Bearing heat treatment methods for foreign machinery occupations (on)

Home>Bearing knowledge> Bearing heat treatment method for foreign machinery occupation (on)
/*728*90 created on 2018/5/16*/ var cpro_id = "u3440131";

Bearing heat treatment methods for foreign machinery occupations (on)

Source: Bearing network time: 2017-12-18

/*250*250 was created on 2017/12/25*/ var cpro_id = 'u3171089';
The quality of heat treatment is directly related to the subsequent processing quality, which affects the function and life of the parts at the end; together with the heat treatment, it is the power consumption and pollution of the mechanical profession. These years; following the advancement of scientific skills and its heat The use of disposal; the main body of heat treatment skills is now the following:
(1) Sanitary heat treatment Wastewater, waste gas, waste salt, dust, noise and electromagnetic radiation, which are produced by heat treatment, will pollute the environment. Dispose of environmental pollution problems of heat treatment; implement sanitary heat treatment (or green heat treatment) Disposal) is one of the directions for the development of heat treatment skills in developed countries. In order to reduce emissions of SO2, CO, CO2, dust and cinders, coal has been used as a fuel; the use of heavy oil is also less and less; Natural gas is still the most ideal fuel. The waste heat application of the incinerator has reached a high level; the optimization of the incinerator layout and the strict control of the air-fuel ratio ensure the rational incineration; the NOx and CO are minimized. Limit, use gas carburizing, carbonitriding and vacuum heat treatment skills instead of salt bath disposal to reduce the pollution of waste water and CN-toxic substances to water sources, use water-soluble quenching oil instead of some quenching oil; use biodegradable Vegetable oil replaces some mineral oil to reduce oil pollution.
(2) Fine heat treatment Fine heat treatment has two aspects: on the one hand, based on the application requirements of the parts, data, layout scale; using physical metallurgy common sense and leading computer simulation and testing skills; optimizing process parameters; The function or the maximum limit to carry forward the potential of the data, on the other hand is to ensure the stability of the optimization process; the quality of the finished product is very disproportionate.
(3) Energy-saving heat treatment Scientific production and power management are the most promising elements for the useful use of power; establishing a professional heat treatment plant to ensure full-load production and abundant development of equipment can be a scientific management choice. Priority is given to selecting a power, using waste heat and waste heat, and selecting a process with low energy consumption and short cycle to replace the long cycle and high energy consumption process.
(4) Less oxidation-free heat treatment is heated by a controlled atmosphere heating instead of an oxidizing atmosphere to control the carbon potential and nitrogen potential in a controlled atmosphere; the function of the parts after heat treatment is advanced; the disadvantages of heat treatment such as decarburization, cracking, etc. Reduction; reduction of finishing allowance after heat treatment; advancement of data utilization rate and machining power. Vacuum heating gas quenching, vacuum or low pressure carburizing, nitriding, nitrocarburizing and boronizing can significantly improve quality Reduce distortion and advance life.
The thermal handling quality of bearing parts is the most severe in the entire mechanical profession. The thermal treatment of bearings has made great progress in the past 20 years; the first table is now the following aspects: the discussion of the basic theory of heat treatment, heat treatment Research on process and application skills, development of new heat treatment equipment and related skills.
1 Spheroidizing annealing of high carbon chromium bearing steel for annealing high carbon chromium bearing steel is to obtain fine, small, uniform and round carbide particles evenly distributed on the ferrite matrix; for future cold working and end quenching Tempering arrangement preparation. The traditional spheroidizing annealing process is performed at a temperature slightly higher than Ac1 (such as GCr15 of 780~810 °C) and then cooled slowly (25 °C / h) to below 650 ° C. The heat treatment time is longer (20h or more) [1]; and the particles of the carbide are not uniform after annealing; affecting the future cold processing and the end quenching and tempering arrangement and function. After; according to the transformation characteristics of supercooled austenite; developing isothermal Spheroidizing annealing process: after heating, it is cooled to a temperature range below Ar1 (690~720 °C) for isothermal; during the isothermal process, the transformation of austenite to ferrite and carbide is completed; after the completion of the transformation, it can be directly The air cooling is performed. The strength of the process is the time of heat saving (the whole process is about 12~18h), and the carbides are finely uniform after the disposal. Another time-saving process is repeated spheroidizing annealing: the first heating to 810 After °C, cool to 650 ° C After heated to 790 deg.] C and then cooled to 650 ℃ cooled baked in time, although the process can save the bound; but the process operation is more complex.
