共查询到20条相似文献,搜索用时 0 毫秒
1.
Yasser Fouad 《Transactions of the Indian Institute of Metals》2014,67(6):979-988
Delamination is a major limitation of lamellar composite structures in general, wherein interface/interphase control is a major factor. Studying/investigating the mitigation of cracks as well as toughening mechanisms is paramount to establish the control of interface/interphase kinetics. Stainless steel 316, Al 6082, CU–Zn sandwich laminate composite-sheets, in a foil–foil processing technique, were fabricated by means of hot uniaxial pressing. A parametric study was introduced using temperature and pressure effects on the composite specimens. The composite-sheet interface and its bond strength were investigated using scanning electron microscopy and tensile test. Microstructural as well as mechanical characterization, were established via optical and scanning electron microscopy; energy dispersive X-ray spectroscopy and mechanical testing. Mechanical characterization of the interfacial shear strength is investigated using hardness testing. The interphase kinetic behavior is observed through localized micro plasticity, metal flow and delocalized Al oxide and Mg oxide. Results showed that low temperature heat treatment can improve the morphology of stainless steel 316, Al 6082, CU–Zn interface and increase its bond strength. Alloying element segregation with diffusion mechanisms induced the formation of localized metal flow along with the interface. Alloy segregation during solidification in a semisolid state processing induces directional solidification with fibrous entities and oxides on structural interphase. For the stainless steel 316, Al 6082, Cu–Zn composite, the reasonable heat treatment is approximately 823 K for 1 and 3 h. 相似文献
2.
采用异步轧制复合工艺制备了铜/铝双金属复合板,分析了轧制工艺参数对复合板变形行为的影响,结合轧制变形区金属受力状态探讨了复合过程中的金属变形及流动规律.结果表明:异步轧制变形区内界面摩擦剪切作用直接影响母材的受力状态,共同变形区内双金属间的搓轧作用对金属流动及结合效果影响最大.异步速比越大,硬质金属变形越大.总压下率增大时,组元金属压下率均呈正比关系增加,且软、硬两种金属的压下率差值越来越小. 相似文献
3.
4.
非金属夹杂物是引起冷轧板坯表面缺陷的主要原因.分析了304不锈钢热轧板坯中非金属夹杂物的成分、形貌及尺寸.对304热轧板坯进行不同压下量的轧制,分析不同厚度冷轧板坯中的夹杂物形状和尺寸,研究非金属夹杂物在板坯冷轧过程中的变形行为.结果表明:304热轧板坯中的夹杂物主要组成为CaO-SiO2-MgO-Al2O3的复合氧化物,为脆性夹杂物;冷轧过程中,夹杂物的塑性变形不明显,随着冷轧压下量的增加,大颗粒的夹杂物不断被轧碎,板坯中夹杂物的平均尺寸逐渐减小. 相似文献
5.
Hot Deformation Behavior of F6NM Stainless Steel 总被引:1,自引:0,他引:1
Long-teng MA Li-min WANG Zheng-dong LIU Gang YANG Lun LU Meng-du PENG 《钢铁研究学报(英文版)》2014,21(11):1035-1041
The hot deformation behavior of F6NM stainless steel was investigated by hot compression test in a Gleeble-1500D thermal-mechanical simulator. The flow strain-stress curves were obtained and the corresponding metallographic observation of this steel under different deformation conditions was also carried out. This steel exhibi- ted dynamic recrystallization (DRX) in the temperature range of 1 273- 1473 K and the strain rate range of 0.01- 0.1 s^-1. The activation energy for hot deformation was determined to be 457.91 kJ/mol, and the hot deformation equations were also established. The flow instability zone was determined and could be divided into two regions. The first one was located in the temperature range of 1 173- 1 348 K and the strain rate range of 0. 056-10 s^-1 , while the second one is in the temperature range of 1398-1448 K and the strain rate range of 1.25-10 s^-1. In the end, the optimum conditions for hot working were provided. 相似文献
6.
用MMS-200热模拟实验机对2507超级双相不锈钢(/%:0.022C、0.58Si、25.35Cr、7.17Ni、4.05Mo、0.28N)12 mm热轧板在1 000~1150℃、应变速率0.01~10s-1下进行了热压缩实验。实验结果表明,在应变速率一定的条件下,变形温度越高,2507超级双相不锈钢峰值应力越低;在变形温度一定的条件下,峰值应力随着应变速率的增加而增加。根据热变形方程计算得到压缩变形时的平均表观应力指数n=3.25,热变形激活能Q=460kJ/mol。基于实验数据构建了2507超级双相不锈钢在相应变形条件下的热变形方程。 相似文献
7.
