球墨铸铁辊在轧机前后辊道中的应用

对QT60 0 -3和 45锻钢的性能及加工工艺进行比较 ,证明球墨铸铁在材料性能、加工工艺等方面都优于或接近于 45锻钢。采用球墨铸铁来取代锻钢作为中板轧机前后辊道材质 ,可满足生产工艺要求 ,并可解决轧机前后因使用 45锻钢辊而造成的钢材或铸坯的表面缺陷 ,大幅度降低生产成本     

在1100初轧机及其他轧机上使用球墨铸铁轧辊

球墨铸铁(又称加镁铸铁)具有较高的强度和耐磨性,用以制造轧辊,使用寿命显著提高;并可代替一部份铸钢、锻钢轧辊,使成本降低50～80%。鞍钢自1954年底试制成功以来,已广泛用于轧制大、中、小型型钢、钢板及无缝钢管。现就其中一些主要问题简述如下。一、球墨铸铁轧辊的种类和用途根据使用上的不同要求,分为:硬面轧辊(即球墨铸铁复合轧辊,下同)及半硬面轧辊。硬面轧辊用于轧制钢板。半硬面轧辊又分为两种:硬度较高(肖氏45～52度)的用于型钢的成品架或成品前架;硬度较低(肖氏35～42度)的用于初轧连轧机架或预轧机架。     

850球墨铸铁初轧辊的试验

首钢850初轧机过去一直使用60CrMnMo 或60SiMnMo 锻钢轧辊,其生产工艺复杂、价格昂贵,易产生环裂报废,耐磨性不高。因此,采用球墨铸铁轧辊代替锻钢轧辊是初轧生产的一项重大技术革新,是实现“以铁代钢,以铸代锻”,降低轧辊成本,提高轧钢产量和生产效率的一项重大技术措施。具有重大的政治经济意义。早在1957年,鞍钢轧辊厂就试制了球墨铸铁初轧辊,经过多年的试验,轧辊的生产     

大型锻钢轧辊工艺研究与生产实践

结合攀长特公司现有装备,研究分析大型锻钢轧辊的工况,选用合适的锻钢材质,强化熔炼、锻造质量控制,优化热处理工艺,成功生产制造两付825初轧机大型锻钢轧辊,为攀长特公司大型锻钢轧辊生产提供借鉴。     

不同材质轧辊在型钢生产中的混合应用

Ф760mm三辊轧机各类孔型轧槽的磨损情况及轧制负荷都不相同,为了降低轧辊消耗,将不同材质轧辊如球墨铸铁辊、锻钢辊和半钢辊等在一套轧辊中进行了混合试用并获得成功,大幅降低了轧辊消耗,同时提高了产品实物质量。     

多辊轧机工作辊制作技术的研究与实践

本文论述了多辊轧机的结构组成、工作原理和应用范围,重点对多辊轧机的工作辊的性能要求、加工技术要求进行了分析。按照分析结果制定了多辊轧机工作辊的加工工艺、热处理工艺、磨削工艺。经过反复试验和工艺的调整,最后成功的研制出多辊轧机工作辊,其各项性能满足用户要求,一次通过用户验收,受到用户好评。     

离心铸造复合球墨铸铁轧辊材质的研究

本文研究了用于离心铸造复合球墨铸铁轧辊的三种球墨铸铁材质,对其组织形态,化学元素分布:力学性能及热处理工艺进行了研究分析。在实验研究基础上,用珠光体球墨铸铁材质生产了马鞍山钢铁公司高速线材轧机φ410 mm轧辊;用针状贝氏体球墨铸铁材质生产了上海宝山钢铁总厂钢管轧机张减辊。两种轧辊上机使用效果显著,轧制量均达到国外设计要求和进口轧辊水平。     

轿车变速器的表面致密化粉末冶金齿轮的使用性能

选择性表面致密化是改进粉末冶金钢的一种方法,高负载齿轮经过这种加工工艺处理,就能达到使用要求.本文介绍了粉末冶金螺旋齿轮的制造工艺与性能,用三轴总成成对试验台架、承载能力试验台架及噪声试验台架测定了齿轮的使用性能,并把试验结果和具有同样几何形状与表面质量的锻钢齿轮的数据进行了比较.结果表明,粉末冶金齿轮的承载能力与噪声级可和锻钢齿轮相媲美.     

