Effect of BainiticTreatment on Microstructure and Mechanical Properties of TRIP Cold-Rolled Steel Sheets

The effects of bainitic treatment on microstructure and mechanical properties of 0.10C-1.5Mn-l.5Al TRIP-aided cold-rolled steels have been investigated.The samples were heated by intercritical annealing at 820℃for 2 min and quenched in banitic temperature with different hoding time for 5 to 300s,two salt bath were used for the heat treatment.Experimental results show that the yield strength and elongation increase with the increasing of bainitic holding time,while the tensile strength decrease.The volume fraction of retained austenite rise at the beginning of bainitic holding and then reduce,the carbon content of retained austenite increase during the bainitic holding.The tensile strengthen multiply elongation reaches the highest value at 120s.The mechanical stability of retained austenite fits well with strain hardening during deformation.     

Microstructure and Mechanical Properties of NANOBAIN Steel

The microstructure and mechanical properties of NANOBAIN steel treated at different isothermal temperatures were investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM),uniaxial tensile tests and X-ray diffraction(XRD).It was found that bainitic ferrite(BF)plate was made of basic shear transformation units arranged in the same direction of subunits.The existence of defects,such as nanoscale twinning and dislocation,suggested that the growth of transformation units was controlled by the surrounding defect plane with dislocation,which was consistent with the moving direction of BF/austenite interface parallel to the twinning plane.The behavior of work hardening indicated that mechanical stability of microstructures obtained at 250 ℃ and 300 ℃ was much more stable than that obtained at 210℃.The evolution of carbon partitioning in retained austenite and bainitic ferrite also indicated that austenite was enriched in carbon at the initial stage step by step;after the formation of BF,the austenite did not seem to be greatly enriched in carbon and the carbon content showed a little decrease instead;subsequently,aphenomenon of little decarburization of supersaturated bainitic ferrite has also been found.     

控轧直接淬火钢的微观组织与力学性能

分析了22SiMn2TiB钢再结晶控轧直接淬火(RCR&DQ)、未再结晶控轧直接淬火(CR&DQ)以及两者重新调质后(CR&DQQ、RCR&DQQ)的微观组织和力学性能。同时,与传统再加热淬火处理(RA&Q)的组织和性能进行了对比,结果表明:试验钢直接淬火后强硬度明显高于再加热淬火钢,塑性基本相当,而韧性也得到了较大幅度的提升。     

低碳贝氏体钢的组织类型及其对性能的影响

低碳贝氏体钢受控冷工艺的影响会得到不同类型的组织，在较慢速冷却时，在奥氏体中先形成针状铁素体，残余奥氏体会被包裹在铁素体之中，形成粒状贝氏体团。工业轧制试验表明．不同控制冷却工艺可得到两类组织，一类出现黑珠组织(富碳马氏体组织)．具有该组织的钢轧态冲击韧性低。另外一类为细化的板条贝氏体组织，具有该组织的钢轧态强度高，冲击韧性好，但伸长率不足。通过回火处理，存在黑珠组织钢的冲击韧性能得到提高，超细化板条贝氏体组织钢的伸长率也能得到改善，但后者屈服强度会比前者高100MPa左右。     

Microstructure and Mechanical Properties of Martensitic High-Strength Engineering Steel

Metallurgist - A promising martensitic steel with good hardenability is studied. In the cooling rate range 0.1–30°C/sec and the only transformation recorded by a dilatometer starts at an...     

超高碳钢的回火组织及力学性能

用CM200型透射电子显微镜研究了超高碳钢双相区淬火 中、高温回火后的组织,用Instron型拉伸试验机测定了力学性能.结果表明:650℃的回火组织为等轴状的铁素体与球状的渗碳体,屈服强度σ0.2=1127MPa,抗拉强度σb=1 266 MPa,均匀伸长率δu=8.26%,总伸长率δt=9.71%,维氏硬度HV为397;450℃回火组织的铁素体保持淬火的形态,回火碳化物为ε碳化物在基体上以断续的片状析出,σ0.2=1 911 MPa,σb=2 028MPa,δu=δt=1.88%,HV为595;400℃回火组织中的铁素体保持淬火的形态,回火碳化物在位错处几乎呈网状析出,拉伸无塑性,HV为703.     