2 Martensitic quenching and tempering of high carbon chromium bearing steel
2.1 Conventional martensite quenching and tempering arrangement and function for nearly 20 years; the conventional high carbon chromium bearing steel martensite quenching and tempering process is mainly divided into two aspects: one is the quenching and tempering process parameters Influence on arrangement and function; such as arrangement change during quenching and tempering, differentiation of retained austenite, tolerance and fatigue after quenching and tempering [2~10], on the other hand, process function of quenching and tempering Such as the influence of quenching conditions on scale and deformation, dimensional stability, etc. [11~13]. The arrangement after conventional martensite quenching is martensite, residual austenite and undissolved (residual) carbide composition. The shape of martensite can be divided into two categories: under a metallographic microscope (expansion multiple is usually less than 1000 times); martensite can be divided into two types: lath martensite and flaky martensite. Usually, after quenching, it is a mixed arrangement of slats and flake martensite; or a central shape between the two, jujube nucleus martensite (bearing occupational so-called cryptocrystalline martensite, crystalline martensite) ), under high power electron microscope; its sub-layout can be divided into dislocation entanglement and twinning. Its detailed arrangement The shape depends mainly on the carbon content of the matrix; the higher the austenite temperature; the less stable the original arrangement; the higher the carbon content of the austenite matrix; the more retained austenite in the post-quench arrangement; the more flaky martensite More; the larger the scale; the greater the proportion of twins in the sub-layout; and it is easy to form quenching microcracks. Usually; the carbon content of the matrix is ​​less than 0.3%; the martensite is the main board of dislocation sub-layout. Martensite, the carbon content of the matrix is ​​higher than 0.6%; martensite is a sheet of martensite with dislocation and twin mixed sub-layout, the matrix carbon content is 0.75%; Large flake martensite in the middle ridge; and the lamellar martensite grows with microcracks at the impact of each other [8]. Together with this; advance with austenitizing temperature; hardness after quenching advances; The resistance is decreased; however, if the austenitizing temperature is too high, the hardness will decrease due to excessive austenite remaining after quenching.
The retained austenite content in the conventional martensite quenching is usually 6-15%; the remaining austenite is a soft sub-stable phase; under certain conditions (such as tempering, natural aging or the application of parts) Middle); its instability attack differentiates into martensite or bainite. The result of differentiation is the hardness of the part advances; the tolerance decreases; the scale attack changes the dimensional accuracy of the part and even the normal operation. The demand for scale accuracy is higher. Bearing parts; usually the less the remaining austenite is expected to be better; such as quenching to compensate for water cooling or cryogenic treatment; the use of higher temperature tempering [12 ~ 14]. But the remaining austenite forward resistance and crack Expanding resistance; under certain conditions; the remaining austenite on the surface of the workpiece can also reduce the concentration of touch stress; the fatigue life of the forward bearing; in this case, adopting certain methods in the process and data composition to preserve the necessary amount Remaining austenite and advance its stability; such as taking the austenite stability element Si, Mn, for stability and disposal [15,16].
2.2 Conventional martensite quenching and tempering process practice High carbon chromium bearing steel Martensitic quenching and tempering: heating the bearing parts to 830~860 °C; quenching in oil; then low temperature tempering. The mechanical function after tempering is related to the original arrangement and quenching process before quenching; it also depends largely on the tempering temperature and time. With the increase of tempering temperature and the extension of holding time; the hardness decreases; the strength and the resistance advance The suitable tempering process can be selected according to the operation requirements of the parts: GCr15 steel bearing parts: 150~180°C, GCr15SiMn steel bearing parts: 170~190°C. For parts with special requirements or before tempering with higher temperature The operating temperature of the inlet bearing; or the cold treatment of -50 to -78 °C between quenching and tempering to achieve dimensional stability of the forward bearing; or martensitic quenching to stabilize the remaining austenite to achieve high dimensional stability Sex and higher tolerance.
