石墨形态和铬含量对铸铁干摩擦学性能的影响

使用ＭＭ—２００磨损试验机研究了石墨形态和铬含量对铸铁与石棉基摩擦材料配副时的干摩擦学性能。结果表明,蠕墨铸铁的磨损率最低;摩擦系数由高到低依次为：片墨铸铁、蠕墨铸铁、球墨铸铁。蠕墨铸铁中,随着铬含量的增加,耐磨性能明显提高,摩擦系数略有降低。在高速、高载荷条件下,铬含量的质量分数达到１．５％时,耐磨性可达普通蠕墨铸铁的４倍以上;随着载荷的增加,蠕墨铸铁的摩擦系数降低,磨损率提高。在高速条件下,摩擦系数降低的幅度比在低速条件下小。铬改善蠕墨铸铁干摩擦学性能的效果在高速使用条件下更为突出。     

Wear resistance of chromium-containing matrices of diamond drilling tools

The paper examines the wear rate in friction of copper-impregnated samples produced by pressing of VK6 powder with chromium additions. The test is conducted on a cast iron disk in the presence of a wet SiC powder and on a diamond wheel without cooling. It is shown that higher chromium content insignificantly increases the sample wear rate in friction with the cast iron disk. At the same time, the wear rate abruptly decreases for the diamond wheel. The hardness of the samples does not significantly change with increasing chromium content to 6 wt.%.     

高铬白口铸铁低速重载条件下的干滑动摩擦磨损特性

研究了不同类型碳化物和不同基体组织的高铬白口铸铁在低速（滑动速度为0.4187～1.0467m/s），重载（接触应力为1～21MPa）条件下与淬火40Cr钢（硬度HRC51～53）配副的干滑动摩擦磨损特性，结果表明，在（Fe,Cr)7C3、（Fe,Cr）3C和（Fe,Cr）33C63种碳化物中，（Fe,Cr）7C3有利于提高高铬白口铸铁的耐磨性，（Fe,Cr）3C有利于降低摩擦系数，共析组织，奥氏体和马氏体3种基体相比，共析组织基体使合金具有较高的摩擦系数，而奥氏体基体合金的耐磨性最好，存在一个临界摩擦应力，当摩擦应力大于此值时，磨损率急剧上升。     

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…     

含钒蠕墨铸铁干摩擦学性能

研究了含钒蠕墨铸铁与钢盘对磨时的干摩擦学性能。结果表明，钒的加入降低了蠕墨铣的的磨损量，提高了接触压力和摩擦速度变化时磨损量的稳定性。含钒０．１％和０．３％时，提高了摩擦系数和高接触压力，高摩擦速度下降摩擦系数稳定性。     

铸铁—铸铁、铸铁—镀铬层在纯油和加磨料润滑条件下磨损特性的研究

利用SRV高温磨损试验机测定了几种铸铁和镀铬层在油润滑和有磨料条件下不同温度时的摩擦系数和磨损率,同时利用SEM和EDX研究了材料去除机理以及表面层和第二相质点在磨损过程中的行为。研究结果表明,在油润滑条件下,镀铬层与铌铸铁配磨高温时以粘着磨损为主,而在较低温度下以疲劳剥落为主,该对摩擦副的磨损率比Cr-Mo-Cu/B铸铁副高;但在有磨料介入的条件下,镀铬层/铌铸铁副则表现出较好的耐磨性。     

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.     

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

ＥｆｆｅｃｔｏｆＲＥＣｏｍｐｌｅｘＩｎｏｃｕｌａｔｉｏｎｏｎｔｈｅＦａｔｉｇｕｅＷｅａｒＢｅｈａｖｉｏｕｒｓｏｆＨｉｇｈＣｈｒｏｍｉｕｍＣａｓｔＩｒｏｎＷａｎｇＪｉｕｂｉｎ（ＩｎｓｔｉｔｕｔｅｏｆＩｒｏｎ＆ＳｔｅｅｌＲｅｓｅａｒｃｈ，ＡｎｓｈａｎＩｒ...     

Resistance to High-Temperature Oxidation and Wear of Various Ferrous Alloys Used in Rolling Mills

Various materials are commonly used to manufacture work rolls for hot rolling mills, such as ICDP (Indefinite Chill Double Pour) cast irons, high-chromium white cast irons, and high speed steels (HSS). Various chemical compositions and microstructures are studied in order to optimize the in-use behavior of those grades of rolls. In this paper, six grades of ferrous alloys (an ICDP cast iron; an ICDP cast iron enriched in vanadium, niobium, and molybdenum; a HSS; a graphitic HSS; a high-chromium white cast iron (Hi-Cr); and a niobium-molybdenum-doped high-chromium white cast iron) were investigated. High-temperature oxidation tests with gravimetric means at 575 °C in water vapor atmosphere and sliding wear tests were carried out. The oxidation kinetics was followed during oxidation test. The microstructure was observed by optical and scanning electron microscopies. The oxides formed on the surface of the samples were analyzed by XRD and EDS. The thickness of the oxide scales and the mass gain were measured after oxidation test. The results showed that the behavior of all the grades differed. The oxide scale of HSS and HSS-G grades was fine and their friction coefficient was low. The weight gain after oxidation test of HSS was high. Hi-Cr and M-Hi-Cr grades presented highly porous oxide layer and an important increase of the friction coefficient during wear test. ICDP and M-ICDP had intermediate behavior.     

