产品与市场

由大连铁道学院研制开发的无莱氏体高速钢不同于低碳莱氏体高速钢和国内外曾研制的渗碳高速钢。新型无莱氏体高速钢的锻、轧、冷拔性能优于普通高速钢,经专门为其研制的三低一高工艺处理后所得组织及性能与粉末高速钢相当,其特色在于不存在碳化物偏析及粗大碳化物,而且碳饱和度可     

产品与市场

高硬高韧高速合金钢麻花钻 由大连铁道学院研制开发的无莱氏体高速钢不同于低碳莱氏体高速钢和国内外曾研制的渗碳高速钢。新型无莱氏体高速钢的锻、轧、冷拔性能优于普通高速钢,经专门为其研制的三低一高工艺处理后所得组织及性能与粉末高速钢相当,其特色在于不存在碳化物偏析及粗大碳化物以及碳饱和度可允许大于1,从根本上克服了普通高速钢的缺点,故淬回火后的硬度高于67HRC而进入超硬范围。新型     

粉末高速钢S690与M35、M42钢组织性能对比

<正>1引言M35、M42钢是国内常用的高性能高速钢牌号,其合金含量较高,同时含有Co元素,因此其红硬性较高。传统的冶炼方法是采用铸锭—锻轧工艺。由于钢的合金量高,化学成分复杂,铸锭尺寸大,冷却速度缓慢,在其凝固时不可避免地会产生粗大莱氏体碳化物偏析组织。偏析的存在不仅给钢的锻、轧等热加工造成困难,而且还损害了钢的各种性能。本文主要对比了粉末高速钢S690与锻轧高性能高速钢M35、M42的组织和性能,从而掌握S690     

对高速钢加热时间定义的探讨

在高速钢热处理工艺中,高温加热时间是非常重要的,它直接影响产品质量和企业的经济效益。 高速钢属高合金钢,在最终热处理前,通常处于退火状态,其显微组织为索氏体 合金碳化物。这种碳化物类型较多,结构复杂,淬火加热时为使其充分溶解,则需要一定的时间。若加热时间太短,则碳化物溶解不良,将不能发挥高速钢应有的性能;若加热时间过长,则会造成晶粒粗大、过热、过烧、脱碳等缺陷,且浪费能源。可见,恰如其分地规定加热时间至关重要。     

变质处理铸造高速钢研究的进展

高速钢作为一种重要的高速切削用刀具材料,自从20世纪初问世以来,一直得到广泛的应用。近年来高速钢轧辊应用于轧钢生产中也获得了较好的效果。在高速钢凝固过程中,由于C及碳化物形成元素W、Mo、Cr、V等的偏析,在高速钢晶界上形成大量粗大的连续网状共晶碳化物。网状共晶碳化物既严重割裂基体,又可作为高速钢断裂时的裂纹源和裂纹扩展的途径,使得高速钢晶界脆化     

ASP2030粉末高速钢拉刀热处理工艺试验及研究

对进口的ASP2030粉末高速钢进行了各种检测及热处理工艺试验,分析了热处理后该材料的淬火晶粒度、淬回火组织、碳化物分布形态及过热程度等,最终确定了可行的热处理工艺。     

铸造高速钢刀具的生产工艺及组织、性能的改善

概述了铸造高速钢的生产工艺、发展过程以及铸造刀具的性能和应用情况。铸造高速钢存在的主要问题是组织中粗大的晶界网状并晶碳化物使铸造高速钢晶界脆化严重，韧性降低；改善的途径有孕育处理、变质及合金化、共晶碳化物的高温顶球化及电渣重熔等。     

超硬粉末高速钢的研制

近代材料和机械工业的发展,对高速钢切削刀具提出了高硬度、强韧性、耐磨、易磨削及高红硬性等要求,但由于熔铸本身造成的碳化物粗大偏析难以克服,因而没有充分发挥合金成份的应有作用和显示材料的应有性能。于是,六十年代末产生了粉末冶金法生产无偏析高速钢的新工艺,七十年代初瑞典的ASEA-STORA和美国的CRUCIBLE公司用热等静压法正式生产粉末高速钢,年产量分别为3000吨和1200吨。在制造工艺上又陆续出现了热挤压、粉末锻造和直接烧结致密法等。据初步估计,目前国外研究和生产粉末高速钢的单位不少于14个国家74个公司。我国七十年代初也开始研究粉末高速钢,但基点是建立在高速钢切屑的利用上。哈一工、哈二工及上工厂均有少量生产,但质量仅能与铸锻钢相比。北京钢铁研究总院用氮气雾化制粉和热挤压成材研制了含钴的T15超高速钢取得一定成绩。我们于1978年开展了水雾化粉末制取无偏析高速钢的研究。继W18Cr4V1粉末高速钢(以下简称PT_1)之后又开展了新型刀具材料的研究,吸收了北京钢铁学院无钴高速钢研究经验,研制成功了W12Mo3Cr4V3N0.4超硬高速钢(以下简称PVN),分别用粉末锻造与直接烧结致密法制成切削刀具,性能优良,使用寿命为铸锻W18Cr4V1钢的2～4倍,优于含铝的5F6超硬高速钢。并有可磨削性好、成本较低的优点。     

