钼镧合金板材高温抗下垂性能的研究

以粉末冶金法生产的180 mm×20 mm×1.5 mm钼镧合金板材为试验原料,通过对比轧制和高温定型处理制备的钼镧合金板材在1 750℃高温和500 g重物荷载条件的下垂值,并研究了这两种板材的组织形态。结果表明:采用常规工艺轧制的钼镧合金板材组织纤维发达,而采用了高温定型处理后的钼镧合金板材形成了一种粗大、组织相互搭接的再结晶组织;在1 750℃高温及500 g重物的载荷条件下,高温定型后的钼镧合金板材的下垂值较小,其下垂值从常规工艺轧制的钼镧板的4.2 mm减小到1.8 mm,表现出良好的高温抗下垂性能。     

聚变堆中面向等离子体的钼板材制备工艺研究

通过对比采用轧制方法和锻造方法生产的钼板材的组织和力学性能,研究了面向等离子体钼板材的制备工艺。结果表明:采用板坯轧制方法生产的钼板材经过完全再结晶退火之后,尽管密度较大,但轧制面方向上金相组织晶粒较粗大,强度值明显偏低;采用钼棒坯经过大加工率锻造加工后生产出的钼板材同样经过完全再结晶退火处理后三向晶粒组织和强度值均匀,可满足聚变堆中钼板材料的使用要求,且进一步加大锻造加工率,可进一步提高板材的强度和密度。     

TYM钼合金轧制工艺与组织结构及再结晶温度的关系

文中用X射线和金相技术研究了TYM钼合金板轧制工艺与组织结构及再结晶退火温度的关系。结果表明，多次交叉轧制态板材织构为聚集很强的{001}<110>，其组织纤维较粗，弥散相粒子分布不均匀，再结晶退火温度约在1300℃以下；一次交叉轧制态板材织构为{001}<110>，但聚集程度较低，同时存在极弱的{001}<100>立方织构，其组织纤维细、长，弥散相粒子分布均匀，再结晶退火温度可达1500℃以上。有关组织结构对合金高温性能的强化机制进行了详细分析。     

掺杂钼板材性能的研究

叙述了掺杂钼板材的室温及高温拉伸性能、弯曲塑－脆转变温度、室温反复弯曲性能，讨论了不同处理温度对其显微组织和性能影响。掺杂钼板材经腐温（1700～1800℃）退火1h后，具有拉长的互相联锁的组织结构，在纵向断口上呈现出排列整齐的细小钾泡列。1800℃退火试样的室温抗拉强度为495MPa，延伸率约为48％，弯曲塑－脆转变温度为－380℃－40℃，室温反复弯曲次数为6～7次。     

钼镧合金厚板材退火工艺对其热成形性影响研究

由于钼具有室温脆性的特点,对于壁厚大于2.0 mm的钼制品无法在室温下进行冲压成形,因此需研究钼及其合金高温成形的特点,对其进行高温力学性能研究,以便制备出合格的产品,并能保证产品的性能稳定。采用传统固-液掺杂方式制备出Mo-0.8%La的合金粉末,通过粉末冶金方法压制、烧结及轧制出厚度为3.5 mm的板材,在不同的退火温度下对板材组织性能进行分析,并进行高温拉伸试验。结果表明:板材的拉伸工艺中两个比较重要的工艺点为:退火温度1 300℃、冲压温度700℃,在此条件下制备的钼镧合金板材具有较好的热成形性。     

钨含量对Mo-W合金板材组织及力学性能的研究

Mo-W合金因为高熔点、低电阻率及优良的高温性能,在工业高温炉、电子光源和平板显示等诸多领域中已得到广泛应用。研究通过采用粉末冶金及轧制变形的工艺制备出Mo-W合金板材,研究了添加不同钨含量对Mo-W合金板材退火组织形貌演变及高温力学性能的影响。结果表明:轧制变形后的Mo-W合金板材与通过理论计算得到的密度值基本一致,且随着W含量的增加,Mo-W合金的密度不断增加;随着W含量的增加,相同退火条件下的Mo-W合金硬度值不断增加;W含量的增加可以提高Mo-W合金板材的再结晶温度,纯Mo 1 100℃退火后已完全再结晶,Mo-30W合金需达1 400℃,而Mo-50W合金为1 500℃;随着W含量的增加,Mo-W合金板材的韧-脆转变温度和相同高温试验条件下的抗拉强度也不断增加。     

钼镧合金和TZM合金的高温性能

研究了钼镧合金和TZM合金在1000～1800℃的高温性能和相应的组织.结果表明小于1400℃的情况下,钼镧合金有较高的强度和塑性的综合性能,当温度大于等于1400℃时,其抗拉强度明显降低,同时塑性也有明显的下降.而随着测试温度的提高,TZM合金的抗拉强度降低,但是其塑性升高,这一点和钼镧合金恰恰相反.同时,不管是强度还是塑性,TZM合金较之相同温度的钼镧合金有明显的优势.组织观察表明这两种钼合金在1100℃开始再结晶,一直延续到1550℃,并且其再结晶晶粒都呈现拉长的组织,这明显不同于纯钼再结晶状态下的等轴晶粒.     

