深冷处理工艺对M2高速钢显微组织与性能的影响

对M2高速钢进行不同时间或循环三次的深冷处理，然后测量深冷处理前后试样的硬度、冲击韧性以及高温摩擦磨损性能，结合X射线物相分析、扫描和透射电子显微分析技术研究深冷处理工艺对M2高速钢硬度、红硬性、冲击韧性、高温耐磨性和组织的影响及机理。结果表明：深冷处理后，残余奥氏体含量降低，一次共晶碳化物分解，二次碳化物弥散析出，并且孪晶马氏体细化。因此，深冷处理后M2高速钢的室温硬度、红硬性、冲击韧性和高温耐磨性均得到提高。延长深冷时间和循环深冷处理均利于提升M2高速钢的性能。循环三次深冷后M2高速钢的显微组织的改善和性能的提升最明显。较未深冷试样，循环三次深冷后试样残余奥氏体含量降低50%,大尺寸一次碳化物数量减少75.2%,二次碳化物析出增加约296%,室温硬度提高2.27%,红硬性提高2.7%,冲击韧性提高15.6%,高温相对耐磨性提高140%。与一次长时间深冷相比，循环深冷处理在提升性能和降低成本方面更有优势。     

新型模具钢012Al在深冷处理过程中的组织转变

本文利用x-射线衍射分析及复型和薄膜透射技术研究了012Al钢经淬火后在深冷处理过程中的组织转变。结果表明,淬火后的残余奥氏体在深冷处理过程中部分转变成马氏体;深冷处理使马氏体发生分解,析出超细碳化物;同时伴有形变晶孪产生。     

激光表面重熔对高速钢显微组织的影响

采用CO_2连续波激光对W18Cr4V高速钢进行表面重熔处理。分析结果表明,经激光重熔后高速钢的显微组织明显细化,重熔层内的相构成为马氏体、奥氏体,过剩的δ铁素体和M_6C、M_(23)C_6型碳化物。枝晶内为孪晶马氏体和部分板条马氏体。枝晶间为富合金元素的奥氏体和M_6C碳化物,孪晶马氏体上沿孪晶面有M_(23)C_6碳化物共格析出。激光扫描速度增加、δ铁素体量增多,重熔层显微硬度下降。     

深冷处理工艺对W6Mo5Cr4V2钢力学性能和微观组织的影响

采用正交实验设计的方法对W6Mo5Cr4V2高速钢循环深冷处理工艺进行了实验研究,分析不同深冷工艺参数对宏观力学性能的影响,使用SEM和TEM观察循环深冷处理断口形貌和微观组织.结果表明,采用循环深冷处理工艺后,随着深冷次数的增加,力学性能明显提高,沿马氏体位错网析出大量超细弥散分布的碳化物数量增多,尺寸和间距减小,与一次长时间深冷处理相比,循环深冷处理效果更好.     

T12高碳钢深冷处理之组织结构研究

采用ＴＥＭ和ＸＲＤ研究了Ｔ１２高碳钢深冷处理过程中组织结构的变化。结果表明,残余奥氏体部分墨迹为马氏体,微细碳化物将在马氏体挛晶带及们错线处析出,碳化物类型为η－Ｆｅ２Ｃｏ延长深冷处理时间将有利于碳化物的析出。     

深冷处理对低碳高合金马氏体轴承钢力学性能及组织的影响

利用洛氏硬度计、X射线衍射仪、扫描电子显微镜及透射电子显微镜等研究了低碳高合金马氏体轴承钢深冷处理后的硬度变化及组织演化。结果表明:深冷处理促使部分残留奥氏体转变为马氏体,导致深冷处理后实验钢的硬度较淬火态硬度有所升高。经深冷处理后实验钢在0~100 h回火过程中的硬度均比未深冷处理实验钢的硬度高。深冷处理促使钢中碳原子偏聚并在回火过程中以碳化物的形式析出,与未经深冷处理的实验钢相比,经深冷处理的实验钢回火后马氏体基体中的含碳量更低,表明实验钢经深冷处理后在回火过程中析出更多的碳化物。透射电镜分析表明,实验钢在回火过程中析出的大量弥散分布的纳米级M2C和M6C型碳化物是实验钢长时间回火后保持高硬度的主要原因。     

热处理对激光选区熔化成型高速钢组织和力学性能的影响EI北大核心CSCD

基于激光选区熔化(selective laser melting,SLM)技术,采用加热打印基板和低功率慢扫描的打印策略,制备了近全致密、低缺陷的高速钢样品;对比分析了固溶淬火及1~4次高温回火等热处理工艺对高速钢显微组织及力学性能的影响。结果表明:SLM极高的熔融/冷却速率产生了细晶奥氏体组织,解决了高速钢中常见的粗大莱氏体组织和网状碳化物问题。固溶淬火处理后高速钢组织由马氏体和残余奥氏体组成。随后在数次高温回火过程中,高速钢逐渐向回火马氏体转变,并析出大量微米级和纳米级MC型碳化物。在马氏体相变强化和MC型碳化物沉淀强化作用下,固溶淬火+3次回火的Tempered-Ⅲ样品硬度60HRC,抗弯强度3621 MPa,弯曲断裂应变为10.1%,获得硬度、强度和韧性匹配较佳的综合性能。继续增加回火次数则导致部分碳化物长大,使得高速钢弯曲断裂应变有所降低。通过SLM技术结合固溶淬火+高温回火,能够充分发挥细晶强化、相变强化和沉淀强化效果,为高强高韧复杂形状高速钢零件的快速制备提供了新途径。     

