Texture Evolution in Ferritic Rolled Ti-IF Steel during Cold Rolling

 Texture evolution of ferritic hot rolled Ti-IF steel was investigated during cold rolling in the reduction from 15% to 85%. It was found that, α fibre intensified monotonously with the increase of the cold reduction, but γ fibre changed in a different way. As the cold reduction was in the range of 15%-35% or 45%-75%, γ fibre intensified. While the reduction was between 35%-45% or 75%-85%, the intensity of γ fibre reduced. γ fibre displayed the maximum intensity at 75% and the highest average plastic strain ratio due to the favorable recrystallization texture was obtained at this point.     

凝固组织对超低碳铁素体不锈钢皱褶和深冲性的影响

为了研究凝固组织对超低碳铁素体不锈钢成形性的影响,采用XRD和SEM等分析手段详细研究了材料的皱褶和深冲性能。研究发现:相对于等轴晶的试样,柱状晶试样展示了更高的皱褶高度,这主要同柱状晶试样中存在明显的晶粒簇有关;经最终的再结晶退火后,等轴晶试样也展示了更好的深冲性能,这同等轴晶试样形成了强烈的γ纤维织构紧密相关。     

Effect of Processing Condition on Texture and Drawability of a Ferritic Rolled and Annealed InterstitialFree Steel

The processing conditions of the texture formation and deep drawability of a TiIF steel strip hotrolled in ferritic region and subsequently annealed were investigated. The rvalue increases with the decrease of reheating temperature, and finish rolling temperature and the increase of reductions in ferritic region. For lubricated ferritic rolling and annealing, the rvalue is raised up to 175, and elongation rate is over 50% at the finish rolling temperature of 650 ℃, which is suitable for DDQ grade products. However, the rvalue is below 10 in the case of unlubricated rolling. The Xray diffraction was used to analyze the textural characteristic of samples. For samples subjected to lubricated rolling and annealing, the strong {111}∥ND recrystallization texture is distributed homogeneously along the thickness direction, and the intensity of {110} recrystallization texture is very low even in surface. However, for unlubricated samples, the {111} texture is distributed inhomogeneously and is weak along the thickness direction, and {110}∥ND recrystallization texture is strong, which deteriorates the formability.     

IF钢铁素体区热轧工艺参数对深冲性能的影响

 采用润滑轧制,在不同压下率、终轧温度及退火制度下,研究了IF钢铁素体区热轧时,不同工艺参数对IF钢深冲性能的影响。结果表明：在实验范围内,随压下率增加,r值提高;终轧温度下降,r值略微增加;高温退火可使变形铁素体充分再结晶,从而提高r值。ODF织构分析结果与检测结果是一致的。     

冷轧压下率对铁素体区热轧Ti-IF钢冷轧板深冲性能的影响

研究了于铁素体区润滑热轧的Ti-IF钢在随后的冷轧及退火工艺中深冲性能的变化.结果表明,在冷轧压下率为75 %时IF钢所获得的r值最高.织构分析表明,于铁素体区润滑热轧的IF钢具有较强的{111}∥ND再结晶织构组分;冷轧时采用75 %的压下率和随后的退火工艺可获得最强的{111}∥ND再结晶织构;冷轧压下率进一步增加时,{111}∥ND再结晶织构将会削弱.这种织构变化与冷轧时ND纤维晶粒内部的剪切带变化有关.     

热轧温度对436不锈钢热轧织构的影响

利用EBSD技术研究了不同热轧温度下436不锈钢热轧织构的变化规律和显微组织特征.试验中选取不同的热轧初轧和终轧温度:分别在1 080和1 050℃开轧,850和800℃终轧.结果表明:较低温下开轧、终轧晶粒内部的缺陷较多,表现为较大的累积取向差,而较高温度下开轧、终轧其累积取向差明显低于低温热变形下的样品;在较高温条...     

