降低弹簧扁钢热轧硬度的工艺探究

通过在连轧生产线上试验51CrV4弹簧扁钢的开轧温度、终轧温度对热轧硬度的影响,探索降低51CrY4弹簧扁钢热轧硬度的工艺。得出开轧温度1100±20℃,终轧温度880～920℃,成品轧机轧制速度3.5m/s。其热轧硬度达标。     

低温轧制提高热轧带材的性能

为确保低温(Ar_3以下终了轧制)热轧钢板的深冲性,住友金属综合技术研究所采用大幅度改变热轧终轧温度和卷取温度的方法研究了温度对材质的影响。试验结果指出:1.材料的显微组织受温度的影响很大。在有α加工组织存在时,YP 呈现高值,E1呈现低值。2.终轧温度从925℃降低至800℃时,γ_0值急剧下降,温度继续降低时γ_0值反而上升,600℃终轧时的γ_0值比900℃终轧时的还高。这种变化趋势与(222)/(200)的变化是一致的。     

热轧终轧温度对形变时效状态QBe2合金薄板性能的影响

通过对QBe2合金薄板的力学及物理性能进行测试,结合其不同热处理状态下的扫描电镜组织,研究了热轧终轧温度对形变时效状态QBe2合金薄板性能的影响.结果表明:热轧终轧温度在540~630℃范围内,较低终轧温度(540℃)的QBe2合金薄板经过形变时效热处理后显微组织中β相含量较高,并且析出物沿晶界局部脱溶的现象更为严重.热轧终轧温度从540℃升高到630℃,形变时效态下QBe2合金薄板的强度提高80~90 MPa,伸长率提高1.2%,弹性模量提高近10 GPa,导电率降低1.8%.造成不同热轧终轧温度的形变时效状态QBe2合金薄板性能不同的主要原因是显微组织中β相含量不同.     

终轧温度对热轧中碳含硼钢40B实际晶粒度的影响

研究了终轧温度(880～935℃)对热轧中碳含硼钢40B实际晶粒度的影响。在开轧温度990～1010℃的情况下,通过控制圆钢轧制节奏,实现不同的终轧温度,得出终轧温度降低有利于改善Φ32mm热轧中碳含硼钢的实际晶粒度。通过试验生产实践,并分析圆钢头、中、尾部1/2半径区域的纵向金相组织,发现当终轧温度在880～890℃时,热轧中碳含硼钢40B的实际晶粒度最细小且均匀。     

含铜取向硅钢热轧工艺优化

针对含铜取向硅钢牌号判级标准提高,通过控制其热轧关键工艺,制定有效的精轧速度控制优化模式,降低精轧纯轧时间和提高精轧终轧温度,显著提升了牌号合格率.研究结果表明:较高的终轧温度下,含铜取向硅钢热轧板中产生更多的弥散析出相、热轧板1/4层处{110}面织构明显增多,生产实践中有效的精轧速度控制优化模式对磁性能提升有明显作用.     

热机械控制工艺对热轧TRIP钢力学性能的影响

通过实验室热轧机研究了热机械控制工艺(TMCP)对热轧TRIP钢力学性能的影响.结果表明:在热轧变形过程中应变诱导铁素体相变,低温大变形量造成铁素体晶粒细化.随终轧温度的降低和终轧变形量的增加,残余奥氏体的稳定性增加,相变诱发塑性(TRIP)效果更好.在700 ℃终轧且终轧变形量为50%时,抗拉强度、屈服强度和总伸长率分别达到791 MPa,538 MPa和36%的最大值.     

终轧温度对低硅含磷系TRIP钢组织性能的影响

通过实验室热轧试验,研究了不同终轧温度下低硅含磷系热轧TRIP钢的组织特征及性能特点。结果表明：终轧温度由900℃降低到790℃,铁素体体积分数增加,贝氏体体积分数降低,残余奥氏体体积分数变化不太明显;终轧温度900和820℃时,得到贝氏体为基体的室温组织;终轧温度降低到790℃时,低温变形促进了奥氏体到铁素体的相变率...     

