Microstructure, Impact Fatigue Resistance and Impact Wear Resistance of Wear Resistant Low Cr-Si Cast Iron

Wear parts are greatly consumed in metallurgi-cal industry,fire power stations and cement works.The consumption of grinding balls and lining platesmay be the greatestunder such impactabrasive wearconditions.In China,annual consumption of ballsand plates is close to 1× 10 6 t.Therefore,develop-ing a new material for impact wear conditions is veryimportant.　　 The martensitic high chromium cast iron(WCr= 15 % ) is widely studied and used as wear resis-tance material[1— 8] ,especially for ma…     

The Properties and Performance of Cast Iron Grinding Media

Cast iron balls have been used for decades as a grinding media in all types of grinding applications. Early applications of cast iron grinding balls in mineral processing operations were disastrous due to spalling and premature breakage. Better control and understanding of a high chromium cast iron metallurgical system have led to the use of high chromium cast iron balls in all types of grinding. This paper reviews the wear properties of cast iron grinding media materials during dry and wet grinding conditions. The media wear mechanisms and the factors influencing the grinding ball wear during grinding are discussed, giving special importance to the corrosion and abrasion properties of cast iron media materials.     

Effect of RE Modification and Heat Treatment on Impact Fatigue Property of a Wear Resistant White Cast Iron

Withhigherhardnessandbetterwearresistance ,whitecastironscanbeusedaswearresistantpartsinmanyfields .Inpractice ,thewearresistantpartsareoftenrequiredtobesubjectedtogrindingofabrasivesandrepeatedimpactaction .Therefore ,fatiguecracksareliabletobegeneratedo…     

Study on the Thermal Fatigue Behavior of Hot Deformed Wear Resistance Cast Iron and Effect of Carbide

The thermal fatigue behavior of wear resistance cast iron with different quantity of deformation has been investigated. The results show that eutectic carbide is the main location and passage for initiation and extension of thermal fatigue cracks, approving that the more serious, the carbide breaks. The higher thermal fatigue resistance of wear resistance cast iron will be and thermal fatigue fracture belongs mainly to brittleness.     

Effect of Heat Treatment on Structure and Wear Re- sistance of High Chromium Cast Steel ContainingBoron

The microstructure, mechanical properties and wear resistance of high chromium cast steel containing boron after different heat treatments were studied by means of the optical microscopy （OM）, the scanning electron microscopy （SEM）, X-ray diffraction （XRD）, hardness, impact toughness, tensile and pin-on-disc abrasion tests. The results show that as cast microstructures of boron-free high chromium steel consist of martensite and a few （Cr, Fe）_7C_3 carbide, and the macro-hardness of boron-free high chromium steel is 55-57 HRC. After 0.5 mass% B was added into high chromium cast steel, as-cast structure transforms into eutectic （Fe, Cr）2B, （Cr, Fe）7 （C, B）a and martensite, and the macro-hardness reaches 58-60 HRC. High temperature quenching leads to the disconnection and isolated distribution of boride, and there are many （Cr,Fe）_23 （C,B）_6 precipitated phases in the quenching structure. Quenching from 1050 ℃, high chromium steel obtained the highest hardness, and the hardness of high chromium cast steel containing boron is higher than that of boron-free high chromium steel. The change of quenching temperature has no obvious effect on impact toughness of high chromium steel, and the increase of quenching temperature leads to tensile strength having an increasing tendency. At the same quenching temperature, the wear resistance of high chromium cast steel containing boron is more excellent than that of boron-free high chromium steel. High chromium cast steel guide containing boron has good performance while using in steel bar mill.     

