合金结构钢渗碳淬火后渗层残余奥氏体的控制

低碳合金结构钢经渗碳或碳氦共渗和淬火后，其渗层组织中存在残余奥氏体，残余奥氏体量过多会使渗层硬度下降，从而影响零件的使用寿命。不同产品对残余奥氏体量的要求量是不同的，可采用相应的热处理工艺进行控制。残余奥氏体量一般采用金相法测定，介绍了检测残余奥氏体的相关标准。     

低碳微合金容器钢经调质处理后的组织与性能

本文研究了含碳0.09%的低碳微合金容器钢的组织与性能。结果表明该钢经调质处理(960℃×1.5 h+630℃×1.5 h)后,获得的性能为:0σ.2=641 MPa,σb=742 MPa,δ=20%,ψ=75%,AKV=321 J,HB=204。室温组织为铁素体及弥散的析出物。     

花键齿轮碳氮共渗淬火变形的控制方法

为了确保４０５１７ａ齿轮的强度,提高其耐磨性,我公司在新产品开发时,将其最终热处理状态,设计成了碳氮共渗直接淬火。由于该齿轮为内花键双联齿轮（如图１）,且形状复杂,碳氮共渗直接淬火虽可提高工件的强度、耐磨性,但内花键孔变形却难于把握和控制,而且,用含碳氮有机液体做渗剂进行深渗层共渗,时间较长。为了解决这两个问题,我们以三乙醇胺＋乙醇做渗剂,在原７５ｋＷ井式气体渗碳炉上实施了滴注式气体碳氮共渗工艺。经多次试验,并采取一系列方法,精确控制了该齿轮的内花键孔变形,并使共渗时间缩短了２－２～２－６ｈ。…     

热处理和磨削工艺对渗碳淬火汽车齿轮残余应力的影响

研究了渗碳热处理过程中淬火冷却和回火状况以及磨削加工对渗碳淬火汽车齿轮表面残余应力的影响.研究表明,充分淬火冷却有利于提高表面残余压应力,正确的磨削工艺不改变残余应力的分布,但过多的磨削热会导致在次表层产生高的拉应力.     

The Effects of Martensite Content on the Mechanical Properties of Quenched and Tempered 0.2%C-Ni-Cr-Mo Steels

Three martensite contents (approximately 35, 50, and 100%) were obtained in a SAE8822 steel by altering the quenching media and section size. Another variation in martensite content (approximately 80 versus 97%) was achieved by quenching a SAE8622 steel in the same section size. The impact toughness and fatigue properties were determined after tempering to various levels of monotonic strength. Toughness and strength-toughness combinations improved with increased as-quenched martensite contents at all levels of as-tempered ultimate tensile strength (UTS). Even at higher levels of yield strength (YS), increased martensite contents produced higher impact energies and lower fracture appearance transition temperatures. The cyclic YS was independent of martensite content (at the same level of UTS), even though the monotonic YS increased with martensite content. When fatigue test results were compared at a tensile strength of 1240 MPa (180 ksi), actual and predicted fatigue lives in the high cycle regime increased with martensite content, but low cycle fatigue resistance was relatively unaffected. Fatigue strength and UTS were directly related, and all the quenched and tempered steels exhibited cyclic softening.     

减少渗碳淬火齿轮花键孔变形的一种有效措施

为了提高我厂ＫＰ２０００、ＫＴ２０００等产品变速箱齿轮的强度,我们对系列内花键齿轮４０５－０９,４０５－１４,４０５－１６进行了渗碳直接淬火处理。众所周知,渗碳直接淬火齿轮的内孔是注定要变形的,而且,其变形的原因也是多方面的。本文只介绍堵孔方法对变形...     

淬火合金钢中的奥氏体稳定化

研究了马氏体(M)和贝氏体(B)两相温度区等温淬火组织中的奥氏体稳定化．在一定等温时间内，奥氏体稳定化程度，即残余奥氏体量与等温温度间的关系呈马鞍型曲线．在实验钢中，其谷底值低于用同冷却介质淬火组织中的AR，表明在一定条件下等温停留并不引起残余奥氏体量增多．可利用马鞍型曲线调整AR与M及B的含量配比，获得无变形或强韧性配合最佳的准贝氏体等温淬火工艺．奥氏体稳定化为热稳定化、化学稳定化、相致稳定化和宏观热应力稳定化诸机制的综合作用．马氏体临界点Mc点无特殊物理意义。     

渗碳淬火件非马氏体组织形成原因分析及对策

对渗碳零件非马氏体组织的形成机理进行了阐述,试验了内氧化、冷却速度和淬火介质对渗碳零件非马氏体组织的影响,并依据笔者一线生产经验提出了一些对策。     

奥氏体不锈钢低温气体渗碳的组织性能

低温盐浴渗碳、等离子渗碳等低温渗碳工艺在提高奥氏体不锈钢表面强度的同时,会降低其耐蚀性能。为克服上述缺陷,开发了一种高效兼顾表面强度与耐蚀性能的表面强化工艺的低温气体渗碳技术。采用该工艺对304、316奥氏体不锈钢进行渗碳处理,并对得到的奥氏体不锈钢低温渗碳组织性能进行分析。结果表明,随着温度升高,试样表面强度提高,而腐蚀性能下降。470℃是兼顾强化与耐蚀性能的低温气体渗碳工艺参数。     

