GH4169合金楔横轧加工过程中动态再结晶及织构演变

为研究GH4169合金楔横轧加工过程中动态再结晶及织构演变规律,采用金相显微镜(OM)和电子背散射衍射(EBSD)对30%,50%两种断面收缩率下GH4169合金楔横轧件表层与心部的微观组织、晶体取向及织构进行分析。结果表明:GH4169合金楔横轧加工过程中,随着动态再结晶的发生,晶体取向逐渐变得随机化分布;轧制表层大角度晶界数量较轧件心部多,轧件表层织构强度变化不大,心部织构强度明显增强;经过楔横轧变形后织构发生转动,原始态织构类型为{001}〈110〉,{111}〈110〉,{111}〈011〉,轧制后主要织构类型为{001}〈010〉,{112}〈110〉,{110}〈111〉,{110}〈112〉;GH4169合金楔横轧件动态再结晶及织构演变规律是由楔横轧特殊变形特点决定的。     

可移式模具在楔横轧工艺中的应用

通过使用可移式轧辊模具,成功地利用一副模具轧制出了形状相似、仅局部尺寸不同的多种规格的阶梯轴,使楔横轧工艺在规格较多、批量较小的轴类零件毛坯成形中得到了应用,楔横轧技术得到了进一步发展和推广.     

非对称楔横轧成形轴类件成形过程仿真分析

目的研究非对称楔横轧轧制单轴类件的成形过程。方法利用有限元技术仿真分析了非对称楔横轧轧制单轴类件的成形过程,获得了非对称楔横轧成形过程中轴的应力应变状态,以及轧制力与接触面积关系的变化曲线。结果仿真分析结果表明,单轴成形过程中,横截面切应变近似呈中心对称分布,由心部沿与水平方向夹角45°的方向呈半拉伸状态,呈椭圆成形特征。结论轧制楔入段需要较大的轧制力,克服材料塑性变形产生的抗力;展宽和精整段,轧制力和模具与轧件的接触面积呈线性增长趋势。     

大断面收缩率楔横轧成形工艺改进

目的研究大断面收缩率一次轧制成形的可行性,降低材料利用率。方法以某型号变速箱二轴为研究对象,将原来的二次楔轧制改为一次楔轧制,用有限元软件对改进前后工艺进行模拟分析,获得了等效应变、应力场分布和轧制力矩的变化。结果模拟结果表明,一次楔轧制变速箱二轴是可行的,料头尺寸得到了减小。一次楔轧制的端头的应力小于极限应力,没有产生缩颈等缺陷。结论改进后的工艺切实可行,节省了材料,而且方便了模具的加工制造。     

输出轴楔横轧成形空心缺陷的研究

针对输出轴轧件出现的空心缺陷现象,采用有限元与实际轧制相结合的方式,对楔横轧轧件成形过程中应力应变场进行了分析,发现轧制过程中轴向金属运动阻力太大,是引起工件出现空心缺陷的原因。通过将二次轧制模的基圆高度整体降低,减小了金属轴向流动的阻力,从而避免了轧件空心缺陷的产生。     

变温度场下楔横轧端头凹心数值模拟研究

目的研究楔横轧凹心产生的原因以及变温度场对端面凹心的影响。方法采用数值模拟的方法,详细分析了楔横轧变形规律下凹心产生的原因。同时利用Deform-3D用户子程序方式,给轧件端部添加一定形式的变温度场,分析了变温度场改善凹心缺陷的机制;研究了变温区表面温度与变温度场长度对凹心深度的影响。结果楔横轧凹心是由轧至极限料头长度Imin时,端面金属变形不均匀引起的,凹心深度随着变温长度的增加和变温区表面温度的减小而减小,结论所提变温度场楔横轧轧制工艺,可以有效改善端面变形的均匀性,添加此变温度场可以有效减小楔横轧凹心深度。     

非对称楔横轧成形缺陷分析与模具参数的确定

分析了楔横轧生产过程中主要的成形缺陷:轧件不旋转、扭曲、折叠、心部缩松等,并提出了改进措施。根据轧制生产经验值及摩擦系数μ与模具成形角α、展宽角β之间的关系理论研究,建立了三者之间的关系曲线;并在此基础上分析了非对称楔横轧轧制过程中轴向力的不均衡问题,为楔横轧模具的参数选择提供依据。实验结果表明,优化后的模具轧制过程减少了轧件缺陷,提高了轧件质量。     

