Apparent Morphologies and Nature of Packet Martensite in High Carbon Steels

The apparent morphologies of packet martensite in eight high carbon steels were researched by using optical microscope, scanning electron microscope, and transmission electron microscope. It was found that the apparent morphologies, substructures, and habit plane of packet martensite in high carbon steels are entirely different from that in low carbon steels; the substructures of packet martensite in high carbon steels possess fully twinned structure, while the substructures of individual coarse martensite plates in these steels bear both fully and partially twinned structures. The formation reason for apparent morphologies, substructures and two habit planes （i. e, { 111 }, and { 225}r） of high carbon martensite were discussed in detail.     

关于低碳马氏体钢强化及其应用的探讨

采用低碳钢强烈淬火工艺代替中碳钢及中碳合金钢的调质处理引起了热处理界的高度重视，这面工艺越来越广泛地应用到生产实际中。实详细地介绍了低碳钢和低碳合金钢强化热处理的特点及有关工艺参数。     

马氏体时效网的时效析出产物

本文采用场离子显微镜原子探针实验技术，对一种马氏体时效钢（Ｆｅ－１８．２％Ｎｉ－８．８％Ｃｏ－２．９％Ｍｏ－０．７％Ｔｉ－０．２％Ｓｉ）的时效析出产物进行了研究。实验研究了该合金在５１０℃时效４ｈ所产生析出物的形貌与成分，发现有两种金属间化合物相（Ｎｉ３Ｔｉ与Ｆｅ７Ｍｏ６型）产生时效强化，在时效组织中还存在有少量回复奥氏体。     

Effect of Heat Treatment on Microstructure and Property of Cr13 Super Martensitic Stainless Steel

 The microstructures and mechanical properties of Cr13 super martensitic stainless steel after different heat treatments were studied. The results show that the structures of the steel after quenching are of lath martensite mixed with a small amount of retained austenite. With the raising quenching temperature, the original austenite grain size increases and the lath martensite gradually becomes thicker. The structures of the tempered steel are mixtures of tempered martensite and reversed austenite dispersed in the martensite matrix. The amount of reversed austenite is from 754% to 2249%. After different heat treatments, the tensile strength, the elongation and the HRC hardness of the steel are in the range of 813-1070 MPa, 101%-212% and 2133-3237, respectively. The steel displays the best comprehensive mechanical properties after the sample is quenched at 1050 ℃ followed by tempering at 650 ℃.     

New Space Morphology and Habit Plane of Low Carbon Martensite

GKraussetal[1]haveobservedthespacemor phologyofmartensiteinas quenchedlowcarbon steelsat750timesmagnificationunderopticalmi croscopeusingserial sectioningexperiment.Speci menswith11μmand18μminthicknesswerere movedbyelectro polishing.Itwasfoundthatth…     

S／SJ2马氏体不锈钢工艺探讨

本文通过双联工艺探讨了S/SJ_2马氏体不锈钢的工艺。找出冷轧薄板热处理制度:淬火1050±10℃×3min,空冷 回火650±5℃×40min空冷。能得到强度与塑性的最佳配合。     

淬火介质对Cu—Al—Ni—Mn—Ti形状记忆合金γ1‘,β1’两马氏体…

对Ｃｕ－１３Ａｌ－５Ｎｉ－１Ｍｎ－１Ｔｉ形状记忆合金样品进行六种不同介质的淬火处理，然后用透射电镜对这些样品进行观察，结果表明：淬火介质对合金中γ１＇、β１＇马氏体的形成量、两马氏体的混合程度以及γ１＇马氏体界面的完整度有明显影响。另一方面，对以上淬火样品采自自制扭转仪进行了记忆性（ＳＭＥ）和伪弹性（ＰＥ）测量，以揭示γ１＇、β１＇马氏体结构与合金宏观性能之间的内在联系。测量和分析表明合金中γ１＇     

低,中碳合金钢中的马氏体与贝氏体形态

低，中碳合金钢中的马氏体除局部区域因成分偏析呈孪晶亚结构外，主要是位错亚结构外，主要是位错亚结构的板条马氏体。低碳合金钢的中温转变组织主要有三类，即粒状组织，上贝氏体和下贝低体。其中上贝氏体又分为粒状贝氏体，准上贝氏体和曲型上贝氏体；下贝氏又有准下贝氏，变态下贝氏体和典型下贝氏体。中碳合金钢的中温转变组织只有上，下贝氏体。其中上贝氏体又分为准上贝氏体和典型上贝氏体，而下贝氏体则包括准下贝氏体，...     

Microstructure Evolution in 9Cr Martensitic Steel During Long-Term Creep at 650℃

 Standardarized creep and rupture strength tests were conducted for commercial T91 martensitic heat-resistant steel at 650 ℃ and corresponding microstructure was characterized by BSED, TEM and EDS. The martensitic microstructure degenerated seriously during creep exposure, including martensitic substructure recovering, carbides coarsening, dissolving and precipitating. EDS analysis shows that the M23C6 carbides in different morphologies have dissimilar compositions. The rod/sheet like M23C6 particles within the matrix contain more additions, which might precipitate in situ while fine MX particles were re-solving. The high content of silicon in these rod/sheet like M23C6 carbides is probably related to self diffusion coefficient increasing for the exposed condition at 650 ℃ close to Curie temperature Tc. For those reasons, martensite substructure becomes unstable, and microstructure evolution is accelerated and leads to creep strength deteriorating severely.     