钛微合金化热轧双相钢的工艺研究

通过模拟实验研究了钛微合金化热轧双相钢的连续冷却转变曲线及终轧温度对组织的影响规律,获得了可行的工艺窗口,并进行了验证性热轧实验.在冷却速率小于5℃·s-1及温度在625~725℃时,实验钢可以形成先共析铁素体.随着终轧温度升高,组织中铁素体及马氏体含量先升高后降低,但幅度不大.同时,当终轧温度较高时,铁素体显微硬度增加,析出强化作用增加.当终轧温度及缓冷温度分别为840℃及700℃时,获得了抗拉强度为672 MPa及屈强比为0.61的性能良好的热轧双相钢.经计算,铁素体组织中析出强化量为78.5 MPa.      

热轧窄带65Mn钢珠光体组织与性能的窄范围控制

为制定65Mn窄范围质量控制工艺参数,利用OM、SEM、拉伸试验机及洛氏硬度仪等,研究热轧窄带65Mn钢的终轧温度、终轧后冷速下以及卷取后冷速对珠光体组织及力学性能的影响。结果表明:在其他工艺参数相同的情况下,随着终轧温度的提高、终轧后冷却速率的减缓和卷取后冷却速率的加快,热轧窄带65Mn钢珠光体球团尺寸和片层间距不断增大、片层变厚、抗拉强度及硬度均逐渐降低,当终轧温度大于960℃、终轧后冷却速率小于5.58℃/s及卷取后冷却速率小于0.1℃/s时,其抗拉强度小于900 MPa。     

冷轧无取向硅钢DW4B热轧工艺优化

本文介绍了冷轧无取向硅钢DW4B合理的热轧工艺,通过试验从理论上分析了不同加热温度、精轧终轧温度和卷取温度对热轧卷质量、成品磁性能的影响。     

Kinetics of texture development and sulfur removal in oriented silicon iron

The kinetics of (110)[001] secondary grain growth, the temperature dependence of selectivity to a (110)[001] texture, and the kinetics of desulfurization in cold rolled-decarburized, thin sheet (semiprocessed 3 pct Si?Fe) were measured as were the parameters requited to produce (110)[001] grain-oriented sheet by high temperature strip annealing. Kinetic studies revealed that (110)[001] grain growth in several semiprocessed sheets exhibited the following characteristics: 1) sigmoidal growth kinetics; 2) an activation energy of ～64 Kcal; and 3) essentially complete (110)[001] secondary grain growth within 8 min at temperatures of 1000°C and higher. Measurements of magnetic torque properties and pole figures of isothermally annealed semiprocessed sheet showed a degradation in selectivity to a (110)[001] texture above 1050°C. Desulfurization kinetics were in good agreement with a theoretical diffusion model which takes into account sulfur removal in the presence of a dispersed second phase of MnS particles. A two-stage high temperature strip annealing cycle in dry hydrogen produced (110)[001] grain-oriented sheet having magnetic properties comparable to those obtained by conventional box annealing.     

Evaluation of Strain Hardening Parameters

The plane-strain compression test for three kinds of materials was carried out in atemperature range between room temperature and 400 ~C. The a- e curves and strain-hardeningrate at different temperatures were simulated and a reasonable fit to the experimental data wasobtained. A modified model created by data inference and computer simulation was developed todescribe the strain hardening at a large deformation, and the predicted strain hardening are in agood agreement with that observed in a large range of stress. The influences of different param-eters on strain hardening behaviour under large deformation were analysed. The temperatureincrease within the test temperatures for stainless steel 18/8 Ti results in dropping of flowstress and strain-hardening rate. For favourable r-fibre texture to obtain high r, the cold roll-ing was applied at large reduction. In the experimental procedure, the X-ray diffraction test wascarried out to compare the strain hardening and microstructure under large deformation for abcc steel (low carbon steel SS-1142). The results indicate that the high strain-hardening ratepossibly occurs when the primary slip plane {110} is parallel to the rolling plane and the strain-hardening rate decreases when lots of {110} plane rotate out from the orientation {110}//RP.     

Formation of internal structure in the rolling of a bcc (110)[001] single crystal