大断面铸态贝氏体球墨铸铁轧辊的试制

本文简述了直径大于４００ｍｍ铸态贝氏体球墨铸铁轧辊的试制过程，包括试制条件、试制工艺及试制品的性能分析。轧辊先后在６５０ｍｍ轧机上用于试轧厚８￣１３．６ｍｍ、宽２４０ｍｍ的扁钢。结果表明，其使用寿命为原铬钼球墨铸铁无限冷硬轧辊的１．５倍。     

大直径锻钢轧辊感应炉热加淬火工艺曲线模拟试验法

前言近年来,为满足冷连轧机用大直径优质锻钢轧辊的高技术性能的要求,双频(如0/250H2)或双工频感应加热淬火等新工艺均得到广泛应用。这种感应加热的温度一时间变化曲线(简称加热曲线)通常呈光滑双峰值马鞍形(图1)很难用试样在箱式电炉.盐浴炉中模拟加热,所以在摸索奥氏体化条件和工艺参数试验阶段,一直在生产现场     

Transient Heat Transfer Analysis of Blast Furnace Cooling Staves

The capability of cooling staves is crucial for a long campaign life of blast furnaces (BF). Transient heat transfer analysis of blast furnace cooling staves made of copper, cast steel, and ductile cast iron are performed. Moreover, the temperature field variations of cooling staves according to different distributions of gas flow temperature are studied. A discussion of cooling staves made of the three different materials is given based on their performance during the transient heat transfer process. The results indicate that copper staves are suited for a long campaign life, as their performance is much better compared to cast steel and ductile cast iron staves especially during unsteady heat transfer. Moreover, the capacity of staves made of cast steel is better than that of ductile cast iron.     

Microstructures and Mechanical Properties of Helical Bevel Gears Made by Mn-Cu Alloyed Austempered Ductile Iron

 Austempered ductile iron (ADI) has several advantages of replacing cast steel and forged steel in many engineering fields. A new Mn-Cu alloyed ADI with excellent mechanical properties has been developed in order to cut the cost and enlarge the application of ADI. The helical bevel gears were made of the new-developed Mn-Cu alloyed ADI. The microstructure and mechanical properties of the standard sample were investigated by optical microscope (OM), scanning electron microscope (SEM) and performance measurement. The results showed that after a series of treatments, the mechanical properties (Rm 10074 to 1200 MPa, A 52% to 88%, HRC 32 to HRC 35, αK 70 to 120 J/cm2) of the Mn-Cu alloyed ADI standard sample could reach European standard EN1564-97/ EN-CJS-1000-5. The surface hardness after helical bevel gears meshing was significantly increased due to the formation of martensite. The bench test and traffic running testing results suggested that the new Mn-Cu alloyed ADI with ultimate life and median life respectively exceeding 30×104 and 50×104 times could replace 20CrMnTi forged steel for manufacturing the EQ140 helical bevel gears.     

氮基气氛中材料的脱硫与氮吸收

介绍了烧结铁基零件的硫损量和硬度、尺寸变化等与氮基烧结气氛成分、压坯含硫量等因素的关系,并比较了以硫或者MnS作为添加剂对增脱硫量及烧结件性能的影响,还介绍了烧结气氛中氮含量对烧结Fe-C材料的物理性能、烧结铁材料的磁性能和烧结不锈钢材料的耐腐蚀性能的影响,以及不锈钢烧结材和冶炼钢锻材在氮吸收上的重要差别。     

高速钢复合辊环离心铸造技术研究

高速钢具有硬度高和红硬性好等特点，适合于制造轧钢机辊环，普通离心铸造高速钢辊环工艺简单，操作方便，但辊环内孔硬度高，加工困难，而且合金用量大，成本高，研究了高速钢／球墨铸铁离心复合铸造辊环工艺，对影响复合层质量的因素进行了分析，金属浇注温度和浇注间隔时间是影响复合层质量的关键因素，严格控制离心铸造工艺参数和注注中加入助溶剂，得到了复合层结合良好的辊环，高速钢淬火温度高，降低内层力学性质，通过改进成分，获得的高速钢辊环铸态直接回火后，硬度达HRC64。     