丝锥用HOP2030粉末高速钢的淬火温度研究

本文对丝锥用粉末高速钢HOP2030的淬火温度进行了试验研究。试验表明,HOP2030钢丝锥的淬火温度通常为1140℃-1180℃,淬火晶粒均匀、细小是粉末高速钢的显著特点之一,HOP2030钢丝锥淬火晶粒度应小于10.5号,碳化物粘连和拖尾长度是评定粉末高速钢过热程度的主要标识。     

大颗粒碳化物对W4Mo3Cr4VSi钻头性能的影响

生产中发现部分W4Mo3Cr4VSi高速钢钻头出现大颗粒碳化物,导致产品的淬火温度大幅度下降。大颗粒碳化物导致材料中碳化物的弥散度和溶解活性大幅度降低。高速钢的耐火程度亦强烈下降,比正常碳化物材料的耐火温度降低20℃以上。耐火温度的剧烈下降导致钻头的硬度和红硬性的明显降低。大颗粒碳化物以及因其造成的晶粒粗大对钻头的韧性构成危害,是导致钻头断裂和掉块的重要原因。     

Abrasive wear resistance of starch consolidated and sintered high speed steel

The abrasive wear resistance of starch consolidated (SC) and super solidus liquid phase sintered (SLPS) M3/2 high speed steel (HSS) samples have been evaluated by a two-body micro-abrasion test (low stress abrasion), using 6 μm diamond abrasive particles, and a three-body abrasion test (high stress abrasion), using significantly larger abrasive particles of blast furnace slag (600 HV) and silicon carbide (2400 HV), respectively. In the tests a commercial powder metallurgical (PM) HSS was used as a reference material.The results show that the microstructure of the SC and SLPS HSS samples is strongly dependent on the sintering temperature used. With increasing temperature the microstructure ranges from a porous (5% porosity) relatively fine grained low temperature sintered microstructure to a fully dense relatively coarse grained high temperature sintered microstructure with eutectic carbides/carbide networks. However, despite the pronounced microstructural differences displayed by the as-sintered HSS microstructures these show a relatively high abrasive wear resistance, comparable with that of a HIPed HSS reference, both under low and high stress abrasion contact conditions. The characteristic features of the low and high temperature sintered microstructures, i.e. the pores and coarse eutectic carbides/carbide networks, only show a limited impact on the wear rate and the wear mode (dominant wear mechanism). The results obtained imply that near net shaped components manufactured by starch consolidation and super solidus liquid phase sintering might be of interest in tribological applications.     

镍基粉末冶金零件的切削试验研究

对陶瓷刀具和硬质合金刀具进行了镍基粉末冶金零件的干切削对比试验,测量了切削力和加工表面粗糙度,分析了刀具的磨损机理。试验结果表明:陶瓷刀具的切削性能明显优于硬质合金,适合于粉末冶金零件的切削加工。     

北京市大气颗粒物分级样品的铅同位素丰度比测量与来源研究

报道了北京市2004年夏、冬季分级采样样品的化学组成和铅同位素丰度比数据,并对铅来源进行了分析。采用电感耦合等离子体原子发射光谱（ICP-AES）和电感耦合等离子体质谱（ICP-MS）技术分析了24个无机元素浓度,同时用多接收器电感耦合等离子体质谱（MC-ICP MS）技术测定铅同位素丰度比。结果表明：细颗粒（PM2.5）中的铅含量明显高于粗颗粒（PM10~2.5）,可吸入颗粒物（PM10）中80%以上的铅存在细颗粒。细颗粒的206Pb/207Pb比值处于1.140~1.156的范围;粗颗粒的206Pb/207Pb比值处于1.127~1.148的范围,总体上低于细颗粒。北京市大气铅来源复杂、多样,有2个或3个以上,主要来源除了燃煤排放还有涉铅有色冶金排放。基于前期工作积累的较多样品测量数据,燃煤排放的206Pb/207Pb代表性比值为1.163 3;涉铅有色冶金排放源的数据较少,初步判断处于1.11~1.15之间,中值为1.13。夏季、冬季细颗粒中燃煤源贡献率分别为0.51和0.59;涉铅有色冶金源的贡献率分别为0.49和0.41。北京市大气铅污染同时具有当地排放和区域性排放的贡献和特征。     

