Air-cooled engine fan gear crack analysis _1923

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Air-cooled engine fan gear crack analysis

It} s also. Parameters of a quenched and tempered 2.2. Quenching: heating temperature of 86O ~ lO ℃, heat 3h, water cooled engine fan gear materials, the German cold; using 39Cr. V, China's production of such materials is not yet tempering: heating temperature of 570_ +10 ℃, heat 3h, water, diesel engine manufacturers with the Weiyang be used instead of 40Cr steel, cold i acceptance by the German technical conditions. Quenched after the mechanical strength: ≥ 883N/mm. In the mass production process, most of the workpiece 2.3 crack crack processes. Found cracks in the finishing of rough work gear in rough quenched quenching heat treatment process,[link widoczny dla zalogowanych], the transfer after the end arts, sampling times the same heat treatment furnace 37 machine shop applications and found different types of cracks, the fine increases , of which 28 cases have cracks, the total number of 75.7. Workers can not be split. There are 3 main categories of grain species (Table 1). 3 2 crack gear failure analysis, manufacturing process and the main parameters chemical composition 0-1. In the sampling gear cracks and carried out chemical analysis of the production processes 2-1 gear then be compared with the national standard. (See Table 2). Forming a raw steel forging a rough one for a normalization of a finishing a chemical quenching heat treatment (nitriding). * 54 * 123 Table 1 the type of crack shape and location of the crack: == Blue: the three parts split fold part Achillea incorporates the 0135 shooting of 35 pieces is better than crack down 75.7 Table 240Cr chemical composition CMnlsiCrSPGB30770.37 ~ 0.50 ~ . 17 ~ 0.8O ~ 00300.030-820.440.8O {0.371.10 retest O. 4O0.56f0.28O. Microstructure of the crack pieces 930.0280.0143.2 by conventional optical microscopy, uneven grain, local coarse (see Figure 1). There are serious cracks oxidation, the surrounding tissue to maintain a martensite orientation,[link widoczny dla zalogowanych], thick tempered sorbite Figure 2. Figure I corrosion Jing: saturated acids increase cleaning hard gaze magnification × 500 Jing erosion corrosion Jing Figure 2: 4% alcohol solution of nitric acid magnification × 4003.3 fracture analysis of observations has broken the old and new compression fracture and the fracture opening comparison, in the scanning electron microscope to observe the morphology was in two parts. To the center line of demarcation, the right is the old fracture, left for the new pressure (artificial) fracture, shown in Figure 3. The fracture mode of the old fracture is intergranular fracture,[link widoczny dla zalogowanych], and the surface oxide has been seriously Figure 4. A I'l ~ I \5); some areas showing a quasi-cleavage fracture; other parts of the overall structure still has traces of intergranular fracture (Figure 6 and Figure 7). From the microscopic point of view, there are features of ductile fracture (dimples porous) See Figure 83.4 for the original fracture surface energy spectrum analysis has been severely oxidized, inconvenience to do spectrum analysis, the fracture surface in the new pressure for spectrum analysis, design unusual situation. * Figure 5 * 55 new morphology of fracture fixation fracture Results May 7, analysis of the causes 4 Crack 4.1 crack crack straight through the fracture and the microstructure of the observation, intergranular fracture cracks, serious cracks within the oxide,[link widoczny dla zalogowanych], the fracture or pit covered with oxides, according to analysis of this situation is that after the quenching. Large crack sensitivity of this material, quenching Shiyou cold water cooled by chilling, dramatic increase in internal stress caused by cracking. 4.2 horizontal crack along the inner ring is in the forging process, not control the beginning and end forging temperature, low temperature, different organizations both inside and outside, in the heat treatment process, the stress increase caused by cracking. 4.3 The coarse intergranular fracture organizations, maintain martensite orientation. This is the process of heat treatment, quenching the high temperature (> 850 ± 1O ℃); · 56 · Figure 6 Figure 8 Fracture Results of a feature or piece of ductile fracture near the resistance wire, high temperature overheating. Because the grain sizes, coarse microstructure,[link widoczny dla zalogowanych], coupled with chilling, will inevitably lead to the stress along the edges and corners where large cracks. 4.4 The chemical composition of the new pressure on the fracture surface uneven, with banded structure, which is due to uneven chemical composition, resulting in segregation, after heat treatment caused the increase of stress cracking. 5 Conclusions and Recommendations 5.1 Conclusions 5.1.1 improper heat treatment. 4ocr by 800 ± 10 ℃ water quenching, the temperature high, cold water quench a sudden increase of stress will inevitably lead to cracking, the formation of quenching cracks. 5.1.2 The poor quality of raw materials, the adverse consequences banded structure, causing material to crack. (Continued on page 53)