Infrared carbon and sulfur analyzer application of steel detection and steel quenching
Conditioning treatment: Heat treatment after quenching at high temperature and tempering is called quenching and tempering. High temperature tempering refers to tempering between 500-650°C. The quenching and tempering can make the performance and material of the steel be adjusted to a great extent, and its strength, plasticity and toughness are all better, and it has good comprehensive mechanical properties. QL- HW2000B frequency infrared carbon and sulfur analyzer with high frequency induction furnace capable of rapid and accurate determination of both the elements are carbon and sulfur in steel, may also detect non-ferrous metals, rare earth metals, cement, ore, coke, coal, The contents of carbon and sulfur in slag, ceramics, iron ore, inorganic organics, and other materials .
45 steel quenching and tempering : 45 steel is a medium carbon structural steel, hot and cold processing performance are good, good mechanical properties, and low price, wide source, so widely used. Its greatest weakness is its low hardenability, large cross-section dimensions and relatively high workpiece requirements.
45 steel quenching temperature in A3 + (30 ~ 50) °C, in actual operation, generally take the upper limit. The high quenching temperature can accelerate the heating of the workpiece, reduce the surface oxidation, and improve the work efficiency. In order to homogenize the austenite of the workpiece, a sufficient holding time is required. If the actual loading capacity is large, it is necessary to extend the holding time appropriately. Otherwise, hardness may be insufficient due to uneven heating. However, if the holding time is too long, there will also be coarse grains, serious defects in oxidative decarburization, and quenching quality. We believe that if the furnace charge is greater than the process documentation, the heating and holding time needs to be extended by 1/5.
Because 45 steel has low hardenability, a 10% brine solution with a high cooling rate should be used. After the workpiece enters the water, it should be hardened, but it is not cold. If the workpiece is completely cold in the brine, it may crack the workpiece. This is because when the workpiece is cooled to about 180°C, the austenite is rapidly transformed into martensite. Excessive tissue stress. Therefore, when the quenched workpiece is cooled to the temperature range, slow cooling method should be adopted. Since the outlet water temperature is hard to grasp, it must be operated by experience. When the workpiece shaking in the water stops, the outlet water can be cooled (if it can be cooled by oil). In addition, the workpiece should not be moved to the water should be static, should be in accordance with the geometry of the workpiece, making regular movements. Static cooling media plus stationary workpieces result in non-uniform hardness, non-uniform stress, large deformations, and even cracking.
The quenched hardness of 45 steel quenched and tempered parts should reach HRC56-59, and the possibility of large cross section is lower, but it cannot be lower than HRC48. Otherwise, it means that the workpiece has not been completely quenched, and sorbite or even ferrite may appear in the structure. Organizations, such organizations, through tempering, remain in the matrix, failing to adjust their quality.
45 steel after quenching high temperature tempering, heating temperature is usually 560 ~ 600 °C, hardness requirements for HRC22 ~ 34. Because the purpose of tempering is to obtain comprehensive mechanical properties, the hardness range is relatively wide. However, if the drawing has hardness requirements, it is necessary to adjust the tempering temperature according to the drawing requirements to ensure the hardness. For example, some shaft parts require high strength and high hardness requirements; while some gears and shaft parts with keyways need to be milled and inserted after quenching and tempering, so the hardness requirements are lower. Regarding the tempering holding time, depending on the hardness requirements and the size of the workpiece, we believe that the hardness after tempering depends on the tempering temperature, which is not related to the tempering time, but it must be reversed. The general workpiece tempering holding time is always More than one hour.
Nanjing Kirin Scientific Instrument Group Co., Ltd.
Testing Center
2015.12.18
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