D.V. Louzguine-Luzgin A. Vinogradov S. Li A. Kawashima G. Xie A.R. Yavari A. Inoue 《Metallurgical and Materials Transactions A》2011,42(6):1504-1510
The present work demonstrates the deformation behavior of Zr-Cu-Ni-Al bulk glassy alloys and Zr-Ni-Cu-Al-Pd glassy foils as
well as Ni-Cu-Ti-Zr bulk crystal-glassy composites. Fracture of Zr60Cu16Ni14Al10 and Zr64.13Ni10.12Cu15.75Al10 bulk glassy alloys is featured by nearly equal fraction areas of cleavage-like and vein-type relief. The observed pattern
of alternating cleavage-like and vein-type patterns illustrates a result of dynamically self-organizing shear propagation
at the final catastrophic stage. The deformation behavior of Zr64.13Ni10.12Cu15.75Al10 alloy has also been tested at LN2 temperature. The strength of the sample decreases with temperature, and no clear serrated flow typical for bulk glassy samples
tested at room temperature is observed in the case of the samples tested at LN2 temperature. We also studied the deformation behavior of Zr-Ni-Cu-Al-Pd glassy foils thinned to electron transparency in situ in tension in a transmission electron microscope. We also present a Ni-Cu-Ti-Zr crystal-glassy composite material having
a superior strength paired with a considerable ductility exceeding 10 pct. The metastable cP2 crystalline phase promotes a strain-induced martensitic transformation leading to pseudoelastic behavior as well as enhanced
plasticity at room temperature. Underlying mechanisms of plastic deformation are discussed in terms of the interplay between
the dislocation slip in the crystalline phase and the shear deformation in the glassy matrix. 相似文献
8.
70MoCu合金室温变形行为与断裂机制 总被引:1,自引:1,他引:1
通过室温下冷轧试验, 研究了70MoCu合金(由质量分数分别为70%的Mo和30%的Cu组成)在不同变形量条件下的微观组织及力学性能. 试验得到了微观组织、力学性能随冷轧变形量的变化规律. 随着变形量的增加, 组织形貌发生显著变化, 钼颗粒沿轴向被拉长, 粘结相铜也被拉成长条状;70MoCu合金最先在Mo-Cu或Mo-Mo界面开裂, 接着是钼自身的开裂;同时, 70MoCu的硬度不断增大. 通过合金的室温拉伸试验, 对断口的观察发现70MoCu合金在室温下的断裂是粘结相Cu的撕裂, Mo-Cu界面的分离, Mo-Mo界面的分离, Mo颗粒的解理断裂等4种断裂模式共同作用的结果, 粘结相Cu的撕裂和Mo-Cu界面的分离是其主要的断裂方式. 相似文献
9.
10.
在Gleeble-1500热模拟试验机上进行热-力模拟试验,得到实验数据并分析试样的热塑性、变形抗力,并利用金相显微镜对其进行金相组织的分析。在950~1 200℃温度区间进行高温拉伸试验,绘制出样品的热塑性曲线与热强度曲线,通过热塑性曲线说明在950~1 200℃范围内具有良好的塑性,通过热强度曲线可以观察到屈服强度随温度的升高而降低;在变形温度为950~1 200℃,应变速率为0.1,1,5和10 s-1时进行高温压缩试验,绘制出真应力-应变曲线和变形抗力曲线,结果显示,变形抗力随应变量的增大而迅速达到最大值,而后趋于平缓,随着温度的升高,变形抗力呈下降的趋势。 相似文献
11.
12.
A ductile fracture criterion of 316LN stainless steel, combined with the plastic deformation capacity of ma- terial and the stress state dependent damages, was proposed to predict ductile fracture during hot deformation. To the end, tensile tests at high temperatures were first performed to investigate the fracture behavior of 316LN stain- less steel. The experimental results show the variation of the critical fracture strain as a function of temperature and strain rate. Second, the criterion was calibrated by using the upsetting tests and the corresponding numerical simula- tions. Finally, the proposed fracture criterion was validated by the designed tests and the corresponding finite ele- ment (FE) simulation. The results show that the criterion can successfully predict the onset of ductile fracture at ele- vated temperatures. 相似文献
13.
Recently, duplex stainless steels (DSSs) are being increasingly employed in chemical, petro-chemical, nuclear, and energy industries due to the excellent combination of high strength and corrosion resistance. Better understanding of deformation behavior and microstructure evolution of the material under hot working process is significant for achieving desired mechanical properties. In this work, plastic flow curves and microstructure development of the DSS grade 2507 were investigated. Cylindrical specimens were subjected to hot compression tests for different elevated temperatures and strain rates by a deformation dilatometer. It was found that stress–strain responses of the examined steel strongly depended on the forming rate and temperature. The flow stresses increased with higher strain rates and lower temperatures. Subsequently, predictions of the obtained stress–strain curves were done according to the Zener–Hollomon equation. Determination of material parameters for the constitutive model was presented. It was shown that the calculated flow curves agreed well with the experimental results. Additionally, metallographic examinations of hot compressed samples were performed by optical microscope using color tint etching. Area based phase fractions of the existing phases were determined for each forming condition. Hardness of the specimens was measured and discussed with the resulted microstructures. The proposed flow stress model can be used to design and optimize manufacturing process at elevated temperatures for the DSS. 相似文献
14.