The stages of structure formation during cold rolling are investigated in bcc (110)[001] single crystals of Fe–3% Si alloy, within the deformation zone. To obtain a visible deformation zone, the laboratory mill is abruptly stopped at the instant of sample rolling. To reduce the frictional coefficient, lubricant is used for some of the samples. The deformational structure is studied by metallography and orientational electron microscopy (EBSD). Deform-3D software is used to analyze the relation between the experimental data and the calculated stress state in rolling, for various values of the frictional coefficient. Depending on the frictional coefficient, the stress state may significantly affect the mesostructure formation and the texture development. In a single crystal rolled with elevated friction, when the deformation is relatively small, deformation bands are formed. Orientational analysis of the contact point of deformation bands reveals alternating microbands, each with slight different orientation, which are separated by small-angle boundaries. In the rolling of a (110)[001] single crystal with lubrication (reduced friction), twinning is observed even with slight deformation. The twinning is evidently due to the reduced contribution of surface energy to the total energy of twin nucleation. Throughout the whole deformation process, either the twins of both systems retain the strict Σ3 crystallographic relation with the matrix or else, on account of the local lattice reorientation, Σ3 disorientations are converted to similar special Σ17b and Σ43c disorientations. On the basis of experimental data, a dislocation model is proposed for the formation of deformational mesostructures in the cold rolling of a (110)[001] single crystal. This model includes the formation of microbands in the initial stage of deformationband generation; the formation of transition bands parallel to the rolling plane with the dynamic retention of the initial orientation; and the formation of transition bands inclined to the rolling plane with a habitus parallel to the {112} matrix plane. These inclined planes are equivalent to shear bands whose habitus is inclined at ~17° to the rolling plane.     

Elastic wave velocities in various alloy strips

The zeroth order plate mode shear wave velocity has been measured in thin strip specimens of Oriented Electrical Steel, Elinvar-Extra, and RMI 464 titanium alloy as a function of the angle between the propagation direction and the rolling direction. Also, the plane wave shear and longitudinal velocities have been measured along the normal to the rolling plane. The results in the Oriented Electrical Steel agree with the known (110)[001] texture. In the Elinvar-Extra there is a texture indistinguishable elastically from (100)[Oil], or partial (100)[011] superimposed on a random background. Different annealing temperatures following cold-rolling yield different degrees of anisotropy and different dependences (1/G)(dG/dT) of the shear modulus upon ambient temperature. At an annealing temperature of about 850‡C, (1/G)(dG/dT) evaluated near room temperature changes from positive to negative, and anisotropy becomes minimum. In the RMI 464 titanium alloy, the shear velocity anisotropy was only 1 pct in the rolling plane. Formerly with Bell Telephone Laboratories, Allen town, Pa.     

EBSD Investigation on Effect of Cooling Rate on Microstructure and Transformation Textures of High Strength Hot-rolled Steel Plates

The effect of cooling rate on the microstructure and transformation textures of high strength hot-rolled steels was investigated.Heat treated samples subjected to different cooling conditions were characterized by optical and scanning electron microscopes using orientation imaging microscopy(OIM).The experimental results demonstrate that there is a significant effect of cooling rate on microstructures and textures resulting from phase transformation.Slow cooling rates lead to the appearance of the cube(001)[010],rotated cube(001)[110]/(001)[110],Goss(110)[001]and rotated Goss(110)[110]components.In contrast,textures developed at rapid cooling rates are preferably of Cu(112)[111],Br(110)[112],transformed Cu(113)[110]and transformed Br(332)[113]/(112)[131].These texture changes are attributed to the selective character of the phase transformation.The OIM technique was used to have a better understanding of the formation of phases and their relationship between microstructure and processing conditions.The volume fraction of micro-constituents resulting from phase transformation such as bainite,martensite and different types of ferrite,can be measured satisfactorily by this technique correlating image quality of EBSD patterns to specific phases.     

终轧温度对SUS444铁素体不锈钢抗起皱性能的影响

通过金相和EBSD等技术,研究了不同热轧终轧温度对SUS444铁素体不锈钢表面抗起皱性能的影响,讨论了热轧退火板表层所产生{110}001高斯织构的演变过程及其对抗起皱性能的影响。结果表明,860℃的终轧温度有利于SUS444铁素体不锈钢热轧及退火过程中由于受剪切应变而形成的{110}001高斯织构的形成,从而提高后续冷轧退火板表面的抗起皱性能。     

Transformation and Deformation Texture Study in Friction Stir Processed API X80 Pipeline Steel

The nature of deformation in friction stir welding/processing (FSW/P) is complex which is further complicated when allotropic phase transformations are present. Electron backscattered diffraction (EBSD) is used as a means to reconstruct prior austenite texture and grain structure to study deformation and recrystallization in austenite and ferrite in FSW/P of high strength low alloy (HSLA) steels. Analyses show evidence of shear deformation textures such as A1* (111)[?1?12], B (1?12)[110], and ?B (?11?2)[?1?10], as well as rotated-cube recrystallization texture in the reconstructed prior austenite. Existence of rotated-cube texture as well as polygonal grain structure of the prior austenite implies that recrystallization is partially occurring in elevated temperatures. Room temperature ferrite exhibits well-defined shear deformation texture components. The observed shear deformation texture in the room temperature microstructure implies that FSW/P imposes deformation during the phase transformation. The evolution of both elevated and room temperature textures in friction stir processed API X80 steel are presented.     