三辊楔横轧轧制空心轧件工艺参数对轧制力的影响规律

目的 研究分析5个工艺参数对轧制力的影响规律。方法 采用Deform软件建立三辊楔横轧轧制空轧件有限元模型,并对比模拟结果和实验检测结果中轧制力的变化规律,验证模拟结果的可靠性。利用正交实验法,全面系统分析各工艺参数对轧制力的影响规律。结果 轧制温度对轧制力的影响最大,其次是轧件轧后外径,然后是轧件内径,展宽角和成形角对轧制力的影响相对较小。结论 Deform软件模拟结果和实验中提取的轧制力曲线变化趋势基本一致,说明各工艺参数对轧制力的影响规律可靠。     

基于响应面法的楔横轧非对称轴类件轴向平衡研究

楔横轧非对称轴类件时由于存在较大不平衡的轴向力,会产生轴向窜动并导致台阶缺损和表面重皮等质量缺陷.为了减小不平衡的轴向力,目前一般采取的方法是结合工艺参数对楔横轧力能参数的影响规律,利用数值模拟手段,通过多次预设计工艺参数并反复试算以获得能使左右两端轴向力相等或近似相等的最佳工艺参数.该试算方法计算量大、繁琐、不直观,且需逐个零件进行,通用性差.本文通过利用中心组合实验设计并结合响应面法获得轴向力的响应曲面图,利用轴向力等值线选取工艺参数以保证非对称轴类件楔横轧的轴向平衡,本方法简单、直观,极大地节省了工艺参数选择所需时间,缩短了非对称轴类件楔横轧的模具设计周期.     

基于有限变形理论的齿轮楔横轧制坯热力耦合模拟

楔横轧齿轮轧制成形是一个全新的课题,在轧制过程中轧件的变形、温度场及力能参数都有待研究。将楔横轧技术与齿轮范成加工原理相结合,设计了楔横轧齿轮轧制的模具,给出了楔横轧齿轮轧制成形热力耦合本构模型,并在SuperForm平台对轧制成形过程进行了有限元模拟,获得了轧件在成形过程中的变形规律、温度场分布及力能参数变化等数据,详细分析了数值模拟结果,为进一步研究齿轮楔横轧制坯提供参考。     

AZ31镁合金室温异步轧制的织构演变

采用异步轧制技术研究了轧制工艺对AZ31镁合金塑性变形和微取向流变行为的影响.结果表明:将AZ31镁合金板材在室温条件下进行单道次异步轧制,织构随着速比增加,与快、慢辊侧相接触的表面层明显不同,但中间区域变化不明显.在快速辊侧,主要织构组份随着速比的增加而迅速增加;在慢速辊侧,主要织构组份随着速比的增加而交替变化.形变量的增大,可以细化晶粒和改善力学性能.     

Hot-cracking of high-alloyed steels evaluated by wedge rolling test

We present a new methodology of determination of hot-cracking of metallic materials, which is based on laboratory application of the wedge rolling test and computer processing of the results obtained. The experiment was made with selected new types of high-alloyed free-cutting (ferritic and austenitic) steels. The initial specimens underwent an additional modification enabling easier development of cracks which consisted in milling out of the defined V-shaped notches on a side wall of a specimen. After taking specimens from the rolled material, we performed the metallographic analysis of microstructures by means of optical microscopy as well as a SEM analysis of the cracks. The resulting microstructure in the propagating crack vicinity was markedly influenced by this fracture. In the crack vicinity, a noticeable refinement of grains was observed due to the stress-induced recrystallization and occurrence of deformation zones that were pronounced by the rolled-out and stretched sulphides. As a rule, fractures were created by the ductile failure with visible pits, caused by tearing of sulphides from the material. Susceptibility of the studied steels to hot-cracking was evaluated and compared. __________ Translated from Problemy Prochnosti, No. 1, pp. 60–63, January–February, 2008.     

压下率对6.5%Si电工钢温轧板织构的影响规律

6.5%Si电工钢是一种优异的软磁材料,织构对其磁性能影响很大。利用温轧工艺对6.5%Si电工钢热轧板进行不同压下率轧制,研究了温轧板织构随压下率的变化规律。实验结果显示,随着压下率的增大,{100}〈110〉、{110}〈100〉和γ纤维织构在薄板表层中的强度先增强后减弱,当压下率达到75%时,沿板厚方向形成3个组织区域:表层细晶粒区({110}〈100〉取向为主)、过渡层({111}〈110〉和{111}〈112〉变形晶粒区)和中心层(以拉长的γ纤维织构和{100}〈110〉取向晶粒为主),这种组织和织构不均性对后期织构的发展有重大影响。     

Effect of initial microstructure on mechanical properties in warm caliber rolling of high carbon steel

