CN104694708A - Vacuum melting technique for austenitic gas valve steel containing nitrogen - Google Patents
Vacuum melting technique for austenitic gas valve steel containing nitrogen Download PDFInfo
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Abstract
The invention relates to the field of high-temperature metal material preparation techniques, in particular to a vacuum melting technique for austenitic gas valve steel containing nitrogen. According to the vacuum melting technique for the austenitic gas valve steel containing nitrogen, material preparation is conducted according to the constituents of the austenitic gas valve steel containing nitrogen, and then two-step deoxidizing melting is conducted; in the first step, half mass of graphite is added into a crucible of a vacuum furnace, metallic iron, metallic chromium, metallic molybdenum and metallic nickel are added, melting is started when the vacuum degree reaches 5-10 Pa, vacuumizing is stopped when the added alloy elements become civilized, inert gas is injected, and refining is conducted after the added alloy elements are molten completely; in the second step, the residual graphite is added into the crucible, refining is conducted, metallic niobium, ferrovanadium, ferromanganese iron and manganese metal nitride are added in sequence, pouring is conducted after the added alloy elements are molten completely, and finally, heat preservation is conducted and a finished product is discharged out of the furnace. The vacuum melting technique for the austenitic gas valve steel containing nitrogen has the advantages that the technological process is simple, the cycle is short, accurate control over the nitrogen content and the manganese content is achieved, deep deoxidation is achieved, the oxygen content is low, and the impurity content is low.
Description
Technical field
The present invention relates to high temperature metallic material preparation technology field, be specifically related to a kind of vacuum metling technique of nitrogen austenite Valve Steel.
Background technology
For making the high temperature steel of power machine petrol motor or cylinder of diesel engine intake valve and vent valve, be called Valve Steel.Steam valve steel can be divided into martensite Valve Steel and austenite Valve Steel two class.Its working temperature the former be 300 ~ 500 DEG C, the latter is 500 ~ 900 DEG C.Austenite Valve Steel, mainly for the manufacture of vent valve, needs to have good high temperature fatigue performance and resistance to high temperature corrosion performance, in addition, also needs to have excellent wear resisting property and processing performance.
At present, comparatively conventional nitrogen austenite Valve Steel is 1.4785 (X-60), ST33-12, and 1.4785 steel chemical compositions are in table 1, and 1.4785 steel contain the N of 0.4% ~ 0.6%.
The chemical component table of table 1 1.4785 nitrogen austenite Valve Steel
Fe matrix will form austenite, needs the Ni adding some amount, is formed and stable austenite phase, increases plasticity and toughness simultaneously.Carbon and nitrogen also have similar effect.Adding Cr in steel is to generate with Cr
2o
3be main oxide film, to improve corrosion resistance, in addition, carbide or nitride can also be formed, put forward heavy alloyed intensity.W, V and Nb etc. add in steel and form carbide, put forward heavy alloyed hot strength and crystal grain thinning tissue.Therefore, austenite Valve Steel composition more complicated, various alloying element reaches more than 10 and plants.
The nitrogen of comparatively high amts is contained in most of austenite air valve steel capital, and the fluctuation of its content is in 0.15% ~ 0.60% scope, and nitrogen is strong austenitic formation and stable element.Nitrogen is present in austenite Valve Steel with solid solution state, nitride or carbonitride form, strengthening austenitic matrix, and fining austenite grains, meanwhile, strengthens Cr
2o
3the compactness of oxide film and stability.In order to save Ni, to reduce costs, austenite Valve Steel adds the Mn of some amount usually, replaces part Ni.Mn can improve Valve Steel plasticity and toughness simultaneously, and increases the solubleness of nitrogen in austenite.Nitrogen austenite Valve Steel adopts the smelting of medium frequency normal pressure induction furnace to add esr two-link smelting process, complex process usually, and the cycle is long, and nitrogen is elemental gas, owing to adding the parameter influences such as nitrogen time, molten steel temperature during steel-making, and general very difficult precise control content.Esr often steel ingot bottom nitrogen content is low, and top is high, causes uneven components.It becomes a key issue in the production of austenite Valve Steel.
The control of Mn content becomes the another difficult problem of austenite Valve Steel.The indirect gasification reaction of Mn is the major cause causing Above The Ingot Bottom Mn scaling loss, and reaction formula is as follows:
[Mn]+(FeO)＝(MnO)+[Fe]
△G°＝-123.35+0.056T
Temperature raises, and be unfavorable for that reaction is carried out to the right, in slag, FeO content is higher, and be more conducive to reaction and carry out to the right, so the esr initial stage, steel Wen Wendu is lower, and FeO content is higher, is conducive to the oxidation of Mn, and Above The Ingot Bottom scaling loss is large, and on the contrary, steel ingot top scaling loss is few.In addition, Mn or high vapour pressure element, comparatively serious in vaporization at high temperature loss, the esr middle and later periods, slag temperature may reach 1750 DEG C, and molten steel temperature, also more than 1650 DEG C, causes steel ingot top Mn to lose serious.