高温轧制对AZ31B镁合金组织和性能的影响

研究了高温轧制工艺对AZ31B镁合金微观组织、织构以及性能的影响规律。在轧制状态下,随着轧制温度从450℃升高至525℃,合金组织内部动态再结晶逐渐增多,孪晶数量不断减少,同时组织的均匀性也得到了改善,基面织构强度也呈下降的趋势。经350℃保温60min退火之后,合金板材内部发生了完全再结晶,孪晶组织消失,显微组织更均匀,板材基面织构强度也进一步减弱。由于基面织构强度的减弱,合金板材的室温成形性能随着轧制温度的升高得到显著提升,其杯突值由450℃时的5.6mm增大到525℃下的6.3mm,比450℃下的5.6mm提高了约12.5%。     

用作真空烧结炉发热体的高温钼板材

叙述了用作真空烧结炉发热体的高温钼（HTM）合金板从制粉到轧制成0．5mm板材的工艺过程；对乳制成的0．5mm厚的板材在不同温度退火后的试样进行了室温拉伸、塑－脆转变温度（DBTT）及反复弯曲性能的测定，同时检验了1200～1400℃的高温拉伸性能，并用金相法观察了温度对高温钼合金板的显微组织的影响，还用扫描电镜对高温钼粉末形貌、烧结坯断口、室温拉伸及高温拉伸断口进行了观察。最后简介了这种钼合金板的使用情况。     

掺杂钼板室温韧性研究

本文对加入K、Si、Al元素的掺杂钼与纯钼烧结板坯进行了对比研究。采用交叉轧制工艺生产出厚1.0mm的板材,沿两种板材的纵向及横向截取试样。对全部样品进行了系统地金相观察、SEM断口分析与TEM观测。结果表明,高温退火后的掺杂钼板具有明显优异的室温韧性。掺杂钼板的再结晶温度区间为1100～1700℃,温度高于1700℃晶粒长大。二维定向分布的钾泡列是掺杂钼具有特殊金相组织与优异室温韧性的内在原因。掺杂是强化与韧化纯钼的重要手段。     

双辊铸轧Cr12钢的热处理工艺对深冲性和抗皱性的影响

将双辊铸轧Cr12钢薄板于1 000℃固溶,再采用炉冷和水淬两种方式冷却至室温,分别获得了多边形铁素体和板条马氏体两种组织,再经过相同冷轧和退火工艺,得到了两种成品板.经拉伸试验测定,水淬板的深冲性和抗皱性均强于炉冷板.组织分析发现:热处理后,水淬板内马氏体板块明显细小于炉冷板内铁素体晶粒;冷轧后,水淬板内板块间界演变...     

Effect of purity and processing procedure on the mechanical properties of beryllium sheet

The purpose of this research was to assess what improvements might be obtained in the bend ductility of beryllium sheet by starting with high purity commercial powder and consolidating it into sheet by techniques that minimized deformation and texturing. Sound sheet was achieved with reduction ratios from 2∶1 to 12∶1 at temperatures from 700° to 1050°C by forging, upsetting and compression rolling. Compression rolling is accomplished by successively changing the rolling direction by 30 deg after each pass so that no preferred rolling direction was developed. It was found that as the plastic bend ductility increased (up to 4 pct) the yield strength decreased. The higher bend ductilities corresponded to lower reduction ratios, lower degrees of preferred orientation and a larger subgrain size as determined by transmission electron microscopy. Sheet prepared by commercial rolling practices from the less pure commercial powder exhibited similar behavior. The ductile-to-brittle transition temperature for bending decreased with improved purity and reduced texture.     

Improvement in Strength and Ductility of Asymmetric-Cryorolled Copper Sheets Under Low-Temperature Annealing

Ultrafine-grained copper sheets have potential micro-electro-mechanical applications. Copper sheets were fabricated using asymmetric rolling and asymmetric cryorolling, respectively, and they were annealed at 373 K for 1 hour. The asymmetric-cryorolled sheet has higher strength compared to the asymmetric-rolled sheet. Low-temperature annealing results in improved strength and ductility for the asymmetric-cryorolled sheet, while the strength was reduced for the asymmetric-rolled sheet. The asymmetric-cryorolled sheets have better thermal stability compared to asymmetric-rolled sheets due to their laminate structure.     

Effect of Through‐Thickness Macro and Micro‐Texture Gradients on Ridging of 17%Cr Ferritic Stainless Steel Sheet

In order to study the formation of ridging in ferritic stainless steel (FSS) sheets, the evolution of the crystallographic texture was investigated by macro and micro‐texture measurements throughout the thickness of the sheets. The as‐received hot band material displayed a pronounced through‐thickness texture gradient with a strong rotated cube orientation in the sheet center layer. The initial texture of the hot band had a high impact on the formation of the cold rolling texture and on the final recrystallization texture. Modification of the cold rolling texture by means of cross‐rolling led to an improvement of the macro and micro‐textures after final recrystallization annealing, which gave rise to an enhanced sheet formability in FSS. Tensile tests of specimens with half thickness revealed that ridging formed in the sheet center was much stronger than that in the surface. This observation was attributed to the more frequent formation of orientation colonies in the sheet center when compared to the sheet surface.     

