EM35丝锥深冷处理工艺试验研究

采用正交设计试验方法研究了EM35高速钢丝锥的深冷处理工艺。通过切削钛合金试验,分析不同的深冷处理温度、保温时间和降温速率对高速钢丝锥寿命的影响。得出深冷工艺的最优方案为深冷温度-170℃、降温速率2℃/min、保温时间10 h;测量深冷前后丝锥硬度,结果表明,丝锥硬度平均提高0.36~1.34 HRC;依据切削扭矩试验,将未经深冷的丝锥和深冷试验后优方化案丝锥进行攻丝扭矩试验对比,验证了新工艺的合理性。     

TV3高速钢及用其制作的丝锥的切削性能

高速钢是制作刀具的主要材料。目前,高速钢已从通用型向专用型发展。TV3钢一种用于制作丝锥的新型高钒高速钢,其红硬性和二次弥散硬化效果均优于M2高速钢。采用TV3、M2和M35钢制作丝锥,经正常淬火、回火后进行了切削性能试验。结果表明:TV3钢丝锥的优于M2钢丝锥,稍逊于M35钢丝锥。此外,从齿部是否易于损坏(俗称"烂牙")这一点评价,TV3钢丝锥与M3钢丝锥相当但优于M2丝锥。采用TV3制作丝锥具有很高的性价比。     

摩焊管螺纹丝锥焊接热处理工艺的选择

管螺纹丝锥是管道联接作业中广泛应用的工具。由于管螺纹丝锥短而粗,目前大多数工厂仍采用整体高速钢材料生产,高速钢材料的利用率只有40％,实际上螺纹丝锥刃部有效的长度可小于总长度的一半。为降低丝锥的成本,减少高速钢材的消耗,合理有效地利用高速钢并能保证刀具的质量、耐用度,提高企业经济效益,在廊坊工具厂的主要产品管螺纹丝锥生产中进行摩擦焊接、焊后退火和淬回火热处理工艺的试验与研究。现已确定了合理的工艺并应用于生产。     

高速钢丝锥的硫氰共渗

研究了高速钢淬火后经低，高不同温度回火加上硫氰共渗对其力学性能和耐磨性能的影响，试验结果表明：经上述适当工艺处理后的试样弯曲强度，冲击韧度和硬度都有改善，高速钢丝锥耐磨性和使用寿命显著提高。     

GV3高速钢丝锥微观组织及切削性能

对新型GV3高速钢丝锥与传统M2高速钢丝锥的切削性能、化学成分和热处理后的微观组织进行了对比分析。结果表明,GV3高速钢与M2高速钢相比,适当提高了含碳量,同时含有较多的V和W元素。V和W元素在钢中能形成均匀细小的VC和W2C碳化物,淬火过程中阻碍奥氏体晶粒的长大,形成细晶粒组织;回火过程中VC和W2C以极细小质点弥散析出,形成钢的二次硬化,不仅明显提高钢的硬度、耐磨性和红硬性,而且保持了良好的韧性和抗冲击性能。因此GV3钢丝锥不仅在常规切削速度(6.3 m/min)下具有良好的切削性能,而且在较高切削速度(10 m/min)下,仍然具有优良的切削性能。     

W6Mo5Cr4V2高速钢力学性能的随机特性分析

通过力学性能试验及数理统计方法分析了W6Mo5Cr4V2高速钢丝锥材料的硬度、600℃×4 h红硬性、抗弯强度的随机特性,首先对试验数据用MATLAB编程分析其分布,随后采用Johnson算法和灰色系统GM(1,1)模型相结合来估计分布参数并用K-S分布来拟合检验。结果表明:W6Mo5Cr4V2高速钢丝锥材料的硬度、600℃×4 h红硬性、抗弯强度都很好地服从三参数威布尔分布,概率分别为0.9779、0.9999、0.9751。     

深冷处理在提高工模具使用寿命方面的应用

对高速钢钻头、丝锥、立铣刀、YT15铣刀片及9Cr Si、Cr12模具材料进行了深冷处理,对深冷处理前后的材料硬度、红硬性进行了检测对比,并对部分工模具进行了生产试验。结果表明,深冷处理可在一定程度上提高材料硬度、红硬性,从而提高材料耐磨性,延长工、模具使用寿命。     

