高成型性细晶粒510MPa级热轧汽车板的开发和应用研究

对高成型性细晶粒510MPa级的热轧汽车板进行了开发和应用研究,文中通过轧制以及有限元分析和热模拟试验,提出表面产生混晶和拉长变形晶粒的原因和避免措施.以及CSP线生产这类高强度高成形板材的工艺.结果表明:采用深过冷轧制可以有效避免表面的混晶和微裂纹,改善冷弯成形性,以此思想作指导设计的合金成分和制定的CSP线轧制工艺,所生产510MPa的汽车热轧板,具有良好的强度和延性匹配,可以冲压成形状复杂的发动机横梁.     

基于动态大压下的510MPa级超细晶粒钢的组织及性能

基于动态大压下方法在1450热连轧机上生产出了510MPa强度级别超细晶粒热轧钢板。结果表明,通过基于动态大压下的热轧工艺,可以使Q235碳素钢的铁素体晶粒细化到4~6μm,可获得屈服强度为400MPa以上、抗拉强度510MPa以上强度级别的超细晶粒热轧钢板。超细晶粒热轧钢板的显微组织为铁素体和珠光体,铁素体晶粒多为细小均匀的等轴铁素体,铁素体晶粒内部及晶界位错密度较高,珠光体中的渗碳体大多以短棒状或颗粒状渗碳体存在。与用常规热轧工艺生产的Q235热轧钢板相比,基于动态大压下工艺生产的超细晶粒热轧钢板具有较高的强度和良好的韧性。     

CSP生产低碳钢的组织演变和析出物研究

为了阐明EAF-LF-CSP工艺生产的低碳钢组织细化机理,在薄板坯和不同道次变形后的同一轧件上取样,利用金相、SEM、TEM、XEDS等技术研究了连轧过程中显微组织演变和钢中第二相析出物.结果表明:与普通连铸板坯相比薄板坯的凝固组织更加细小;随轧制道次增加,薄板坯表面和心部的组织差异逐渐减小,轧后室温组织细化;CSP生产的低碳钢中存在大量纳米尺寸的氧化物和硫化物,起到细化晶粒的作用.CSP生产中采用快速冷却和凝固工艺、单道次大压下连轧工艺和层流冷却工艺,是成品组织细化的主要原因.     

工艺因素对AZ31镁合金板材室温成形性能的影响

通过不同的加工工艺制备具有不同晶粒尺寸和织构的AZ31镁合金板材,通过室温埃里克森试验研究了工艺因素对提高镁合金板材室温成形性能的影响。结果表明:增大晶粒尺寸,减弱基面织构,可以改善镁合金轧板在变形过程中产生的在轧制方向的硬取向,增大镁合金轧板的延伸率,从而提高镁合金室温成形性能;用异步轧制工艺(轧制和退火温度为400℃、异速比为1.5)制备的试样晶粒尺寸增大到20μm、(0002)极图最大极密度仅为2,室温杯突实验测得IE值达到了5.71,显著提高了材料室温成形性能。     

CSP流程生产低碳高强度汽车板组织性能的研究

研究了珠钢电炉CSP工艺生产低碳高强度钢板的热轧工艺与组织性能之间的关系,通过光学显微镜和力学性能试验等检测分析技术分析了控制轧制和冷却各阶段工艺参数对成品板显微组织和力学性能的影响.研究表明:降低终轧温度和卷取温度可有效细化晶粒,提高钢板的强度;采用适当的控轧控冷工艺制度,可以获得不同强度级别强韧性能良好的热轧低碳高强度汽车用钢板.     

不同加工成形方法对银靶微观组织性能的影响

目的 研究锻造和轧制两种不同加工成形方法对银靶微观组织的影响,解决纯银靶材内部晶粒粗大、分布不均匀的问题。方法 采用锻造和轧制方法分别对纯银靶材铸锭进行加工,通过对微观组织的观察和测试分析,研究两种不同加工方法对银靶微观组织的影响。结果 锻造加工的纯银靶材致密性更好;轧制加工的纯银靶材在冒口处存在大量缺陷。锻造加工的纯银靶材晶粒细小且分布均匀;轧制加工的纯银靶材晶粒较粗大、分布均匀性差,存在部分粗大晶粒。锻造加工的纯银靶材硬度值(73HV0.05)明显高于轧制加工的纯银靶材(55HV0.05)。结论 在晶粒细化及分布均匀性方面,锻造比轧制加工纯银靶材更具优势。     