CSP热轧及冷轧工艺对深冲板组织和性能的影响

以某钢厂CSP工艺生产的SPHE热轧板为研究对象,在实验室条件下,研究了CSP卷取温度对SPHE冷轧深冲板组织和性能的影响。研究结果表明,CSP工艺生产的SPHE热轧板的卷取温度应控制在560-565℃;冷轧工艺相同时,基于CSP工艺生产的SPHE深冲板的退火温度越高,再结晶进行越充分,晶粒尺寸越大,对性能越有利,尤其是560-565℃卷取的SPHE板在700℃退火时已可以获得很好的深冲性能。     

镀锌板表面胞状凸起缺陷

 采用SEM、EDS和大样电解法研究了某种镀锌板表面胞状凸起缺陷的形成原因。结果表明：冷轧板表面起皮缺陷是造成镀锌板表面胞状凸起缺陷的直接原因。冷轧原料板近表层分布着尺寸大于300 μm的长条状硅酸盐夹杂带,且夹杂带中分布着块状氧化铁夹杂。与缺陷镀锌板同批次酸洗板机械研磨去掉近表层,随后冷轧试验表明,块状氧化铁夹杂不是造成镀锌板表面胞状凸起缺陷的主要原因。缺陷镀锌板铸坯中夹杂物含量为100.32 mg/10 kg,夹杂物主要由尺寸大于140 μm大型夹杂物组成,而正常镀锌板铸坯中夹杂物含量为20.98 mg/10 kg,证实钢中大型硅酸盐类夹杂是导致镀锌板表面凸起缺陷的根本原因。     

国外汽车用钢板开发新进展

综述了国外汽车板研究开发的新进展,重点介绍了板带热轧工艺中ＩＦ钢热轧卷取温度控制、铁素体区轧制、ＴＲＩＰ钢、ＢＨ钢、冷轧与退火工艺及钢板表面质量检测与控制等汽车板品种、质量研究开发的新成果。     

Effect of asymmetric rolling on the texture and mechanical properties of AA6111-aluminum sheet

Aluminum-alloy sheets are considered to be one of the high-potential substitutes for steel sheets, when considering the weight reduction of automobiles. However, aluminum-alloy sheets have inferior formability, mainly due to their lower plastic-strain ratios. The plastic-strain ratios of aluminum-alloy sheets can be increased with the formation of shear-deformation texture through the sheet thickness. Asymmetric rolling, in which the circumferential velocities of working rolls are different, is a favorable process for imposing shear-deformation texture through the sheet thickness. In this study, commercial AA6111-alloy sheets were used to compare the effects of conventional symmetric rolling and asymmetric rolling in controlling the shear textures and grain refinement, as well as the mechanical properties of the tensile and plastic-strain ratio.     

Elastic‐Plastic Finite Element Analysis of Sheet Rolling Using Co‐Rotational Formulation

A new elastic‐plastic finite element analysis for rolling processes is proposed. This analysis is based on a co‐rotational formulation with finite deformation theory. It enables to perform an accurate characterization of the rolling process in a short computation time, as it allows a large increment in plastic strain and the direct implementation of the neutral point into the analysis. The basic mathematical formulation of the proposed analytical model is described first, and its application to the simulation of sheet rolling with large and small thickness reductions is presented. Through this investigation, it has become clear that the proposed model is capable of analysing the elastic‐plastic deformation characteristics of a sheet under rolling, which is indispensable for the design of a rolling process for the manufacture of sheets with accurate flatness and profile.     

Evolution of Microstructure and Ordering in Rolling Process of Fe-6.5 mass％ Si Alloy

Fe-6. 5 mass% Si alloy is an excellent soft magnetic material with good application prospects. After rolling,the structure of the sheet is likely to be heterogeneous along the normal direction. The microstructure and ordering evolution in the thickness range of the sheets during hot-warm rolling process was studied by means of optical microscope and transmission electron microscope. The results show that dynamic recrystallization occurs in the surface parts during the hot and warm rolling processes,where the grains are equiaxed but have high density of dislocations due to the large deformation. The grains in the center part are elongated along the rolling direction. It is also found that in the hot rolled sheet,the center part has lower density of dislocations because of dynamic recovery. Meanwhile,this part has higher ordering content compared with the surface part,indicating that the high density of dislocations can inhibit the formation of ordering in the air cooling process after hot rolling. In the warm rolling process,both of the parts are deformed heavily. Large deformation destroys ordered phases and induces disordering. The ordering content is low in the whole warm rolled sheet.