Effect of Microstructure on Impact Fatigue Resistance and Impact Wear Resistance 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 improves the morphology of eutectic carbide; (5) there is no secondary 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.     

配副体积比对铸铁干摩擦学特性的影响

金属干摩擦副双方的相对体积比影响摩擦热在干摩擦学系统中的分配,从而影响材料的干摩擦磨损性能,在铸铁／４０Ｃｒ钢摩擦副和铸铁闸瓦的实际装车运行试验中,均发现随着铸铁材料的磨损,其干摩擦磨损性能有不同程度的降低。蠕墨铸铁比灰铸铁具有理钕的干摩擦学稳定性。     

Effects of heat treatment and counterface on the wear behaviour of Cr21 cast iron

The unlubricated sliding wear test of high chromium white cast irons (HCCIs) was conducted using a pin-on-disc configuration under different heat treatments and different hardnesses of the counterface. With the increase of counterface hardness (20?HRC–47?HRC–54?HRC), the mass loss of the sample first increases then decreases. When the counterface hardness is 20?HRC, adhesion wear mainly takes place between the high chromium cast iron and the surface of 1045 steel. When the hardness is 47 or 54?HRC, first HCCI’ matrix wear takes place, then carbide bump flakes under alternating stress. The mass loss of the counterface decreases with the increase of hardness for the same sample. The mass loss of quenching, once tempering and twice tempering sample decreases gradually for the same counterface hardness, but fluctuation of the samples’ surface increased. The disc material is always softer than the pin material and results in a severe wear regime operation.     

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.     

高铬铸铁叶片局部定向凝固组织与性能研究

对高铬铸铁叶片的局部定向凝固组织与性能关系进行了实验室研究和工业性装机试验，确定了定向凝固对组织、硬度、密度和耐磨性能的影响，得出了适合的局部定向凝固工艺，所研制的高铬铸铁叶片耐用性获得明显提高。     

Evaluation of deterioration mechanisms and roll life of different roll materials

Evaluation of wear loss of rolls in operation is very difficult since the rolling conditions are hard to keep under control. To solve this problem a high temperature test rig was designed. A conventional roll material was compared to a hot work tool steel. The main wear mechanisms were different. The conventional roll grade was mainly subjected to thermal fatigue as could be expected. The hot work tool steel was mainly subjected to abrasive wear, and no evidence of thermal fatigue was found. The rate of material loss was 6 times higher in the hot work tool steel, but when the deterioration caused by thermal fatigue of the cast iron is taken into consideration, the deterioration rate was of the same order in both materials. The friction between the hot steel and the roll materials were of the same order. The frictional value should be a measure of the wear rate. Since the wear mechanisms are not equal, the coefficient of friction found in the test rig is only qualitatively related to roll wear.     

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

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

高铬铸铁的强韧化探讨

在高铬铸铁的铸造过程中运用适当的工艺方法能够极大地改善材料的韧性.但不同的处理方法对高铬铸铁韧化所起的作用也是不同的.笔者系统地分析影响高铬铸铁韧性的因素和各种工艺方法对高铬铸铁韧化的作用原理,并指出提高高铬铸铁材料韧性的努力方向.     

石墨形态对含铸铁干摩擦磨损行为的影响

本文利用自制的干摩擦磨损试验机,系统地研究了不同石墨形态含磷铸铁在不同接触压力及不同摩擦速度条件下的干摩擦磨损行为。试验结果证明,合磷蠕墨铸铁具有最佳的耐磨性及最高的摩擦系数。随着接触压力的提高,含磷铸铁的磨损量呈直线增加,而随着摩擦速度的提高,含磷铸铁的磨损量首先增加,而后则大幅度下降。随着接触压力和摩擦速度的提高,含磷铸铁的摩擦系数首先大幅度降低,而后趋于一相对稳定值。随着石墨长宽比的增加,摩擦系数趋于相对稳定值的接触压力和摩擦速度呈直线增加。     

Experimental Study on Surface Deterioration of Hot RollingMill Rolls under Near Service Conditions

ＥｘｐｅｒｉｍｅｎｔａｌＳｔｕｄｙｏｎＳｕｒｆａｃｅＤｅｔｅｒｉｏｒａｔｉｏｎｏｆＨｏｔＲｏｌｌｉｎｇＭｉｌｌＲｏｌｌｓｕｎｄｅｒＮｅａｒＳｅｒｖｉｃｅＣｏｎｄｉｔｉｏｎｓＣｕｉＰｅｉｙｏｎｇＡｂｓｔｒａｃｔ：Ｗｉｔｈｓｐｅｃｉａｌｌｙｄｅｓｉｇｎｅ...     

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…