The use of worn crushing blade is causing serious problems in recycling factories and ship recycling sites such as decreased sorting efficiency and increased running costs. The attachments of heavy equipment show larger wear than other parts. For this reason, materials with wear resistance and high hardness are in high demand for use for attachments to the tooth of excavators and shearing blades. In the previous research, multi-component white cast iron and spheroidal carbide cast iron were reported to exhibit excellent wear resistance.

  This study investigated the abrasive wear characteristics of multi-component white cast iron (10% Co) and spheroidal carbide cast iron (SCI-W, SCI-VMn) using a shear cutting tester. The target material was continuously cut at a length of 7mm into strips. Cutting load, strain acting on the blades, and change of the cutting edge shape were investigated. The hydraulic pressure of the tester was measured and converted to cutting load.

  As a result, 10% Co was found to be a material exhibiting high performance equivalent to that of conventional cutting blades.

  The hot hardness and oxidation properties of target materials have a strong influence on erosion behaviors at elevated temperatures. The correlation between hot hardness and oxidation properties of multi-component white cast iron and its erosion resistance were investigated to estimate high temperature erosion behaviors in this study. Three kinds of multi-component white cast irons were used in this study. High temperature erosion tests were performed using 1mm alumina particles with impact angle of 30degrees, particle velocity of 30m/s, and test temperature of 1173K.

  In order to clarify the correlation of hot hardness, oxidation, and erosion resistance of specimens, the hot hardness test was carried out and erosion damage caused by solid particle was estimated. The hot hardness value of specimens was comparable to 200HV10. The results of the erosion and oxidation tests indicated that the erosion rate and amount of oxidation of the specimens were suppressed by Co addition. They also showed that the increasing erosion rate was related to the increasing amount of oxidation in the specimens.

  These findings suggest that increasing the addition of Co can inhibit the production of oxidation, which would reduce the erosion rate of specimens at high temperatures.

  Erosive wear (or erosion) is a phenomenon where the material surface is damaged and removed by the continuously impacting of particles. According to researches on erosion, three types of parameters affect erosion ; namely, particle properties, impact condition, and target material properties.

  This study investigated the impact angle dependency of erosion by 3D Finite-Element-Method (FEM).

  In the FEM analysis, the impact velocity of the particles was set at 20m/s and the analysis duration at 0.01ms. The size of the target material was 10 × 10 × 10mm. The parameters of the target materials were set the same as spheroidal carbide cast iron (SCI) and spheroidal graphite cast iron (FCD). The impact particle was spherical shaped steel shot with a diameter of 700μm. The impact angle was changed from 10degrees with a 10degree interval, up to 90degrees. To verify the analysis results, single particle impacting tests was conducted at the same time.

  The results showed no difference in the equivalent plastic strain and Von Mises stress for spheroidal carbide cast iron with increasing impact angle, respectively. Both the equivalent plastic strain and Von Mises stress of FCD were largest at 60degrees. In addition, both the experimental and analytical results of the materials showed the same tendency. Therefore, by focusing on the plastic deformation of the material surface, it is possible to verify impact angle dependency by 3D FEM analysis. The results of analysis indicate that spherical carbides can restrain the plastic deformation of the eroded surface.

  High chromium cast irons, spherical vanadium carbide cast irons, and multi-component white cast irons are used as wear resistant materials, but they are costly because of their high content of rare alloys such as Cr, Ni, Mo, V, and W. While production costs can be reduced by reducing the addition of these elements. In order to develop cost-effective wear resistant materials in this study, nine types of cast irons with 4.0mass%Mn plus varying Cr of 0,4.5 and 9.0mass% and V of 5.0,7.5 and 10.0mass% were prepared to investigate their erosive wear properties. Solid particle erosion tests were conducted using irregularly-shaped steel grits of 770μm, 810HV with impact angles between 30° and 90°, and particle velocity of 100m/s.

  Erosive wear tests revealed that impact angle dependencies of 12Cr, 10V-9Cr, 7.5V-9Cr and 5V-9Cr became small, but difference in the erosion rate was seen. The erosion rate of 10V-9Cr, 7.5V-9Cr and 5V-9Cr was one-third that of 12Cr, and half that of 17Cr. In order to characterize their erosion behavior, the hardness of eroded surfaces was measured before and after tests, and EDS and XRD analyses were carried out to determine the carbide volume fraction and retained austenite in the structure.

