Heat the course of development
(1) Clean the heat treatment
Wastewater, waste gas, waste salt, dust, noise and electromagnetic radiation and so on heat production causes environmental pollution. Solve the heat problem of environmental pollution, the implementation of the clean heat treatment (or green heat treatment) is one of the direction of the heat treatment technology of developed countries. Reduce so2, co-co2, dust and cinder emissions, has been basically put an end to the use of coal as fuel, the use of heavy fuel oil is less and less, switch to the majority of the light oil, natural gas is the ideal fuel.
Has reached a very high level waste heat utilization of the combustion furnace, burner structure optimize and air - fuel ratio of strict control to ensure reasonable combustion under the premise of nox and co reduce to a minimum; gas carburizing, carbonitriding and vacuum heat treatment technology to reduce waste containing salts and cn-toxic water pollution alternative to salt treatment; synthetic water-soluble quenching oil instead of part of the quenching oil, the use of biodegradable vegetable oil instead of part of the mineral oil to reduce oil pollution.
(2) precision heat treatment
Precision heat treatment has two meanings: the one hand, the requirements are based on the use of parts, materials, structure size, the use of the knowledge of physical metallurgy and advanced computer simulation and testing technology, optimization of process parameters to achieve the required performance or to maximize their material potential; the other hand, is sufficient to ensure optimization of process stability, product quality dispersion is small (or zero) and heat treatment distortion is zero.
(3) energy-saving heat treatment
Scientific production and energy management is the efficient use of energy, most potential factors, the establishment of a specialized heat treatment plant in order to ensure full capacity, give full play to the equipment capacity is the choice of scientific management. Heat energy structure, the first choice of primary energy; take full advantage of waste heat, waste heat; low power consumption, short cycle process instead of a long cycle, energy-consuming process.
(4) less non-oxidative heat treatment
By the use of protective atmosphere heating alternative to controlled atmosphere heating, part of the performance is improved after heat treatment, heat treatment defects, such as decarburization, cracks, etc. greatly reduced, the heat treatment after finishing allowance to reduce the oxidizing atmosphere is heated to precisely control the carbon potential, nitrogen potential to improve the efficiency of utilization of materials and machining. Vacuum plus hot gas quenching, vacuum or low pressure carburizing, nitriding, nitrocarburizing and boriding can significantly improve quality and reduce distortion, and increased life expectancy.
Heat treatment technology effect
(1) expand the scope of application of the gcr15 steel, general steel gcr15 m quenching when the ferrule wall thickness 12mm below bl quenching saltpetre cooling ability, the use of a stirring, string action, add water and other measures, rings The effective wall thickness can be expanded to about 28mm.
(2) hardness and stability, good uniformity
Bl change is a slow process, and general gcr15 steel required 4h, gcr18mo steel required 5h, rings in the nitrate time waiting for temperature, the surface of the heart, organization into almost the same time, so the hardness and stability, good uniformity, is generally gcr15 steel bl The hardness after quenching 59 ~ 61hrc, uniformity ≤ 1hrc, unlike the quenching ring wall thickness slightly larger on the low hardness, soft spots, and poor uniformity.
(3) to reduce quenching, grinding cracks
In the production of railway, rolling mill bearing, ring size and weight, oil quenching m organization brittleness, often take a strong cooling measures so that after quenching, high hardness, resulting in quenching the microcrack; and bl quenching the bl organization better toughness than m organization, formed on the surface compressive stress of up to -400 ~-500mpa greatly reduce the quench cracking tendency; offset some of the grinding stress to compressive stress in the grinding surface, and the overall level of stress decline, greatly reducing the grinding cracks.
(4) bearing service life
[object Object]
Under impact loading of the railway, mill bearing, m after quenching the main failure in the form of: sets of cracks within the assembly during use by the impact of outer ribs off blocks, inner fragmentation, isothermal quenching bearing impact toughness, and surface stress, regardless of sets of cracks within the assembly, or use the process of coat ribs off blocks within the set of fragmentation tendency is greatly reduced, and can reduce the roller edge stress concentration. Therefore, upon isothermal quenching quenching than m, the average life expectancy and reliability improved.



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