高铬镍无限冷硬铸铁轧辊材料的磨损性试验

利用自行开发研制的高温滑动磨损与热接触疲劳材料试验机,并运用表面覆膜技术、金相分析和扫描电镜,研究了用于精轧机的高铬镍无限冷硬铸铁轧辊材料在热轧状态下的耐磨特性,分析了这种轧辊材料的表面形貌、表层组织的变化情况。结果表明,当轧制公里数达到88km时,高铬镍无限冷硬铸铁轧辊表面产生了碳化物的浮凸和剥落。     

Effect of Hot Deformation on Formation and Growth of Thermal Fatigue Crack in Chromium Wear Resistant Cast Iron

Chromium wear resistant cast iron is widelyusedin engineering, mining and power industry forits high strength,hardness and wear resistance .Inproduction process , some wear-resistant parts ser-ving in alternative stress due to rapid heating andcooling rate ofteninduces thermal fatigue andresultsinfailure .The badthermal fatigue property of chro-mium wear resistant cast iron is due to eutectic car-bides which distribute as continuous net in matrix.Recent researches showthat hot deformation can …     

Effect of Microstructure on Impact Wear Resistance Impact Fatigue Resistance and of Medium Cr-Si Cast Iron

A great amount of iron grinding balls in tube mills have been consumed. Under this impact abrasive wear working condition, the failure of wear resistant alloying white irons grinding balls is mainly caused by fatigue spalling. The impact wear resistance of martensitic high chromium cast iron （Cr of 15%） is not high sometimes, but its cost is not low. Thus, medium Cr-Si wear resistant cast iron is recommended. The influence of the iron on impact fatigue resistance and impact wear resistance is pronounced. Ball-on-ball impact fatigue test and high stress impact wear test of the grinding balls have been carried out. The results show that the impact fatigue resistance （IFR） and impact wear resistance （IWR） of medium Cr-Si cast iron are superior to those of martensitic high chromium cast iron （Cr of 15%）. The main reasons are that （1） the stress in medium Cr-Si cast iron is released in the as-cast state; （2） the matrix is fine pearlite with better toughness and plasticity; （3） the pearlite is more stable compared with a retained austenite under repeated impact load and less phase transformation can take place; （4） high silicon content im- proves the morphology of eutectic carbide; （5） there is no seeondary carbide which results in less crack sources. All these factors are beneficial to improvement of impact fatigue spalling resistance. The eutectic carbide M7C3 is the main constituent to resist wear.     

90Cr6MoRE耐磨铸钢的研究

本文研究了中铬钢的化学成、分淬火温度、回火温度、显微组织、相结构与力学性能和耐磨性的关系。结果得出,中铬钢在同一热处理条件下,随碳含量的提高耐磨性随之提高,对同一碳含量大,随淬少温度的提高耐磨性亦随之提高。90Cr-6MoRE钢在磨损试验条件下,耐磨性接近于高铬钢或高铬铸铁,明显地高于高锰钢和低合金钢。90Cr6MoRE钢的碳化物为M_7C_3型加少量M_3C型。90Cr6MoRE钢衬板装机试验寿命比同机高锰钢衬板提高1倍以上。     

高碳高钼高速钢导辊的研究与应用

导辊是高速线材轧机上的主要消耗工具 ,要求高耐磨性、抗粘钢性和热疲劳抗力。普通奥氏体耐热钢 ,马氏体耐磨钢或耐磨铸铁导辊满足不了上述要求 ,使用寿命短 ,降低了轧机作业率。硬质合金导辊具有良好的耐磨性和高温稳定性 ,使用效果好 ,但生产成本高。高碳高钼高速钢具有硬度高、红硬性和耐磨性好等特点 ,但铸造高速钢脆性大 ,采用RE -Mg -Ti复合变质处理 ,可以改变共晶碳化物的形态和分布 ,使铸造高速钢冲击韧性提高 86 .2 % ,热疲劳抗力和耐磨性也明显改善。变质处理高速钢导辊使用中不粘钢、不破碎、不剥落 ,使用寿命比高Ni-Cr合金铸钢导辊提高 3倍以上 ,接近硬质合金导辊     