等温正火对汽车齿轮渗碳淬火变形的影响

随着汽车行业飞速发展,对汽车齿轮质量要求愈来愈高,因此,寻找一种新的预先热处理工艺愈来愈得到齿轮行业重视,通过对不同材料齿轮毛坯采用等温正火处理,发现毛坯显微组织均匀,硬度波动范围小于25HB,晶粒度为6～8级.本文着重对等温正火处理工艺对汽车齿轮渗碳淬火变形的影响.     

Effect of Deformation and Heat Treatment in Metallurgical Production on Lattice Distortions and Mechanical Properties of Steels

Metal Science and Heat Treatment -     

Microstructure and Mechanical Properties of Direct Quenched Versus Conventional Reaustenitized and Quenched Plate

Direct quench processing of steels may be employed as a more cost efficient mechanism to produce low-carbon martensitic plate steels. However, the strengthening mechanisms of direct-quenched (DQ) steels, which can include grain size, dislocation density, and precipitation, are not well understood. Three experimental alloys containing 0.19 wt.% carbon with microalloy additions of Nb and V were developed to compare direct-quench processed steels to steels processed through reaustenitizing and quenching, the more conventional method to produce martensitic plate steels. Two different direct quench processing routes, conventional controlled rolling and recrystallization controlled rolling, with variations in the amount of final rolling reduction were investigated with two of the alloys. The third alloy was processed through reaustenitizing and quenching. The microstructures were quantified using light optical microscopy, scanning electron microscopy, and electron backscattered diffraction and correlated with tensile test results to assess the strengthening mechanisms in each of the conditions. The strength of the DQ steels was similar and matched that of the reaustenitized and quenched steel. It was found that the martensite block size was constant across the experimental conditions, and might play a major role in strengthening the DQ plates.     

齿轮渗碳淬火表层非马氏体组织产生的原因及对策

从内氧化及降低零件淬透性两个角度探讨了齿轮渗碳淬火非马氏体组织产生的原因.并从这两个角度依据笔者长期的一线生产经验提出了一些解决方法.     

新型微变形齿轮钢渗碳特性及力学性能

对一种新型微变形齿轮钢的渗碳特性和力学性能进行研究。结果表明,经渗碳空冷,渗层碳浓度梯度平缓,表层硬度为61～63HRC,心部硬度达到35～42HRC。表层组织为细小分散马氏体 少量残留奥氏体,过渡层为针状贝氏体 板条马氏体,心部主要为束状贝氏体。渗层耐磨性好,基体力学性能优良,能很好地满足齿轮的服役条件。     

渗碳淬火件表层非马氏体组织形成原因和防止措施

在渗碳淬火件表面层中经常出现连续或不连续的网状或块状黑色组织 ,此处恰好是表层压应力最大区域 ,已被公认是由于内氧化而贫合金化元素导致形成屈氏体类组织 ,也被称为非马氏体组织。一旦形成此类组织 ,其后果是降低表面硬度和耐磨性以及疲劳极限。因此国内外知名的车辆制造厂家大都对非马氏体层厚度有明确规定 ,如德国波尔特、奔驰、宝马公司要求此层厚度必须在 3μｍ以下。一汽集团公司原先规定把此层控制在 0 0 2ｍｍ内 ,现在准备将其减少到 3μｍ以下。但是国内尚有不少工厂未把非马组织作为渗碳淬火件的质量指标。本文的目的是重申…     

Influence of Ni Content on Dry Sliding Wear Behavior of Sintered and Carburized Steels

The dry sliding wear behavior of two sintered and carburized steels with different Ni amounts has been investigated. The microstructure of the two steels comprises martensite, bainite, and the Ni-rich austenite. Under the sliding conditions investigated, wear is either oxidative or adhesive. In both cases, the lower amount of the soft Ni-rich austenite results in a better wear resistance. A design procedure for parts subject to dry sliding wear applications is proposed, based on the maximum acceptable wear depth, in order to evaluate the practical significance of the differences between the two materials.     

Investigation of Variables Affecting Impedance Plane in Eddy Current Testing of Carburized Steels

Impedance plane is one of the most important ways for presenting results in Eddy current testing, which includes major data for evaluation of results. In this study, the impedance plane was drawn for carburized steel with different surface carbon content. The influences of temperature, fill factor, and edge effect on impedance plane were investigated. The ability of Eddy current testing for determination of surface carbon content using normalized impedance was also shown. Results demonstrate a strong relationship between normalized impedance and surface carbon content (R ² = 0.82). Besides the effects of temperature, fill factor, and edge effect on determination of surface carbon content were investigated. The fill factor and temperature have the largest and the least effect on correlation coefficient between surface carbon content and impedance plane, respectively.