  The results suggested that when solid particles impact the test surface, the austenite matrix in 5V-9Cr, 7.5V-9Cr, and 10V-9Cr changes to martensite by strain-induced transformation, which results in increased hardness and absorption of impact energy. All these contribute to sounder erosive wear resistance and less impact angle dependency than others.

  Recently, many researchers are studying the variety of alloys and attempting to develop wear resistant materials. Multi-component white cast iron has been reported to exhibit good erosive wear and abrasive wear resistance. There exists a niobium (Nb) which can easily form carbides in the same manner as vanadium, but not much is known about the effects of Nb addition to the cast iron on wear resistance. Therefore, multi-component white cast irons containing about 2% C, 5% each of Cr, Mo, W, and V (used as alternative to Nb), and 0.5% Co were prepared as test materials in this study. As a result, the amount of wear loss of the multi-component white cast iron containing Nb was less than that of the multi component white cast iron containing V. It also had good abrasive wear resistance. Especially, 5Nb-5Co showed excellent abrasive wear resistance. The area ratio of eutectic carbides and secondary carbides in all the specimens were comparable. However, given that the eutectic MC carbide of multi-component white cast iron containing Nb is bigger than that of multi-component white cast iron containing V, it is thought to have shown higher resistance to contact with the abrasive grains. These results suggest that a new wear-resistant material can be developed by adding Nb as a substitute of V.

  The erosive wear of metals such as stainless steel increases remarkably at high temperatures compared to room temperature. The impact angle dependence was known as erosive wear increases at the low angle side.

  In this study, high chromium cast irons, which are used widely as wear resistant materials, were used as samples. Four kinds of high chromium cast irons, containing 3mass% carbon and varying chromium content ranging from 12mass% to 27mass%, were used as experimental materials. Erosion tests were conducted at 1173K. The microstructure in the surface after tests was observed by SEM and TEM.

  Regardless of the chromium content, erosive wear at the impact angle of 30degrees was higher than that of larger impact angles. This is similar to the erosion mechanism of the cutting wear mode. From the observation of the worn surface, it was found that the worn surfaces were covered with elongated protrusions. The protrusions on the eroded surfaces were found to be ductile due to the fragmentation and spheroidization of eutectic plate-like carbides and austenite grain size refinement.

  This study aims to investigate the influence of tempering temperature on strength, hardness, and wear characteristics of alloy tool steel casting. Test samples added with 0.5mass%Ti with lower C and Cr contents than those in SKD11 (JIS G4404) were manufactured by the investment casting process, and tempered at temperatures 453K, 573K, 673K, 773K, and 873K after quenching from 1293K. The amount of M₇C₃ type Cr carbides decreased, and continuity of the carbides was greatly reduced with the decrease of C and Cr contents. In addition MC type Ti carbides were observed in the matrix microstructure. Carbide structure did not change with varying tempering temperature. Although hardness tended to decrease with increasing tempering temperature, the hardness increased by secondary hardening at temperature of 773K and significantly decreased at 873K. Bending strength did not change largely with tempering temperature and showed maximum value at 453K. Fraction of wear loss did not change during tempering temperature from 473K to 773K but it increased significantly at 873K. The optimum tempering temperature for this alloy steel was found to be 453K from experimental results of strength, hardness, and wear characteristics.

  In this study, the heat treatment behavior of ductile cast iron hardened by induction heating and quenched (induction method), and by furnace heating and quenched (furnace method) was investigated. The abrasive wear characteristic was also studied by Suga type and Rubber wheel wear tests.

  With the specimens hardened using the short-time induction method, the matrix structure near the surface consisted of martensite and retained austenite, while ferrite and pearlite only partially precipitated in the central region. In the case of long-time furnace method, the matrix structure consisted of martensite and retained austenite in the whole specimen.

  Compared to the furnace method, the specimen hardened by the induction method has higher hardness, and less volume fraction of retained austenite (Vγ).

  There was not much difference in the wear behavior between the two heating methods. In the case of the Suga wear test, the wear rate (Rw) decreased lineally with increasing macro-hardness. On the other hand, the Rw of Rubber wheel wear test increased once and then decreased as the macro-hardness increased ; the lower the macro-hardness, the better the wear resistance. Furthermore, the macro-hardness was lowest at high wear resistance. The wear behavior of ductile cast iron was different from that of high chromium cast iron.