Preparation of Ni60-WC Coating by Plasma Spraying, Plasma Re-melting and Plasma Spray Welding on Surface of Hot Forging Die

In order to produce the hear-resistant inner layer of hot-forging die, the plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2, including 10%, 20%, 30% tungsten carbide （WC） ceramic powder used as coating material to obtain different Nickel-based WC alloys coating. Micro-structure and micro-hardness analysis of the coating layer are conducted, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70%Ni60, 30%WC powder has the best properties with plasma spray welding, in which the micro-hardness can achieve 900HV, meanwhile it can improve the thermal property of hot-forging die dramatically.

STUDY ON DESIGN TECHNIQUES OF A LONG LIFE HOT FORGING DIE WITH MULTI-MATERIALS

A new design technique for the long life hot forging die has been proposed. By finite element analysis, the reason .for the failure of hot forging die was analyzed and it was concluded that thermal stress is the main reason for the failure of hot forging die. Based on this conclusion, the whole hot forging die was divided into the substrate part and the heat-resistant part according to the thermal stress distribution. Moreover, the heat-resistant part was further subdivided into more zones and the material of each zone was reasonably selected to ensure that the hot forging die can work in an elastic state. When compared with the existing techniques, this design can greatly increase the service life because the use of multi-materials can alleviate the thermal stress in hot forging die.

Tempering stability of Fe–Cr–Mo–W–V hot forging die steels

The tempering stability of three Fe–Cr–Mo–W–V hot forging die steels(DM, H21, and H13) was investigated through hardness measurements and transmission electron microscopy(TEM) observations. Both dilatometer tests and TEM observations revealed that DM steel has a higher tempering stability than H21 and H13 steels because of its substantial amount of M_2C(M represents metallic element) carbide precipitations. The activation energies of the M_2C carbide precipitation processes in DM, H21, and H13 steels are 236.4, 212.0, and 228.9 kJ/mol, respectively. Furthermore, the results indicated that vanadium atoms both increase the activation energy and affect the evolution of M_2C carbides, resulting in gradual dissolution rather than over-aging during tempering.

Ni60-SiC Coating Prepared by Plasma Spraying, Plasma Re-melting and Plasma Spray Welding on Surface of Hot Forging Die

In order to produce the hear-resistant inner layer of hot-forging die, plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2, including 10%, 20%, 30% SiC ceramic powder used as coating material to obtain different Ni-based SiC alloys coating. Micro-structure and micro-hardness analysis of the coating layer were followed, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70% Ni60, 30% SiC powder has best properties with plasma spray welding, in which the micro-hardness can achieve 1100 HV, meanwhile can improve the thermal property of hot-forging die dramatically.

Effect of Alloying Elements on Thermal Wear of Cast Hot-Forging Die Steels

The effect of main alloying elements on thermal wear of cast hot-forging die steels was studied. The wear mechanism was discussed. The results show that alloying elements have significant influences on the thermal wear of cast hot-forging die steels. The wear rates decrease with an increase in chromium content from 3% to 4% and molybdenum content from 2% to 3%, respectively. With further increase of chromium and molybdenum contents, chromium slightly reduces the wear resistance and molybdenum severely deteriorates the wear resistance with high wear rate. Lower vanadium/carbon ratio （1.5-2.5） leads to a lower wear resistance with higher wear rate. With an increase in vanadium/carbon ratio, the wear resistance of the cast steel substantially increases. When vanadium/carbon ratio is 3, the wear rate reaches the lowest value. The predominant mechanism of thermal wear of cast hot-forging die steels are oxidation wear and fatigue delamination. The Fe2O3 and Fe3O4 or lumps of brittle wear debris are formed on the wear surface.

Research on Thermal Wear of Cast Hot Forging Die Steel Modified by Rare Earths

Thermal wear of cast hot-forging die steel modified by rare earths（RE） was studied and compared with commercially used die steels. The function of RE and the mechanism of thermal wear of cast steel modified by RE were discussed. The results showed that with increasing content of RE, the wear rate of cast steel reduced at first and then increased. By adding 0.05% （mass fraction） RE, the cast hot-forging die steel with optimum thermal wear resistance was obtained, which was better than that of H13 and 3Cr2WSV. The large amount of coarse inclusions, （RE）2O2S, resulted from excessive RE, which obviously deteriorated thermal wear resistance. The mechanism of thermal wear of the modified cast die steel is oxidation wear and oxide fatigue delamination. The wear debris are lumps of Fe2O3 and Fe3O4.