采用GPS+HIP生产工艺制造Al2O3基陶瓷刀片

介绍了采用GPS +HIP生产工艺制造Al2 O3 基陶瓷刀片所涉及的混料、压制、排胶、气氛保护烧结(GPS)、热等静压 (HIP)处理、刀片刃磨等主要生产工序     

提高我国高压超高压液压件铸件质量的必备设备(HIP)热等静压机

该文对工程机械的变量柱塞泵、整体式多路阀的零件特别是较复杂的铸件进行了研究,对解决铸件微小气孔的(HIP)热等静压机进行了研究。通过国际、国内对航空航天、军工用的高压、超高压液压件铸件普遍采用HIP技术处理的情况得出结论:我国对液压件铸件进行攻关时,仅偏重材料的化学成分是不够的,应把铸件处理设备和HIP设备作为必备设备,则高压、超高压液压件铸件才能真正过关。     

铁基粉末冶金材料的高速干切削试验研究

用陶瓷刀具、涂层刀具和硬质合金刀具进行了铁基粉末冶金零件的干切削对比试验,研究了切削速度、切削深度以及进给速度与刀具耐用度和加工表面粗糙度的关系,分析了陶瓷刀具的磨损机理。结果表明所选用陶瓷刀具的切削性能明显优于涂层刀具和硬质合金刀具;陶瓷刀具前刀面主要磨损形式为月牙洼磨损与剥落,后刀面的主要磨损原因为磨粒磨损;认为陶瓷刀具更适合用于粉末冶金零件的切削加工。     

粉末冶金零件的车削加工

分析了粉末冶金零件的机械性能和加工难点，从机械加工的角度探讨了有利于提高粉末冶金加工性能的刀具材料和切削参数，并推荐使用整体PCBN刀具，同时也介绍了金属陶瓷和硬质合金刀具的应用场合。     

Machinability of Elongated Coarse Grain Fe-Based Superalloys

□ In conventional metal cutting process, materials are assumed to be homogeneous and isotropic structure. However, some materials with a single crystal or coarse elongated polycrystalline demonstrate strong anisotropic behavior in physical and mechanical properties in machining of some superalloy materials. The anisotropic structure always leads to variation at machinability properties of the material. In this study, machinability properties of ferritic superalloy PM2000, which had elongated a few coarse grains, were investigated. These properties were determined by investigation of chip formation, cutting forces and surface roughness. Machinability was assessed by single-point turning on a CNC lathe and turning forces were measured by using a Kistler Lathe Dynamometer. The chip formation mechanisms in machining of PM2000 at various cutting speeds were determined by using a quick-stop device (QSD). Chip roots and machined surfaces were analyzed by means of scanning electron microscopy (SEM). The results indicated that the machinability properties of the PM2000 were changed by orientated coarse grain structure. Three types chip formation mechanism were determined at the same cutting conditions. Also, surface roughness on the machined each grain changed with changing the grain to be cut. Surface roughness and force fluctuations decreased with increasing the cutting speed; however, tool wearing increased.     

A study of abrasive wear mechanisms using diamond and alumina scratch tests

Scratch tests using alumina (Al₂O₃) abrasive particles and Vickers diamond pyramids were employed to study material removal mechanisms in the abrasion of cobalt-base powder metallurgy alloys 6 and 19. The alloys were specially prepared to produce either fine or coarse carbides in order to study the effects of carbide size. Scanning electron microscopy was used to analyze the scratch grooves, the scratch tools and the wear debris particles.

Comparison of scratch tests with Al₂O₃ and diamond pyramids shows that many features produced by the extremely hard regularly shaped diamond tools are different from those produced by irregular Al₂O₃ particles. Except for differences produced by tool wear, multiple-pass Al₂O₃ scratch tests provide excellent reproduction of the material removal processes which occur in low stress Al₂O₃ abrasion. Al₂O₃ scratches produced both chip-like and fine irregular debris particles similar to those extracted from spent abrasive used in wear testing.

Material removal in the fine carbide alloys is facilitated by the direct removal of entire carbides within the volume of micromachining chips removed from the scratch groove. In coarse carbide alloys, machining chips from large carbides are observed, but the depth of cut in the carbide phase is less than that in the f.c.c. matrix and this leads to a decrease in the volume of material removed. Direct comparison of chips removed from fine and coarse carbide alloys by the same Al₂O₃ particle shows larger chips from the fine carbide material.

The effects of subsurface deformation and surface irregularities on material removal were studied by carrying out scratch tests on specimens subjected to prior abrasion and by investigating multiple-pass scratches in the same scratch groove.