CN1026499C - Heat treatment of corrosion resistant steels - Google Patents
Heat treatment of corrosion resistant steels Download PDFInfo
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- CN1026499C CN1026499C CN 89104431 CN89104431A CN1026499C CN 1026499 C CN1026499 C CN 1026499C CN 89104431 CN89104431 CN 89104431 CN 89104431 A CN89104431 A CN 89104431A CN 1026499 C CN1026499 C CN 1026499C
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Abstract
The present invention relates to a heat treating method for corrosion resistant steel pieces, corrosion resistant steel is preferably in a curly mode and has transition temperature between 650DEG C and 850DEG C for that an austenitic part is converted into ferrite and carbide. The corrosion resistant steel also has a composition which makes that the steel preferably has the following obvious mechanical properties: 350MPa of proof stress, 520MPa of ultimate tensile stress, 25 percent of an elongation rate and one hundred and sixty five of brinell hardness, and Martensite microstructures generally disappear in cooling speed lower than 5 DEG C /min. The method comprises the steps: heat processing is carried out on the steel pieces under the transition temperature; the steel pieces on which the heat processing is carried out are cooled to be lower than the transition temperature, and the cooling speed is between 10 DEG C/min and 1 DEG C /min, so that the Martensite microstructures disappear for the entire steel pieces.
Description
The invention relates to corrosion-resisting steel, particularly about non-austenite Heat Treatment Of Steel.
In general, corrosion-resisting steel more or less all contains chromium, and major part is used for producing the rolling steel plate or the steel sheet of all thickness.These steel normally take out molten steel by ladle and pour in steel billet or the steel ingot and cast continuously from smelting furnace, then steel billet or steel ingot are carried out hot rolling and handle, and steel plate that will come out from hot rolls or steel sheet material are reeled, and cool off under envrionment conditions then.Then this steel are heat-treated, comprise reheat processing and annealing or temper.Steel has the desired mechanical properties of design when this annealing or tempering stage finish.
Producing the steel in this stage can be sold, or by cold rolling further reduction thickness.
Generally speaking, usually consider sell or cold rolling before all coils of hot-rolled steel are annealed or temper.
Heat treatment process can be:
A. continuous annealing or temper.At this, coil of strip is unfolded delivers to the processing stove, is incubated under the temperature of a certain specific grade of steel being suitable for.Typical example is that for the 3Cr12 steel of selling on the market by name, temperature is approximately 750 ℃.
B. another kind of method adopts batch annealing to handle, and wherein one or more coil of strips is placed that a suitable stove heats, insulation and refrigeration cycle, thereby finishes necessary annealing or tempering.Batch annealing needed whole time of circulating is depended on the quality of coil of strip, the performance characteristic of equipment and equipment, but need 30 to 40 hours time for a collection of 30 tons of coil of strips usually.
C. also have a kind of method, can be cut into suitable length to steel, and in a certain equipment such as roller bottom type annealing furnace, each steel section is annealed.
Usually adopt the corrosion-resisting steel of above-mentioned treatment process in trade, to sell, and have following application respectively by following trade name:
Treatment process A
Aforesaid 3Cr12-needing to be used for the mild corrosion environment of good welds characteristic.
Treatment process B
4003-container steel.
Treatment process c
409-uses with limitation, as is used for exhaust system.
The 410-cutter
As mentioned above, all these steel and the treatment process that is adopted all need to use the annealing furnace of certain form, and this just relates to a large amount of capital consumption on production and equipment.
The purpose of this invention is to provide a kind of heat-treating methods and do not adopt annealing furnace to produce the equipment of corrosion-resisting steel.
According to the heat treating method of a kind of anti-corrosion steel part provided by the present invention, wherein corrosion-resisting steel has the transformation temperature A that (1) austenite changes to ferrite and carbon body
3Between 650 ℃ and 850 ℃, (2) make steel have usually the composition of following mechanical property-
Proof stress 350 MPas
Tension ultimate stress 520 MPas
Unit elongation 25%
Brinell hardness 165
And being lower than 5 ℃/timesharing in speed of cooling does not occur the little present method of organizing of martensite basically and comprises:
At above-mentioned A
3Hot-work steel part under the transformation temperature; Steel part after the cooling heat processing is to being lower than transformation temperature, and speed of cooling martensitic microstructure do not occur to guarantee whole steel part between 10 ℃/minute and 1 ℃/minute.
According to the present invention, another feature comprises the calorific loss that prevents that steel part is too much, partly airtight steel part in insulating container, and the insulating container internal surface can comprise heat-reflecting body.
According to the present invention, also having a feature is the insulation liner that insulating container can have a non-conduction, and the bottom can be opened wide and can be suitable for above steel part toward transferring.
