冷变形对Fe-19Mn合金的组织和阻尼性能的影响

Fe-Mn合金具有良好力学性能的同时,还具有较高的阻尼性能,因此被认为是一种非常具有应用前景的高阻尼合金,并可用于结构和汽车零部件。为了研究冷变形对Fe-Mn合金阻尼性能的影响,通过室温拉伸的方法,对Fe-19Mn合金进行了变形量为0～15%的冷变形处理。采用动态机械分析仪(DMA)对变形前后的Fe-19Mn合金的阻尼性能进行了测试,利用OM、SEM和TEM观察了显微组织的演变,以及XRD进行了物相分析和不同类型层错几率的计算。结果表明:当变形量小于15%时,Fe-19Mn在冷变形前后的阻尼性能均随振幅的增加呈近似线性增加,当变形量达到15%时,阻尼性能随振幅的变化偏离线性关系;随着频率的增加,不同变形量时的阻尼性能均基本不变。由G-L图可知,当振幅小于临界振幅时的阻尼性能变化符合G-L位错模型,振幅高于临界振幅时的阻尼性能变化与微塑性变形有关。随着变形量的增加,在不同的振幅范围内,Fe-19Mn的阻尼性能呈现不同的变化特征:当振幅小于20μm时,阻尼性能随变形量的增加而增大,并且与ε-马氏体中的形变层错几率的变化趋势相似;当振幅高于20μm时,阻尼性能呈先增加后降低的趋势,变形量为5%时的阻尼性能最好,并且与γ/ε相界面长度的变化趋势相似。因此,振幅小于20μm时,Fe-19Mn的阻尼性能随冷变形量的变化主要受ε-马氏体中的形变层错的边界影响;振幅高于20μm时,Fe-19Mn的阻尼性能随冷变形量的变化主要受γ/ε相界面长度的影响。由γ-奥氏体中的层错观察和层错几率计算可知,在变形前后,γ-奥氏体中的层错边界对Fe-19Mn合金的阻尼性能均无明显贡献。     

添加Si对FeMn阻尼合金组织及性能的影响

采用倒扭摆测试仪、SEM、TEM等方法研究了添加Si对FeMn阻尼合金组织和性能的影响.结果表明,Si的加入增加了FeMn合金的层错和ε马氏体片层的数量,但由于马氏体片的交叉及Si引起的晶格畸变都阻碍了合金阻尼源界面的移动,使得合金阻尼性能降低;预变形后Fe-19Mn合金阻尼性能呈现先增加后降低的趋势,而Fe-19Mn...     

磷元素对Fe-Mn阻尼合金性能影响研究

Fe-Mn基阻尼合金是近些年来发现的一种新型金属阻尼材料。以Fe-Mn基阻尼合金为研究对象,对经不同固溶温度（800、900、1 000℃）处理后的Fe-Mn、Fe-Mn-P阻尼合金的力学性能、耐蚀性能、阻尼性能进行了测试,利用EBSD进行了显微组织结构表征。结果表明：磷元素添加提高了阻尼合金的屈服强度,有利于提高合金的耐腐蚀性能,但极大地恶化了阻尼合金的低温韧性,降低了阻尼合金的阻尼性能。在800℃固溶状态下,Fe-Mn-P合金阻尼性能最佳,随着固溶温度的升高,Fe-Mn-P阻尼合金强度降低,阻尼性能降低;ε/ε和ε/γ界面密度是影响FeMn-P阻尼合金阻尼性能的重要因素。     

冷轧对Fe-Mn和Fe-Mn-Al合金组织和性能的影响

本文研究了Fe-Mn和Fe-Mn-Al合金的冷轧强化和应变诱导马氏体相变规律.定量地测定了合金经过不同冷轧变形后的相体积和力学性能.实验结果表明,在15～30％Mn范围内的Fe-Mn合金中,增加Mn含量可抑制α-马氏体相变.进一步添加Al含量又可以抑制ε-马氏体相变,从而在一定的合金成分下得到了冷轧后仍然具有稳定奥氏体组织的铁锰铝合金.     

冷剧烈变形对Fe-50%Ni合金组织性能的影响

对Fe-50%Ni合金进行50%冷剧烈变形处理,同时变形前后进行适当氢气保护热处理.利用金相显微镜、X射线衍射和软磁测量系统对不同处理方式软磁合金的组织结构和性能进行表征.结果发现,Fe-50%Ni合金软磁性能比较低,经过50%冷剧烈变形的合金磁滞同线圆润,磁性能有所下降,但经氢气保护热处理后可获得粗大的等轴状晶粒,磁滞回线变得修长,表现出优良的软磁性能.     