粉末高速钢丝锥剖析

通过化学成分分析、金相显微镜和扫描电镜等观察,对M12粉末高速钢丝锥进行了剖析.分析结果表明,丝锥中的碳和合金含量很高,其中Co和V含量分别高于10%(质量分数,下同)和4%,合金总含量超过了40%,钢质纯净,夹杂物很少.丝锥硬度高达70 HRC左右,表面经过Ti(C、N)涂层,厚度约2 μm,与基体结合紧密,能够切削硬度高于50 HRC的超高强度钢.丝锥中的碳化物类型为M6C和MC,单颗碳化物直径≤3 μm,分布比较均匀;但碳化物粘连现象较严重,并有部分沿奥氏体晶界延伸生长等过热缺陷,使丝锥脆性增大.这是由于钢中合金含量很高,碳化物数量多且细小,使其容易合并、长大、粘连.因此在粉末高速钢的生产过程中,应根据这些特点合理制定生产工艺并严格执行,避免产生过热,使粉末高速钢的高性能特点得到充分发挥.     

采用饱和磁化法测定高速钢残留奥氏体

采用SJ-SM-200A磁饱和测量仪测定了丝锥用M2高速钢在不同热处理状态下的残留奥氏体含量。结果表明,经不同工艺热处理的M2高速钢的饱和磁化强度与残留奥氏体含量之间存在着对应关系。因此,根据饱和磁化强度可以精确测定高速钢中残留奥氏体的含量,准确判断高速钢产品的回火程度。     

W4Mo3Cr4VSiN钢丝锥表面处理及应用

对W4Mo3Cr4VSiN低合金高速钢丝锥经1160℃真空加压气淬以及560℃×1h回火3次后,分别进行蒸汽处理和离子镀TiN表面处理,研究了其显微组织和性能,并进行了寿命试验。结果表明,蒸汽处理使丝锥表面获得厚度为(3~4)μm的蓝色Fe3O4薄膜,且表层的显微硬度为766HV,比心部略低(833HV),但具有良好的润滑性和减摩性,蒸汽处理丝锥的使用寿命比未表面处理的提高了1.15倍。丝锥表面离子镀后,获得约2.5μm厚的金黄色TiN涂层,与基体结合牢固,均匀致密,离子镀TiN丝锥的使用寿命比未表面处理的提高了1.66倍。     

Fluxless joining of aluminium alloy to steel by laser irradiation method

A6061 aluminium alloy was joined with steel using Zn filler metal under laser irradiation process. The quality of joint was evaluated by the strength of a lap joint. The effects of laser power irradiation conditions such as travelling speed and defocused distance on the joint strength were investigated. The maximum joint strength was obtained at relatively medium laser travelling speed. The excess reaction between filler metal and aluminium formed thick brittle intermetallic compounds between steel and aluminium alloy. The compounds are considered to lead to the reduction in joint strength. It was found that low wetting at high travelling speed and excess reaction layer formation at low travelling speed were responsible for low joint strength. The study revealed that the relatively high joint strength between aluminium alloy and steel was obtained by laser joining method using Zn filler without the use of flux in air atmosphere.     

Influence of oxygen on the tool wear in machining

High temperatures generated in machining are known to facilitate oxidation wear. A controlled atmosphere chamber was developed to investigate the effects of oxygen on tool wear and high speed machining tests were conducted on air and in argon. Cemented carbide, cermet and cubic boron nitride tooling was used on alloyed steel, hardened tool steel and superalloy Alloy 718. Machining in argon resulted in higher flank wear, higher cutting forces, and larger tool–chip contact length on the rake face. However, in hard machining, argon atmosphere reduced rake cratering. Transmission electron microscopy of tools worn on air showed formation of nanocrystalline Al₂O₃ film on the rake when machining aluminium containing Alloy 718, while no oxide films was detectable in the other cases.     

Molten aluminium attack on iron based alloys

Liquid aluminium alloys affect the moulds, by formation of intermetallic layers at their surface; such attack is enhanced by the flow of the molten metal on the surface of the tooling. Metal tooling are used to promote high heat transfer rates and increase the solidification rate to enhance mechanical properties in cast pieces, but the damage to their surface affects their quality and increases the production costs due to the need to repair them. This work presents the results of a series of studies conducted to evaluate the attack produced by molten aluminium on samples of iron based materials commonly used in the manufacture of dies and moulds. The studies were conducted in a machine that imposes a rotating movement to experimental specimens to simulate the flow of liquid metal. The damage observed in the samples was compared to that experienced by tooling in the melt shop.     