Medium-frequency induction furnace smelting austenitic Valve Steel deoxidization technique is complicated, through in advance degassed, spread degassed and final deoxygenation, final oxygen level is higher, and oxide inclusion is more, significantly reduces the properties of steel.
Summary of the invention
The object of this invention is to provide that a kind of technical process is simple, the cycle is short, nitrogen content and Fe content precise control, degree of depth deoxidation the vacuum metling technique of nitrogen austenite Valve Steel, the nitrogen austenite Valve Steel oxygen level obtained is low, and impurity is few.
The vacuum metling technique of nitrogen austenite Valve Steel of the present invention, comprises the following steps:
(1) prepare burden: graphite, metallic iron, chromium metal, metal molybdenum, metallic nickel, metal niobium, vanadium iron, ferromanganese and the nitrogenization manganese metal elemental composition according to nitrogen austenite Valve Steel is prepared burden;
(2) the first step deoxidation is smelted:
The graphite of half quality is joined in vacuum oven crucible, then adds metallic iron, chromium metal, metal molybdenum and metallic nickel, when vacuum tightness reaches 5 ~ 10Pa, start melting; After the alloying element added becomes civilized, stop vacuumizing, filling with inert gas, after the alloying element fine melt added, then under temperature 1540 ~ 1560 DEG C, power 70 ~ 80kw condition, refining 15 ~ 20min;
With volume basis, described rare gas element consists of: nitrogen 60%, argon gas 40%;
(3) second step deoxidation is smelted:
Remaining graphite is added in crucible, under temperature 1540 ~ 1560 DEG C, power 70 ~ 80kw condition, refining 15 ~ 20min; After being cooled to 1440 ~ 1460 DEG C, add metal niobium, vanadium iron, ferromanganese, nitrogenization manganese metal successively; After the alloying element fine melt added, under power 110 ~ 120kw condition, stir 2 ~ 3min, then power is down to 70 ~ 80kw pours into a mould, be finally incubated 10 ~ 12min, come out of the stove.
Wherein, preferred technical scheme is:
In step (2), when vacuum tightness reaches 10Pa, start melting.After the alloying element fine melt added, then under temperature 1550 DEG C, power 80kw condition, refining 20min.The become civilized alloying element that refers to of alloying element has just started fusing.
In step (3), under temperature 1550 DEG C, power 80kw condition, refining 20min.After the alloying element fine melt added, under power 120kw condition, stir 2min, then power is down to 80kw pours into a mould, be finally incubated 10min, come out of the stove.
In step (3), add successively metal niobium, vanadium iron, ferromanganese, nitrogenization manganese metal feed postition be: front a kind of material under 110 ~ 120kw condition after fine melt, then adds rear a kind of material, till all adding.Nitrogenization manganese metal must in the end add.
What the present invention prepared is 1.4785 nitrogen alloyed austenitic steels.
In mass percentage, material purity is: C content >=99% of graphite, metallic iron is technically pure iron, Fe content >=99.8%, Cr content >=99.99% of chromium metal, Mo content >=99.99% of metal molybdenum, Ni content >=99.99% of metallic nickel, Nb content >=99.9% of metal niobium, vanadium iron is FeV80A, V content 78 ~ 82%, ferromanganese is FeMn88C0.2, Mn content 85 ~ 92%, C content 0.2%, the product of nitrogenization manganese metal preferred Jinzhou, Liaoning Zhong Xin iron alloy limited-liability company, trade mark JMnN6, Mn content >=90% of nitrogenization manganese metal, N content >=6%.Above-mentioned raw materials is commercially available prod.
The present invention utilizes vacuum induction furnace smelting, gives full play to vacuum reaction between carbon and oxygen advantage, carries out degree of depth deoxidation to austenite Valve Steel, deoxygenation product is CO, constantly to float from molten steel eliminating, significantly reduce the oxide inclusion in steel, improve the quality and performance of steel.And the present invention proposes two step smelting technologyes i.e. two step carbon deoxidation smelting technologyes, the first step adds the carbon of total amount half, puts into furnace bottom.When molten steel temperature reaches 1540 DEG C ~ 1560 DEG C, start refining, 15 ~ 20 minutes time.Second step adds second half carbon in the reduction later stage from hopper, carries out the deoxidation of secondary carbon, identical with the first step temperature and time.