Formation of the Goss orientation near the surface of 3 pct silicon steel during hot rolling

The influence of hot rolling conditions such as reduction rate, rolling temperature, rolling speed, lubrication, and initial orientation on the formation of the Goss orientation near the surface of hot rolled 3 Pct silicon steel was studied. A (110) [001] orientation was stably formed at the reduction rate of over 85 Pct in any initial orientation used, even from (100) [001] and (100) [011] single crystals. A strong (110) [001] orientation was obtained in the specimen hot rolled by multi-pass rolling (low reduction rate per pass) and by slower speed rolling in the range of 6 to 50 m/min. It was found that the Goss orientation was formed not by recrystallization during and after hot rolling but by slip rotation near the surface due to constrained deformation. The high friction between the roll and sheet characteristic to hot rolling was important for this texture formation. This paper is based on a presentation made at the symposium “Physical Metallurgy of Electrical Steels” held at the 1985 annual AIME meeting in New York on February 24–28, 1985, under the auspices of the TMS Ferrous Metallurgy Committee.     

Recovery and recrystallization in rolled tantalum single crystals

The recovery and recrystallization behavior of rolled tantalum single crystals having initial orientations of (001) [110], (112) [110] and (111) [110] has been studied. Each crystal developed a simple, single component texture upon rolling. The texture became more diffuse and the local lattice curvature more intense as the rolling plane deviated from (001) towards (111). The (001) [110] and (112) [110] crystals formed a uniform dislocation array and polygonization occurred on annealing. No recrystallization of the (001) [110] crystal took place at temperatures up to 1673 K. A few randomly-oriented recrystallized grains were nucleated in the (112) [110] crystal but these may have been artificially nucleated. Only the (111) [110] crystal reoriented during rolling; it also formed a cellular dislocation microstructure. This orientation was the only one to recrystallize easily, primarily because of the large lattice curvature. The recrystallized grains could be related to the deformation texture by a rotation of 23 to 24 deg about a common <111> direction that was parallel to the normal direction of the sheet. The nature of the misorientation spread after rolling may have dictated this relation as a compromise to the one usually found in bcc materials,viz. 25 to 30 deg rotation about a common <110> axis. Also, wide dislocation cell size distributions were noted in the (111) [110] crystal. The cell size distributions were log normal in nature. Subgrain growth was very much more rapid in this crystal. There was a large discrepancy between the observed subgrain growth and that predicted theoretically by the coalescence model. W. B. SNYDER, JR., formerly with Union Carbide Nuclear Division, Y-12 Plant, Oak Ridge, TN. This paper is based on a presentation made at a symposium on “Recovery, Recrystallization and Grain Growth in Materials” held at the Chicago meeting of The Metallurgical Society of AIME, October 1977, under the sponsorship of the Physical Metallurgy Committee.     

终轧温度对600 MPa级高钛高成型性铁素体-珠光体酸洗带钢组织与织构的影响

利用扫描电子显微镜(SEM)与电子背散射衍射技术(EBSD)研究了高Ti高成型性铁素体-珠光体型热轧酸洗带钢不同终轧温度下的组织与织构特征.研究结果表明, 终轧温度对显微组织的演变影响较小, 但却引起了大角晶界密度的升高.不同终轧温度时形成的组织均以铁素体为主, 少量的珠光体弥散分布在铁素体基体之间.终轧温度的提高引起了织构类型的显著改变, 随着终轧温度的升高, 织构强度整体增强, 并形成了明显的对冲压成型性有利的近γ织构.当终轧温度为850℃时, 近α织构与γ织构强度均较弱, 此时的织构类型主要为{001}[110]、{113}[471]、{114}[110]和{223}[110]成型不利织构, 成型不利织构强度更高; 当终轧温度升高至875℃时, 织构类型主要为近γ织构和{001}[110]旋转立方织构, 近γ织构体积分数由19.9%升高至41%, 成型有利织构强度显著增强.