铁素体体积分数对Q&P钢组织与性能的影响

为了研究铁素体体积分数对于QP钢组织与性能的影响,设计了系列连续退火试验研究缓冷过程中相变形成的铁素体体积分数对于QP钢组织与性能的影响.相较于单相区淬火的情况下,相变铁素体的引入可以将延伸率由6%提高至26.7%,强塑积由由7.5GPa%提升至26.6GPa%.CCE模型计算表明,引入缓冷相变铁素体后,QP钢淬火前的奥氏体晶粒实现了富碳,提高了奥氏体晶粒的稳定性,从而使得QP钢的加工硬化能力增强,在略微损失强度的情况下大大增强了延伸率和强塑积.实测的残余奥氏体体积分数最大值的峰值对应的快冷温度为250℃, 420℃配分350 s的情况下,QP钢的屈服强度为640 MPa,抗拉强度为998 MPa,强塑积≥20GPa%,各项指标满足980 MPa级QP钢要求.     

铁素体—珠光体钢中的疲劳裂纹扩展行为

在扫描电镜下对两种铁素体－珠光体钢中的低周疲劳裂纹扩展进行了动态原位观察，发现疲劳裂纹只在铁素体中扩展，而珠光体晶团阻碍其扩展，提出疲劳裂纹扩展的形态及方式与材料的疲劳裂纹扩展阻力之间存在着一定的关系。     

奥氏体/铁素体异种钢焊接接头熔合区组织的研究

采用光学显微镜和透射电子显微镜研究了熔合区马氏体层的组织特征,并用模拟成分炼钢的方法测得了马氏体层内Ms点的分布规律。实验结果表明:熔合区马氏体层的组织是位错型马氏体,在马氏体层内,距熔合线位置不同的点有不同的马氏体转变温度Ms;马氏体转变温度主要受熔合区成分梯度控制。在实验的基础上,提出了熔合区马氏体组织形成的模型。     

临界区淬火铁素体对钢性能的影响

研究了铁素体形态和亚结构对临界区淬火强韧性的影响。表明：临界区淬火温度不同时，铁素体形态有所差异；当铁素体呈针状，与马氏体相间分布且含量为２０￣３５％时强韧化效果最佳。临界区淬火时，铁素体可产生位错强化、固容强化等强化效果，提高钢的强韧性。     

热变形温度对先共析铁素体等温转变动力学的影响

试验研究了一种Ｃｒ－Ｍｎ－Ｍｏ－Ｂ低碳低合金高强钢奥氏体热变形温度对相变前奥氏体组织状态及对先共析铁素体等温转变动力学的影响。结果表明，随着奥氏体热变形温度的降低，相变前奥氏体晶粒减小，并且先共析铁素体等温转变孕育期缩短，先共析铁素体转变量增多。     

调质处理对低碳贝氏体钢组织和性能的影响

通过对低碳贝氏体钢的调质处理工艺试验,研究不同的淬火介质、淬火温度及回火温度对实验钢组织和性能的影响。结果表明:经过930℃加热保温并10min油淬后,再选取500℃回火70min,实验钢的微观组织为细小的块状铁素体基体上分布着均匀的碳化物。实验钢的硬度由未调质处理前的260.7HV提高到322.2HV。     

高扩孔型铁素体/贝氏体双相钢组织性能研究

对540MPa级铁素体/贝氏体双相钢的组织性能进行分析研究。结果表明,试验钢的显微组织为85%左右的铁素体加上15%左右的贝氏体;铁素体晶粒尺寸细小,基体中有较高的位错密度和大量细小弥散的析出物;贝氏体在铁素体基体上分布均匀,以板条状为主,板条间分布有较多碳化物颗粒。通过合适的成分设计和控轧控冷手段获得的铁素体/贝氏体双相钢组织形态,可较好地保证材料所需的强度-拉伸凸缘性能匹配。     