According to the present invention, also having a feature is that steel part has the designed material composition of the non-austenitic microstructure corrosion-resisting steel of generation, and preferably the material composition of steel part is in the scope of following ingredients (weight %):
Manganese maximum 2.5%
Silicon maximum 2.0%
Nickel 0.0～5%
Carbon maximum 0.25%
Nitrogen maximum 0.1%
Aluminium maximum 0.5%
Phosphorus maximum 0.1%
All the other are iron and unavoidable impurities.
According to the present invention, also a feature to be the ferrite coefficient formed of steel part material determined-ferrite coefficient=%Cr+6 * %Si+8 * %Ti+4 * %Nb+4 * %Mo+2 * %Al-2 * %Mn-4 * %Ni-40 * (%C+%N)-20 * %P-5 * %Cu(%=weight percent by following formula), make continuous refrigerative phase transformation figure with determined steel part ferritic series numeral system, determine the required speed of cooling of minimum formation martensitic microstructure with this figure again.Preferably the ferrite coefficient is between 8 and 12.
According to the present invention, also a feature is that steel part can be the form of curling.
The present invention includes the equipment of implementing heat treating method as described herein, this equipment comprises an airtight basically steel part and the container with heat-insulating property.Described container can have reflexive internal surface or have the insulation liner of a non-conduction, or above-mentioned both has.Simultaneously, this container can be suitable for above steel part toward transferring in bottom-open.
With reference to diagram, the present invention will be described in more detail, wherein:
Fig. 1 illustrates that performance is the variation of air cooled coil of strip position after the rolling with respect to coil of strip, and coil of strip has passed through the water-cooled and the delay of rolling mill in the operation of rolling;
Fig. 2 illustrates performance variation shown in Figure 1, but does not postpone or water-cooled in the operation of rolling;
Fig. 3 illustrates the influence of coil of strip quality to performance variation illustrated in figures 1 and 2;
Fig. 4 represents the exemplary of CCT figure;
Fig. 5 represents that the another kind of same CCT figure represents;
Fig. 6 and Fig. 7 represent to change the phase transformation that composition produced of the nickel and the phosphorus of 11%Cr steel;
Fig. 8 explanation is according to changes of properties after the thermal treatment of the present invention.
Referring to figs. 1 through Fig. 3, related rolling back air cooling coil of strip type is well-known, and its performance variation usually as shown in Figure 1.Generally all know, cause that the major cause that these coil of strip mechanical propertys change largely is:
The water cooling of ⅰ on rolling mill, and/or
The delay that ⅱ causes owing to operational issue in course of hot rolling, and/or
ⅲ has a mind to pause so that check the specification of steel.
These performance variation make and are necessary to carry out anneal.When omitting water cooling or operational delay and carrying out uninterrupted rolling, will produce the variation figure of rigidity matter as shown in Figure 2, wherein coil of strip is soft-hearted and outside hard in being basically.Say that further for the composition of known coil of strip width and steel, the coil of strip quality has been done to illustrate to the influence of performance variation in Fig. 3.Connect with the phase transformation of steel in the continuous cooling process reason that causes these performance variation can be described, be i.e. the continuous cooling transformation diagram of so-called material (CCT curve).In a hot coil of strip on the different positions material with different speed naturally cooling.Under envrionment conditions, it is more faster than the speed of cooling of coil of strip center that the outer rim of coil of strip and the overlap joint of ectonexine (lamination) are located the speed of cooling of material.The transformation of time-temperature track and the microstructure that therefore takes place can pointwise in coil of strip variation.
In order to determine the ferrite coefficient useful, can use R.H.Kaltenhauser type equation to the present invention.These equation corrections comprising the influence of phosphorus, have been become even more important factor in the influence of this phosphorus.
Therefore, ferrite coefficient=%Cr+6 * %Si+8 * %Ti+4 * %Nb+4 * %Mo+2 * %Al-2 * %Mn-4 * %Ni-40 * (%C+%N)-20 * %P-5 * %Cu(%=weight percent).
(above-mentioned ferrite coefficient formula is to be proposed in " metal engineering quarterly " May in 1971 the 41st page " improving the engineering property of ferritic stainless steel " by R.H.Kaltenhauser.) coefficient of Cu and P is predefined for-5 and-20 respectively.
Fig. 4 represents to have the CCT curve of composition when different cooling of the steel of 10,44 ferrite coefficient.
Another CCT curve representation among Fig. 5 is converted to the per-cent of pre-phasing under a series of speed of cooling with a kind of steel.
Such fact clearly has been described here, and promptly a certain relatively specific composition existence one can access the critical cooling velocity of abundant phase transformation product.The speed of cooling slower than this critical velocity can not produce remarkably influenced to the performance of product.
