复合材料的性能进行测试和表征,表明添加改性后BN粒子,可以使PVC和BN结合的更加紧密,复合体系的热学和耐油性能得到提高。同时添加BN含量为10%,PA6含量为25%(质量分数)时,复合材料的热学性能和耐油性达到最佳,远好于PVC材料。     

Carbothermal formation and microstrutural evolution of α′-Sialon–AlN–BN powders from boron-rich blast furnace slag

Boron-rich blast furnace slag of low activity is one of the major products created during the separation of iron and boron from ludwigite in a blast furnace process, and the high-efficiency utilisation of its is of great importance to the Chinese boron industry. This paper proposes one new application process to synthesize α′-Sialon–AlN–BN powders by a carbothermal reduction–nitridation method using boron-rich blast furnace slag as the staring material and describes a series of experimental studies that were performed to elucidate the mechanism of phase formation and microstructure evolution during CRN. The experimental results revealed that the phase compositions and microstructures of the synthesized products were greatly affected by the initial compositions ((Ca,Mg)_xSi_12–3xAl_3xO_xN_16–x), x = 0.3–1.8), temperature and holding time. With the compositions shifting from values of x of 0.3–1.8, the relative amount of α′-Sialon, AlN and BN increased gradually, and the amount of α′-Sialon reached a maximum at a value of x of 1.4. The optimal condition for powder synthesis was a temperature of 1480 °C with a holding time of 8 h, under which the crystalline phases included α′-Sialon, AlN, BN and less SiC. More elongated α′-Sialon grains were observed at higher x values and temperatures. During the CRN process, MgAl₂O₄, Mg₂SiO₄, Ca₂Al₂SiO₇, MgSiN₂, β′-Sialon and 27R appeared sequentially as intermediate products. The volatilisation of SiO gas and magnesium vapour resulted in additional weight loss of the samples, which was aggravated with increases in the synthesis temperature and holding time.     

Pyrolytic-grown B–C–N and BN nanotubes

We report the growth of pyrolytic boron–carbon–nitrogen (B–C–N) nanotubes on iron (Fe) and nickel (Ni) catalysts. It was discovered that different catalysts had effect on the elemental compositions of B–C–N nanotubes, which may allow one to tune the transport properties of B–C–N nanotubes in a wide range. A new synthetic route was also developed to generate H₃N:BH₃ as the precursor and yield boron nitride (BN) nanotubes by pyrolysis. The typical growth scenario of multi-wall BN tubes will be discussed.     

Synthesis of boride and nitride ceramics in molten aluminium by reactive infiltration

The infiltration of solid powder mixtures with molten aluminium has been investigated as a potential route for the synthesis of ceramic/metal composites. Either titanium or tantalum powder was mixed with boron nitride flakes for the reaction powder mixture. The infiltration occurred spontaneously at 1473K for both [Ti+BN] and [Ta+BN] powder mixtures. Owing to reactions between the starting materials, both boride and nitride ceramics were produced in molten aluminium. TiB2 and AlN were produced from the [Ti+BN] powder mixture, and TaB2 and AlN were produced from the [Ta+BN] powder mixture. When the [Ti+BN] powder mixture was used, a reaction producing Al3Ti took place immediately after the infiltration of the molten aluminium, and a subsequent reaction producing TiB2 and AlN proceeded gradually. The time required to convert BN flakes to TiB2 and AlN particles at 1473K was in the range of 1800–3600 s. On the other hand, when the [Ta+BN] powder mixture was used, there was an initial incubation period to allow the tantalum and molten aluminium to react with each other. The reaction between tantalum, BN and aluminium took place after this incubation period. This revised version was published online in November 2006 with corrections to the Cover Date.     

氮化铝/氮化硼/碳纳米管/硅橡胶复合材料的力致填料取向对导热性能的影响

随着科学技术的发展,电子元器件发热量大幅度增加,因此开发兼具高导热和高绝缘性能材料日益迫切。以甲基乙烯基硅橡胶（SR）为基体,碳纳米管（CNTs）、六方氮化硼（BN）以及氮化铝（AlN）为导热填料,通过机械共混法制备导热复合材料。研究3种导热填料复配对复合材料的导热性能、绝缘性能和力学性能的影响,研究填料取向对复合材料导热性能的影响,研究材料表面温升与加热时间的关系。采用Agari模型预测复合材料的理论热导率。通过热红成像、扫描电子显微镜、X射线衍射分析、热重分析等对复合材料进行表征。结果表明：随着复配导热填料中AlN用量的减少,BN和CNT_S用量的增加,复合材料的热导率逐渐升高;当AlN为80 phr,BN为68 phr,CNTs为2 phr时,复合材料的垂直热导率为1.857 W·m^-1·K^-1,平行热导率为2.853 W·m^-1·K^-1,体积电阻率为2.18×10¹² Ω·cm,拉伸强度达4.3 MPa,复合材料的综合性能较好。     

Pyrolytic-grown B–C–N and BN nanotubes

We report the growth of pyrolytic boron–carbon–nitrogen (B–C–N) nanotubes on iron (Fe) and nickel (Ni) catalysts. It was discovered that different catalysts had effect on the elemental compositions of B–C–N nanotubes, which may allow one to tune the transport properties of B–C–N nanotubes in a wide range. A new synthetic route was also developed to generate H₃N:BH₃ as the precursor and yield boron nitride (BN) nanotubes by pyrolysis. The typical growth scenario of multi-wall BN tubes will be discussed.     

硼对刃具钢组织与性能的影响

为研制开发适合水淬的新型刃具钢,采用显微组织观察、力学性能测试、热处理试验和磨粒磨损试验等技术手段,对比研究了含硼中碳钢与不含硼的65Mn钢热轧后与热处理后的显微组织和应用性能.结果表明:热轧态中碳含硼钢中存在较多铁素体相,强硬性更低,韧塑性更好;中碳含硼钢水淬回火后组织为回火马氏体,硬度可达50 HRC以上,高于油淬回火的65Mn钢,韧塑性和耐磨性也明显好于65Mn钢.中碳含硼钢完全适合水淬工艺,减少了工业污染,符合环保要求.