变质高碳硼钢的冲击磨料磨损行为研究

对高碳硼钢进行稀土变质处理,在MLD-10动载磨料磨损试验机上研究了变质高碳硼钢的冲击磨料磨损性能,并与高铬铸铁(Cr26)进行了比较.结果表明,适量稀土元素的加入,能有效提高高碳硼钢的耐磨性和冲击韧度;冲击功为2.0 J时,变质高碳硼钢的耐磨性不如高铬铸铁,冲击功为2.5 J时,变质高碳硼钢的耐磨性相当于高铬铸铁(Cr26);在磨损过程中,高碳硼钢的冲击磨损机制主要是塑性变形及疲劳剥落,切削所占的比例较小.     

深冷处理在高铬铸铁中的应用

本试验中将深冷处理工艺引入高铬铸铁的性能研究,初步探讨了深冷处理对材料宏观力学性能及耐磨性的影响。试验结果表明适当的深冷处理能够提高高铬铸铁硬度、冲击疲劳性能及滑动磨损与滚筒磨损性能,但其作用效果有限。     

高铬铸铁磨料磨损耐磨性的研究

高铬铸铁在磨料磨损条件下工作具有较好的耐磨性和应用效果。为了进一步地发挥高铬铸铁的优点，特别是在复合结构特定条件下能够取得耐磨性的第一手资料，对高铭铸铁的低应力磨料磨损、冲击条件下的磨料磨损、宏观硬度和金相组织等作了系列的试验研究，现将结果介绍如下。一、试验内容在化学成分方面，采取分别改变铬、碳和硼的加入量来观察高铭铸铁的组织和耐磨性的变化。试样的化学成分加附表所示（附表见后）。热处理对高铝铸铁的组织和性能有重要影响，为此分别取铸态、950℃正火和1050℃正火三种状态，试样共有72种成分状态。在自制的…     

锻造高铬铸铁的组织和性能

本文对高铬铸铁进行单向拔长热塑性变形试验,研究了锻造比(K_L)为1～4.14的高铬铸铁的组织、机械性能和抗磨料磨损性能。结果发现随着K_L增大,碳化物分布越来越均匀、孤立和细化;抗弯强度、冲击韧性及抗磨料磨损能力明显提高,而硬度变化不大。     

加硼高铬铸铁

从降低成本和提高耐磨性的角度出发 ,对高铬铸铁进行了加硼的试验研究。考察了加硼量和热处理工艺对高铬铸铁的硬度和冲击韧性的影响 ,并进行了销盘磨损试验。实验结果表明 :只要添加适量的硼和采取合适的热处理工艺 ,可以使高铬铸铁的碳化物细化 ,基体淬透性增加 ,并使高铬铸铁的硬度和韧性同时得到提高 ,从而增加了材料的耐磨性。     

15Cr-3Mo-0.6V高铬铸铁的热处理

白口铸铁是性能优良的抗磨料磨损的材料,其中高铬铸铁尤为突出.抗磨材料的耐磨性能,首先取决于材质的硬度,而硬度则与抗磨材料所含碳化物数量有关.根据马拉特雷提出的计算碳化物数量的经验公式:碳化物%=12.33%C 0.55%Cr-15.2,高铬铸铁(C=3%)中     

27%Cr高铬铸铁组织及性能研究

对不同碳、钼含量的27％高铬铸铁的组织、硬度及耐磨性等进行了试验。结果表明：高铬铸铁的淬火硬度及抗磨料磨损能力随含碳量增加而提高。但当铬、碳含量比低于7时,宏观硬度降低。钼对改变大量析出奥氏体的临界含碳量有一定影响,铬、碳含量比低于7时,加钼量不应低于2％。无论含钼或不合钼,过共晶高铬铸铁（3．7％C）抗磨料磨损能力均优于亚共晶高铬铸铁,冲击韧度与后者相近。     

一种混凝土湿喷机衬板材料的研究及应用

本文设计出耐磨合金铸钢衬板化学成分和制造工艺，并与高铬铸铁衬板试样进行硬度、耐磨性、韧性、金相对比试验，结果表明，该耐磨合金铸钢综合性能达到设计指标，具有应用价值。     

