Influence of sliding frequency on reciprocating wear of mold steel with different microstructures

The wear resistance of a low alloy plastic mold steel has been studied under pin-on-flat reciprocating configuration against AISI 52100 steel pins, under variable sliding frequency. The as-received material (HTO; 33 HRC) was heat treated under variable conditions to obtain different microstructures and hardness (HT1, quenched 880 °C, 58 HRC; HT2, tempered 550 °C, 43.4 HRC; HT3, tempered 300 °C, 52 HRC; HT4, annealed, 26 HRC). Under low sliding frequency (1 Hz), no significant differences in the wear resistance of the different materials are observed. Only at 8 Hz, a relationship between hardness and wear resistance is found. The softer annealed material HT4 shows an increasing wear rate under increasing frequency, while the quenched steel HT1 gives the lowest wear at the highest frequency. Wear mechanisms have been studied from SEM and EDS observations. Only HT4 shows a transition from the abrasive and oxidative wear mechanisms found in all cases to an adhesive wear mechanism under the highest frequency.     

The effects of welding processes on abrasive wear resistance for hardfacing deposits

In this research, four kinds of welding deposits were evaluated, applied through two different welding processes: flux cored arc welding (FCAW) and shielded metal arc welding (SMAW). The other variable of the tests was the deposited layers. The hardfacing deposits were evaluated using the dry sand-rubber wheel machine according to procedure A of the ASTM G65 standard. Optical and scanning electron microscopy was used for the characterization of the microstructure and worn surface of deposits. FCAW welds presented higher abrasive wear resistance than the SMAW deposits. The hardfacing deposit formed by uniformly distributed carbides rich in titanium presented the highest abrasive wear resistance. Abrasive wear resistance was higher when three layers were applied, except for SMAW-D deposit. It was not possible to get a clear relation between hardness and the abrasive wear resistance of the deposits. The results showed that the most important variable to improve abrasion resistance is the microstructure of hardfacing deposits, where the carbides act as barriers to abrasive particle cutting.     

基于傅里叶变换轮廓术的磨痕形貌测量

往复冲击条件下,由磨损引起的接触表面磨痕的三维形貌的改变对接触润滑效应的研究具有非常重要的影响。在传统傅里叶变换轮廓术(Fourier transform profilometry,FTP)测量系统中引入正弦光强产生装置以及图像实时采集处理系统,利用单幅条纹图像,快速、准确地重构出磨痕表面三维形貌。利用该测量系统对施加PB2400型润滑油方式下快速冲击一万次后的磨痕形貌进行了测量,利用FTP对采集的条纹图进行处理,获得该磨痕的三维形貌。将测量结果与粗糙度轮廓测量仪所得结果进行对比分析,验证该方法的可行性和有效性。将该测量方法与高速摄像机相结合,可以实现连续冲击过程中磨痕的瞬时三维形貌测量,为进一步研究接触润滑效应提出一种新的试验依据和方法。     

水轮机过流件的磨蚀与表面防护

文章简述了材料水力磨蚀方面的有关研究成果,应用试验证明非金属弹性护面涂层有较好的抗气蚀与泥沙磨损性能,值得推广。     

棉纺细纱机钢领使用寿命的探讨

深入分析了钢领使用情况后,得出重要的结论是：钢领的结构、表面光洁度、表层组织、表面强度、锭子转速、钢丝圈匹配等对钢领的使用寿命影响很大。     

Effect of cold deformation on the abrasive resistance of coatings with applications in the mining industry

Machinery components of the mining industry are often involved in severe wear processes. This is the case of the support wheels of the crawler track of the excavators in the open cast mine. Surface coating technologies are essential to improve the surface performance of such components. In this work, the effect of cold deformation on the wear resistance of several Fe–Cr–Mn alloys welding coated over a steel substrate is studied. After being coated, the specimens were pressed by means of a block hammer which produced surface distortion and thickness variation. This deformation process generates micro structural changes and material which may improve the abrasive wear resistance. Abrasion wear tests were carried out based on the standard test method for conducting wet sand/rubber wheel abrasion tests (ASTM G105-89).     

A novel PM-wear protection method to meet high comminution demands

High-pressure grinding roller presses have been used to an increasing extent in recent years for grinding cement because of their better energy utilization. However, the service life of the roller surfaces, an important factor in the cost-efficiency of high compression comminution, still needs to be improved. This formed the background for the introduction of a novel wear protection called HEXADUR^®, in which a very hard, wear-resistant, roller surface is generated by a special combination and distribution of two different materials in a selected pattern. The new HEXADUR^® wear protection system is based on a fundamental examination of the wear system occurring during high compression comminution.     

Abrasion resistance of high Cr cast irons at an elevated temperature

A novel wear tester was employed to investigate the comparative abrasive stability of metallic materials at elevated temperatures. This tester consists of a symmetric π-shaped specimen holder that is rotated in a stainless steel tank filled with quartz sand, and an electrical furnace surrounds this tank to heat the abrasive sand. The test material and its comparative, of a size of 20 mm×20 mm×5 mm, were set in the respective branches of the holder. During the atmospheric condition experiment, only one 20 mm×20 mm face of each specimen was suffered with abrasion, while the other faces which were mounted in the holder were oxidized. Then the volume loss of the specimens can be accurately calculated with the aid of additional oxidation experiments, and by choosing the same comparative material the abrasive stability of different materials can be compared. A newly developed high Cr cast iron 4.5C–40Cr–8Ni–9Nb–5Mo was employed as the test alloy, while the comparative was the widely used 25Cr cast iron (Fe–25Cr–2.9C–0.5Ni–0.5Mo). The results show that, at the temperature of 925 K, the test alloy exhibited a superior abrasive stability to the 25Cr alloy; the average wear rate of the former was only about 36% of that of the latter.     

濮城油田井下管杆偏磨原因分析及对策

分析了濮城油田抽油井井下油管与抽油杆偏磨原因,提出了相应的治理措施。现场应用结果,有效地延长了抽油井的检泵周期。