FEM‐Simulation of Drawing Out in Open Die Forging

Experiments and finite element simulations were performed in order to study how the bite ratio influences the closing of inner flaws such as voids and pipes in the open die forging process. Square rolled blooms of carbon steel with a transversal hole in the centre were forged with a constant height reduction but with different bites in order to study the closing of voids during the process. Corresponding finite element simulations were performed in full 3D with full thermo‐mechanical coupling. Also the influence of the friction and of the temperature gradient in the workpiece were studied. The elimination of an artificial defect by forging was successfully simulated by the finite element method. It is established that the closure of voids is highly dependent on the bite ratio. The closure of voids under the edge of the tool is however not improved by a higher bite ratio. There is a slight tendency that the situation under the tool edge is worse when the bite ratio is increased.     

不同锻造比对P91管坯组织及性能的影响规律研究

采用不同的锻造比工艺制备P91管坯,对管坯的显微组织、低倍及力学性能进行了分析研究。结果表明:当锻造比为2时,制备的P91管坯组织晶粒粗大,管坯横向截面组织分布不均匀,无法实现探伤;当锻造比提高到3时,可制备晶粒细小且组织分布均匀的P91管坯;锻造比为3时,制备的管坯低倍组织明显优于锻造比为2制备的管坯低倍组织,有利于后续的制管工艺;当锻造比为3时,可制备满足标准ASME SA335、GB5310—2008要求用的P91管坯。     

铝型材分流模上模带凸台模坯的锻造

材料的选择和模坯的锻造对于铝型材挤压模具是十分重要和关键的。通过例子介绍了挤压模具中的分流模上模带凸台的模坯的锻造方法,包括材料的选择、工艺方案、锻造过程的控制及镦挤胎模的设计,同时介绍了锻件的后处理退火工艺。上模采用带凸台的锻件,提高了模具强度,同时又降低了成本。这些已经应用于实际生产中,并经实践证明是行之有效的。     

热加工工艺对铝合金热模锻锻模寿命的影响

分析研究了冶炼、锻造及热处理等锻模热加工的各工序对锻模使用寿命的影响，并制定了预防锻模早期失效和提高锻模使用寿命的措施。     

基于Abaqus的多接触自由锻造压机侧隙量研究

为了研究自由锻造压机侧隙量对压套与上、下梁的接触状态以及上、下梁强度的影响,以Abaqus软件为工具建立了多个接触对的有限元模型并进行了不同侧隙量工况时的计算,分析结果表明：侧隙量越大,压套与上、下梁的接触状态越来越好,但是上梁以及下梁的变形、最大主应力越大;经过反复计算得到侧隙量取1.57mm时接触情况较好,且应力值在100MPa以内,研究成果对于如何设定侧隙量有一定的参考价值。     

润滑对冷锻模具寿命的影响

在冷锻过程中,模具受到极高的载荷和磨料磨损,表面粗糙度和残余应力受到影响很大。以经过热处理的高速钢制成的模具作为研究对象,试样经过镦粗过程,得到了不同锻造条件下锻件表面粗糙度、残余应力和试样变形随锻造循环次数的变化,并在"有润滑"和"无润滑"条件下,得出了采用两种不同的锻造载荷进行了冷锻镦粗工艺对冷锻模具的影响。     

楔横轧模具脱空对轧制力影响规律研究

减小设备在现有工艺下的受力,是提高轧机轴承等关键零部件寿命和产品质量的有效方法之一。为此,采用有限元法对楔横轧模具在不脱空和脱空情况下进行了轧制过程数值模拟,详细分析了模具脱空对轧制力影响的规律,得到了在一定断面收缩率范围内模具脱空有利于减小轧制力的研究结果,并与测试结果进行比较。研究结果为合理设计楔横轧模具、改善轧机受力状况提供了重要的理论依据。     

Effects of Lanthanum on Mechanical Properties of 5CrNiMo Forging Die Steel

The alteration of the strength, hardness and impact ductility of 5CrNiMo steel using three different additions of RE La element is studied in this paper. The mechanical properties of 5CrNiMo steel with RE La additions are be compared with that of the 5CrNiMo steel on the same heat-treatment condition without RE La element addition. The results show that the strength. hardness and impact ductility of 5CrNiMo steel will be improved obviously when the content of RE La element is proper, and as the content of RE La element is 0.033% (mass fraction), the 5CrNiMo steel has the best mechanical properties.     

