Specifications: diameter: 320 to 127 mm thickness: 0.4 to 12.7 mm Length: 6 m above, and, in accordance with customer demand, supply and other specifications of steel pipe

45# steel pipe and 40Cr seamless steel pipe quenching heat t

45 # and 40Cr seamless steel quenching heat treatment process
General structure of the tube
40# carbon steel pipe
45# seamless steel pipe
Apply to the general structure, engineering support, mechanical processing, etc
40cr Seamless Alloy Steel Pipe for Military Industry

we product 40Cr alloy steel pipes
1.OD: 1-820mm
3.Length:5.8m,6m,12m or as the requirement
40 cr,40cr seamless alloy steel pipe

Quenching is hardening plus hot tempered double heat treatment , which aims to make the workpiece has a good overall mechanical properties. 
  Quenched and tempered steels are carbon steel and alloy quenched and tempered steel two categories, either carbon steel or alloy steel, the carbon content of more stringent controls. If the carbon content is too high, the strength of the workpiece after quenching may be high, but the toughness is not enough, as the carbon content is too low, increase the toughness and lack of strength. In order to get a good piece quenched overall performance, the general control of the carbon content of 0.30% to 0.50%. 
  When the tune of hardened, requires the entire cross section of the workpiece hardenability of the workpiece with a fine needle to obtain quenched martensite microstructure dominated. By tempering obtain uniform sorbite oriented microstructure. Small plants can not engage each furnace metallurgical analysis, generally for hardness testing, which is to say, the hardness after quenching must meet the material quenched hardness, hardness Figure request to check after tempering. 
  Workpiece quenching operation must be in strict accordance with the implementation process documents, we are just on the procedure of how to implement the process to ask some opinions. 
  1, 45 quenched and tempered steel 
  pipe 45 is in carbon steel, hot and cold processing performance are good, good mechanical properties, and low prices, wide source, so widely used. Its biggest weakness is low hardenability, cross-sectional dimensions of Japanese high demand artifacts should not be used. 
  No. 45 steel quenching temperature in A3 + (30 ~ 50) ℃, in practice, is usually taken ceiling. High quenching temperature to heat the workpiece speed, reduce surface oxidation, and can improve work efficiency. To make the workpiece austenite homogenization, we need sufficient holding time. If the actual installed furnace capacity, would be appropriate to extend the holding time. Otherwise, there may be insufficient due to uneven heating caused by the hardness of the phenomenon. However, the holding time is too long, will also appear coarse grains, oxidation and decarbonization serious ills affecting quenching quality . We believe, as installed furnace is greater than prescribed process documents, heating holding time need to extend 1/5. 
  Because No. 45 steel hardenability low, it should be large cooling rate 10% saline solution. Workpiece into the water, should hardenability, but not cold through, if the workpiece in cold saline through, it is possible to make the workpiece cracking, this is because when the workpiece is cooled to about 180 ℃, the austenite into martensite caused rapid Stress caused by excessive. Therefore, when the fast-cooling to the hardening of the workpiece temperature region, it should take the slow cooling method. Because the water temperature is difficult to grasp, accountable operating experience, when the workpiece stop dithering water, the water can be air-cooled (if they can be better oil cooling). In addition, the workpiece should move into the water should not be static, should be in accordance with the geometry of the workpiece, as the rules of sport. Stationary cooling medium plus stationary workpiece, resulting in uneven hardness, stress leaving uneven workpiece deformation, even cracking. 
  45 pieces of steel tone quality hardness after quenching should reach HRC56 ~ 59, the possibility of some low-profile big, but not less than HRC48, otherwise, it shows the workpiece is not fully hardened, the organization may appear even ferrite sorbite body tissue, this tissue by tempering, still retained in the matrix, reach quenching purposes. 
  No. 45 steel tempering after quenching, the heating temperature is usually 560 ~ 600 ℃, hardness is HRC22 ~ 34. Because the purpose of quenching is to get a comprehensive mechanical properties, so the relatively wide range of hardness. However, there are drawings of hardness, it is necessary to adjust the tempering temperature by drawing, in order to ensure hardness. For example, some shaft parts requiring high strength, hardness is high; and some gear, shaft parts with keyway, because after quenching also for milling, insert processing, hardness is lower. About Tempering time, depending on the hardness and size of the workpiece, we believe, depends on the hardness after tempering tempering temperature, tempering time with little to do, but it must go back through the general workpiece always Tempering time more than one hour. 
  2,40Cr quenching of steel 
  Cr can increase the hardenability of steel, increase strength and stability tempered steel, with excellent mechanical properties. Sectional size large or important piece of quenched and tempered, Cr steel should be used. But there is a second class Cr steel temper brittleness. 
  40Cr workpiece quenching quenching tempering process card has prescribed various parameters, we realized in practice is: 
  (a) should be used after 40Cr quenching oil cooling, 40Cr steel hardenability better, in oil cooling can be hardened, and the deformation of the workpiece, cracking tendency small. But small businesses in the oil supply tight, not complex shape of the workpiece can be quenched in water, found no cracking, but the operator must strictly control their experience into the water, the water temperature. 
40cr alloy pipe
  After the (two) 40Cr quenched hardness of the workpiece is still high, the second tempering temperature will increase 20 ~ 50 ℃, otherwise, the hardness decreased difficult. 
  (C) 40Cr workpiece after tempering, complex shapes in oil cooling, a simple water cooling, the purpose is to avoid the impact of the second temper brittleness. Workpiece rapid cooling after tempering, if necessary, and then subjected to stress relief treatment. 
  Influence quenched workpiece quality level operatives is an important factor, but there equipment, materials and tone processing precursors to various reasons, we believe that: 
  (a) the workpiece is transferred from the furnace to a cooling tank slowly, workpiece into the water temperature has dropped below the critical point Ar3, resulting partially decomposed, the workpiece is not completely quenched get organized, reach hardness requirements. So pay attention to small parts coolant velocity, large parts I want to master the cold time. 
  (B) the piece installed furnace capacity to be reasonable and appropriate level of 1 to 2, resulting in uneven heating of the workpiece overlap, resulting in uneven hardness. 
  (C) the arrangement of the workpiece into the water should be kept at a distance, through the dense vapor membrane rupture near the workpiece is blocked, resulting in close to the low surface hardness of the workpiece. 
  (D) hardening furnace, can not breath quenching finish, depending on the oven temperature should be the extent of decline in the middle of re-heating furnace closed for consistent hardness after quenching the workpiece. 
  (E) to note the temperature of the cooling liquid, such as a 10% brine temperature is higher than 60 ℃, can not be used. Coolant can not have oil, mud and other impurities, otherwise, there will be insufficient or uneven hardness. 
  (Vi) unprocessed rough quenched hardness is not uniform, if you want to get good quality quenched and tempered, rough should roughing, to be forged bar. 
  (Seven) strict quality control, low hardness after quenching from 1 to 3 units, the tempering temperature can be adjusted to achieve the hardness requirements. But after quenching hardness of the workpiece is too low, or even only HRC25 ~ 35, must be re-quenching, must not only impose or tempering temperature to reach the drawings get away, or lost the meaning of quenched and may produce serious consequences.

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