Fe-Cu-Mn-C合金的性能与烧结行为

以FeMn合金粉末的形式在铁基合金粉末中添加Mn元素,退火后得到Fe-Cu-Mn部分预合金粉末,采用模壁润滑温压工艺制备Fe-Cu-Mn-C合金,通过对合金密度与硬度的测定以及形貌观察,研究Fe-Cu-Mn-C粉末的压制与烧结行为,以及Mn含量对合金密度和力学性能的影响。结果表明,通过退火处理实现部分预合金扩散而得到的Fe-Cu-Mn粉末具有很好的压制性能,Fe-2Cu-0.5Mn-0.9C压坯密度达到7.37 g/cm3,烧结密度为7.33 g/cm3;添加适量Mn能有效提升铁基合金的力学性能,其中Fe-2Cu-0.5Mn-0.9C合金的性能最佳,抗拉强度达到715 MPa;随Mn含量增加,合金的孔隙增多、密度下降,导致强度和硬度下降。合金的局部氧化对性能产生一定的负面影响。Mn含量对合金组织影响不大,Fe-2Cu-Mn-0.9C合金呈现混合显微组织,由铁素体、珠光体和少量贝氏体构成。Mn的蒸发与凝聚是Fe-Cu-Mn-C的烧结机制。     

Mn含量对粉末冶金铁铜碳低合金钢组织与力学性能的影响

采用铜粉、石墨粉和铁粉为原料,以Fe-74.8Mn-6.9C中间合金粉的形式加入Mn元素,制备粉末冶金Fe-x Mn-(2-x)Cu-0.3C(x=0,0.2,0.4,0.6,0.8,1。质量分数,%)低合金钢,研究Mn含量对该合金组织与力学性能的影响。结果表明,合金组织由铁素体和珠光体构成。加入含Mn中间合金粉对混合原料粉末的压制性能没有明显影响。随Mn含量增加,合金中孔隙的数量增多,尺寸变大;合金密度先升高后降低,Mn含量为0.4%时合金密度最大,达到7.24 g/cm~3;合金硬度先升高后降低,Mn含量为0.6%时硬度最大;合金抗弯强度下降,冲击韧性升高,Mn含量超过0.4%时二者变化均较小。因此Fe-0.6Mn-1.4Cu-0.3C合金具有较好的综合性能,硬度(HRB)和冲击韧性分别达到57.4和8.80 J/cm~2,比Fe-2Cu-0.3C合金分别提高5.3和0.82 J/cm~2,材料呈部分韧性断裂特征。     

电渣重熔对CuMn50合金组织和性能的影响

CuMn50合金是一种高阻尼实用型变形Mn-Cu合金,不仅具有金属材料的高强度,同时具有非金属材料的高阻尼性能,在减振、降噪方面性能突出.传统高阻尼合金基本采用铸造工艺制备,虽然具有良好的机械性能和良好的阻尼性能,但耐蚀性较差.本文对CuMn50合金进行电渣重熔,使用ZEISS金相显微镜、扫描电镜、MFDL-100慢应变速率应力腐蚀试验机及弹性模量测量装置等对合金组织和性能进行检测,分析研究电渣重熔对CuMn50高阻尼合金组织和性能的影响.研究表明对CuMn50合金进行电渣重熔,可改善合金元素偏析问题,提高合金纯净度.电渣重熔过后,合金组织均匀致密,拉伸性能和耐应力腐蚀性能大幅提高.     

氮对Fe-38Mn奥氏体钢低温冲击韧性的影响

研究了不同氮含量对真空熔炼的Fe-38Mn合金77K冲击韧性及断口形貌的影响。结果表明适当氮含量可以显著提高Fe-38Mn合金的低温冲击性能，其断口形貌由沿晶断裂断口转变为准解理断口。     

淬火工艺对Fe-13Cr-2.5Mo合金内耗的影响

利用倒扭摆仪研究了经过不同淬火工艺后Fe-13Cr-2.5Mo合金的阻尼性能,并用MTS力学实验机测试了合金的拉伸性能,用JSM-5900LV型扫描电镜分析了晶界析出物的形态及组成.研究发现,在900℃下保温2 h后水冷,合金的拉伸性能较好,抗拉强度为467 MPa,屈服强度为270 MPa,伸长率为23%,同时具有较强的阻尼性能,对数衰减率δ达0.14.在900℃保温2 h的热处理过程中,尽管有析出物析出,但回复和再结晶转变使组织的残余内应力降低,磁弹性能降低,磁畴的移动性增强,阻尼性能提高.     

