Heat treatment development process
 
(1) clear heat treatment
 
Heat treatment of the formation of the production waste water and gas, FeiYan, dust, noise and electromagnetic radiation etc all can cause to the environment pollution. To solve the heat treatment problem of the pollution of the environment, a clean heat treatment (or says the green environmental protection heat treatment) is the developed countries heat treatment technology and its development direction of one. To reduce SO2, CO and CO2, dust and coal emissions, has basically eliminate the use of coal as fuel, heavy oil in the use of less and less to the majority of light oil, natural gas, is still the most ideal fuel.
Furnace of waste heat utilization has reached a high degree, burner optimization and empty fuel-than the strict control of the guarantee reasonable under the premise of burning, NOX and CO reduce to lowest level; Use gas carburizing, carbon and nitrogen were permeability and vacuum heat treatment technology substitution treatment to reduce salt bath containing CN-FeiYan and toxic substances for water pollution; The synthesis of quenching oil instead of water quenching oil, using biodegradable vegetable oil to replace some mineral oil to reduce oil pollution.
 
(2) precision heat treatment
 
Precision heat treatment two meanings: on the one hand is the use of parts according to requirements, material, structure size, use physical metallurgy knowledge and advanced computer simulation and testing technology, the optimization of process parameters, to the required performance or maximize the potential of materials; On the other hand is fully guarantee the stability of the optimization of process, and realize the product quality dispersion is small (or zero) and heat treatment distortion is zero.
 
(3) energy saving heat treatment
 
The scientific production and energy management is the effective utilization of energy most potential factors, establish a professional hot treatment plant to ensure full load production, give full play to the equipment ability is the choice of scientific management. In terms of energy structure heat treatment, preferred choice a energy; Make full use of waste heat, waste heat; The low energy consumption and short cycle technology instead of cycle is long, energy consumption of technology and so on.
 
(4) less without oxidation heat treatment
 
By using alternative protective atmosphere heating oxidation atmosphere heating to precise control of carbon potential, nitrogen potential controlled atmosphere heating, heat treatment parts of the performance improved, heat treatment, such as crack defects, such as decarburization greatly reduce, heat treatment, after finishing a decrease, improve material utilization ratio and machining efficiency. Vacuum add heat quenching, vacuum or low voltage carburizing and seepage nitrogen, carbon and nitrogen of permeability boronizing etc can greatly improve the quality and reduce distortion, improve life.
Heat treatment technology application effect
 
(1) expanded GCr15 steel application scope, generally GCr15 steel M hardened effective wall thickness in collar 12 mm the following, but because XiaoYan BL quenching cooling ability strong, if the stirring, dynamic and measures of water, rings the effective wall thickness can be expanded to 28 mm or so.
 
(2) hardness stability, good uniformity
Because change is a slow BL process, general GCr15 steel need 4 h, GCr18Mo steel need 5 h, long time XiaoYan rings in isothermal, surface microstructure transformation of heart almost at the same time, so the hardness stability, good uniformity, general GCr15 steel BL after quenching in 59-61 hardness HRC, uniformity than 1 HRC, don't like hardened wall thickness slightly bigger rings appeared low hardness, soft point, uniformity poor etc.
 
(3) decrease quenching, grinding crack
In the railway, rolling mill bearing production, the size, weight heavy rings, oil hardened M organization brittleness is big, to make harden get high hardness often take strong cooling measures, the result of micro cracks quenching; And BL quenching, as the BL organization than M organization toughness good much the same surface formation as high as 400-500 MPa pressure stress, greatly reducing the quenching cracking tendency; In the grinding process surface compressive stresses to offset the grinding of stress, make whole stress levels drop, greatly reducing the grinding crack.
 
(4) bearing service life improved
To withstand large impact load of railway, rolling mill bearing, etc., the M hardened when using main failure form for: when the assembly of inner sleeve craze, use process by shock raised edge DiaoKuai, inner circle between fracturing, and because the isothermal quenching bearing impact toughness, good surface compressive stress, no matter when the assembly of inner sleeve craze, or use process of Chinese and foreign
DiaoKuai raised edge, in the set of fractured greatly decreased orientation, and can reduce the edge of roller stress concentration. Therefore, after the isothermal quenching than M after quenching average life expectancy and reliability.




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