The effective control of crackle of large forging miscellaneous sex reachs processing

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1. Summarize large forging to serve as important or crucial part, the crucial device that already was used extensively at the industry place such as heavy machinery, the sources of energy, metallurgy, mine, enginery, aviation, spaceflight, oil, chemical industry. Accordingly, large forging produces horizontal on any account, be regarded as to measure industry of a nation to develop horizontal standard on certain level, important place is had in national economy. Cake kind with module kind the main product that forging is large forging, cake kind forging includes turbine boiler to use carapace of pressure of tube plate and impeller, nuclear reactor to make the same score bottom of container of tube plate of coping, heat exchanger, chemical industry to seal first class, and module forging basically is used do those who make all sorts of compressor and forging hammer to forging tool. In actual production, percent defective of this kind of forging is tall, manufacturing difficulty is great, the report in production is the most serious is problem of crackle of sex of be mingled with. As a result of the influence of a variety of elements, there is the field trash of all sorts of types inevitably inside the steel ingot that large forging uses. To ab extra field trash, the method that solves a problem is relatively simple, in can adopting all measure to prevent them to enter steel, what the academic research of this respect and actual application job undertake in recent years is more, progress is very great. And to inside unripe field trash, the problem is about many complex, because they are the component of steel, although it is its amount, size, appearance, OK to distributing to wait with composition,get ameliorative, but avoid completely impossibly absolutely. The existence of these field trash reachs his to change mediumly in forming, formed crackle of sex of generation be mingled with the mainest because of,move. In the steel such as the 5CrMnMo of commonly used material of forging of the 20MnMo of commonly used material in tube plate forging, module, the mainest metalloid be mingled with is sulfide (it is a delegate with MnS) , aluminous acerbity salt kind (it is a delegate with aluminous acerbity calcium) reach a few oxide be mingled with, and hot forge crackle basically arises wait for plasticity field trash at vulcanization manganese around. In cake, piece of kind of forging forging in the process, below inhomogenous metabolic action, the metallic flow of forging core is far relatively all round more acuteness, the polymerization of crackle is more easy. Consequently, the blemish of generation more also, size is larger. Accordingly, study the mechanism that crackle of sex of be mingled with forms, discuss the possibility of rehabilitate of this kind of crackle, forging through the change craft achieves pilot goal, it is a task of very significant sex of course forward position. 2. The formation of crackle of sex of be mingled with we know, all sorts of field trash that exist in steel ingot are the main reason that produces problem of quality of large forging interior, along with the addition with forging and steel ingot heavy sheet, contradiction is more outstanding. However, be out of shape in plasticity to field trash the analysis with the more thorough problem such as the relation between the behavior in the process, field trash and crackle of sex of be mingled with considers to be lacked very. To solve plasticity be mingled with to be affected to metallic matrix metabolic, we are used contain plasticity be mingled with and the model sample that do not contain be mingled with to be in have recrystallization was out of shape undertake compression a test below the condition with what do not have recrystallization. It is when deformation 15% when, gets cloud grain picture. Inside the plasmodium that does not contain plasticity be mingled with, of Yun Wen distributinging basically is even equidistant, be out of shape namely distributing equably; And in be out of shape the condition falls likewise, in the top position of field trash, the directional cloud grain that becomes 45 ° part about with horizontal axis is relatively concentrated, and other place becomes few and far between relatively. When occurrence recrystallization, all the more of this kind of circumstance is serious, be out of shape inhomogenous degree mushroom. You Yunwen pursues, calculate and draw gives corresponding equivalent meet an emergency to distributing. Can see, in the model sample that does not have be mingled with, the numerical value of equivalent meet an emergency all is in 0.

1 ～ 0.