Another important process of the present invention is after alloying element that the first step adds becomes civilized, and passes into protection of inert gas, be conducive to alloying toward vacuum chamber.Shielding gas is not single argon gas, neither single nitrogen, but 60% nitrogen adds 40% argon gas, effectively can suppress nitrogen and manganese effusion, accurately control nitrogen and Fe content.
The present invention utilizes nitrogenization manganese metal as the addition agent of nitrogen, and its fusing point is low, only about 1200 DEG C, and high containing nitrogenous ferrochrome fusing point, reaches 1600 DEG C, not easily melts, therefore do not adopt this iron alloy.The key controlling nitrogen and manganese is opportunity and the condition that grasp molten steel adds nitrogen.Nitrogenization manganese metal should add after reduction end of term molten steel alloying, and molten steel temperature should keep 1450 ± 10 DEG C.Increase the solubleness of nitrogen in steel because Cr, Mn, Mo, V and Nb add molten steel, and the elements such as C, Ni, Si reduce the solubleness of nitrogen, therefore, during batching, the former should by upper limit value, and the latter should by lower limit value.
Beneficial effect of the present invention is as follows:
Smelt with traditional normal pressure medium-frequency induction furnace and add electroslag remelting process and compare, present invention process flow process is simple, the cycle is short, nitrogen content and Fe content precise control, degree of depth deoxidation, oxygen level is low, impurity is few.
Embodiment
Below in conjunction with embodiment, the present invention is described further.
Embodiment 1
For the nitrogenous Valve Steel of 1.4785 austenite, adopt 200Kg vacuum induction melting.
Described vacuum metling technique is as follows:
(1) prepare burden:
Graphite, metallic iron, chromium metal, metal molybdenum, metallic nickel, metal niobium, vanadium iron, ferromanganese and the nitrogenization manganese metal elemental composition according to nitrogen austenite Valve Steel 1.4785 is prepared burden;
(2) the first step deoxidation is smelted:
The graphite of half quality is joined in vacuum oven crucible, then adds metallic iron, chromium metal, metal molybdenum and metallic nickel, in material alloying bucket, put into remaining graphite, metal niobium, vanadium iron, ferromanganese, nitrogenization manganese metal respectively.
When vacuum tightness reaches 10Pa, power transmission carries out alloy melting.After the alloying element added becomes civilized, stop vacuumizing, start to carry out smelting gas shield to vacuum chamber filling with inert gas, after the alloying element fine melt added, then under temperature 1550 ± 10 DEG C, power 80kw condition, refining 20min;
Described rare gas element, with volume basis, consists of: nitrogen 60%, argon gas 40%;
(3) second step deoxidation is smelted:
In crucible, add remaining graphite by hopper, carry out secondary high-temperature refining, simultaneously degree of depth deoxidation, under temperature 1550 ± 10 DEG C, power 80kw condition, refining 20min;
After being cooled to 1450 ± 10 DEG C, add metal niobium, vanadium iron, ferromanganese, nitrogenization manganese metal successively; Have a power failure cooling after front a kind of material melts under 120KW power, then add lower a kind of material, until all add, nitrogenization manganese metal must in the end add;
After the alloying element fine melt added, under power 120kw condition, stir 2min, then power is down to 80kw pours into a mould, be finally incubated 10min, come out of the stove.
Alloy pours into diameter of phi 50 or diameter of phi 80, long 0.8 meter of bar.Chemical analysis is carried out in sampling, and the results are shown in Table 2, visible chemical composition is completely qualified.
Table 2 1.4785 alloying ingredient composition and chemical analysis results
Embodiment 2
Described vacuum metling technique is as embodiment 1, and food ingredient and analytical results are in table 3, and visible chemical composition is completely qualified.
Table 3 1.4785 alloying ingredient composition and chemical analysis results table
Embodiment 3
For the nitrogenous Valve Steel of 1.4785 austenite, adopt 200Kg vacuum induction melting.
Described vacuum metling technique is as follows:
(1) prepare burden:
Graphite, metallic iron, chromium metal, metal molybdenum, metallic nickel, metal niobium, vanadium iron, ferromanganese and the nitrogenization manganese metal elemental composition according to nitrogen austenite Valve Steel 1.4785 is prepared burden;
(2) the first step deoxidation is smelted:
The graphite of half quality is joined in vacuum oven crucible, then adds metallic iron, chromium metal, metal molybdenum and metallic nickel, in material alloying bucket, put into remaining graphite, metal niobium, vanadium iron, ferromanganese, nitrogenization manganese metal respectively.