Carbide Coating Preparation of Hot Forging Die by Plasma Processing

To meet the performance requirements of hot forging die heat resistant layer, the Ni60-SiC coating, Ni60-Cr3C2 coating, and Ni60-WC coating were prepared using W6Mo5Cr4V2 as substrate material with 30%SiC, 10%Cr3C2, 30%WC powder by means of plasma spraying and plasma spray re-melting and plasma spray welding, respectively. Microstructure of each carbide coating was analyzed, micro-hardness was tested, and mainly thermal parameters of coating were detected. The experimental results show that using plasma spray welding, the performance of 70%Ni60/30%SiC powder is the best, and its micro-hardness can achieved 1100HV, showing good thermal-physical property.

Hot-forging Die Cavity Surface Layer Temperature Gradient Distribution and Determinant

Based on the car front-wheel-hub forging forming process of numerical simulation, the temperature gradient expression of forging model cavity near the surface layer was got ten, which illustrates that the forging temperature gradient is related to forging die materials thermal conductivity, specific heat and impact speed, and the correlation coefficient is 0.97. Under the different thermal conductivity, heat capacity and forging speed, the temperature gradient was compared with each other. The paper obtained the relevant laws, which illustrates the temperature gradient relates to these three parameters in a sequence of thermal conductivity 〉 impact speed〉 specific heat capacity. To reduce thermal stress in the near-surface layer of hot forging cavity, the material with greater thermal conductivity coefficient and specific heat capacity should be used.

Determination and Analysis of Hardenability for Hot-Forging Die Steels with Deep-Hardening

ERH end-quenching method was used to determine the hardenability of four kinds hot-forging die steels with deep-hardening and hence the order of their hardenability was given.The tempering hardness of the steels was measured and the tempering resistance was studied.It was approved that ERH method is effective for the determination of hardenability of deep-hardening steel and the beginning of hardness drop in the ERH specimen is caused by bainite occurring.

Analysis of Forging Dies Coated with Tungsten Carbide through HVOF Processing

In this paper we present a performance evaluation of thermal spraying coated hot forging dies conducted in a production line. The High Velocity Oxy-Fuel process was used for the deposition of a tungsten carbide coating, which is characterized by its optimal adherence and low porosity. A metallurgical characterization of the layer was previously done, in order to obtain reference information to assist in the interpretation of the practical tests results. The coated die allowed an increase in productivity of 37.5%, besides better dimensional stability results through the process and legibility of printed numbers.

涡旋盘热模锻自动化生产线及智能检测控制系统设计

针对汽车空调压缩机涡旋盘成形难度大、缺陷多、依赖人工调整参数等问题,结合锻造行业的智能化发展需求,分析涡旋盘锻造工艺,设计涡旋盘自动化生产线、全流程在线检测控制系统,为热模锻智能检测提供参考。

6061铝合金自润滑热锻条件下工件和模具摩擦磨损特性

基于热锻条件,使用销-盘摩擦设备对6061热锻铝合金和H13钢基自润滑模具材料进行了高温对磨实验,通过电子探针和能谱仪分析了不同工况下工件和模具的磨损机理。结果表明,随着载荷的增加,工件和模具之间的摩擦因数与磨损率先降低后升高;随着转速的增加,工件和模具之间的摩擦因数增大,磨损率呈倍数增加;当载荷为12 N、转速为100 r·min^(-1)时,工件和模具之间的摩擦因数最小,其值为0.416,磨损率仅为24.591 mm 3·N^(-1)·m^(-1);随着转速和载荷的增加,工件和模具之间的粘着磨损加重并且逐渐出现磨粒磨损和氧化磨损。

齿环热精锻成形工艺参数优化及组合模具设计

针对某齿环热精锻成形材料利用率低、模具寿命短的问题,构建了齿环热精锻成形有限元模型,分析了齿环热精锻成形过程中金属塑性流动规律及各物理量的变化情况。其次,以避免齿环成形缺陷、提高材料利用率和降低最大成形载荷为目标,采用响应面法和灰狼优化算法优化了齿环的坯料尺寸、始锻温度和成形速度,并通过数值模拟仿真和工艺实验进行了验证。最后,设计了齿环热精锻成形组合凹模结构,通过数值模拟优化了组合凹模的过盈量,模具危险区域的最大主应力值降至945 MPa,改善了模具应力集中现象,有效避免了模具的早期失效。