Research on Stress-Induced Nucleation of ε-Martensite in Fe-17Mn-10Cr-5Si-4Ni Polycrystalline Alloy

ForFeMnSifamilyalloy ,thestress inducedγ→εmartensitictransformationisthebasisofSMEproduction[1 3 ] ,thusthestudyonmechanismofγ→εmartensitictransformation ,especiallyonnucle ationofε martensite ,hasgreatsignificanceforun derstandingthenatureofshapememorycharacterandapplicationofthistypealloy .Anequationde ducedbyHsuTYforstackingfaultprobabilityPsfandMsinlowstackingfaultenergyalloyfromther modynamicsis :Ms=C -D /Psf,whereCandDareplusconstants[4 ] .InagakiHetalhavealsore portedthatu…     

Development and characterization of high strength impact resistant Fe-Mn-(Al-, Si) TRIP/TWIP steels

Iron manganese steels with Mn mass contents of 15 to 30 % exhibit microstructural related superior ductility and extraordinary strengthening behaviour during plastic deformation, which strongly depends on the Mn content. This influences the austenite stability and stacking fault energy γ_fcc and shows a great impact on the microstructure to be developed under certain stress state or during severe plastic deformation. At medium Mn mass contents (15 to 20 %) the martensitic γ-ε-ά phase transformation plays an important role in the deformation mechanisms of the TRIP effect in addition to dislocation glide. With Increasing Mn mass content large elongation is favoured by intensive twinning formation. The mechanical properties of plain iron manganese alloys are strongly influenced by the alloying elements, Al and Si. Alloying with Al Increases the stacking fault energy and therefore strongly suppresses the martensitic γ-ε transformation, while Si sustains the γ-ε transformation by decreasing the stacking fault energy γ_fcc. The γ-ε phase transformation takes place in Fe-Mn-X alloys with γ_fcc ≤ 20 mJm⁻². The developed light weight high manganese TRIP and TWIP (twinning induced plasticity) steels exhibit high ultimate tensile strength (600 to 1100 MPa) and extremely large elongation of 60 to 95 % even at high strain rates of έ = 10³ s⁻¹. Particularly due to the advanced specific energy absorption of TRIP and TWIP steels compared to conventional deep drawing steels high dynamic tensile and compression tests were carried out in order to investigate the change in the microstructure under near crash conditions. Tensile and compression tests of iron manganese alloys with varying Mn content were performed at different temperatures and strain rates. The resulting formation of γ twins, ά- and ε martensite by plastic deformation was analysed by optical microscopy and X-ray diffraction. The deep drawing and stretch forming behaviour at varying deformation rates were determined by performing cupping tests and digitalised stress-strain-analysis.     

Deformation Microstructure and Deformation-Induced Martensite in Austenitic Fe-Cr-Ni Alloys Depending on Stacking Fault Energy

The deformation microstructure of austenitic Fe-18Cr-(10-12)Ni (wt pct) alloys with low stacking fault energies, estimated by first-principles calculations, was investigated after cold rolling. The ?-martensite was found to play a key role in the nucleation of α′-martensite, and at low SFE, ? formation is frequent and facilitates nucleation of α′ at individual shear bands, whereas shear band intersections become the dominant nucleation sites for α′ when SFE increases and mechanical twinning becomes frequent.     

The γ → ε-martensitic transformation and its reversion in the FeMnSiCrNi shape-memory alloy

The hcp martensitic transformation and its reversion in an Fe-16.86Mn-4.50Si-10.30Cr-5.29Ni alloy have been studied. The fine structure and morphologies of ε-martensite were systematically investigated using transmission electron microscopy. It is found that, in the overlapped region of the stacking faults, the nucleus of ε-martensite may form by shear and grow along the {111}γ plane, which is not the stacking fault plane. The nucleus may grow into a small, thin plate and may act as the basal structure unit of ε-martensite. When the stress increases, the thin plates continue to grow into an ε-martensite ribbon along this preferred orientation and, during the subsequent recovery annealing, the reverse transformation of these basal structure units occurs. As a result, the ε-martensite plates shrink in both length and thickness.     

Dynamic Strain Aging Phenomena and Tensile Response of Medium-Mn TRIP Steel

Dynamic strain aging (DSA) and rapid work hardening are typical behaviors observed in medium-Mn transformation-induced plasticity (TRIP) steel. Three alloys with manganese ranging from 10.2 to 13.8 wt pct with calculated room temperature stacking fault energies varying from ? 2.1 to 0.7 mJ/m² were investigated. Significant serrations were observed in the stress-strain behavior for two of the steels and the addition of 4.6 wt pct chromium was effective in significantly reducing the occurrence of DSA. Addition of chromium to the alloy reduced DSA by precipitation of M₂₃(C,N)₆ during batch annealing at 873 K (600 °C) for 20 hours. Three distinct DSA mechanisms were identified: one related to manganese ordering in stacking faults associated with ε-martensite and austenite interface, with activation energies for the onset and termination of DSA being 145 and 277 kJ/mol. A second mechanism was associated with carbon diffusion in γ-austenite where Mn-C bonding added to the total binding energy, and activation energies of 88 and 155 kJ/mol were measured for the onset and termination of DSA. A third mechanism was attributed to dislocation pinning and unpinning by nitrogen in α-ferrite with activation energies of 64 and 123 kJ/mol being identified. Tensile behaviors of the three medium manganese steels were studied in both the hot band and batch annealed after cold working conditions. Ultimate tensile strengths ranged from 1310 to 1404 MPa with total elongation of 24.1 to 34.1 pct. X-ray diffraction (XRD) was used to determine the transformation response of the steels using interrupted tensile tests at room temperature. All three of the processed steels showed evidence of two-stage TRIP where γ-austenite first transformed to ε-martensite, and subsequently transformed to α-martensite.     