热处理工艺对12Cr1MoV钢板组织的影响

对12Cr1MoV钢板进行淬火、等温盐浴淬火,利用光学显微镜和电镜观察组织形貌并分析其形成机理.12Cr1MoV钢板均匀化缓冷得到铁素体珠光体的组织,经280℃等温盐浴淬火后得到粒状贝氏体及马氏体组织,其力学性能满足“GB5310-85”标准要求.     

回火温度对Cu-Cr-Ti马氏体耐磨钢组织及强韧性的影响

摘要：矿山机械用耐磨钢构件服役环境恶劣而常常出现磨损失效,研究适用于复杂工况下的高耐磨钢成分、工艺与组织性能的关系,有利于提高耐磨构件的服役寿命并降低经济损失。利用SEM、TEM、洛氏硬度计、万能拉伸试验机及冲击试验机等,研究了160～400℃不同回火温度下Cu-Cr-Ti马氏体耐磨钢的组织形貌、强度硬度及-20℃冲击韧性的变化。结果表明,试验钢淬火态组织主要为板条马氏体,当回火温度为160℃时,马氏体板条依然清晰,但随回火温度升高到400℃,马氏体板条界渐渐消失,基体中出现大量片状或粒状渗碳体。EDS分析发现样品钢基体中含有纳米级Ti、Nb的碳氮化物。随回火温度升高,基体组织演变导致强化机制发生变化,回火温度为300℃,综合力学性能最佳,其抗拉强度为1500MPa,屈服强度1100MPa,伸长率为15.5%。随回火温度升高,-20℃冲击韧性由60J/cm2逐渐降低到36.3J/cm2。     

马氏体型不锈钢热加工后软化处理工艺研究

对马氏体型不锈钢进行了分类，依据各类钢的相变参数及特点，结合冶金生产的实践经验，制定了几组软化处理工艺规范，使其既能满足软化效果要求、易于操作，又能降低生产成本、提高工作效率。     

关于18Ni（250级）马氏体时效钢纯度的控制

本文对18Ni(250级)马氏体时效钢的纯度控制进行了研究。指出以双真空工艺冶炼较为合适     

多元低合金贝氏体铸钢磨球的研究和应用

针对常用磨球材质性大,耐磨性低,磨耗高,研制了多元低合金贝氏体铸钢磨球。该磨球具有硬度高、硬度均匀笥好的韧性高等特点,用于磨矿生产,磨耗接近高铬铸铁球,成本降低３０－４０％,综合效益显著。     

Isothermal and athermal type martensitic transformations in yttria doped zirconia

The phase transformation from the high temperature tetragonal phase to the low temperature monoclinic phase of zirconia had been long considered to be a typical athermal martensitic transformation until it was recently identified to be a fast isothermal transformation. The isothermal nature becomes more apparent when a stabilizing oxide, such as yttria, is doped, by which the transformation temperature is reduced and accordingly the transformation rate becomes low.Thus it becomes easy to experimentally establish a C-curve nature in a TTT (Time-Temperature-Transformation) diagram. The C-curve approaches that of well known isothermal transformation of Y-TZP (Yttria Doped Tetragonal Zirconia Polycrystals), which typically contains 3mol% of Y2O3. In principle, an isothermal transformation can be suppressed by a rapid cooling so that the cooling curve avoids intersecting the C-curve in TTT diagram. Y-TZP is the case, where the stability of the metastable tetragonal phase is relatively high and thus the tetragonal phase persists even at the liquid nitrogen temperature. On the other hand, the high temperature tetragonal phase of pure zirconia can never be quenched-in at room temperature by a rapid cooling; instead it always turns into monoclinic phase at room temperature. This suggests the occurrence of an athermal transformation after escaping the isothermal transformation, provided the cooling rate was fast enough to suppress the isothermal transformation. Thus, with an intermediate yttria composition, it would be possible to obtain the tetragonal phase which is not only metastable at room temperature but athermally transforms into the monoclinic phase by subzero cooling. The objective of the present work is to show that, with a certain range of yttria content, the tetragonal phase can be quenched in at room temperature and undergoes isothermal transformation and athermal transformation depending on being heated at a moderate temperature or under-cooied below room temperature. Because both of the product phases are essentially the same monoclinic phase, both transformations are regarded as martensitic transformation, i. e. isothermal and athermal martensite. In some steels such as Fe-Mn-Ni and Fe-Ni-C, the occurrence of both isothermal and alhermal martensitic transformations has been reported. However, in these cases, the isothermal transformation occurs at temperatures slightly above the Ms (Martensite start) temperatures, and thus these transformations are considered to conform the same C-curve. On the other hand, the Ms temperature of the present material is well below the C-curve, which suggests that completely different mechanisms are controlling the kinetics of these two modes of transformations. Other aspects on these transformations are also to be reported..