喷丸强化对热锻模零件的影响

介绍了热锻模常见的失效形式,分析了喷丸强化工艺的作用机制和强化机理,强调表面强韧化处理的概念,综述了各种喷丸技术的发展及研究现状,总结喷丸强化工艺对热锻模零件的影响效果,探索热锻模喷丸强化研究中存在的问题,为未来的喷丸强化研究方向提供参考。

基于DEFORM-3D的轴承座热模锻工艺优化研究

为了解决铸造轴承座产生的气孔、夹渣等导致应力集中而承载能力下降,内部成分偏析、晶粒偏大导致综合力学性能低等问题。在对矿用轴承座进行锻造工艺分析的基础上,进行三维模型及其模具的设计,利用DEFORM-3D对其进行金属流动规律的锻造工艺仿真分析,在此基础上对零件进行产品优化设计,分析结果表明优化后的锻件设计满足模锻工艺要求。

俄罗斯KB8046-4000型热模锻压力机维修保养

介绍了俄罗斯KB8046-4000型热模锻压力机曲轴、传动轴及其相关零部件的检修方法。其中曲轴及传动轴是其传动系统中最主要的两个部件,其维护保养状况直接影响压力机的使用寿命。

国内热锻模具钢的发展现状

我国模具工业规模大、年产值高、市场潜力巨大,但由于起步晚,产品以中低端为主,大型、精密、复杂模具仍严重依赖进口。热锻模是模具钢重要分支,产品主要分为中碳低合金热作模具钢、铬系中合金热作模具钢和改进型热作模具钢3大类,使用温度涵盖300~700℃温度区间,在汽车工业和机械制造业应用广泛。简要介绍了国内热锻模具钢的发展概况;分析了热锻模具钢的使用工况、失效形式和性能要求;结合国内模具使用情况和合金化特点,为热锻模具钢的选材与产品研发提供了参考依据,同时展望了利用W、Mo、V、Co等元素合金化设计和成形情况,指出通过热处理工艺提高热锻模具钢的强韧性和耐磨性是热锻模具钢的发展趋势。

汽车半轴热锻模工况仿真及机器人电弧增材制造路径生成

为了确定热锻模具修复方案,使用有限元仿真软件模拟汽车半轴摆碾成形过程,生成机器人电弧增材制造路径。当连锻次数达到20次后,模具进入热平衡状态,中心圆台表层温度稳定在788℃,表层与540℃等温线相对深度约为28mm,应力场510MPa以上的模具增材层约为26.3mm,确定使用温度场划分模具增材制造区域。利用MATLAB提取540℃以上的点云部位,逆向建立3D模型,进行路径规划并在焊接机器人上运行。

热作模具钢1.2344横向冲击功的提升措施

针对张宣科技在高端热作模具钢生产过程中无缺口冲击功平均只有230 J,没有达到预期目标300 J以上,无法满足客户质量要求的问题,分析了冲击功偏低的原因并提出了提高冲击性能的一系列优化措施。电炉冶炼环节采用EAF+LF+VOD三联工艺降低钢中有害元素含量、O、N、H气体含量以及硫化物、氮化物和氧化物等有害非金属夹杂物数量,提高钢水纯净度,适当降低影响冲击韧性的硅元素和钒元素含量,进一步优化成分;锻造环节采用多向镦拔锻造,有效将钢锭各个方向柱状枝晶打碎,实现细化晶粒,提高材料致密性效果;热处理采用锻后水冷快速冷却和超细化混合工艺,降低因冷却不当造成的二次网状链状碳化物析出数量,稳定晶界间结合力。工艺优化效果显著,钢中晶粒尺寸更加均匀细小,带状偏析基本消失,退火态组织中碳化物分布更加均匀弥散,冲击断口韧窝数量明显增多,冲击功进一步提高,稳定在平均300 J以上。

某热模锻压力机湿式离合制动器液压系统故障分析

某40 MN热模锻压力机湿式离合制动器液压系统在安装调试过程中,连续动作时速度缓慢,液压系统压力明显降低,无法满足设备正常运行节拍要求。通过分析设备结构与工作情况,结合液压系统工作原理配置,经过核算后找到问题原因并最终解决问题,并针对此类工况的液压系统设计提出了注意事项。