Abrasive Wear Behavior and Mechanism of High Chromium Cast Iron

The abrasive wear behavior of high chromium cast iron(containing 12.9mass%chromium)austenitized at1 050 ℃for 2hand austempered in salt bath at 320℃for 4hwas evaluated.Abrasive wear was performed using alumina abrasive under four different loads,namely 50,100,150,and 200 N,for 36 000 cycles.The worn surfaces and wear debris were analyzed by scanning electron microscopy,laser confocal microscopy and X-ray diffraction.Microhardness profiles were also obtained in order to analyze the strain-hardening effects beneath the contact surfaces.Results indicate that the retained austenite in high chromium cast iron has experienced induced martensitic transformation after tests,for small amounts of retained austenite could be detected by X-ray diffraction.In addition,there is a close relationship between wear mechanism and test load.Under the condition of lower test load,the wear mechanism is an uninterrupted and repeated process,during which matrix is cut at first and then fine carbides flake off.As to higher test load,scratching and spalling induced by cleavage fracture of blocky carbide are the wear mechanism.     

中锰白口铸铁的组织对其抗磨性的影响

中锰白口铸铁是适应我国资源和生产条件而研究发展的抵抗磨料磨损材料。由于其优异的经济效益和生产便利,已成功地用于制做砂浆泵体和分级机衬铁等矿山易磨件。
本文根据不同成分及热处理的中锰白口铸铁在各类磨料磨损试验机上测试的结果讨论组织对抗磨性的影响及此影响与各类磨料磨损的机制的关系。
低应力冲刷磨损的测试是在混砂盘及橡胶轮两种磨损试验机进行。高硬度的马氏体-碳化物组织最抗磨。脆性相的存在对抗磨性不利。硼加入中锰白口铸铁能使碳化物显微硬度和宏观硬度增加,但使强度和韧性降低。硼适量加入对抗磨性有利。这与此类磨损是宏观冲刷磨损机制有关。
高应力碾研磨损的测试是用肖盘对磨和三体滚轮挤轧两种磨损方式进行。抗磨性与硬度和韧性有关,但基体组织的显微硬度时常起决定性影响。中锰白口铸铁采用Cu Cr Mo综合合金化提高淬透性。残留奥体量大对抗磨性不利。这与此类磨损是以显微切削磨损机制为主有关。
最后小能量多次冲击磨损的测试是以冲头连续冲撞方式进行。抗磨性与材料的冲击韧性有很大关系。低碳含量,稀土变质处理改变碳化物为断开分布的板块状都可起有利影响。这是由于形变磨损机制在这类磨损中起主要作用。
如此可以得出结论,抗磨材料的最合适的组织与磨料磨损的类别和其磨损机制有关。     

斜轧中铬半钢磨球的冲击疲劳和磨损性

通过落球和冲击磨损试验,研究了斜轧1．85％C、5．86％Cr中铬半钢磨球的抗小能量多冲击破坏能力和耐磨性,结果表明：斜轧中铬半钢磨球的冲击疲劳寿命高于铸造半钢磨球,该球经适当的热轧余热热处理,可获得较抗多冲击破坯能力与耐磨性能。     

Structures and Properties of Iron Matrix Composites with Tungsten Carbide Particle by EPC-V Process

Ｍｏｄｅｒｎｉｎｄｕｓｔｒｙｍａｋｅｓｄｅｍａｎｄｓｏｎｗｅａｒｒｅｓｉｓ－ｔａｎｃｅｏｆｅｎｇｉｎｅｅｒｉｎｇｍａｔｅｒｉａｌｓ．Ａｓａｋｉｎｄｏｆｓｕｒｆａｃｅｔｒｅａｔｍｅｎｔｔｅｃｈｎｏｌｏｇｙ,ｃａｓｔｉｎｇｐｅｒｍｅａｔｉｎｇｔｅｃｈｎｏｌｏ－ｇｙｃａｎｓａｔｉｓｆｙｔｈｅｎｅｅｄｓｏｆｗｅａｒｒｅｓｉｓｔａｎｃｅｏｆｍａｔｅｒｉ－ａｌｓ,ｂｕｔｔｈｅｒｅａｒｅｍａｎｙｄｉｓａｄｖａｎｔａｇｅｓｉｎｔｒａｄｉｔｉｏｎａｌｃａｓｔｉｎｇｐｅｒｍｅａｔｉｎｇｔｅｃｈｎｏｌｏｇｙｗｈｉｃｈ…     

