Si含量对冷作模具钢Cr8Mo2SiV组织和性能的影响

研究了Si含量对25 kg真空感应炉冶炼的Cr8Mo2SiV钢(%:0.96～0.97C、0.31～0.36Mn、7.98～8.04Cr、2.01～2.08Mo、0.31～1.52Si、0.20V)组织和力学性能的影响。结果表明,随着Si含量的增加,共晶碳化物尺寸变大,数量增多,淬火峰值硬度向高温区移动;经1 030℃淬火,550℃回火后,随着Si含量的提高,Cr8Mo2SiV钢的二次硬化能力和冲击韧性明显提高。Cr8Mo2SiV钢最佳的Si含量为1.5%。     

微量镁改善H13钢中碳化物的机理研究

H13热作模具钢属于中碳钢,钢中的Cr、Mo、V含量较高,因此钢在凝固过程中这些碳化物形成元素会偏聚析出大量的网状碳化物,经过热处理也很难完全消除,从而降低了钢的性能。实验室条件下研究了向H13钢中加入不同含量的镁对钢中碳化物的影响。结果表明:微量的镁能够改善H13钢中碳化物的形状和分布,使碳化物由粗大的网状转变成细小的短条状,经过镁处理后,碳化物呈细小均匀地分布在钢中。当加入0.004%的镁时,对碳化物的改质效果最好。镁在晶界处的偏聚是改善碳化物分布的主要原因,通过理论分析发现,在钢凝固冷却的过程中镁元素在晶界处的偏聚程度较高,从而阻碍了碳化物的生长,达到细化碳化物的目的。     

RE-Mg-Ti变质对铸造高速钢组织和性能的影响

用RE－Mg-Ti对低碳铸造高速钢（6W6Mo5Cr4V)模具进行变质处理，消除了钢中网状共晶碳化物，并细化了基体组织，还可减轻W、Mo元素偏析，变质处理后，高速钢硬度、红硬性和强度变化不大，断裂韧性（K1c）和疲劳裂纹扩展门槛值（△Kth）有所提高，冲击韧性（αk）提高1倍以上，耐磨性也明显提高，各项性能指标达到了锻造高速钢水平，RE－Mg-Ti变质低碳铸造高速钢，有望实现“以铸代锻”。     

铸态 00Cr22Ni5Mo3N 的热塑性

采用Gleeble1500对00Cr22Ni5Mo3N铸态试样进行了热拉伸和热压缩试验,找出了铸态00Cr22Ni5Mo3N的最佳热塑性温度区间为1 150～1 250 ℃,并且分析了该钢的热塑性与其组织、性能的关系.     

Ce-Mg合金加入对GCr15轴承钢夹杂物和凝固组织的影响

研究了加Ce(0～0.32%)-Mg(0～0.04%)合金对GCr15轴承钢的铸态夹杂物和凝固组织的影响。结果表明：添加Ce-Mg合金，能够促使夹杂物改性，生成大量的形状较规则，尺寸细小，分布弥散的Ce、Mg夹杂物；并且当0.016%[Ce]、0.002%[Mg]时，夹杂物更为细小弥散。在凝固组织方面，随着Ce-Mg合金的增加，钢的铸态组织碳化物分布更为均匀，网状碳化物的网状结构变得更加纤薄，当0.016%[Ce]、0.002%[Mg]时，珠光体片层更为纤薄，片层间距更小。Ce-Mg合金的添加能够显著减弱钢中C和Cr在枝晶间与枝晶干的合金元素偏析，减少枝晶间距，阻碍枝晶的粗化。     

高 速 钢 中 的 碳 化 物 缺 陷

 大量碳化物的存在是高速钢组织的重要特征,也是影响高速钢质量和性能的关键因素。碳化物颗粒细小、形状规则和分布均匀的钢其质量和性能都好。但是,钢中的碳化物并不都这样理想,往往存在缺陷。根据对W18Cr4V、W6Mo5Cr4V2、W9Mo3Cr4V和W2Mo9Cr4VCo8等钢中碳化物的研究结果,分析了高速钢中常见的几种缺陷：①碳化物分布不均匀;②颗粒尺寸粗大,形状不规则,多为角状等;③碳化物微裂纹;④碳化物粘连等;⑤二次碳化物稀少。另外,还分析了以上碳化物缺陷产生的原因和危害性,并指出了减少缺陷应采取的措施。     