2 between, and distributing even; And when be mingled with should be being contained in sample, the drawing near in field trash inside area, the local concentration of equivalent meet an emergency the phenomenon is more apparent, gradient of meet an emergency increases, there is big plasticity to be out of shape in the way that becomes 45 ° part with axis of field trash level of the area outspread; When having recrystallization, not only and apparent cut belt appear, and the numerical value that cuts the limits of the belt and equivalent meet an emergency also is increased. afore-mentioned results and metabolic of most advanced to crackle plasticity imperceptible view observes gets result undertook contrast, can think, the meet an emergency of field trash top distributings with the meet an emergency after crackle top passivation basically is consistent. Can solve according to skid wire theory piece, in the forward position direction of field trash top, stress value is contented the physical phenomenon that goes to earning and on type undertakes integration analysis, attainable undermentioned conclusion: 1) because plasticity field trash is in by squash,metallic matrix interior produces a stress, meet an emergency to center an area (influence area) , the incidence of this area is: Double what in field trash top forward position direction is 2Rb of field trash ply about; 2) the peak value that stress amasses reachs the unit deformation force that brings to bear on to be in hereat to concern with the characteristic parameter K of material itself only; 3) if bring to bear on,be worth at the dead water pressure of field trash area not quite big, those who produce horizontal way will arise to pull stress inside area of concentration of the stress in field trash top, meet an emergency, namely σ X ＞ 0; 4) the biggest the way that the effect way that cuts stress is affecting the top of the area and horizontal axis to become 45 ° part, namely the greatest shearing stress direction. These apparent phenomena, accord with imperceptible view crackle to be in the behavior of patulous phase. Can think consequently: In plasticity metabolic process, plasticity field trash is beginning metabolic instantaneous, namely by micro-crack produce entered its patulous phase. Field trash by the process of squash, can regard crackle most advanced passivation the patulous process of micro-crack. 3. The rehabilitate of crackle of sex of be mingled with is current, fine view injures the conclusion that process place gives out to metallic stuff in mechanical research, apply to the analysis of the injury in material cold working and figuration limit problem only commonly. Below cold working condition, scathing happening and development are process of one one-way growth, injure what variable can last only to increase namely. But in fact, the metal falls in hot-working condition, the development of microcosmic injury got some is planted the inhibition of the mechanism, its influence makes while micro-crack is patulous, have one reversible repair process. Many experimental result makes clear [1] ; Crackle of sex of be mingled with is by many shape be mingled with (micro-crack) the aggregate crackle system that causes loss. Be in a shape field trash between, cut crackle place to join for what bullion belongs to matrix. Piece space of shape be mingled with metallic matrix, this kind of injury is not repairable; And the crackle part between pure metal matrix is possible below certain condition, through the metal between diffuse reach other action and repair. In crackle in the process from repair, the change that metallographic organizes near crackle. Pass the observation to sample and analysis, can be the repair process cent of crackle two phase: 1) crackle locates empty stuff: In the initial stage of repair process, crackle is empty partial bulk by as same as base metal component metallic place stuff. Filler is comprised by very petty grain, contain many microscopical hole, the interface of fill part and matrix is clear; 2) grain is grown: The petty grain inside fill area is brought up gradually, the interface swoon of filler and metallic matrix, in filler microscopical hole size and amount are reduced gradually, till the grain inside fill area and matrix are identical. Those who be mensurable descriptive crackle from repair process, we were measured actually with acoustical microscope different heat below temperature and heat preservation condition, the percentage of crackle rehabilitate. Crackle repair rate is main and controlled at heating temperature; To given experimental data, when prep above of heat preservation time when 15 minutes, continue to increase heat preservation time relatively lesser to the contribution of crackle rehabilitate. To certain metallic material, below the condition of close-up, its in-house crackle plays the discovery that self-educated reproduction resembles in high temperature condition, it is very significant, to its mechanism still remains at further research. 4. Control crackle of sex of be mingled with effectively forging on the foundation that technique studies in imitate, apply already some research conclusion, gave out respectively: One ingot forgings large reach oversize cake kind forging, one ingot forgings many times large and medium-sized cake kind forging of forging, close quadrate module and forging of board form module wait for what blemish is characteristic 4 kinds this to forging with controlling crackle of sex of be mingled with craft. The purpose of this kind of technique, it is namely in the process of forging figuration, outside achieving a requirement except precision of forging external dimension, have synchro control to forging interior quality even. Length of be confined to, be opposite only here in large cake kind in the craft formulate of forging, except forging by convention technology is certain outside partial craft parameter, the criterion branch that still should follow lists as follows: 1) control beforehand when Dui thick deflection produces tube plate forging with common steel ingot, no matter hole and loose squeezing ramming rely on to unplug long operation still relies on Dui thick operation to come true, undertake to steel ingot beforehand Dui is thick it is inevitable. The result that imitate studies makes clear, h/D of ratio of height to diameter is in 0.

6 ～ 2.

The 0 steel ingot between, the Dui thick deflection that crackle of sex of in-house small be mingled with begins group is 50% . The further action that is out of shape considering sequel to forging core be mingled with is extended, of steel ingot beforehand Dui thick deflection should be controlled in 40% the left and right sides is advisable. If need to reduce the height of forging further, can use rotate to come down to come true into anvil pressing. 2) assure what squeezing ramming place needs to be out of shape common steel ingot produces craft parameter cake kind when forging, because Dui is thick,compare big, general steel ingot is in-house hole, loose wait for blemish to be possible in the process of figuration by squeezing ramming. Weight of Dan Regang ingot is great and press tonnage is small, or finished product forging is thicker, appear likely the condition that cannot obtain squeezing ramming to ask. Accordingly, when using FM law to forging, should satisfy anvil wide than W/H ＞ 0.

6, bosseyed press ＞ issueing an amount the requirement of 15% . 3) control eventually forge fire second the pace before reaching deflection to be repair forgings the possibility in craft arises, the crackle of sex of be mingled with with visible flaw detection, the requirement is in common forging in craft, increase right eventually forge fire second the control requirement with deflection. Because forging interior is not complete,be issued to be OK in certain condition by the crackle of field trash space of repair. Specific when carrying out, after can returning semi-manufactured goods forging furnace, heat preservation falls in high temperature, the hole that makes crackle is in forging interior by sufficient fill, the deflection that needs by squeezing ramming place next undertakes eventually forge is out of shape reach plastic, what squeezing ramming interior still exists is microscopical the dimension requirement that hole achieves pair of forging. Right eventually forge fire second have pilot another purpose is to use the high temperature of forging to stop forge effect, in order to make sure forging interior agrees of grain dimension equably, avoid to mix the happening of brilliant phenomenon. Because the size of grain dimension can pass follow-up heat treatment to undertake modulatory, but mixing brilliant is hard to change. 5. Citing of actual application effect 5.