Therefore, the composition that depends on steel in the last position in boundary line mutually of CCT curve (Fig. 4 and Fig. 5).The phase boundary line can move along with the change of forming, as shown in Figure 6 with respect to the variation and the variation example with respect to phosphorus composition shown in Figure 7 of nickel composition.The position in phase boundary line has with other example that the variation of forming changes:
Increase magnesium, cobalt, aluminium and niobium and make usually between the phase change zone, top and move right, make usually between the phase change zone, top and be moved to the left and increase titanium, vanadium and molybdenum.
The further critical mass characteristic actual production by steel and have the ferrite coefficient that changes between 8 to 12 and determined.
For this principle is described, adopt an insulation can, its Outside Dimensions is 1900 cubic millimeters, one 25 millimeters refractory fibre liner, the internal diameter of coil of strip is approximately 760 millimeters, and is as follows for the critical mass of different in width cooling coil of strip under adiabatic and envrionment conditions:
Width 1000 ± 50 1250 ± 3 1550 ± 30
6 tons 8.5 tons 11.5 tons on cover is arranged
There is not 10 tons 12.5 tons 15 tons on cover
Can be than the coil of strip that the coil of strip quality shown in " not having cover " is also big by air cooling, still however, whole coil of strip still can obtain the transformation of pre-phasing.For between shown in the table between two numerical value the coil of strip of quality can in cover, cool off.This cover is the metal box that suitable lagging material that a kind of bottom-open is lined with as above to be mentioned is made.Handling lower restriction for " cover is arranged " can further reduce by thicker or more effective insulation.Whether the size of coil of strip and composition have shown here needs to use cover.Note having a bit very important, promptly these covers might not need to remain on the coil of strip till reaching envrionment temperature always, and cover just can remove when being lower than interval mutually top in case temperature drops to.For example among Fig. 4, when dropping to 600 ℃, temperature just can remove cover.
Very clear, the starting temperature of coil of strip should be higher than and begins temperature between the phase change zone.This generally is to be higher than by control to finish rolling processing under 850 ℃ the temperature and realize.Normally carry out hot rolling, and the millman is not had additional requirement.
In order to further specify this point, 68 steel shown in Figure 8 adopt cover to produce.Cover was placed on the coil of strip two hours, removed then and covered on the next coil of strip that shuts out from rolling mill.By this method, in 20 hours, can effectively produce steel more than 1000 tons with 5 covers.Therefore, can free for the annealing device that carries out continuous heat treatment in batches and be used for the processing of traditional austenitic stainless steel.
The present invention goes for having in the steel of microalloy composition, as known AISI 409,410,420 on the market and have the steel that complicated ingredient is more formed.So, the composition that is specially adapted to steel of the present invention is in following scope:
Manganese maximum 2.5%
Silicon maximum 2.0%
Nickel 0.0～5%
Carbon maximum 0.25%
Nitrogen maximum 0.1%
Aluminium maximum 0.5%
Phosphorus maximum 0.1%
All the other are iron and unavoidable impurities.
Below be the example that the steel that is suitable for is formed:
C P Mn Si Ti Cr Ni N
2V
.025 .025 1.2 0.4 0.35 11.25 0.6 0.015 .1
.015 .025 1.0 0.5 - 11.2 0.15 0.015 .1
Last list position is weight percentage.
Have many steel not to be suitable for the present invention in above-mentioned compositing range, because their CCT curve requires very low speed of cooling, this is inapplicable for the production in enormous quantities that becomes ton.Yet it also is possible changing this situation, and for example, a kind of method is the per-cent decimal that increases molybdenum or titanium.
For those skilled in the art, effect of the present invention is very clearly.The productivity of rolling mill that has annealing device and produce corrosion resistant plate is only owing to the pause of having avoided anneal to cause improves.
Say that further the rolling mill that does not have annealing device can adopt method of the present invention to produce rolled sheet material.
Further say, can obtain needed character in fact needing very long die of batch annealing cycle can utilize big quality and insulation to combine to produce now, and handle without batch annealing.
Corrosion-resisting steel right and wrong involved in the present invention are austenitic, and particularly the phase transformation of martensite and bainite does not take place these steel.Therefore make steel have all engineering properties that only after the control anneal, just can obtain usually.
Say further that again have been found that the alloy composition of these steel must not comprise stable element in many cases, as titanium, niobium, zirconium or vanadium, condition is suitably to reduce carbon content.For example, these steel are applicable to the manufacturing barnacle, skewed slot and funnel liner, mine car, coal and sugar washing unit and be applicable to wet sliding friction condition usually.
Adopt present method can reduce energy significantly.Heat one ton of steel depends on steel to for example 750 ℃ of energy needed theoretical values thermal properties.Usually, for 13% chromium steel about 350MJ per ton.The thermo-efficiency of continuous annealing, batch annealing or roller hearth furnace depends on design and actually operating, but 20% to 25% is the reasonable value that illustrates.Therefore used actual energy per ton is approximately 1400MJ.