高速钢丝锥的切削性能

目前,丝锥主要采用高速钢制作。为了解钢的冶炼工艺和显微组织,如碳化物的尺寸和分布、晶粒度等,对丝锥切削性能的影响,采用喷射冶炼和粉末冶金HSF825K、HOP2030和HSF838高速钢制作了螺旋槽丝锥,检测了丝锥的硬度、显微组织和切削性能。结果表明:3种钢丝锥热处理后的硬度均高于66HRC,钢的碳化物的尺寸、圆整度和分布对丝锥韧性的影响比淬火、回火后的硬度和冶炼工艺的影响大。弥散、细小、圆整、均匀分布的碳化物有利于提高丝锥的韧性和切削性能。采用喷射冶炼的HSF825K钢制作的丝锥的切削性能最佳。     

铝/钢异种金属Nd:YAG激光-MIG复合热源熔-钎焊接工艺

铝与钢异种金属的优质高效焊接一直是焊接领域的一项技术难题.针对铝与钢焊接的技术困难和特点,提出了可实现铝与钢熔-钎连接的大光斑激光-电弧复合热源焊接方法,用该焊接方法实现了5A02铝合金板与镀锌钢板的优质高效连接.试验结果分析表明,接头钢母材未发生熔化,焊缝与钢母材为钎焊连接,拉伸试样的破坏位置发生在接头铝母材热影响区,接头的抗拉强度与铝合金电弧熔化焊接头强度相当.     

Numerical and experimental investigation on friction stir lap welding of aluminium to steel

Use of multimaterial fabrication such as aluminium to steel to reduce overall vehicular body weight has gained significant attention in the automotive industries. Since fusion welding of aluminium to steel is difficult, friction stir welding of the same is considered as an effective recourse. Quantitative studies on friction stir welding of aluminium to steel are thus important but scarce in the literature. We present here a numerical and experimental study on friction stir lap welding of AA6061 to high strength interstitial free coated steel sheets under different combinations of tool rotational speed and welding speed. The computed values of thermal cycle, torque and traverse force are found to be in good agreement with the corresponding experimentally measured values. The computed thermal cycles along the AA6061 to steel interfaces are related qualitatively with the experimentally measured trend and distribution in Fe–Al intermetallics along the weld joint interface.     

Evaluation of dissimilar friction stir lap joints using digital X-ray radiography

A digital X-ray radiography methodology is proposed for quality assessment of aluminium–zinc coated steel dissimilar lap joints produced by a friction stir welding process. This methodology uses digital frame integration for acquisition of data to reduce the image noise followed by high pass filtering to sharpen the image by gradient operation and contrast adjustments to detect micro defects in FSW joints. The effect of welding parameters such as rotational and travel speed of weld tool and penetration depth on quality of the weld is studied. The new methodology has resulted in three-fold increase in signal-to-noise ratio (SNR) with improved defect detection sensitivity. The present study clearly shows that the weld tool rotational speed, travel speed and plunger depth have a decisive role on the quality of the weld obtained by the friction stir welding process.     

钢管内螺纹的检测方法及系统

内壁螺纹槽超深的热轧无缝钢管不符合相关质量标准。用漏磁高速检测技术结合计算机智能识别软件构成的内螺纹钢管高速检测方法和系统可准确探测和识别内螺纹，能标记超深螺纹位置和持续范围。此检测信息反馈到轧制工艺中，可明显提高合格钢管产量。系统检测速度20～60m／min；检出内螺纹槽深0．4～2mm。     

我国高速铁路客车轻量化车体最优结构研究

客车轻量化结构是我国铁路实现高速的关键技术之一。通过对国外铁路调整客车先进技术的分析，结合我国实际情况，提出我国目前现阶段高速铁路客车采用全铝合金车体结构或全不锈钢车体结构的时机尚不成熟；而铝合金－不锈钢混合车体结构是最佳选择。     

大吨位卧式双动正向钢挤压机设备及工艺优化

热挤压工艺是生产不锈钢、高温合金及其它高合金钢管材和异型材的重要方法.大吨位卧式双动正向钢挤压机是指带独立立式穿(扩)孔系统的卧式正挤压机,最大挤压力在40 MN以上,挤压速度较大,挤压品种主要为钢.本文介绍了大吨位卧式双动正向钢挤压机国内外应用现状,重点讨论了其设计及使用过程中普遍存在的问题,包括设备、工艺、工模具及润滑问题,并提出了优化措施.