1 forginging the application in craft is on 84MN water press, press afore-mentioned technique, formulate by one ingot a means produces ф the tube plate forging of 1620 × 420mm forgings craft, cast makings organization to produce forging of 8 tube plate. Detect via supersonic flaw detection confirm: Forging all sorts of detecting index is accorded with entirely " JB3963 - 85 " pressure vessel forging is supersonic flaw detection standard. photograph contrast, by former common forging the ratio of defects of flaw detection of manufacturing statistic eventuate that craft produces this kind of forging 44.

1% , percent defective 14.

7% . With afore-mentioned technique, on 25MN water press, successfully organization produced forging of tube plate of stainless steel of more than tons of 100 austenite. In addition, some factory is with this technique on 125MN water press, produced two to exceed forging of large and quadrate tube plate, via examining complete qualification. Current, forging of large to what discard as useless because of crackle of sex of be mingled with module is general in the factory handle with law changing forge, be about to after big forging heats, cut forging afresh for small forging, basic won't reappear reject. This also was to use the crackle below high temperature condition actually the principle from repair, but serve as a kind of not self-conscious application only. For this, we put forward to have finished product measure to the large module forging that discard as useless changeless forging afresh method, undertook productivity experiments, the large module forging that result classics forgings afresh is all and eligible. 5.

The application of law of 2 self-educated compound is from repair method to inspect crackle in large forging production applied possibility, the large forging that in using production, examines to already discarded as useless via supersonic flaw detection undertook sex of test and verify experiments. The experiment is the forging of large tube plate that discards as useless with 5 undertakes, because the dimension of forging of finished product tube plate is unalterable, reason can undertake high temperature is handled only. According to the material of forging of different tube plate and dimension, decided heat time, heat heat preservation time and temperature, temperature. After high temperature of afore-mentioned classics of tube plate forging are handled again flaw detection detects confirm, among them blemish of two flaw detection is eliminated completely, forging quality accords with national level completely, leave factory as eligible forging; Additionally two have apparent effect, flaw detection discovers the limits of blemish of crackle of sex of be mingled with already reduced ф 300mm by ф 900mm, and the equivalent of single defect also drops by ф 14mm ф 9mm is the following, forging is basic and eligible. The rod that some factory used this method to handle 6 to had discarded as useless kind forging, via detecting complete already qualification leaves factory. The actual application above explains, crackle has theoretic sense not only in the rule of the rehabilitate below high temperature condition, and having more extensive real sense, forginging this kind of law is used in production, the in-house quality to raising forging, reduce cost, rise become a useful person rate, it is tremendous that its use latent capacity. To important or large structural member of injury discovering in actual application, also can undertake similar processing, have better applied prospect. The research work of the article is only germinant, still remain to develop at development. 6. Conclusion 1) the imitate result that forms mechanism to crackle of sex of be mingled with makes clear: Be out of shape in plasticity in the process, be produced in base metal interior by the plasticity field trash of squash a stress, meet an emergency centers an area. Can field trash by the process of squash, regarding is crackle most advanced passivation small cracked patulous process. 2) the research result that self-educated to material interior crackle reproduction resembles makes clear: The repair speed of crackle to heating temperature has stronger dependence action, lengthen heat preservation time to have certain stimulative effect from repair to crackle. Below constant temperature and condition of heat preservation time, micro-crack is OK by repair. 3) to the tube plate that already discarded as useless, module and axis kind the result that the productivity repair that forging place has experiments makes clear: The crackle of sex of be mingled with in major large forging can come through specific processing technique repair. The further development research of large to this kind forging and even method of rehabilitate of crackle of interior of large structural member and craft is a kind of resource that has great latent capacity, have very remarkable economic benefits and social beneficial result. 4) the large forging that controls crackle of sex of be mingled with effectively forgings main technique characteristic of the method is: Of ① control steel ingot beforehand Dui thick deflection, in order to control the generation that the form appearance of field trash reduces crackle of sex of be mingled with; ② has the squeezing ramming, control that breaks casting appearance organization and forging homogeneous deformation into pieces to the whole process of forging figuration working procedure, in order to improve the in-house quality of forging; ③ is controlled eventually forge fire second heat reach forging operation, remove the limitation of crackle of sex of be mingled with that produces possibly; ④ uses high temperature to stop forge effect to restrain the happening of the phenomenon that mix brilliant. The application of aborning of this kind of method makes clear as a result, this technique can control crackle of sex of the be mingled with in forging of large tube plate, module effectively to wait forging blemish, can raise the n of forging greatly, have considerable economy and social beneficial result, be worth to be popularized energetically. CNC Milling CNC Machining