深冷处理对W6Mo5Cr4V2钢强度和冲击磨损性能影响的研究

研究了深冷处理对W6Mo5Cr4V2钢的抗弯强度和冲击磨损性能的影响。研究结果表明明，随深冷时间的延长，晶体中空位密度有所增加。经透射电镜观察，深冷处理后在马氏体的孪晶带上弥散折出颗粒为3-6nm的碳化物。经深冷处理的W6Mo5Cr4V2钢其冲击磨损性能得到了提高。     

热处理对超高强度钢的精细结构和性能的影响

用透射电镜对钢的精细结构、碳化物的类型、形态、分布及残余奥氏体在基体中的分布进行了观察和鉴别。对钢的机械性能和马氏体亚结构间的关系也进行了研究。结果表明,板条马氏体内存在少量的微孪晶。碳化物往往沿此孪晶界优先析出,残余奥氏体在回火过程中的分解伴有碳原子的扩散。残余奥氏体分解产物之一是串状的渗碳体。板条间渗碳体和回火马氏体间的晶体学关系不符合关系。残余奥氏体的分解性质为上贝茵体反应。冲击韧性开始下降的温度和残余奥氏体开始分解的回火温度一致。残余奥氏体对裂纹扩展起延缓作用。     

一种自动控制的液压式低温改性处理机

低温 (深冷 )处理作为一门新的工艺技术对高速钢、工具钢、模具钢、高碳高合金钢和轴承钢等材料均能明显的改善其力学性能 ,提高耐磨性与延长其使用寿命。在原真空室型低温处理装置的基础上 ,开发成功了一种操作简单、使用方便及性能可靠的自动控制液压式低温改性处理机。实现了低温处理工艺的自动化 ,增加了处理工艺的准确性 ,提高了金属材料改性处理工件的效果     

Effect of cryogenic treatment on microstructure, mechanical and wear behaviors of AISI H13 hot work tool steel

This paper focuses on the effects of low temperature (subzero) treatments on microstructure and mechanical properties of H13 hot work tool steel. Cryogenic treatment at −72 °C and deep cryogenic treatment at −196 °C were applied and it was found that by applying the subzero treatments, the retained austenite was transformed to martensite. As the temperature was decreased more retained austenite was transformed to martensite and it also led to smaller and more uniform martensite laths distributed in the microstructure. The deep cryogenic treatment also resulted in precipitation of more uniform and very fine carbide particles. The microstructural modification resulted in a significant improvement on the mechanical properties of the H13 tool steel.     

深冷处理时间对M2高速钢红硬性的影响

使用洛氏硬度计、X射线衍射仪、扫描电子显微镜和透射电子显微镜等手段研究了深冷处理时间对M2高速钢的硬度和红硬性的影响及其机理.结果表明:深冷处理提高了M2钢的室温硬度和红硬性,深冷12h使650℃红硬性的改善最显著.随着深冷时间的延长残余奥氏体含量不断降低,其形貌由长条形块状转变为薄膜状分布在马氏体板条间;马氏体轴比和...     

GCr15钢深冷条件下的组织转变

以GCr15钢轴承套圈为对象,采用深冷处理的方法对淬火后的零件进行处理以减少零件中的残余奥氏体含量。通过X射线衍射法检测残余奥氏体含量和扫描电子显微镜(scanning elec-tron m icroscopy,SEM)观察深冷处理后的零件组织,研究了深冷处理温度和时间对GCr15钢淬火后的残余奥氏体转变的影响。结果表明,深冷处理可以大幅降低淬火GCr15钢零件中的残余奥氏体,最多可使零件中71.6%的残余奥氏体可以转变为马氏体。     

Effects of deep cryogenic treatment on property of 3Cr13Mo1V1.5 high chromium cast iron

Effects of deep cryogenic treatment on the microstructure, hardening behavior and abrasion resistance of 3Cr13Mo1V1.5 high chromium cast iron subjected to sub-critical treatment were investigated in this paper. The results show that deep cryogenic treatment after sub-critical treatment, the hardness and abrasion resistance of high chromium cast iron can be boosted obviously due to abundant retained austenite transforming into martensite and secondary carbides precipitation. In the course of sub-critical treatment with cryogenic treatment, the amount of precipitated secondary carbides was more than that in air cooling, and the secondary hardening peak advanced at a lower temperature. When abrasion resistance reach the maximal, there was about 20% retained austenite in microstructures. Cryogenic treatment can further reduce the austenite content but can not make retained austenite transform to martensite completely.     