Many experts have studied the transformation in the heating process [2; 7~9, 17]; such as the composition of austenite, the recrystallization of austenite, the dispersion of residual carbides and the use of non-spherical arrangements as the original arrangement Etc. G. Lowisch et al [3;8] studied the mechanical function of the bearing steel 100Cr6 after austenitizing twice: first; austenitizing at 1050 °C and cooling to 550 °C for air cooling; obtaining uniform fines Pearlite; followed by secondary austenitization and quenching at 850 ° C; after quenching, the scale of martensite and carbide is fine, the carbon content of martensite matrix and residual austenite content are higher; Higher temperature tempering causes austenite to differentiate; many fine carbides are separated in martensite; reduced quenching stress; advancing hardness, strong tolerance and bearing bearing capacity. Under the effect of touch stress; Further research is needed; however, it can be estimated that its touch fatigue function should be better than conventional quenching.
Jiu Jiuyu et al [7] studied the micro-arrangement and mechanical function of SUJ2 bearing steel after cyclic heat treatment: firstly heated to 1000 ° C for 0.5 h to make spheroidal carbide solid solution; then; pre-cooled to 850 ° C quenched Oil. Then repeat 1~10 times of heat cycle from rapid heating to 750 °C, heat preservation for 1 min, oil cooling to room temperature; finally heat up to 680 ° C for 5 min oil cooling. At this moment, arrange for ultra-fine ferrite and fine Carbide (ferrite grain size less than 2μm, carbide less than 0.2μm); superplasticity at 710°C (crack elongation can reach 500%); this characteristic of data can be used for warm processing of bearing parts Forming. Finally; heating to 800 ° C to maintain the quenching oil and tempering at 160 ° C. After this treatment; touch fatigue life L10 is much larger than the conventional treatment; its failure method is changed from the early failure type of conventional treatment to wear failure type.
The bearing steel is austenitized at 820 °C and then subjected to short-time grading isothermal air cooling at 250 ° C; followed by 180 ° C tempering; the carbon concentration in the martensite after quenching can be more evenly distributed; the impact resistance is more than the conventional quenching and tempering Advance twice. Thus; В. В. БЁЛОЗЕРОВ et al. proposed that the uniformity of carbon concentration of martensite can be used as a quality standard for heat treatment parts [6].
2.3. Martensite quenching and tempering deformation and dimensional stability Martensite quenching and tempering; because of the uneven cooling of parts of the parts; inevitably presenting thermal stress and arranging stress and inducing deformation of the part. Quenching back The deformation of the part after fire (including scale changes and shape changes) is affected by many factors; it is a proper messy problem, such as the shape and scale of the part, the uniformity of the original arrangement, and the roughing condition before quenching (the amount of feed during turning) The size of the machine, the residual stress of machining, etc.), the heating rate and temperature during quenching, the placement method of the workpiece, the oil inlet method, the characteristics of the quenching medium and the circulation method, and the temperature of the medium all affect the deformation of the part. This has been studied a lot; many methods for manipulating deformation have been proposed; such as rotary quenching, die quenching, oil handling methods for controlling parts, etc. [11,13;18]. The study by Beck et al. When the transition temperature to the jubilant period is too high; the large cold speed and the large thermal stress cause the austenite attack at the low yield point to deform and cause distortion of the part. Lübben et al. Non-uniform oil immersion between parts or parts; especially the use of new oil is more likely to present this scene. Tensi et al. thought that the cooling rate at Ms point has a decisive effect on deformation; the temperature at Ms point and below is low. The cooling rate can reduce the deformation. Volkmuth et al. [13] systematically studied the quenching medium (including oil and salt. ┒ 沧 沧 鲎 鲎 鲎 谕馊 慊鸨湫 慊鸨湫 慊鸨湫 慊鸨湫 慊鸨湫 慊鸨湫 慊鸨湫. The results indicate: because the cooling method is not the same; ferrule The diameter will have a different degree of "increasing"; and with the advancement of the medium temperature; the diameter of the ferrule at the end of the diameter tends to be common; that is, the "horn" deformation is reduced. The 惶 Φ Φ 耐 耐 耐 耐ヒ痪 蚱 蚱 蚱 婺诘 侗涠 侗涠 侗涠 侗涠 侗涠 d d d d d d d d d 侗涠 侗涠 侗涠 侗涠 侗涠 侗涠 侗涠 侗涠 侗涠 谌 谌
The dimensional stability of parts after martensite quenching and tempering is mainly affected by three different transformations [12,14]: carbon migration from martensite lattice constitutes ε-carbide, residual austenite differentiation and composition of Fe3C The three transitions are superimposed on each other. Between 50 and 120 ° C; because the deposition of ε-carbide is separated; the volume of the part is reduced. 懔慵 After 150 ° C tempering, this transformation has been completed; The effect of dimensional stability can be neglected between 100 and 250 °C; residual austenite differentiation; transformation to martensite or bainite; with accompanying volume increase, above 200 °C; ε-carbide carburization Volume transformation; incurs volume reduction. The study also indicates that the remaining austenite can also differentiate under the effect of external load or at a lower temperature (or even at room temperature); incurring changes in the scale of the part. Thus; in practical use; The tempering temperature of the bearing parts should be higher than the operating temperature of 50 °C; the parts with higher requirements for dimensional stability should be reduced as much as possible of the retained austenite; and a higher tempering temperature is selected.