Nb10Zr靶材制备工艺研究

研究了Nb10Zr铸锭预处理、锻造、轧制、热处理等工艺及Nb10Zr靶材的制备工艺。结果表明,1450℃保温90 min的铸锭预处理,可以改善锻造塑性;1 300℃径向圆周锻造、1 000℃轧制及1 200~1 450℃热处理,可以避免锻造和轧制开裂,晶粒度达到8级且组织均匀。     

CSP热轧1.0mm超薄规格低碳钢板的组织及性能

采用光学显微镜、扫描电镜和拉伸实验等方法研究了CSP线轧制工艺与薄规格低碳钢板显微组织、力学性能特征之间的关系.显微组织观察和力学性能实测结果表明:CSP线生产的低碳钢连铸坯铸态组织比较均匀,靠近表面层的枝晶宽度与心部区域差别很小,皆为较细的树枝晶,枝晶宽度在几微米至30μm之间;成品1.0mm低碳钢薄板的组织很细,约为5μm,但轧向与横向组织中的铁素体晶粒形貌和尺寸存在差异;由于晶粒组织细小且钢中有害元素、夹杂物的含量低,故板的强度和延伸率高.     

轧制和热处理工艺对Bi系超导带材晶粒取向的影响

利用Ｘ射线晶面衍射分析和扫描电镜观察手段，分析了Ｂｉ系超导带材在轧前后以及热处理前后的晶粒取向性。实验结果表明轧制工艺导致了有利于超导材料电学性能的晶粒取向性分布，超导晶粒的片平面即晶面沿轧制平面作一致排列，这种取向性在热处理中得到了保留和加强。     

超薄取向硅钢组织及织构与磁性能的关系

本工作旨在探讨超薄取向硅钢组织及织构与磁性能的关系,并从加工工艺角度揭示如何减少不利于磁性能的组织和织构的产生。利用电子背散射衍射(EBSD)技术和X射线衍射(XRD)技术对两种磁性能不同的商业超薄取向硅钢带材的显微组织和织构进行对比分析,结果发现,二者组织、织构差异均比较明显。磁性能差的带材样品的组织尺寸不一,均匀性较差,η线织构(〈100〉//RD)所占比例偏低,非η线取向晶粒所占比例高且晶粒尺寸大,其取向特征主要表现为{210}〈001〉、{411}〈148〉及{111}〈110〉。这些不利组织的产生可能与轧制、退火工艺控制不当有关。因此,晶粒尺寸及η线取向晶粒所占比例的不同是造成两种带材性能差异的主要原因,在高性能取向硅钢超薄带材制备过程中,应精准控制轧制、退火制度等相关工艺,以避免非η线取向晶粒形成、长大。     

铸态AZ31镁合金板材等温轧制工艺及组织性能研究

为研究铸态AZ31镁合金轧制工艺及轧制后组织性能,通过试验得到不同道次和变形量对铸态AZ31镁合金板材显微组织和力学性能的影响规律,并采用扫描电子显微镜研究了轧制后板材组织.结果表明,铸态AZ31镁合金板材经等温4道次、等变形量轧制后,板材厚度由20mm变化到4.8 mm,抗拉强度和屈服强度分别达到275 MPa和18...     

Manufacturing large 2A14 aluminium alloy cylinders by a warm rolling technology

This paper aims at the problem of high performance manufacturing of large 2A14 Al-alloy cylindrical components for aerospace applications. A warm rolling process was put forward to substantially refine the grains and secondary phases of 2A14 Al alloys. The results indicated that compared with hot rolling, warm rolling was easier to implement to form abundant subgrains and fully crushed the coarse particles. Coarse second phases dissolved and the precipitated T phases (AlCuMn) hindered the migration of grain boundaries and restrained grain growth during the heat treatment.The tensile strength, yield strength and elongation of the 2A14 aluminium alloy were significantly increased by 59?MPa (an increase of 14%), 71?MPa (an increase of 21%), 4% (an increase of 67%), respectively.     

Application of nanoengineering to research and development and production of high strength steel sheets

Abstract

The design concepts and properties of three unique high strength steel sheets developed utilising nanoengineering are reviewed. The first steel is developed by optimising the distribution of nanoprecipitates and exhibits low yielding ratio in spite of being strengthened by grain refinement and precipitation hardening. The second is the ferrite single phase tensile strength 780 MPa grade advanced high strength steel sheet utilising the thermally stable nanosized precipitates, which possesses significantly well balanced elongation and stretch flangeability. These two were already commercialised. The last is the ultrahigh strength steel, of which the formability is enhanced by optimising the combination of hard phases. The steel consists of bainite, retained austenite and tempered martensite and exhibits 35% of elongation with 1470 MPa of tensile strength. Although further optimisation of the composition and the processing are needed to produce and commercialise the steel, the results indicate that the approach has the potential to improve formability dramatically.     