航空齿轮钢16Cr3NiWMoVNbE的真空低压渗碳

对航空齿轮钢16Cr3NiWMoVNbE进行真空低压渗碳热处理,研究了真空渗碳、淬火、冰冷处理以及回火工艺对材料的组织和性能的影响。结果表明：实验钢经渗碳淬火处理后,从表面到心部的组织可分为碳化物区、碳化物与针状马氏体混合区、针状马氏体区和心部板条马氏体区。在碳化物区的晶界有大量的块状Cr碳化物析出,在析出位置Ni元素较少。在针状马氏体和板条马氏体基体中细小的析出物为Nb、V、Mo微合金元素的碳化物。从渗碳钢表面到心部,随着碳浓度的降低硬度曲线呈现先升高后降低的趋势,渗层深度为0.95 mm。冰冷处理使残余奥氏体进一步转化为马氏体,使实验钢的硬度大幅度提高。     

前驱体对含Cu低碳钢I&Q&P处理后组织性能的影响

采用IQP工艺和EPMA、SEM和XRD等手段,研究了3种前驱体对含Cu低碳钢残余奥氏体含量及力学性能的影响。结果表明,双相区保温初期试验钢奥氏体长大由C配分控制,后期由合金元素Mn、Cu配分控制;双相区保温奥氏体化后,双相区配分后形成弥散分布的局部高浓度Mn、Cu区域仍保留富集效果,在随后的淬火-碳配分阶段易于形成残余奥氏体。经IQP处理后,前驱体为P+F的钢室温组织中马氏体板条较粗,原始奥氏体晶界并不明显;前驱体为F+M钢得到的马氏体板条有序细密;前驱体为M的钢室温组织中马氏体板条更加细密。其中,前驱体组织为M的钢中残余奥氏体量最高,延伸率为24.1%,强塑积可达25 338 MPa·%,综合性能最好。     

Hardness and toughness investigations of deep cryogenic treated cold work die steel

In consideration of good results about the application of deep cryogenic treatment (DCT) on materials, the effect on the microstructure and properties (hardness, toughness and the content of retained austenite) of a new developed cold work die steel (Cr8Mo2SiV) was examined. The execution of the deep cryogenic treatment in different processes showed a varying effect on materials. It was shown that the hardness of the DCT specimens was higher (+0.5HRC to +2HRC) whereas the toughness was lower when compared with the conventionally treated specimens (quenching and tempering). Following the DCT process retained austenite transformed into martensite, however, not completely.     

Effect of deep cryogenic treatment on the microstructure and wear performance of Cr–Mn–Cu white cast iron grinding media

The phase transformation and grinding wear behavior of Cr–Mn–Cu white cast irons subjected to destabilization treatment followed by air cooling or deep cryogenic treatment were studied as a part of the development program of substitute alloys for existing costly wear resistant alloys. The microstructural evolution during heat treatment and the consequent improvement in grinding wear performance were evaluated with optical and scanning electron microscopy, X-ray diffraction analysis, bulk hardness, impact toughness and corrosion rate measurements, laboratory ball mill grinding wear test etc. The deep cryogenic treatment has a significant effect in minimizing the retained austenite content and converts it to martensite embedded with fine M₇C₃ alloy carbides. The cumulative wear losses in cryotreated alloys are lesser than those with conventionally destabilized alloys followed by air cooling both in wet and dry grinding conditions. The cryotreated Cr–Mn–Cu irons exhibit comparable wear performance to high chromium irons.     

Effect of cryogenic treatment on tensile behavior of case carburized steel-815M17

The crown wheel and pinion represent the most highly stressed parts of a heavy vehicle; these are typically made of 815M17 steel. The reasons for the frequent failure of these components are due to tooth bending impact, wear and fatigue. The modern processes employed to produce these as high, durable components include cryogenic treatment as well as conventional heat treatment. It helps to convert retained austenite into martensite as well as promote carbide precipitation. This paper deals with the influence of cryogenic treatment on the tensile behavior of case carburized steel 815M17. The impetus for studying the tensile properties of gear steels is to ensure that steels used in gears have sufficient tensile strength to prevent failure when gears are subjected to tensile or fatigue loads, and to provide basic design information on the strength of 815M17 steel. A comparative study on the effects of deep cryogenic treatment (DCT), shallow cryogenic treatment (SCT) and conventional heat treatment (CHT) was made by means of tension testing. This test was conducted as per ASTM standard designation E 8M. The present results confirm that the tensile behavior is marginally reduced after cryogenic treatment (i.e. both shallow and deep cryogenic treatment) for 815M17 when compared with conventional heat treatment. Scanning electron microscopic (SEM) analysis of the fracture surface indicates the presence of dimples and flat fracture regions are more common in SCT specimens than for CHT and DCT-processed material.