R.D.K. Misra S. Nayak P.K.C. Venkatasurya V. Ramuni M.C. Somani L.P. Karjalainen 《Metallurgical and Materials Transactions A》2010,41(8):2162-2174
We describe here an electron microscopy study of shear reversion-induced nanograined/ultrafine-grained (NG/UFG) structure
and evolution of tensile strained microstructure in metastable type 301 austenitic stainless steel. The NG/UFG structure with
grain size in the range of 200 to 500 nm was obtained by severe cold deformation and controlled annealing in the narrow temperature
range of 973 to 1073 K (700 to 800 °C). The different stages of annealing involve the following: (a) transformation of strain-induced
martensite to highly dislocated lath-type austenite, (b) formation of dislocation-cell structure and transformation to recovered
austenite structure with defect-free subgrains, and (c) coalescence of subgrains to form a NG/UFG structure concomitant with
a completely recrystallized structure, and consistent with martensitic shear-type phase reversion mechanism. The optimized
cold working and annealing treatment resulted in NG/UFG material with a high yield strength (~1000 MPa) and high ductility
(~30 pct) combination. Multiple deformation mechanisms were identified from postmortem electron microscopy examination of
tensile strained NG/UFG 301 austenitic stainless steel and include dislocation glide and twinning. The evidence of heterogeneous
nucleation of overlapping stacking faults and partial dislocations points toward deformation 相似文献
15.
通过对粉末冶金法制备Wp/AZ91镁基复合材料的热变形行为分析,发现该复合材料非常敏感于应变速率.随应变速率升高,真应力-真应变曲线特征从“平缓”型向“锯齿”型转变,材料热变形软化特征增强.材料的软化作用一方面来自基体合金自身的再结晶软化,另一方面来自第二相的强化所引发的再结晶软化.通过微观组织观察发现低应变速率下,材料内析出相呈板条状,而高应变速率下,材料内析出相呈细小短棒状和棱柱状弥散析出,强化作用明显,一方面使晶体内产生大量高畸变能区域从而为再结晶形核提供驱动力,有利于再结晶行为.另一方面也有利于再结晶晶粒的均匀长大,从而有利于再结晶软化.因此高应变速率下材料的软化率更高. 相似文献
16.
The tensile behavior of Nicalon fiber-reinforced silicon carbide matrix composites (Nicalon/SiC) was investigated with the
aid of nondestructive evaluation (NDE) techniques. The NDE techniques include ultrasonic testing (UT), X-ray computed tomography
(CT), and infrared (IR) thermography. Before mechanical testing, UT C-scans were developed to investigate defect distributions
and to detect variations in the internal flaws. X-ray CT was used to characterize the type of defects and the location of
flaws in composites to compare with UT C-scan results. The IR thermography was employed to monitor temperature evolution during
tensile testing. This article also investigated the feasibility of using multiple NDE techniques as a means of assessing integrity
for Nicalon/SiC composites. Microstructural characterization was performed using scanning electron microscopy (SEM) to investigate
failure mechanisms of Nicalon/SiC composites, and the results were compared with NDE data.
This article is based on a presentation given in the symposium entitled “Deformation and Fracture from Nano to Macro: A Symposium
Honoring W.W. Gerberich’s 70th Birthday,” which occurred during the TMS Annual Meeting, March 12–16, 2006 in San Antonio,
Texas and was sponsored by the Mechanical Behavior of Materials and Nanomechanical Behavior Committees of TMS. 相似文献
17.
18.
19.
The fracture behavior of cold sprayed 304 stainless steel coating in cold rolling process was studied. The 304 stainless steel coatings were deposited on low carbon steel substrate by cold gas dynamic spray (CGDS) and then cold rolled, respectively. The fracture morphology of the coatings was observed and analyzed, and the crack distributions along the longitudinal rolling direction of the coatings were also investigated and discussed. The results showed that the cohesive strength of the cold sprayed 304 stainless steel coating was too low to be cold rolled. Microcracks were formed in the as-sprayed coatings and ran perpendicularly to the rolling direction. The spacing distance between these cracks decreased with the increase of the cold rolling reduction. In addition, it was also found that the initial crack generated at the surface of the coating and propagated from the surface to the interface along the weakly bonded particles. A theoretical analysis was developed for the coating fracture. It gave a critical minimum cohesive bonding strength of the coating for non-breaking in cold rolling process. The crack propagation manner of the cold rolled coatings was also discussed. 相似文献