异步轧制对SUS430铁素体不锈钢织构和深冲性能的影响

利用X射线衍射技术和金相显微镜观察等手段,研究异步轧制工艺对SUS430铁素体不锈钢组织织构与深冲性能的影响。结果表明:异步轧制技术可以适当细化再结晶晶粒,但是晶粒大小、分布不均匀。织构分析表明,采用异步一次冷轧工艺沿着板厚方向可获得均匀、完整的γ纤维织构,但强度相对较弱,而应用异步二次冷轧,经过两次退火工艺,再结晶织构弱化,获得接近随机的取向织构。综合分析表明,异步一次轧制有利于提高材料的深冲性能。     

Ti-IF钢铁素体区热轧退火板的织构特征和成形性能

研究了铁素体区热轧压下率和润滑条件对一种Ti-IF钢的热轧后退火钢板的力学性能的影响以及润滑条件对再结晶织构的影响.结果表明,随铁素体区压下率的增加,采用润滑轧制时Ti-IF钢的成形性能提高;另一方面,随润滑条件的改善,成形性能得到提高,而其他力学性能变化不大.织构分析表明,采用润滑轧制,可以减少试样沿厚度方向的《110》∥ND剪切织构,有利于《111》∥ND织构的生成,使有利织构的强度大大增加,因此提高了IF钢的成形性能.     

Effect of Hot Band Annealing Processes on Microstructure,Texture and r-Value of Ferritic Stainless Steel

The effect of hot band annealing processes,namely simulating batch annealing and continuous annealing,on microstructure,texture,grain boundary character and r-value of ferritic stainless steel was investigated.The hot band displayed a highly elongated ribbon-like structure and a pronounced deformation texture.The fully recrystallized grains were observed after continuous annealing while the typical hot rolled structure was remained after batch annealing.Also,the α-fibre texture formed during hot rolling almost disappeared after continuous annealing and a weak γ-fibre texture was obtained.By contract,the α-fibre texture remained very stable after batch annealing.After cold rolling and recrystallization annealing,the favorable γ-fibre texture was achieved in the continuous annealed steel.Instead of forming the γ-fibre texture,the recrystallization texture was notably shifted toward {223}582 in the batch annealed steel.Finally,the improvement in drawability with high r-value and low Δr-value were also displayed in sheet through the initial continuous annealing process.     

Effects of Finish Rolling Temperature on Microstructure and Mechanical Properties of Ferritic-Rolled P-Added High Strength Interstitial-Free Steel Sheets

  The steels were rolled at 3 different finishing temperatures. The mechanical properties were tested by tensile tests. The results show that as finish rolling temperature decreases from 620 to 560 ℃ in ferrite region, the deep drawability of ferritic rolled P added high strength IF steels is improved, and r value rises from 114 to 137. Finish rolling temperature (FT) has less influence on other mechanical properties, such as yield strength, tensile strength and elongation. Microstructures of hot rolled and annealed steel sheets and precipitates of annealed steel sheets were also analyzed.     

退火温度对Nb+Ti双稳铁素体不锈钢织构的影响

利用电子背散射衍射技术(EBSD)研究了不同退火温度对Nb+Ti双稳铁素体不锈钢织构的影响。结果表明,随着退火温度的升高,α织构逐渐减弱,γ织构逐渐增强,当退火温度为920℃时,α织构基本消失,材料以γ织构为主。对再结晶织构的形成机制的探讨认为,铁素体不锈钢具有较强的γ织构归因于定向形核和选择生长共同作用的结果。     

精轧温度对超纯21%Cr铁素体不锈钢织构演变和成形性能的影响

研究了超纯21%Cr铁素体不锈钢精轧温度对织构演变规律和成形性能的影响。将粗轧板坯切块并在900~750℃范围内进行精轧,随后经相同的热轧退火、酸洗、冷轧及退火处理,系统研究了试样的宏观织构、显微织构和成形性能的变化规律。结果表明:精轧温度对铁素体不锈钢的织构演变有重要影响,降低热轧精轧温度有利于增加热轧退火板中{111}再结晶织构组分;冷轧及冷轧退火板的织构分布具有明显的遗传性,热轧板中较高的{111}再结晶织构组分,促进了冷轧退火板中{111}再结晶织构的生成,从而提高了铁素体不锈钢的成形性能。     