Recommend to friends comments close window

Bearing related knowledge
The bearing defects in the grinding process constitute the spiral wire. The new process technology of the anti-friction layer of the sliding bearing is analyzed: the functional requirements of the motor bearing grease
NSK bearing device cooperation method Wheel bearing equipment matters


This article links to http://
Please indicate China Bearing Network http://

Previous:Inspection of the thrust bearing device Next:The key to the bearing protection skills of the pump

LED Grow Light For Indoor Plants

Advantages of LED Grow Light for indoor plants:

  • Full spectrum. Ideal for all stages of plants growth, from seedlings to flowering to harvets.
  • No worry about dark and terrible weather. You plants can be under light all the time if you open the light all the time. Growing withought resting.
  • Shorten growing cycle but increase yields quality and quantity.
  • Energy saving. LED grow lamp is efficient light only consume less energy put output powerful light. Environment friendly and saving bill.
  • Long lifespam. LED is durable and with long life 50,000 hours. Which also ensure you lower maintenance cost. Traditional HPS MH grow lights is very easy to fail and almost need to change each year.
  • Better for plants growth. LED grow lights are usually with full spectrum, Plants can use nearly all the light emitted from led grow lights. But usually only 35% of light generated by MH HPS is useful for plants growth.
  • Low heat output. LED grow lights produce very little heat, and they usually with fans or efficient dissipation heat sink. Ensure better growing environment to plants. Traditional lights usually delivery lots of heat. It's very hard for plants especially in summer.


Available AGLEX LED grow lights.

C Series led Grow Light : cob 600w 1200w 2000w 3000W LED Grow Light, with advanced cob technology, focusing lighting, ensure high ppfd. And this series led grow lights are with veg bloom switches, you could change spectrum from seeding to flowering. And they are daisy chained. easy to use and install.


G series led grow light: G110w G220w led grow light. This series led grow lights are with compact shape, suitable for small space. But they are powerful with samsung leds and reflector. and it's waterproof.


K series led grow light: K1000 K2000 K4000 led grow light, with dimmer. Freely to adjust lighting intensity according plants needs. when seedling, turn dowm it, when flowering, turn up. And down at night, up at noon. Very convenient. The K4000 with a specially design, it can be fold up. easy to carry and install.


L series led grow light: 700w led grow light is a decent light, foldable and dimmable and you could add controller. 700w powerful led grow light is great for weed. PPE 2.8-3.0 μmol/J. Spider grow light design can delivery uniform light, great for weed growing.


M series led grow light: 240w 320w 400w 600W LED Grow Light. This series led grow light is like L700 with dimmer and foldable. They also with spider design. but it with external driver. So you could put driver out of tent, ensure lower heat and easy to control.


If you want to see more, please contact us for details.


led grow light for indoor plantsled grow light 200wled grow light full spectrum

Indoor Plant Grow Light, 100W COB Grow Light, Spectrum LED Grow Light, Kingbright grow light

Shenzhen Ameri Technology Co., Ltd. , https://www.aglexz.com