深冷处理对高铬白口铸铁组织与性能的影响

将空淬过的高铬白口铸铁经-196℃深冷处理后在不同温度下回火,研究了深冷处理对该铸铁硬度、冲击韧度、滑动磨损、滚筒式磨损和金相组织等的影响。结果表明：经深冷处理后,其硬度有较大幅度提高,但冲击韧度略有下降;深冷处理后再经250℃回火,可以获得较好的硬度和韧性的配合;经深冷处理后再回火的硬度峰值比未经深冷处理的提前了约100℃;深冷处理对耐磨性影响不明显。     

稀土变质处理对高铬铸铁组织和性能的影响

一、前言高铬铸铁是指含铬量为10～30％的白口铸铁,由于高铬的存在使铸铁的凝固特性发生很大的变化。铬含量超过12％时,铸铁中的碳化物由M_3C型转变成为M_7C_3型,这种碳化物的显微硬度达1800H_v,且呈断续块状分布,因此,高铬铸铁不仅有较高的硬度,而且有一定的韧性。     

我国热作模具钢性能数据集

对国内生产和应用的25种（其中7种测部分性能）热作模具钢,在相同的试样尺寸、机械加工、热处理、试验设备和测试方法以及在相同的评判标准等条件下,实测了力学性能（室温、高温拉伸和冲击韧性、室温断裂韧性、高温硬度）;特殊性能（冷热疲劳、热磨损、热稳定性、热熔损、热塑性摩擦系数、抗氧化性）;工艺性能（锻造性、回火稳定性、心部性能、切削性）等16种性能,另外,还对部分钢种测定了物理性能和室温缺口拉伸性能。其性能数据具有可比性,更适宜有关专业人员作为热作模具选材和用材的依据。     

Some aspects of solid particle erosion of cermets

The erosive wear resistance of cermets with different composition, structure and properties has been investigated. It was shown that the erosive wear resistance of cermets can not be estimated only by hardness, characterizing resistance to penetration. The differences in wear resistance between cermet materials with equal hardness levels can be attributed to differences in their resistance to fracture and fracture toughness. The mechanism of erosion depends first on testing conditions. The present paper discusses some features of the material removal process during particle-wall collision. Systematic studies of the influence of the impact variables on the collision process have been carried out.     

论渗碳钢中残余压应力的作用

本文研究结果表明,渗碳钢淬火形成的残余压应力对提高疲劳强度、多次冲击抗力、疲劳断裂韧性、宏观疲劳裂纹萌生与扩展寿命,降低疲劳缺口敏感性,和疲劳载荷抑制脆性等均起着主要的作用。表层材料强度或硬度与残余应力的相关性在于高的表层材料强度或硬度能减小残余应力的衰减,有助于发挥残余应力对疲劳性能的有利作用。长期以来对渗碳钢中微观组织和残余压应力作用的含混看法得到了澄清。     

论高强度螺栓的材料及其强度问题

本文从高强度螺栓的服役条件出发论述了高强度螺栓选材的考虑因素。用低碳马氏体钢和中碳调质钢进行了静拉伸、偏斜拉伸、冲击韧性、疲劳强度和延迟断裂强度等试验。试验结果表明,与中碳调质钢相比,低碳马氏体钢的强度提高1/3以上,同时保持较高的塑性和韧性,螺栓的承载能力提高45～70%,而缺口偏斜敏感性并不显著升高;螺栓的疲劳强度与中碳钢调质态螺栓大体相同：低碳马氏体钢的延迟断裂敏感性比相同强度水平的40Cr钢小,并且在盐水和水中对延迟断裂是不敏感的。因此,选用低碳马氏体钢作高强度螺栓材料,不仅在综合机械性能方向有许多优点,而且其优良的工艺性能更是中碳钢不能比拟的。本文还进行了热处理前和后滚制螺纹对螺栓疲劳强度的影响试验,结果表明,热处后滚制螺纹可有效地提高螺栓的疲劳强度。根据本文的试验结果,作者对低碳马氏体螺栓钢的成分设计作了某些探讨。     

港口桥吊用钢丝绳断丝原因分析

港口桥吊用钢丝绳在使用中发生多处断丝现象,通过化学成分分析、力学性能测试、断口分析、金相检验和显微硬度测试等方法对断丝原因进行了分析。结果表明:钢丝绳断丝的性质为疲劳断裂,断裂源位于钢丝表面的损伤或磨损处;断丝表面存在的较多磨损、挤压剥落等缺陷以及断丝显微组织中存在一定数量的铁素体共同导致了钢丝绳中钢丝的早期疲劳断裂。     