合金元素Mo对冷轧双相钢组织的影响

分析Mo微合金冷轧双相钢和普通C-Mn冷轧双相钢在不同双相热处理工艺下微观结构,讨论Mo对冷轧双相钢组织变化规律的影响。实验结果表明：当两种双相钢以1700℃／s冷却时,均获得了铁素体、马氏体双相组织,马氏体均匀分布在铁素体基体上,随着加热温度的升高,普通C-Mn双相钢得到的马氏体体积分数多。当以5．4℃／s冷却时,Mo微合金双相钢得到的马氏体体积分数多;当加热到820℃保温结束后以5．4℃／s的速率冷却时,普通C-Mn钢的组织组成相为铁素体、珠光体、马氏体;Mo微合金钢的组织组成相为铁素体、贝氏体、马氏体;Mo对铁素体晶粒的细化作用不明显。     

Redistribution of Boron during Ferrite Reaction in Nb-B Microalloyed Steel

By contrast of microstructure and boron distribution in the same area of samples, the behavior of boronduring ferrite reaction in Nb-B microalloyed steel was studied. Boron atoms have segregated to original austeniteboundaries betfore ferrite reaction starts during isothermal treatment. The concentration of boron in small Pieces offerrite foming along austenite boundaries may be remarkably higher than that in austenite matrix, but it will reducegradually when the ferrite continuously grows. There is no obvious boron segregation on interface of γ/α and α/α.These facts indicate that ferrite growth is not controlled by diffusion of boron in austenite.     

Microstructural Features During Strain Induced Ferrite Transformation in 08 and 20Mn Steels

The microstructure evolution during strain induced ferrite transformation was followed in thermal-simulation tests of clean 08 and 20Mn steels. The influences of carbon equivalence and initial austenite grain size on ferrite grain refinement and the volume frac- tion of ferrite during straining were inspected. The results revealed that the accelerating effect of ferrite transformation by strain was increased as the carbon equivalence decreased. However, finer ferrite grains were obtained at higher carbon content. At strain of -1 .5 ferrite grains less than 3 μm and 2 μm can be obtained in 08 and 20Mn steels respectively. Whereas the ferrite grain refinement in 08 steel was due to both effects of strain induced transformation and ferrite dynamic recrystallization, that in 20Mn was mainly due to st fain induced transformation. Heavy strain can produce fine ferrite grains in coarse austenite grained 08 steel, but it would lead to band microstructure in coarse austenite grained 20Mn.     

Comparison of Ferrite Refinement Mechanisms by Different Processing Schedules in 08 and 20Mn Steels

The influence of deforming temperature on ferrite refinement was analyzed by comparing the microstructures obtained by de-formation at above Ar3, in two-phase region of(α+γ) and at below A1 in clean 08 and 20Mn steels. The results indicate that ferrite refinement through strain induced transformation by deformation at above Ar3 is more effective than that by deformation simply through ferrite dynamic recrystallization. The main problem of ferrite refinement by deformation at below Ar3 is the inhomogeneity of microstructure which is controlled by the orientations and sizes of ferrite grains and the distribution of second phases. Ferrite dynamic recrystallization after strain induced transformation can further effectively refine ferrite.     

用钢板酸洗液及废电池制作锰锌铁氧磁体铁芯

利用钢板酸洗废液的含铁成份及还原性,利用废干电池的含锰锌成份及二氧化锰的氧化性,产生氧化还原反应,使废干电池释出锰锌等离子,产生含铁锰锌等离子的溶液。此溶液经过ICP分析,加入二氧化锰,配成适合制成锰锌系铁氧磁体所需的成份,再利用化学共沉法加碱,产生铁、锰、锌的混合氢氧化物。此氢氧化物经过水洗、烘干、煅烧、研磨、造粒、成型及烧结,制成锰锌系铁氧磁体铁芯。结果显示,锰锌系铁氧磁粉的晶体为尖晶石立方结构,其晶粒大小为30—50 nm,饱和磁束密度为58.6 emu/g,经1 200℃烧结铁芯的饱和磁束密度为93.4 emu/g(5 023 gauss)。其初导磁率从数百到数千,q值约数十,依频率而定。     