Microstructure and Mechanical Properties of High-strength Micro-deformation Steel GDL-1

对一种新型高强韧微变形钢(GDL-1)在七种热处理状态下的显微组织与力学性能进行了分析.结果表明,该钢在900℃保温1h空冷回火后的显微组织以窄束状贝氏体+粒状贝氏体为主加少量马氏体,而油淬回火后的组织为回火马氏体;910℃加热奥氏体化1h的晶粒度普遍在8～9级.在低温回火温度范围内,随着回火温度的升高,冲击韧性逐渐增大,屈服强度逐渐降低,硬度变化不大.     

TC4包复叠轧薄板组织与性能特征

对TC4薄板包复叠轧及单片轧制工艺生产板材取样分析，研究了包复叠轧产品性能、显微组织、极图、ODF织构等的特征，数据表明包复叠轧产品具有组织和性能各向异性小，塑性好，利于超塑成形的特点。     

Microstructure and Mechanical Properties of High-Strength Steel with Improved Machinability

Metallurgist - A structural steel (grade 40KhGM) with improved machinability was studied. The steel contains an increased amount of sulfur and was modified with calcium during metallurgical...     

NM400高强度低合金耐磨钢的组织与性能

采用Ti-Cr-B微合金化成分设计、奥氏体再结晶区直接轧制及淬火加低温回火的热处理工艺,开发出低成本的NM400级别高强度、高韧性的低合金耐磨钢板.利用光学显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)等对其组织、性能、断口形貌及析出物进行了研究.结果表明:试验钢的组织主要为高密度位错板条马氏体及分布在板条上的碳化物;抗拉强度≥1400 MPa,表面硬度≥HV450,-40℃冲击功在60 J以上;钢板淬透性好,厚度方向硬度分布均匀;除固溶强化和细晶强化外,马氏体板条上的大量位错以及10 nm左右的Ti(C,N)析出颗粒起到强烈的硬化作用;经能谱分析,断口韧窝处存在的第二相粒子主要为MnS和Al2O3颗粒,最大尺寸在2 μm左右.     

一种具有优化组织和优异性能的超高碳钢

研究了超高碳钢不同组织结构与其力学性能之间的关系,分析了珠光体和球化组织各自的优点和缺点,并提出将这两种组织结合起来,进行优化组合的创新性的思路。研发了一种具有特别结构的超高碳钢,其晶内为细密珠光体,晶界邻区为球化组织。这种材料同时兼有珠光体所能提供的高强度和球化组织所能提供的高塑性,达到了抗拉强度1300MPa,伸长率18％的优异综合力学性能。     

1000MPa级TRIP钢的组织性能及强化机理

鉴于热镀锌TRIP钢在成分和工艺上的特殊性,试验采用低Si含P以及V微合金化的成分设计思路,并进行镀锌连续退火工艺模拟,分析其微观组织和性能。探讨了残余奥氏体稳定性的影响因素及强化机理。结果表明,添加P和采取较高的冷轧变形量均有利于提高残余奥氏体量及其稳定性。在残余奥氏体的形变诱导马氏体相变、贝氏体和V析出的强化作用以及铁素体晶粒细化的共同作用下,抗拉强度和强塑积分别达到1 035 MPa和25 875 MPa·%。     

Mechanical Properties Optimization Metal Bars and Sheets Made of 34CrNiMo6 Steel

Currently available and well known materials treated by a special procedures can provide superior properties in the comparison to presently obtained ones.Special treatment procedures are efficiently developed with the use of physical simulators nowadays.Physical simulators allow treatment optimization on small scale laboratory samples which can be subsequently transferred to real production processes later on.Nevertheless,there is always need of successful transfer from small scale laboratory experiments to real production of for example metal sheets.In the current paper thermo-mechanical procedure developed for 34CrNiMo6 steel under laboratory conditions is applied to metal sheets production.There were obtained very promising properties on the bulk material samples processed in the physical simulator,the challenge was to obtain similar properties on a real metal sheets by a transfer of laboratory procedure to metal sheet production process.In the considered case the combination of tensile strength and elongation were especially required for considered application in a train body.In order to achieve excellent elongation for high strength hardened steel,very fine microstructure has to be attained through the thermo-mechanical process optimization.Very good results were achieved on produced metal sheets.6% elongation was attained allowing the possibility of further material processing,e.g.bending of sheets,with tensile strength exceeding 1500 MPa.The study presented here confirms usefulness of thermo-mechanical simulators for new procedures development.With the use of the simulator of thermaldeformation cycles a materials with optimized properties for certain application can be efficiently developed.     