止回阀焊缝安全评定研究

分析了复杂载荷条件下止回阀焊缝的应力分布,研究了焊接模拟试件的拉伸性能、冲击韧性、断裂韧性、疲劳性能、疲劳裂纹扩展速率和门槛值等性能,采用国际上应用的安全评定体系BS7910对止回阀环焊缝中存在的未熔合缺陷进行了安全评定。     

The erosion of heat-treated steels

The erosion behavior of a plain carbon steel (AISI-SAE 1020), an austenitic stainless steel (type 304) and a low alloy steel (AISI-SAE 4340) in various heat-treated conditions was determined. The testing was conducted at room temperature using aluminum oxide particles with an average size of 140 μm in an air stream. An attempt was made to characterize the erosion behavior as it relates to the mechanical properties obtainable in these alloys by conventional heat treatments. It was found that the ductility of the steels had a significant effect on their erosion resistance which increased with increasing ductility and that hardness, strength, fracture toughness and impact strength had little effect on erosion behavior. The platelet mechanism of erosion occurred in all the steels tested at all conditions.     

Abrasive wear resistance of some commercial abrasion resistant steels evaluated by laboratory test methods

The aim of the present study is to evaluate the abrasive wear resistance of some potential abrasion resistant steels exposed to different types of abrasive wear contact conditions typical of mining and transportation applications. The steels investigated, include a ferritic stainless steel, a medium alloyed ferritic carbon steel and a medium alloyed martensitic carbon steel.The abrasive wear resistance of the steels was evaluated using two different laboratory test methods, i.e. pin-on-disc testing and paddle wear testing that expose the materials to sliding abrasion and impact abrasion, respectively. All tests were performed under dry conditions in air at room temperature. In order to evaluate the tribological response of the different steels post-test characterization of the worn surfaces were performed using optical surface profilometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. Besides, characterization of the wear induced sub-surface microstructure was performed using optical microscopy.The results show that depending on the abrasive conditions a combination of high hardness and toughness (fracture strain) is of importance in order to obtain a high wear resistance. In the pin-on-disc test (i.e. in sliding abrasion) these properties seem to be controlled by the as-rolled microstructure of the steels although a thin triboinduced sub-surface layer (5–10 μm in thickness) may influence the results. In contrast, in the paddle wear test (i.e. in impact abrasion), resulting in higher forces acting perpendicular to the surface by impacting stones, these properties are definitely controlled by the properties of the active sub-surface layer which also contains small imbedded stone fragments.     

Effect of Composition and Physical Properties of Silicon Nitride on Rolling Wear and Fatigue Performance

The improved performance of silicon nitride components over all-steel bearings in several applications has been demonstrated. However, the effects of grain size, intergranular phase composition, fracture toughness, and hardness on rolling wear and fatigue performance are not completely understood. Three commercial bearing materials were tested under standard conditions and their physical properties were obtained. Wear and fatigue properties were compared to physical properties and material composition. It was found that a high fracture toughness is not required for high fatigue life and wear resistance. Total wear and fatigue life of the assembly must be considered, in addition to performance of the ceramic material alone, for specific applications. Grain boundary composition did not appear to affect the wear mechanism of these hot-isostatically-pressed materials.     

Propagation of fatigue cracks in acrylic bone cements containing different radiopaque agents

In this work three iodine-containing monomers were proposed as new radiopaque agents for acrylic bone cements. In previous studies the addition of iodine-containing methacrylate monomers provided a statistically significant increase in tensile stress, fracture toughness and ductility, with respect to the barium sulphate (BaSO4)-containing cement. However, since fatigue resistance is one of the main properties required to ensure a good long-term performance of permanent prostheses, it is important to compare the fatigue properties of these new bone cement formulations with the radiolucent and BaSO4-containing bone cements. Because the acrylic cements have initial cracks, fatigue crack propagation studies were performed. It can be observed that these acrylic cements followed the Paris-Erdogan model. The results showed that the addition of some organic radiopacifiers (DISMA, TIBMA) increased the fatigue crack propagation resistance as compared to the radiolucent cement, being similar to the BaSO4-containing cement. The radiolucent cement showed a low crack propagation resistance.