气体雾化快凝W9高速钢粉末的组织特征

研究了颗粒粒度不同的气体雾化W9Mo3Cr4V高速钢粉末的组织、形貌及结构.结果表明:粉末由铁素体和奥氏体基体和分布在周围的MC及M2C型碳化物组成,基体组织为等轴晶及树枝晶,碳化物在空间上呈连续网状或树枝状分布;粉末中相的含量与粉末粒度相关,随高速钢粉末粒度减小,组织中的铁素体和MC型碳化物含量增加,奥氏体和M2C型碳化物含量减少.     

(30~90)mm×(400~605)mm Cr12Mo1V1(D2)冷作模具扁钢的组织和性能

试验用Crl2MolV1(D2)冷作模具扁钢(/%:1.50C,0.35Si,0.40Mn,12.00Cr,0.95Mo,0.80V)的生产流程为30 t EAF-LF-VD-3 t铸锭轧制-890℃退火工艺。研究了D2冷作模具钢的断面尺寸(/mm:30×400,70×360,90×605)对该钢组织、共晶碳化物的尺寸、分布以及不均匀度、冲击韧性的影响。结果表明,随着扁钢截面尺寸的减小,共晶碳化物的颗粒尺寸、形态以及分布均匀性得到改善,扁钢的碳化物级别由90 mm×605 mm扁钢的4~6级降至30 mm×400 mm扁钢的1~4级,冲击韧性提高;钢的心部共晶碳化物分布最差(4~6级),边部最好(1~4级),心部的冲击韧性明显低于边部。     

102Cr17Mo轴承钢铸坯夹杂物及碳化物解析

102Cr17Mo钢属于高碳高铬马氏体不锈钢,钢中夹杂物及碳化物的形貌及分布对其性能有重要影响。依托于某厂La-Ce复合稀土改质的102Cr17Mo模铸坯,用光学显微镜、扫描电镜、夹杂物三维腐刻、Thermo-calc软件对其进行解析。结果表明,在102Cr17Mo铸坯中,夹杂物的等效直径集中分布在1～3μm,夹杂物数量密度集中分布在47～54个/mm²,夹杂物面积占比分布在0.025 3%～0.028 4%;夹杂物的整体尺寸较小,分布弥散化,不同部位的夹杂物数量密度、面积比例差距较小;夹杂物主要成分为氧、铝、铈、镧和其他等少量元素,夹杂物类型包括稀土氧化物Ce-La-Al-O、稀土氧硫化物Ce-La-Al-O-S,未发现单独存在的Al₂O₃夹杂和MnS夹杂。铸坯中碳化物形貌主要分为3类,即大颗粒状碳化物、聚集状碳化物、网状碳化物。大颗粒状碳化物尺寸约为20μm,所含主要元素为铁、铬、碳和钼,聚集状碳化物尺寸约达100μm,所含主要元素为铁、铬、钼和碳,网状碳化物尺寸约为80μm,所含主要元素为铁、铬、钼和碳。从边部到心...     

铌含量对Cr8WMo2V2SiNb钢组织和性能的影响

研究了0～0.89%Nb含量对淬火(1 000～1 200℃)-回火(200～650℃)CrSWMo2V2SiNb钢组织和力学性能的影响。结果表明,随着Nb含量提高,钢的铸态组织和共晶碳化物形态得以改善,难熔铌的碳化物增多,明显抑制了淬火奥氏体晶粒长大;加铌可相应提高淬火温度,增加钢的二次硬化能力和耐磨性,使钢具有较高综合机械性能。     

As-cast carbides in high-speed steels

The spatial distribution and structure of as-cast carbides and the effects of W, Mo, and V content on the morphology and amount of as-cast carbides in high-speed steels were studied systematically. It was shown that increasing the Mo and decreasing the W content led to a decrease in the amount of total eutectic carbide and an increase in the MC and M₂C carbides. The eutectic morphology changed from skeletal to platelike when the content of Mo increased. The presence of V favored not only the formation of MC carbide but also the formation of M₂C carbide and reduced the formation of M₂C carbide. Increasing V led to an increase in the size of the eutectic carbides.     