LZ63和LZ113合金板材室温力学性能与显微组织演变

采用熔铸、均匀化、热轧和冷轧方法制备了新型Mg-6Li-3Zn和Mg-11Li-3Zn合金板材.研究了合金的室温力学行为、热轧组织与热轧脱锂现象.两种合金的室温抗拉强度和拉断真应变分别为208MPa,0.13和170 MPa,0.375.真应力-真应变曲线表明Mg-6Li-3Zn合金室温变形发生加工硬化,而Mg-11Li-3Zn合金室温变形发生加工软化.Mg-11Li-3Zn合金中β相室温处于回复温度、β相层错能低和β相中Li原子的快速扩散降低了位错的产生速度是该合金加工软化的原因.热轧组织由带状晶粒组成.显微组织研究发现Mg-11Li-3Zn合金573 K热轧过程中发生严重的"脱锂"现象和出现大量α相现象.脱锂是锂原子扩散速度极快造成的.脱锂造成α相增多,β相减少.     

Study of Microstructure and Mechanical Properties of Boron-Containing Hot-Rolled Steel Reinforcement

Metallurgist - Stiffened specifications for quality of reinforcement product are dictated by the contemporary market that is expressed in the introduction of new TU and GOST for manufactured...     

Microstructure and Mechanical Properties of Semi-continuous Equal-channel Angular Extruded Interstitial-free Steel

An innovative method called semi-continuous equal-channel angular extrusion(SC-ECAE)has been developed to produce ultrafine grained steel by inducing severe plastic deformation.In contrast to the external forces that are exerted on specimens in traditional ECAE,the driving forces are applied on the dies in the novel SC-EACE process.Commercial interstitial-free steel sheets with width of 160 mm and thickness of 2 mm were processed repeatedly to various passes at room temperature using this method.The microstructural evolution was characterized using high-resolution electron backscatter diffraction(EBSD),and the mechanical properties were investigated by tensile testing.The EBSD images indicated that the fraction of high-angle boundaries(HABs)began to increase gradually after four passes;after six passes,elongated HAB structures with nearly submicron-scale average spacings were formed.The tensile testing results showed that strengthening was accompanied by a decrease in tensile ductility,but no significant anisotropy was observed.After 10 passes,a final HAB fraction of about 90% and an overall grain size of 0.55μm,yield strength of 638.7 MPa,an ultimate tensile strength(UTS)of 710.3 MPa,and a total elongation of 12.0% were obtained.     

Microstructure and Mechanical Properties of Ultrafine-Grained Interstitial-Free Steel Processed by ECAP

Equal-channel angular pressing (ECAP) of interstitial-free (IF) steel at equivalent strain, ε_vm = 12 has been employed to develop ultrafine-grained (UFG) microstructure with high fraction of low angle grain boundaries, that enhances strength significantly with reduced tensile ductility. ECAPed IF steel has been deformed further by cold rolling/cryorolling at ?50 °C to >90 % reduction in area. It is observed that the UFG structure gets refined with an improvement in high angle grain boundary fraction and heavily stressed non-equilibrium grain boundaries in cryorolled state resulting in significant strengthening. However, the decrease in grain size to an ultrafine level with the increased lattice strain lowers the work hardening ability of the material that limits its ductility. Hence, the rolled samples are flash annealed at 675 °C in order to recover the ductility of the material by achieving partially recrystallized structures. Consequently, the increased subgrain size as well as the grain size, the reduced residual lattice strain, lower hardness and strength with marginal recovery of ductility is maintained in order to attain the yield strength 2–3 times compared to that of as-received coarse-grained IF steel.