铁素体区热轧高温卷取条件下IF钢的织构特征

 研究了铁素体区热轧高温卷取条件下，2种不同成分的IF钢的织构特征。结果表明，高温卷取后，普通Ti IF钢发生了完全再结晶，中心面和1/4面上形成了很强的<111>∥ND再结晶织构；高强Ti IF钢大部分晶粒仍处于轧制状态，只有极少部分晶粒发生了再结晶，中心面和1/4面上形成的织构组分以<110>∥RD为主，<111>∥ND再结晶织构较弱。织构分析表明，2种钢的表面织构均较弱，普通Ti IF钢表面上<001>∥ND组分占优，高强Ti IF钢表面上<110>∥ND组分强度最高。     

终轧温度对超纯铁素体不锈钢组织、织构及成形性能的影响

研究了终轧温度对铌、钛双稳定化超纯Cr17铁素体不锈钢的组织演变、织构演变及成形性能的影响。研究结果表明,降低终轧温度能有效细化、均匀化热轧及退火组织。降低终轧温度能增强冷轧退火板的γ纤维再结晶织构、减轻偏离{111}121组分的程度。降低终轧温度是提高r值、降低Δr值、改善冷轧退火板成形性能的有效手段。     

Effect of Processing Conditions on Mechanical Properties of a Ti Interstitial Free Steel

The effect of thermal cycle, cold reduction and temper rolling on texture, microstructure and mechanical properties of a Ti‐added IF steel is presented. Sheets with different cold reductions were annealed using cycles with temperatures, heating rates and soaking times including extreme annealing conditions like continuous and batch regimes. Microstructure is characterized by equiaxed grains of about 17 to 20μm, being independent of the annealing cycle applied. As a function of the processing variables, texture depended mainly on heating rate and cold reduction degree, showing little dependence on soaking time or temperature. Despite the great differences between batch and continuous annealing cycles, yield strength, ultimate tensile strength and hardening coefficient n show little variation between these extreme regimes. This characteristic makes this steel almost insensitive to annealing conditions, strongly differing from other deep drawing materials like Al‐killed steels. The influence of texture on r‐value was studied using a Taylor‐based model which showed good agreement with experimental relationships. Finally, temper rolling of annealed materials was simulated with elongations varying from 0.5 to 7%. This resulted in an important increase of YS and a decrease of n, but had a deleterious effect on stretchability.     

冷轧工艺对IF钢r值和n值的影响

研究了经铁素体区热轧后的IF钢板坯在随后的一次冷轧和两次冷轧工艺中所表现出的深冲性能规律。试验结果表明：经两次冷轧及两次退火后，IF钢的深冲性能获得了明显的良性遗传，在应变硬化指数n有所提高的情况下，塑性应变比r超出一次冷轧工艺相应值的30％左右。同时发现，两次冷轧工艺中总变形率在前后两次轧制中的分配方式是影响IF钢最终性能指标的关键。     

铁素体轧制生产超深冲冷轧板

通过铁素体轧制生产超深冲冷轧Ti-IF钢的工业试验,研究了化学成分、工艺制度对热轧IF钢金相组织、织构和第二相粒子析出的影响,分析了热轧IF钢再结晶状态与产品性能的关系,阐述了提高冷轧Ti-IF钢深冲性能的生产控制要素.试验结果表明:在采用适宜的成分、低的加热温度、高的卷取温度和铁素体区强润滑轧制时,热轧板具有粗大的二相粒子和强的{111}织构;与常规轧制相比,冷轧板的r值在横向和45.方向平均提高1.3和1.0,试验冷轧板的最高r值达到了3.23.     

Effect of Through‐Thickness Macro and Micro‐Texture Gradients on Ridging of 17%Cr Ferritic Stainless Steel Sheet

In order to study the formation of ridging in ferritic stainless steel (FSS) sheets, the evolution of the crystallographic texture was investigated by macro and micro‐texture measurements throughout the thickness of the sheets. The as‐received hot band material displayed a pronounced through‐thickness texture gradient with a strong rotated cube orientation in the sheet center layer. The initial texture of the hot band had a high impact on the formation of the cold rolling texture and on the final recrystallization texture. Modification of the cold rolling texture by means of cross‐rolling led to an improvement of the macro and micro‐textures after final recrystallization annealing, which gave rise to an enhanced sheet formability in FSS. Tensile tests of specimens with half thickness revealed that ridging formed in the sheet center was much stronger than that in the surface. This observation was attributed to the more frequent formation of orientation colonies in the sheet center when compared to the sheet surface.     

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。