Carbides in high-speed steels containing silicon

The effects of silicon additions up to 3.5 wt pct on the as-cast carbides, as-quenched carbides, and as-tempered carbides of high-speed steels W3Mo2Cr4V, W6Mo5Cr4V2, and W9Mo3Cr4V were investigated. In order to further understand these effects, a Fe-16Mo-0.9C alloy was also studied. The results show that a critical content of silicon exists for the effects of silicon on the types and amount of eutectic carbides in the high-speed steels, which is about 3, 2, and 1 wt pct for W3Mo2Cr4V, W6Mo5Cr4V2, and W9Mo3Cr4V, respectively. When the silicon content exceeds the critical value, the M₂C eutectic carbide almost disappears in the tested high-speed steels. Silicon additions were found to raise the precipitate temperature of primary MC carbide in the melt of high-speed steels that contained d-ferrite, and hence increased the size of primary MC carbide. The precipitate temperature of primary MC carbide in the high-speed steels without d-ferrite, however, was almost not affected by the addition of silicon. It is found that silicon additions increase the amount of undis-solved M₆C carbide very obviously. The higher the tungsten content in the high-speed steels, the more apparent is the effect of silicon additions on the undissolved M₆C carbides. The amount of MC and M₂C temper precipitates is decreased in the W6Mo5Cr4V and W9Mo3Cr4V steels by the addition of silicon, but in the W3Mo2Cr4V steel, it rises to about 2.3 wt pct.     

3Cr2W8V大截面锻材热处理工艺探讨

经酸浸低倍和金相组织检验及超声波探伤，证明大锭型存在链状亚稳定共晶碳化物组织。这种组织是构成钢材内裂的裂纹源。大截面锻材还存在“白点”问题。通过适当加钛和稀土合金，保证锻造前加热透烧，加大横向锻比等，可改善碳化物分布。通过锻后回炉再烧 出炉后在Ar1附近温度快冷 扩氢处理。可熔断链状碳化物，防止二次网状碳化物析出，可消除“白点”缺陷，钢材缺陷呈点状分布，缺陷当量满足技术要求。     

Mg对热作模具钢H13组织和力学性能的影响

试验钢的生产流程为2 t中频感应炉-200 kg电渣重熔(Φ180 mm)-退火-镦粗至Φ325 mm-球化退火-1050℃淬火-590℃回火,炉冷。试验研究了0~0.0010%Mg对热作模具钢H13(/%:0.40~0.41C、0.98~1.01Si、0.29Mn、4.95~5.08Cr、1.21~1.22Mo、0.91-0.93V、0.023~0.027P、0.006~0.007S)组织和力学性能的影响。结果表明,随钢中Mg含量由0提高至0.0010%时,试验模具钢H13的平均抗拉强度和HRC硬度值分别从1 617.6 MPa和45.7提高至1 702.9 MPa和47.8;Mg可以增加钢中回火马氏体的稳定性,高温回火后含Mg模具钢H13的组织中出现大量回火屈氏体,而且部分碳化物在Mg-Al夹杂物周围析出,成球形,尺寸小于10μm,有利于改善钢的性能。     

Al对M2高速钢铸态组织的影响

试验M2高速钢(%:0.85C、5.92W、4.74Mo、3.86Cr、1.81V)由25 kg真空感应炉熔炼,并用砂型铸造成锭。研究了0～1.3%Al对钢铸态组织的影响。结果表明,加入0.6%Al,可细化共晶莱氏体网,改善碳化物分布;加入过量Al(1.3%),初生晶粒内部出现大量由δ铁素体通过共析转变产生的针状碳化物。Al促进M₂C共晶碳化物形态由弯曲棒状变为平直片层状,并提高其合金元素含量。与片层状M₂C相比,棒状M₂C在高温易分解成短棒状或球状碳化物,有利改善碳化物形态。     