挤压包覆轧制对SiCP增强镁合金(AZ91)复合板显微组织和力学性能的影响

通过热挤压复合的方式将AZ91合金引入至SiC_P增强镁合金（AZ91）（SiC_P/AZ91）复合材料中,制备出厚度为2 mm的AZ91-（SiC_P/AZ91）复合板,研究了热轧对其显微组织和力学性能的影响规律。研究结果表明:AZ91的引入显著提高了SiC_P/AZ91的轧制成形能力。与AZ91层相比,SiC_P/AZ91层内晶粒尺寸小,硬度高。随轧制压下量的增加,AZ91-（SiC_P/AZ91）复合板晶粒尺寸变大,析出相数量减少且尺寸增大,导致硬度呈现下降的趋势。与挤压态AZ91-（SiC_P/AZ91）复合板相比,当压下量为50%时,轧制态AZ91-（SiC_P/AZ91）复合板屈服强度由272 MPa提高至341 MPa,抗拉强度由353 MPa提高至404 MPa。在拉伸过程中,因SiC_P与基体界面脱黏导致裂纹优先在SiC_P/AZ91层内萌生和扩展,AZ91层对微裂纹扩展具有一定的阻碍作用。      

静磁场深冷处理对铝黄铜组织和性能的影响

对铝黄铜进行静磁场条件下不同时间的深冷处理,并与初始试样和同时间单独深冷试样进行对比分析,结果表明静磁场能够进一步提高铝黄铜的强韧性。在T=24h时,MDCT试样的强韧性最好,其抗拉强度为602.5 MPa,延伸率为7.2%,较初始样分别提高了6.4%和53.2%,较DCT24试样分别提高3.1%和28.6%。分析原因在于从深冷回复到室温过程中铝黄铜发生了回复再结晶,起到了细晶强化作用;同时基于磁致塑性效应,位错运动灵活性增加,有助于提高延伸率和塑性变形能力。另外,静磁场在深冷过程中起到抑制铝黄铜α→β相转化和促进γ相转变的作用,使得MDCT试样平均晶粒尺寸较DCT试样大。     

Achieving an excellent strength–ductility synergy in Zircaloy-4 by FSW with rapid cooling

Zircaloy-4 plates of 2?mm in thickness were successfully joined by friction stir welding with rapid cooling. The processing temperatures were strictly controlled below the α/β phase transformation point. The stir zone (SZ) has an ultra-refined grain structure with high dislocation density and abundant twin boundaries. Grain subdivision and discontinuously dynamic recrystallisation contributed most to the grain refinement. A good match of strength and uniform elongation of 895?MPa and 16.8%, respectively, was achieved in the SZ by using liquid nitrogen cooling. This work provides an effective strategy to enhance the strength of friction stir welded Zircaloy-4 joint without ductility loss.     

Microstructural and mechanical properties of ultra-high-strength dual-phase steel produced by ultra-fast cooling

ABSTRACT

In the present study, grain refinement of Fe–Si–Mn–Nb–B steel was achieved by high reduction hot rolling. Through the following ultra-fast cooling (UFC) and relaxation process, martensite-ferrite complexes with soft phase embedded in the hard phase were prepared. Extremely tiny ferrite grains significantly increased the toughness of the test steel, a large number of big-angle grain boundaries existing in fine martensite lath bundles effectively improved the strength and the strain hardening ability of the investigated material. The test steel with a relaxation time of 6?s shows the best comprehensive performance with a tensile strength of 1473?MPa, an elongation of 15.0%, a low yield ratio of 0.72 and a product of strength and elongation (PSE) of 22.10?GPa%.     

450~780 MPa系列双相钢扩孔性能实验

目的避免双相钢在成形过程中经常出现的翻边或扩孔开裂的问题,提高生产效率。方法以几种强度级别为450~780 MPa的双相钢为实验对象,测试材料的单向拉伸和扩孔性能,并从微观组织上分析影响双相钢强度和扩孔性能的因素。结果 450~780 MPa强度级别双相钢的屈服强度随铁素体晶粒尺寸的减小而增加,抗拉强度随马氏体体积分数的增加呈近似线性增加。双相钢的扩孔性能随着材料强度的提高呈下降的趋势。DP500与DP450和DP600相比,抗拉强度(579 MPa)居中,伸长率最高,但由于其马氏体形态和分布的差异,其扩孔性能反而最低。结论双相钢的扩孔性能会受到马氏体的含量、尺寸、形态和分布的影响,与材料强度和伸长率没有必然的关系,当马氏体呈颗粒状均匀分布时,具有更好的扩孔性能。