高锰合金钢的SME、TRIP、TWIP效应

 由于锰的价格低廉以及在材料中的重要作用而成为钢铁工业常用的合金元素。锰含量高时,可使Fe Mn合金形成的奥氏体在较低温度下存在。加入Si、Al元素可对合金中奥氏体的稳定性产生不同程度的影响,从而使材料在承受外界载荷时呈现出不同的反应。研究表明：Si可降低奥氏体层错能,有利于A→ε M相变,从而使合金易产生形状记忆效应。加大变形量,由于大量的奥氏体转变为α′ M时体积膨胀,在使材料伸长率提高的同时,强度也得到提高(相变诱发塑性效应),因此可用作高性能结构件。Al和Mn是提高奥氏体层错能的合金元素。对于Al、Mn含量高的钢,在外力作用下则可通过孪生诱发塑性变形产生孪晶诱发塑性效应,因而材料在具有较高强度的前提下,还具有60%~80%的伸长率。     

Work Hardening Behavior in Steel with Multiple TRIP Mechanisms

Transformation-induced plasticity (TRIP) behavior was studied in steel with the composition Fe-0.07C-2.85Si-15.3Mn-2.4Al-0.017N that exhibited two TRIP mechanisms. The initial microstructure consisted of both ε- and α-martensites with 27 pct retained austenite. TRIP behavior in the first 5 pct strain was predominately austenite transforming to ε-martensite (Stage I), but upon saturation of Stage I, the ε-martensite transformed to α-martensite (Stage II). Alloy segregation also affected the TRIP behavior with alloy-rich regions producing TRIP just prior to necking. This behavior was explained by first-principles calculations which revealed that aluminum significantly affected the stacking fault energy in Fe-Mn-Al-C steels by decreasing the unstable stacking fault energy and promoting easy nucleation of ε-martensite. The addition of aluminum also raised the intrinsic stacking fault energy and caused the ε-martensite to be unstable and transform to α-martensite under further deformation. The two-stage TRIP behavior produced a high strain hardening exponent of 1.4 and led to an ultimate tensile strength of 1165 MPa and elongation to failure of 35 pct.     

铝、铜、铬合金元素对Fe 21Mn 04C TWIP/TRIP钢层错能和力学性能的影响

  参考文献建立了Fe Mn C合金层错能的热力学模型,用模型计算了铝、铜、铬元素对Fe 21Mn 04C合金层错能的影响规律;在Fe 21Mn 04C合金中添加合金元素,研究其对层错能的影响。研究结果表明：铝和铜增加合金的层错能,而铬则降低合金的层错能;当层错能低于107mJ/m2时,Fe 21Mn 04C合金相组成为γ+ε,当层错能为10~1902mJ/m2时,合金的相组成为γ+ε+a,当层错能高于1902mJ/m2时,合金的相组成为单相的γ;层错能的变化和添加了合金元素铝、铜、铬的Fe 21Mn 04C合金性能变化没有相一致的关系,说明影响Fe 21Mn 04C合金力学性能的因素很多,需要进一步的研究。     

Crystallographic Orientation of the ε → α′ Martensitic (Athermal) Transformation in a FeMnAlSi Steel

The presence of athermal ε- and α-martensite (α′) in the as-cast structure of a Fe-0.08C-1.95Si-15.1Mn-1.4Al-0.017N alloy has been revealed by electron backscattered diffraction analysis. The alloy exhibited two athermal martensitic transformations described by γ → α′ and γ → ε → α′. The Shoji–Nishiyama orientation relationship was observed between γ-austenite and ε-martensite, while α-martensite nucleated from γ-austenite exhibited a Kurdjumov–Sachs orientation relationship. Six crystallographic variants of α-martensite consisting of three twin-related variant pairs were observed in ε-bands. A planar parallelism of {0001}ε || {110}α′ and a directional relation of \( \left\langle {1\bar{1} 1} \right\rangle \alpha ' \) lying within 1 deg of \( \left\langle {\bar{1} 2\bar{1} 0} \right\rangle \varepsilon \) existed for these variants.