M42高速钢电渣重熔及锻造退火后碳化物的析出

 通过X射线衍射分析、光学显微镜和透射式电子显微镜观察以及相关热力学计算,对比研究了M42高速钢电渣锭及锻后退火两种状态所析出碳化物的类型、尺寸、分布及析出条件。得出M42高速钢电渣锭中的碳化物主要为Mo2C亚稳态碳化物和少量Cr7C3碳化物,Mo2C碳化物尺寸较大,主要呈层片状、纤维状和棒状沿晶界析出。锻造退火后的M42高速钢中碳化物类型主要为Cr7C3,VC和Fe2Mo4C,平均尺寸小于10 μm且分布均匀,形态以方形、不规则球形和小颗粒为主。M42高速钢电渣锭中的Mo2C在锻造过程中可以分解为Fe2Mo4C和VC。根据冶金热力学计算得出,Mo2C和VC在固液两相区析出,析出温度分别为1 229 和1 222 ℃;Cr7C3在固相中析出,析出温度为842 ℃。     

Effects of mischmetal addition on phase transformation and as-cast microstructure characteristics of M2 high-speed steel

The influence of mischmetal (Ce-La) addition on phase transformation and as-cast microstructure characteristics of M2 high-speed steel (HSS) was investigated using Thermo-Calc software, differential scanning calorimetry, X-ray diffractometry and scanning electron microscopy with energy dispersive spectrometry. The results showed that the measured phase transition points of M2 HSS were broadly consistent with the theoretical results. After mischmetal addition, the liquidus peak temperature, the peak temperature of the eutectic precipitation of M₆C and MC were all increased, especially for the M₆C which was affected significantly and increased about 31 °C. The contents of Mo and V in the eutectic carbide decreased and that of Fe increased, while in the matrix, the Mo, V and Cr contents all increased slightly. Furthermore, the microstructure of as-cast dendrite and ledeburite were refined, the total eutectic carbide content decreased and distributed into a discontinuous network, the lamellar spacing of M₂C was reduced and the lamellae became thinner.     

Optimizing structure,toughness and wear performance of 15 % Cr cold work cast tool steel

A series of six Cr-, Cr + Mo-, Cr + Mo + V cold work cast tool steels were produced and investigated for microstructure, impact toughness and both experimental and industrial abrasive wear. Grain refinement of the steel matrix even in as-cast condition was obtained on using 2.3 % Mo + 0.9 % V and that ensured increasing impact toughness and abrasion resistance. An optimum impact toughness of about 85 J-cm^?2 was obtained in air quenched (970°C) and tempered (450°C) Mo + V containing steels in which area fraction of carbides reached 38 %. The abrasion resistance improved in case of steels tempered at 250°C and had fine grain structure.     

钒含量对Cr8Mo2SiV冷作模具钢组织与性能的影响

研究了钒含量(0.28%和0.50%,质量分数,下同)的变化对Cr8Mo2SiV钢组织和性能的影响。结果表明,随着钒含量的增加,一次碳化物尺寸增大,淬火峰值硬度向高温区移动,钒含量0.5%的Cr8Mo2SiV钢的淬火晶粒尺寸明显小于钒含量0.28%的Cr8Mo2SiV钢。经1 040℃淬火、180~520℃回火后,随着钒含量的升高,Cr8Mo2SiV钢的二次硬化峰值硬度以及二次硬化峰之前的回火硬度均明显提高。钒对提高Cr8Mo2SiV钢的淬火温度和二次硬化效应有利。     

钼含量对铁基激光熔覆层组织和性能的影响

采用激光熔覆在45#钢基体上制备了不同Mo含量的FeCrNi熔覆层,探讨Mo元素含量对熔覆层组织和性能的影响。试验结果表明,五种熔覆层均主要由马氏体和M_7C_3碳化物组成,当Mo添加量大于等于1wt.%时,熔覆层中出现了少量Mo_2C和Laves相。Mo元素能够改善熔覆层中的碳化物分布和形态,使鱼骨状共晶碳化物增多,提高熔覆层的硬度和耐磨性,但Mo加入过多时,碳化物聚集长大成粗网状,使熔覆层耐磨性降低。