软磁铁氧体材料

总结了近几十年来软磁铁氧体材料的发展过程，评述了国内软磁铁氧体材料及器件的发展现状、应用和市场，并对其中的锰锌系和镍锌系两大类型的软磁铁氧体材料做了重点介绍，指出了在其广泛的应用领域内，软磁铁氧体将进一步向高频、高磁导率和低损耗方向发展，以适应由新科技新设备的不断推出所带来的其产品如电感、线圈等器件向小型化片式化的发展要求．     

Effect of Nanophase on the Nucleation of Intragranular Ferrite in Microalloyed Steel

MnS, MnS+V(C, N) complex precipitates in micro-alloyed ultra-fine grained steels were precisely analyzed to investigate the grain refining mechanism. The experimental results shows that MnS, MnS+V(C, N) precipitates provide nucleation center for Intra-granular ferrite (IGF), so that refined grain remarkably. Moreover, substructures such as grain boundary, sub-boundary, distortion band, dislocation and dislocation cell in austenite increased as the deformation energy led by heavy deformation at low temperatu...     

钢结构的地震反应修正系数

现代结构抗震设计利用结构的延性和超强,并引入地震反应修正系数对设防地震下的单质点弹性反应谱进行折减,得出结构的设计地震作用后按弹性设计结构。结构地震反应修正系数的取值是否合理关系到结构抗震设计的安全与经济,采用Pushover推覆、改进的能力谱法计算了按我国规范设计的12个抗弯钢框架、15个V型偏心支撑钢框架的地震反应修正系数、延性折减系数、超强系数,并与国内现行抗震规范隐含的地震反应修正系数进行了对比。     

铁磁性 Mn-Zn、Ni-Zn 铁氧体与铁电性 BaTiO_3 复合材料吸收电磁波能力研究

本文研究了铁磁性Ｍｎ－Ｚｎ、Ｎｉ－Ｚｎ铁氧体与铁电性ＢａＴｉＯ３复合材料在１～１０００ＭＨｚ频段内的吸波能力。结果表明：随频率升高,Ｍｎ－Ｚｎ铁氧体／ＢａＴｉＯ３和Ｎｉ－Ｚｎ铁氧体／ＢａＴｉＯ３复合材料的吸波能力逐渐增加;随Ｍｎ－Ｚｎ或Ｎｉ－Ｚｎ铁氧体含量增加,这两类复合材料的吸波能力也逐渐增加;相同配比时的Ｎｉ－Ｚｎ铁氧体／ＢａＴｉＯ３复合材料吸波能力大于Ｍｎ－Ｚｎ铁氧体／ＢａＴｉＯ３。     

软磁材料锰锌铁氧体共沉粉料的研制

本文研究了碳酸盐—氢氧化物法共同沉淀Ｆｅ２＋、Ｍｎ２＋、Ｚｎ２＋时，反应最终ｐＨ值、沉淀温度、加料方式、加料速度及搅拌强度等因素对恒定共沉粉Ｆｅ２Ｏ３、ＭｎＯ及ＺｎＯｍｏｌ％组成、粒度和颗粒形状的影响，并进一步考查了共沉粉组成与软磁材料性能的关系。在研究基础上确定生产高频低功耗锰锌铁氧体材料Ｈ７２４（ＰＣ４０）和高磁导率锰锌铁氧体材料Ｈ５Ｃ２（μｉ＝１００００±３０％）共沉粉合成的最宜条件。     

Effect of Nb on the transformation kinetics of low carbon （manganese） steel during deformation of undercooled austenite

The hot compression tests using Gleeble 1500 were performed by varying the true strain up to 1.6 （80% reduction） in Nbfree and Nb-microalloyed steels. The effect of Nb addition on the transformation kinetics during deformation of undercooled austenite was investigated. It was found that as compared with Nb-free steel, the transformation incubation period of Nb-bearing steel was prolonged and the transformation kinetics curves parallelly moved to higher strain because of the solute Nb drag effect. Studies on kinetics also showed that the deformation-enhanced ferrite transformation （DEFT） of the two steels were composed of three stages, which can be expressed by the J-M-A equations individually. However, the parameter n related to the mode of nucleation and growth is somewhat different in the first and second stages of the two steels, and the same in the third stage for both the steels corresponding to the nucleation Of retained austenite.