Investigation of stress corrosion cracking of the cast and forged steel in water

The aqueous stress corrosion behavior of cast steel and forged steel of the same heat has been examined. It was shown that the activation energy of crack growth of both cast and forged steels was identical,i.e., Q = 5540 cal/mol, and was comparable with the apparent diffusion activation energy of hydrogen in the steel. Theda/dt for cast and forged steel increased under both cathodic and anodic polarization conditions. Correspondingly, the steady-state hydrogen permeation flux increased steeply with the increase of polarizing current under either cathodic or anodic polarization. The influences of the polarization upon theda/dt and the hydrogen permeation flux were similar. TheK _ISCC of the cast steel was larger than that of the forged steel. This may be due to the observation that the steady-state permeation flux for the forged steel was twice as large as that of the cast steel. For both cast and forged steels the fracture modes were clearly dependent uponK _I at the crack tip, and a transition from dimple to quasi-cleavage or intergranular was observed on the fracture surfaces with decreasingK _I . Formerly Students at Beijing University of Iron and Steel Technology     

高耐磨性贝氏体球墨铸铁磨球的研制

试制了一种高耐磨性贝氏体球墨铸铁,在空冷条件下获得贝氏体一马氏体复相组织和残余奥氏体组组织,该组织具有良好的强韧性配合和高耐磨性,与中锰球铁、高铬铸铁磨球比较,耐磨性和耗球率都有明显改善。该材料磨球综合性能好,生产工艺简单,制造成本低廉,具有推广价值。     

钒对贝氏体球墨铸铁组织和硬度的影响

研究钒对贝氏体球墨铸铁组织和性能的影响,研究结果表明,随着钒加入量的增加,贝氏体组织数量增加,贝氏体针尺寸明显减小,贝氏体球铁的宏观硬度提高,但钒对贝氏体球铁中奥氏体和贝氏体组织的显微硬度影响不大,测定了钒在贝氏体球铁中的存在形态,探讨了钒的作用机制。     

Effect of graphite morphology on modulus of elasticity of low carbon equivalent ductile iron

The modulus of elasticity (Young’s Modulus) of cast irons is known to be a function of graphite volume fraction in the microstructure. Low carbon equivalent ductile iron is a low carbon cast iron in which, carbon is present as graphite in nodular form. It is observed that the modulus of elasticity of these irons is higher than that of conventional ductile iron. In the present investigation, an interrelationship of modulus of elasticity with graphite nodule counts, nodule size and graphite volume has been investigated. A significant relationship is observed between the modulus of elasticity and the above mentioned morphological characteristics of graphite.     

Tribological Performance of Austempered and Tempered Ductile Iron

Austempered ductile iron with its unique ausferritic structure is produced by an isothermal heat treatment process. Austempered ductile iron is a potential material to substitute for traditional steel castings and forgings in current industry due to its excellent mechanical properties. The tempering process is frequently used to enhance the ductility and toughness of a material and reduce residual stress. In this research, the phase transformation of austempered ductile iron was studied by applying various tempering temperatures with constant holding duration. It was found that the ausferritic structure was decomposed into dispersive cementite particles after receiving a tempering temperature of 538 °C or higher. The specific amount of retained austenite was analyzed by X-ray diffraction. The wear resistance of tempered austempered ductile iron was investigated by using a ball-on-disk sliding test configuration. The results were compared with conventional quenched and tempered ductile iron under equivalent hardness. Both austempered ductile iron and tempered austempered ductile iron samples had better wear resistance than quenched and tempered ductile iron. The results presented in this research can be utilized as a reference in the tempering treatment of austempered ductile iron material for future applications.     

The Effect of Graphite Fraction and Morphology on the Plastic Deformation Behavior of Cast Irons

The plastic deformation behavior of cast irons, covering the majority of graphite morphologies, has not been comprehensively studied previously. In this investigation, the effect of graphite morphology and graphite fraction on the plastic deformation behavior of pearlitic cast irons has been evaluated. The investigation is based on tensile tests performed on various different cast iron grades, where the graphite morphology and volume fraction have been varied. Pearlitic steel with alloying levels corresponding to the cast irons were also studied to evaluate how the cast iron matrix behaves in tension without the effects of the graphite phase. It is concluded that as the roundness of the graphite phase increases, the strain hardening exponent decreases. This demonstrates that the amount of plastic deformation is higher in the matrix of lamellar cast iron grades compared to compacted and nodular cast iron grades. Furthermore, this study shows that the strength coefficient in flake graphite cast irons increases as the graphite fraction decreases due to the weakening effect of the graphite phase. This study presents relationships between the strain hardening exponent and the strength coefficient and the roundness and fraction of the graphite phase. Using these correlations to model the plastic part of the stress-strain curves of pearlitic cast irons, we were able to calculate curves in good agreement with experimentally determined curves, especially for gray cast irons and ductile iron.