The expense of energy changes greatly along with the energy such as combustion gas, coal, oil or electricity, and a country also is not easy to make further comparison to another country.
The principal benefits that obtains from the present invention is to reduce expenses, and this benefit comes from and saved annealing or tempering.Especially effectively saving the Combination that depends on existing equipment on each rolling mill and product is the ratio of austenite and non-austenitic stainless steel.Under certain particular case, can reach the productivity of about raising 12% according to the inventive method.In addition, adopting present method to produce in the past can not fertile grade of steel with existing installation.
For example, 410 and No. 420 steel of AISI classification are hardenable stainless steels, are used for cutter and cutting tool.These steel are offered the user under the remollescent condition, and the user is made into behind needed shape such as the blade again with its sclerosis.Existing production process relates to the tempering or the anneal of steel, generally anneals in batch annealing equipment before transporting.And employing the present invention needn't carry out any thermal treatment and just can make the steel that is in abundant remollescent state after hot rolling.
Claims (5)
1, a kind of heat treating method of anti-corrosion steel part, the austenitic transformation of this steel part to the transformation temperature (A3) of ferrite and carbon body between 650 to 850 ℃; And the composition that is lower than gained steel under 10 ℃ of/minute conditions in rate of cooling does not exist micro-group of martensite strong in fact; The method is characterized in that:
(a) a kind of corrosion-resistant steel part is carried out hot-work being higher than under the above-mentioned A3 phase transition temperature condition,
(b) steel part insulation that should heat is in case too much loses heat;
(c) the hot worked steel part of process of insulation is cooled to and is lower than described phase transition temperature, the speed of cooling of its mensuration guaranteeing there is not martensitic microstructure in the whole steel part in fact, thereby obtains through heat treated steel part between 10 ℃ to 1 ℃ of per minute.
2, by the method for claim 1, it is characterized in that this component is composed as follows, by weight:
Chromium 10-18%
Manganese is the highest by 2.5%
Silicon is the highest by 2.0%
Nickel 0.0-5%
Carbon is the highest by 0.25%
Nitrogen is the highest by 0.1%
Titanium 0-1%
Molybdenum 0-1%
Vanadium 0-1%
Zirconium 0-1%
Niobium 0-1%
Copper 0-2%
Aluminium is the highest by 0.5%
Phosphorus is the highest by 0.1%
Its surplus is iron and unavoidable impurities.
3, by the method for claim 1, it is characterized in that, describedly carry out for the steel part insulation that prevents too much loses heat is enclosed in this steel part at least a portion in the insulating container.
By the method for claim 3, it is characterized in that 4, described insulating container is that open the bottom, this method comprises this container dropped to entangles this steel part, thereby steel part is enclosed in this container, and gradually in the refrigerative process, has heat to reflect up from the internal surface of this container at steel part.
5, by each method among the claim 1-4, it is characterized in that, comprise this is become coil of strip through hot worked steel part moulding, just carry out cooling off the process of this steel part then with 10 ℃ of speed of per minute to 1 ℃ of per minute.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 89104431 CN1026499C (en) | 1989-05-18 | 1989-05-18 | Heat treatment of corrosion resistant steels |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 89104431 CN1026499C (en) | 1989-05-18 | 1989-05-18 | Heat treatment of corrosion resistant steels |
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| CN1047345A CN1047345A (en) | 1990-11-28 |
| CN1026499C true CN1026499C (en) | 1994-11-09 |
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| CN 89104431 Expired - Fee Related CN1026499C (en) | 1989-05-18 | 1989-05-18 | Heat treatment of corrosion resistant steels |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100434543C (en) * | 2005-10-26 | 2008-11-19 | 万向钱潮股份有限公司 | Homogenization treatment process of SAE8620 carburizing steel |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102505805A (en) * | 2011-11-22 | 2012-06-20 | 江苏国建新材料股份有限公司 | Mixed reinforcement high-strength reinforced concrete component |
| WO2016073218A1 (en) * | 2014-11-04 | 2016-05-12 | Dresser-Rand Company | Corrosion resistant metals and metal compositions |
| CN106591736B (en) * | 2016-12-13 | 2018-08-21 | 山西太钢不锈钢股份有限公司 | High-strength low straight-chromiun stainless steel and its heat treatment method |
| CN107641757B (en) * | 2017-09-08 | 2019-03-26 | 首钢集团有限公司 | A kind of corrosion resistant steel bar and preparation method thereof based on concrete structure durability |
-
1989
- 1989-05-18 CN CN 89104431 patent/CN1026499C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100434543C (en) * | 2005-10-26 | 2008-11-19 | 万向钱潮股份有限公司 | Homogenization treatment process of SAE8620 carburizing steel |
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| Publication number | Publication date |
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| CN1047345A (en) | 1990-11-28 |
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