低成本高铬硅耐磨铸铁的研究与应用

冲击疲劳落球试验和冲击磨损试验结果表明,铸态去应力处理的高铬硅耐磨铸铁抗冲击疲劳剥落和抗冲击磨料磨损性能优于马氏体Cr15耐磨铸铁;且高铬硅耐磨铸铁断面硬度均匀、生产成本较低,适宜制造球磨机磨球。     

Effect of RE Complex Inoculation on the Fatigue Wear Behaviours of High Chromium Cast Iron

ＥｆｆｅｃｔｏｆＲＥＣｏｍｐｌｅｘＩｎｏｃｕｌａｔｉｏｎｏｎｔｈｅＦａｔｉｇｕｅＷｅａｒＢｅｈａｖｉｏｕｒｓｏｆＨｉｇｈＣｈｒｏｍｉｕｍＣａｓｔＩｒｏｎＷａｎｇＪｉｕｂｉｎ（ＩｎｓｔｉｔｕｔｅｏｆＩｒｏｎ＆ＳｔｅｅｌＲｅｓｅａｒｃｈ，ＡｎｓｈａｎＩｒ...     

Solidification structure and abrasion resistance of high chromium white irons

Superior abrasive wear resistance, combined with relatively low production costs, makes high Cr white cast irons (WCIs) particularly attractive for applications in the grinding, milling, and pumping apparatus used to process hard materials. Hypoeutectic, eutectic, and hypereutectic cast iron compositions, containing either 15 or 26 wt pct chromium, were studied with respect to the macrostructural transitions of the castings, solidification paths, and resulting microstructures when poured with varying superheats. Completely equiaxed macrostructures were produced in thick section castings with slightly hypereutectic compositions. High-stress abrasive wear tests were then performed on the various alloys to examine the influence of both macrostructure and microstructure on wear resistance. Results indicated that the alloys with a primarily austenitic matrix had a higher abrasion resistance than similar alloys with a pearlitic/bainitic matrix. Improvement in abrasion resistance was partially attributed to the ability of the austenite to transform to martensite at the wear surface during the abrasion process.     

落球冲击下高铬铸铁磨球中残余奥氏体的形变与相变

用透射电镜和微区Ｘ射线衍射分析了落球冲击后高铬铸铁磨球皮下不同深度残余奥氏体形变和相变情况。发现不同深度发生形变和相变的程度是不同的，在磨球表面最大，随着深度增加形变和相变的程度减小。产生可观塑性变形的深度在５ｍｍ以内，而发生相变的深度可达１０ｍｍ。不同深度相变的机理不同。共晶碳化物在落球冲击下也能发生一定的塑性变形。最后分别讨论了显微组织变形和相变对磨球抗剥落破碎性能的影响。     

Effects of Rare Earths and Al on Structure and Performance of High Chromium Cast Iron Containing Wolfram

High chromiumcast ironis ani mportant grade ofwear-resistant material.It exhibits high hardness,ex-cellent wear resistance,andlowdeflection onrupture.Moreover,combined properties of high chromiumcastiron are better than that of other white cast irons.Therefore,it has many applications[1~4]in concrete,electric power,mine,metallurgy,and especially ap-plicationin ball mill with large diameter subjected toheavy i mpact loading[5].However,the brittle natureof this material often causesfailure under…     

Properties of Cross-Rolled Low Alloy White Cast Iron Grinding Ball

Lowalloy white cast iron has high hardness andwear-resistance ;however ,the material has lowduc-tility ,because the carbideinthe structureis distrib-uted in the formof continuous network, which li m-its its application. Therefore , the method to i m-prove the toughness of this material has attractedthe interests of the researchers worldwide . The ex-peri mental results showed that when white cast ironis hot deformed, the network structure of carbidebreaks and becomes independent blocks , which…