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Thestudies[1,2 ] havestatedthatretainedausteniteinadual phasesteelistransformedtomartensiteundertensilestrain .Suchstrain inducedtransformationofretainedaustenitecanenhanceductilityofsteelwhentheretainedausteniteisratherstableagainststraining[3 ] .Basedonthi… 相似文献
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H. Ashrafi M. Shamanian R. Emadi N. Saeidi 《Transactions of the Indian Institute of Metals》2017,70(6):1575-1584
In the present study, tensile properties, strain hardening and fracture behavior of dual-phase (DP) steels were correlated with martensite volume fraction (V M ). A series of DP steels with different amounts of V M (28–50 %) were produced by cold rolling and subsequent intercritical annealing of a ferrite-pearlite starting structure. Hardness and tensile tests results of DP steels showed that variation of hardness, uniform elongation and total elongation with V M was linear and obeyed the rule of mixtures, whereas yield strength and ultimate tensile strength exhibited a nonlinear variation with V M . Analysis of strain hardening behavior of DP steels by the Hollomon analysis showed two stages of strain hardening corresponding to ferrite deformation and co-deformation of ferrite and martensite, respectively. The strain hardening exponent of first stage (n I ) increased with increasing V M , while the strain hardening exponent of second stage (n II ) as well as transition strain between the deformation stages decreased. 相似文献
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The microstructure and mechanical properties of cold rolled TRIP steel containing C 0.2, Si 0.5, Mn 1.5, A1 1.3, and Nb-kV 0.13 (mass%) with annealed martensite (TAM steel) were investigated using optical microscopy, field emission gun scanning electronic microscope (FEG SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and mechanical testing. The mierostructure of the TAM steel mainly consisted of polygonal ferrite, bainite, annealed martensite and retained austenite. The martensite after annealing did not spheroidize, which consisted of annealed lath martensite structure and interlath second phase. Compared with the traditional TRIP steel with polygonal ferrite matrix (TPF steel), the TAM steel has more excellent elongation rate over 32%. The TAM steel also has better strain hardening behavior than the TPF steel. The excellent elongation and strain harden- ing behavior of TAM steel result from high retained austenite stability of the TAM steel, which is attributed to its fine distribution and medium strength ratio of second phase to matrix. 相似文献
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Influence of microstructure of the experimental steels on the corrosion fatigue behavior in 35% of NaCl aqueous solution was studied. Experimental results show that compared with the full martensite (FM) steel, the carbide free bainite/martensite (CFB/M) steel has higher corrosion fatigue strength and corrosion fatigue crack threshold (ΔKthcf), and lower corrosion crack propagation rate [(da/dN)cf]. 相似文献
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Generally ,thequenchedandtemperedlowalloysteelswithtensilestrengthabove 12 0 0MPaaresus ceptibletohydrogen induceddelayedfracture(HIDF) [1,2 ] .Extensivestudiesonthedelayedfracturebehaviorofhighstrengthsteelshavebeenperformedtheseyears,butthesatisfactorys… 相似文献
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Martensite transformation comprises two steps: In the first, martensite midribs propagate resulting in a network of midrib planes. In the second, this midrib network thickens and the final microstructure is obtained. Based on this concept, a new relationship between the volume fraction and the number density of martensite units is derived in this paper. The model proposed here describes quite well a wide range of experimental data on a thermal and isothermal martensite. 相似文献
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The quenchedandtemperedlowalloysteelswithtensilestrengthexceeding 12 0 0MPaaresus ceptibletohydrogen induceddelayedfracture(HIDF )wheninuse[1,2 ] .Despitetheenormousamountofresearchworkperformedondelayedfrac tureofhighstrengthsteelintheseyears ,thesolu tiontothisproblemstillhasnotbeenobtained .TheresistanceofanalloytoHIDFisstronglyaffectedbytheinteractionofhydrogenwithmicrostructuralhet erogeneitiesthatactashydrogentraps ,andthere foreinasearlyas 1980s ,GMPressouyre[3 ] suggest edtheappli… 相似文献
