78results about How to "Improve hardness uniformity" patented technology

The invention relates to a hot processing technology method for bearing steel parts. The hot processing technology method for the bearing steel parts comprises the steps of forging a blank, cooling after forging, keeping warm, spheroidizing annealing, quenching and tempering after machining. Through optimal control on the cooperation in the multiple steps, the carbide particles in the manufacturedbearing steel parts are fine, the quantity of the carbide particles is more, and the grain size can be further improved, so that the strength, the impact toughness, the hardness uniformity and the service life of the parts can be improved, the overall performance of the bearing steel parts is improved extensively, and the hot processing technology method for the bearing steel parts can meet the use performance requirement on bearing steel under the working condition of high temperature in the field such as bearings, and is suitable for popularization and application.

The invention discloses a large-thickness wear-resisting steel plate with good low-temperature toughness and a preparing method. The steel plate comprises, by weight percent, 0.16 to 0.18% of C, 0.20to 0.30% of Si, 1.15 to 1.30% of Mn, not larger than 0.010% of P, not larger than 0.002% of S, 0.010 to 0.020% of Nb, 0 to 0.05% of Cu, 0.40 to 0.60% of Cr, 0.45 to 0.60% of Mo, 0.95 to 1.20% of Ni, 0.025 to 0.040% of V, 0.001 to 0.0025% of B, larger than or equal to 0.060% of Alt, 0.002 to 0.004% of Ca, and the balance Fe and trace impurities. The hardenability index of steel is larger than or equal to 140, the wear-resisting index is larger than or equal to 0.59, the steel plate thicknesses ranges from 80 to 100 mm, the NQT process is adopted, the large-thickness wear-resisting steel plate with good -40 DEG C low-temperature toughness is excellent in mechanical property, the steel plate surface hardness ranges from 330 HBW to 380 HBW, the hardness average value in the thickness directionis not lower than the surface hardness by 90%, and -40 DEG C impact energy at the 1 / 4 thickness is 60 to 80 J.

The invention discloses a heating processing technology for tooth punching and tempering on an open large gear. The heating processing technology comprises the following steps: before tempering heating process, performing coarse tooth punching on the open large gear, and uniformly reserving allowances on tooth thickness and diameter according to the diameter of the open large gear; putting the open large gear into a furnace by virtue of a lifting appliance, and then performing the heating process for tooth punching and tempering on the open large gear; when reaching the holding time, hanging the open large gear into a quenching tank so as to be subjected to oil cooling, wherein the precooling time ranges from 3 minutes to 8 minutes, the temperature of the large gear wheel ranges from 760 DEG C to 790 DEG C when the large gear enters oil, the oil cooling time ranges from 60 minutes to 90 minutes per 100mm (which means the thickness of the rim wall of the gear), and the oil outlet temperature ranges from 260 DEG C to 300 DEG C; and after quenching, performing tempering process on the open gear, and cooling the open gear to 250+ / -10 DEG C at a cooling speed of 40 DEG C to 60 DEG C per hour, and air-cooling after discharging. According to the invention, the hardness uniformity of the open large gear subjected to the heating process is enhanced, the hardness attenuation gradient of the open large gear subjected to the heating process is reduced, the deformation of the open large gear in subsequent processing is reduced, and the quality of the open large gear is improved wholly.

The invention relates to high-uniformity and high-polishing type plastic mould steel ZW636 and a preparation method thereof. The plastic mould steel particularly comprises the following components inpercentage by mass: 0.20 to 0.30 percent of C, 0.10 to 0.40 percent of Si, 1.20 to 1.60 percent of Mn, less than or equal to 0.010 percent of P, less than or equal to 0.005 percent, 1.20 to 1.80 percent of Cr, 0.90 to 1.20 percent of Ni, 0.48 to 0.70 percent of Mo, 0.08 to 0.15 percent of V, 0.015 to 0.030 percent of Als, less than or equal to 0.25 percent of Cu, O of less than or equal to 12 ppm,N of 60 to 100 ppm, H of less than or equal to 1.5 ppm and the balance of Fe and unavoidable impurities. Through the specific preparation method, the plastic mould steel has the following characteristics: (1) the tissue is uniform, the grain crystal is small, the tissue rating is less than or equal to level 4, and the grain size is more than level 6; (2) the hardness is uniform and the hardness uniformity of the same section is less than or equal to 3 HRC; and (3) the high-uniformity and high-polishing type plastic mould steel ZW636 has high polishing property and can be polished to 8000 meshes, and the polishing rate is 95 percent.