In this study, the effect of initial microstructure on change of mechanical properties was investigated by warm caliber rolling (WCR) of high carbon steel. Experiments were carried out with two different kinds of initial microstructures of pearlite and tempered martensite at the temperature of 500 °C. For comparison, the microstructure of austenite phase obtained from the conventional hot rolling at the temperature of 900 °C up to about 83% of the accumulative reduction in area was assumed to be a reference case. It was found that the WCR provided better mechanical properties in terms of strength and toughness compared to the conventional hot rolling based on experimental results of micro-hardness, tension, and Charpy impact tests. The improvement of strength and toughness was attributed to smaller ferrite grain and dispersed cementite particles with smaller interspacing aligned to the rolling direction after the WCR owing to field emission scanning electron microscopy. The investigated WCR might be useful in obtaining the high strength material with better toughness without adding new alloying elements for industrial applications according to the present investigation.     

热轧C-Si-Mn系TRIP钢的组织与力学性能

为了探讨热轧TRIP钢的制备工艺与其组织及力学性能的关系,采用热轧控冷工艺在实验室制备了C-Si-Mn系TRIP钢,利用光学显微镜、扫描电镜及透射电镜对试验钢的组织进行了观察,利用能谱仪对试验钢中的夹杂进行了观察.研究得到试验钢的力学性能为:σb=605 Pa,σs=440 Pa,δ=28.4%,σs/σb=0.73.定量金相检测结果表明,试验钢中三相含量分别为:残余奥氏体5.6%,铁素体67.6%,贝氏体26.8%.     

异步轧制对硅钢极薄带三次再结晶的影响

分别采用同步和异步轧制将成品工业取向硅钢板冷轧到0.045～0.10mm,然后在纯氢气热处理炉中进行三次再结晶高温退火,研究轧制工艺参数对取向硅钢极薄带织构和磁性能的影响,探索异步轧制对硅钢极薄带三次再结晶行为影响机理.结果表明,采用异步轧制取向硅钢极薄带的磁性能优于同步轧制的;硅钢极薄带厚度愈薄,磁性能愈好,三次再结晶发展得越完善.     

冷轧形变量对异步轧制高纯铝箔织构的影响

应用取向分布函数(ODF)研究和分析了异步轧制高纯铝箔的形变织构和再结晶织构.结果表明:异步轧制高纯铝箔的形变织构除了C{112}<111>、B{110}<112>和S{123}<634>织构组分外,还有较强的CubeND{001}<110>和{102}织构.异步轧制高纯铝箔的再结晶织构由强的立方织构{001}<100>和弱的R{124}<211>织构组成.随着形变量的增加,异步轧制高纯铝箔的形变织构和再结晶织构呈现规律性的变化,{102}织构减少,S织构先增后减,速比较小时C织构近线性减少,速比较大时C织构则先增后减.异步轧制高纯铝箔的退火样品中有很强的立方织构,这与异步轧制提高高纯铝箔的形变储能有关,形变量过大时,立方织构随形变量的增加急剧减少.{102}织构有利于再结晶立方织构的加强.     

Magnetic properties of grain oriented ultra-thin silicon steel sheets processed by conventional rolling and cross shear rolling

A new procedure consisting of the cross shear rolling (CSR) and the subsequent tertiary recrystallization annealing under dry hydrogen atmosphere was developed to produce the grain oriented ultra-thin silicon sheets less than 0.1 mm with high magnetic property performance. For comparison, the conventional rolling (CR) was also used to process the grain oriented ultra-thin silicon steel sheets. The effect of processing parameters on magnetic properties of the grain oriented ultra-thin silicon steel sheets was investigated. With the increase of annealing temperature and holding time, magnetic properties of the sheets processed by both rolling methods reach saturation as the result of the proceeding of the tertiary recrystallization. The thin sheets rolled by CSR did achieve better magnetic properties than those rolled by CR.     

TSCR热轧工艺对3.2%Si无取向硅钢组织性能的影响

研究了薄板坯连铸连轧流程（TSCR）条件下热轧工艺对3.2%Si-0.7%Al无取向硅钢组织、织构演变及磁性能的影响规律。结果表明,提高均热温度和热轧温度有助于获得粗大的变形组织和强烈的{001}〈110〉织构,进而对后续的组织、织构演变进程及磁性能产生有利的遗传影响。与低温均热和低温热轧相比,高温均热和高温热轧得到的最终成品板的再结晶晶粒较粗大,λ纤维再结晶织构较强而γ纤维再结晶织构较弱,磁感应强度较高。