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Abstract: Microstructure evolution and mechanical properties of newly designed 01C-6Mn-05Si-1Al TRIP-aided steels under different annealing conditions and the effects of matrix microstructure before intercritical annealing on the final microstructure were studied by means of X-ray diffraction (XRD), scanning electron microcopy (SEM), dilatometric simulation, optical microstructure (OM) and tensile testing in this work. The experimental results indicate that the TRIP steel with Mn of 6% could form a considerable amount of retained austenite with good TRIP effect after a simple intercritical annealing treatment, and the matrix microstructure before intercritical annealing treatment can greatly affect the final microstructure. The original microstructure of the ferritic matrix steel was eliminated, while annealed martensite was remained from the martensite matrix steel under the same intercritical annealing conditions. 相似文献
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通过等温形变研究了形变参数(形变温度、形变速率、形变量)对高强度汽车钢WHT1300HF的微观组织转变和形貌的影响规律。研究结果表明:增加奥氏体等温形变量,有利于铁素体的缺陷形核,促进了形变奥氏体向铁素体转变;奥氏体的形变强化导致马氏体相变阻力增大,马氏体相变开始温度(Ms)下降,细小晶粒数量和小角度晶界数量增多;增加奥氏体等温形变(40%)速率能同时促进马氏体和铁素体相变,但马氏体体积分数和小角度晶界数量减少,细小晶粒数量略有提高;降低等温形变温度加剧奥氏体的形变强化,导致Ms温度下降,马氏体体积分数、小角度晶界比例减少,细小晶粒数量增多,铁素体含量明显增加。 相似文献
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Fahrettin Ozturk S Toros S Kilic 《钢铁研究学报(英文版)》2009,16(6):41-46
In recent years, the use of advanced high strength steels in automotive industry has been increased remarkably. From advanced high strength steels, dual-phase (DP) steels have gained a great attention due to a combination of high strength and good formability. However, high strength usually increases springback behavior of material which creates problem for the parts during the assembly. In this study, uniaxial tensile deformation and springback behaviors of DP600 advanced high strength steel were investigated at rolling (0o), diagonal (45o), and transverse (90o) directions in the temperature range from room (RT) to 300 oC. All tests were performed at 25 mm/min deformation speed. A V-shape die (60o) was used for springback measurements. Results indicate that the formability and springback of the material were decreased with increasing the temperatures. The material showed complex behaviors at different directions and temperatures. 相似文献
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Jesus Israel Barraza-Fierro Bernardo Campillo-Illanes Ximing Li Homero Castaneda 《Metallurgical and Materials Transactions A》2014,45(9):3981-3994
Different thermomechanical treatments were applied to a high strength low carbon steel with a novel chemical composition. As a result, three different microstructures were produced with dissimilar mechanical and corrosion properties. Subsequently, a tempering heat treatment was applied to redistribute the phases in the steel. Microstructure A with 56 pct martensite and 32 pct bainite presented high strength but medium ductility; microstructure C with 95 pct ferrite and 3 pct martensite/austenite resulted in low strength and high ductility, and finally microstructure B with 98 pct bainite and 2 pct martensite/austenite resulted in high strength and ductility. Alternatively the corrosion behavior obtained by polarization curves was characterized in 0.1 M H2SO4, 3 M H2SO4, 3.5 wt pct NaCl, and NS4 solutions resulting in similar magnitudes, while the corrosion behavior acquired by electrochemical impedance spectroscopy had slightly differences in 3 M H2SO4. 相似文献
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采用冷等静压、烧结的方法制备了钼棒坯,对钼棒进行了旋锻和挤压处理,得到了一种高抗拉强度钼棒,并探讨了旋锻工艺和挤压工艺对材料组织结构以及性能的影响。结果表明:采用加热温度为1300~1350℃,道次压缩量30%,总压缩量150%的旋锻工艺可获得相对密度98%以上的钼棒。旋锻对钼棒具有较好的致密化效果。旋锻后的材料抗拉强度和伸长率均随变形量增大而提高。经旋锻热变形后钼材的组织结构均匀、晶粒为等轴状晶粒、垂直于长度方向的平均晶粒度小于5μm、室温抗拉强度大于610 MPa。经挤压变形致密后钼材的组织结构均匀、晶粒呈纤维状,内部组织形成初步的具一定长宽比的加工织构,室温抗拉强度大于810 MPa。热处理制度为850℃/60 min退火消除热加工过程造成的残余应力,加工织构得以保存,性能最好。 相似文献