美标H13热作模具钢的锻造工艺优化

莱钢开发了美标H13热作模具钢并对锻造工艺进行了优化,优化后的锻造工艺采用三火成形,加热温度1260℃,锻造过程合理控制砧宽比、料宽比等工艺参数,提高锻件中心压实效果,锻后快冷并采用合理的球化退火工艺抑制网状碳化物析出,组织均匀,锻件的各项技术指标均完全满足技术要求。     

空心型材挤压模具模芯变形的有限元分析

针对挤压时平面分流组合模模芯变形对空心型材壁厚影响的问题，简述了分流组合模模芯发生变形的原因，并应用有限元方法对模芯的受力变形进行了分析。首先利用ANSYS软件对分流组全模上模进行三维造型，然后综合考虑分流组合模在挤压时的受力状况，将所受各力加载到有限元模型上，通过计算获得了模芯在受力作用下的偏移变形量及模芯沿挤压方向的变形量，结合实例分析表明计算结果与实际吻合较好，说明有限元方法对模芯变形的分析是有限的。     

Ferritic Fine Structure Characteristics in Hot Die Forged Powder Steels. I. Effect of Heating Temperature during Die Forging on Ferritic Fine Structure in Specimens of Powder Technical Grade Iron and Carbon Steels

We have studied the effect of the composition and heating temperature during die forging on the microstructure and fine structure of ferrite in powder iron and powder carbon steels. From the structural characteristics obtained for different planes of the blank, we used harmonic analysis of the x-ray line shape to establish the nonuniformity of deformation over the volume. We have established the heating temperature during die forging of powder technical grade iron and carbon steels, for which the deformation is close to uniform over the die forging volume: 1050 °C for technical grade iron and low-carbon steel, 1100 °C for carbon steel. __________ Translated from Poroshkovaya Metallurgiya, Nos. 5–6(443), pp. 108–119, May–June, 2005.     

7075模锻件心部裂纹原因分析

7075模锻件横截面断口上有白色带状缺陷,表现形式为紊流状和小裂纹,这是心部强烈变形区组织薄弱点被拉断所致。产生裂纹与锻造温度不当和两次锻造变形量分配不合理有关。为了消除锻件心部裂纹,应控制好铸锭加热温度,合理分配两次锻造变形量。     

FE–Analysis of Simultaneous Hot/Cold Forging

A new, highly innovative manufacturing method is under development in research and industry, where the workpiece undergoes simultaneously a hot and a cold forging process followed by press hardening directly in the forging dies. Such a high complex forging technology is simulated by means of the finite element method, where the inductive electrical heating is modelled with substitute sources for the heat production besides the forming and the cooling process with thermal deformation and eigenstress evolution. The measured data for the temperature field and the final geometry of the forging test are compared to the results of the simulation, showing a very good agreement.     

SP侧压过程板坯头部失宽的有限元分析

为了分析定宽过程中板坯头部失宽的变化规律,利用数值模拟的方法建立了板坯侧压的有限元模型。系统分析了在固定板坯宽度和不同侧压规程的前提下, 板坯头部失宽量的变化情况,得到了失宽量和侧压量的变化规律。并相应地进行了测试研究,对比模拟结果与现场实测值,两者吻合良好。表明建立的模型真实可靠,对控制侧压过程中板坯头部失宽有重要理论和参考价值。     

SP轧制过程及侧压模块受力的测试研究及有限元分析

针对SP轧制过程,通过有限元模拟和现场测试认为,框架内部间隙、轧制负荷是引起模块振动、衬板受力不均和侧压不同步的主要原因,分析了轧制板坯头部和中间部位时板坯的变形规律和侧压模块的受力,给出了轧制狗骨的产生机理。同时定量模拟了当模块的垂直度出现偏差时产生向下分力的大小,这是加剧衬板损坏的一个原因。通过与实测结果的比较,证明建立模型的正确性和计算结果的可靠性。