When vacuum tightness reaches 5Pa, power transmission carries out alloy melting.After the alloying element added becomes civilized, stop vacuumizing, start to carry out smelting gas shield to vacuum chamber filling with inert gas, after the alloying element fine melt added, then under temperature 1550 ± 10 DEG C, power 70kw condition, refining 18min;
Described rare gas element, with volume basis, consists of: nitrogen 60%, argon gas 40%;
(3) second step deoxidation is smelted:
In crucible, add remaining graphite by hopper, carry out secondary high-temperature refining, simultaneously degree of depth deoxidation, under temperature 1550 ± 10 DEG C, power 70kw condition, refining 18min;
After being cooled to 1450 ± 10 DEG C, add metal niobium, vanadium iron, ferromanganese, nitrogenization manganese metal successively; Have a power failure cooling after front a kind of material melts under 110KW power, then add lower a kind of material, until all add, nitrogenization manganese metal must in the end add;
After the alloying element fine melt added, under power 110kw condition, stir 2min, then power is down to 70kw pours into a mould, be finally incubated 12min, come out of the stove.
Alloy pours into diameter of phi 50 or diameter of phi 80, long 0.8 meter of bar.Chemical analysis is carried out in sampling, and the results are shown in Table 4, visible chemical composition is completely qualified.
Table 4 1.4785 alloying ingredient composition and chemical analysis results table
Claims (7)
1. a vacuum metling technique for nitrogen austenite Valve Steel, is characterized in that comprising the following steps:
(1) prepare burden: graphite, metallic iron, chromium metal, metal molybdenum, metallic nickel, metal niobium, vanadium iron, ferromanganese and the nitrogenization manganese metal elemental composition according to nitrogen austenite Valve Steel is prepared burden;
(2) the first step deoxidation is smelted:
The graphite of half quality is joined in vacuum oven crucible, then adds metallic iron, chromium metal, metal molybdenum and metallic nickel, when vacuum tightness reaches 5 ~ 10Pa, start melting; After the alloying element added becomes civilized, stop vacuumizing, filling with inert gas, after the alloying element fine melt added, then under temperature 1540 ~ 1560 DEG C, power 70 ~ 80kw condition, refining 15 ~ 20min;
With volume basis, described rare gas element consists of: nitrogen 60%, argon gas 40%;
(3) second step deoxidation is smelted:
Remaining graphite is added in crucible, under temperature 1540 ~ 1560 DEG C, power 70 ~ 80kw condition, refining 15 ~ 20min; After being cooled to 1440 ~ 1460 DEG C, add metal niobium, vanadium iron, ferromanganese, nitrogenization manganese metal successively; After the alloying element fine melt added, under power 110 ~ 120kw condition, stir 2 ~ 3min, then power is down to 70 ~ 80kw pours into a mould, be finally incubated 10 ~ 12min, come out of the stove.
2. the vacuum metling technique of nitrogen austenite Valve Steel according to claim 1, is characterized in that: in step (2), when vacuum tightness reaches 10Pa, starts melting.
3. the vacuum metling technique of nitrogen austenite Valve Steel according to claim 1 and 2, is characterized in that: in step (2), after the alloying element fine melt added, then under temperature 1550 DEG C, power 80kw condition, and refining 20min.
4. the vacuum metling technique of nitrogen austenite Valve Steel according to claim 1, is characterized in that: in step (3), under temperature 1550 DEG C, power 80kw condition, and refining 20min.
5. the vacuum metling technique of nitrogen austenite Valve Steel according to claim 1, is characterized in that: in step (3), after the alloying element fine melt added, 2min is stirred under power 120kw condition, again power is down to 80kw to pour into a mould, is finally incubated 10min, come out of the stove.
6. the vacuum metling technique of the nitrogen austenite Valve Steel according to claim 1,4 or 5, it is characterized in that: in step (3), add successively metal niobium, vanadium iron, ferromanganese, nitrogenization manganese metal feed postition be: front a kind of material is under 110 ~ 120kw condition after fine melt, add rear a kind of material again, till all adding.
7. the vacuum metling technique of nitrogen austenite Valve Steel according to claim 1, it is characterized in that: in mass percentage, material purity is, C content >=99% of graphite, metallic iron is technically pure iron, Fe content >=99.8%, Cr content >=99.99% of chromium metal, Mo content >=99.99% of metal molybdenum, Ni content >=99.99% of metallic nickel, Nb content >=99.9% of metal niobium, vanadium iron is FeV80A, and ferromanganese is FeMn88C0.2.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101372721A (en) * | 2008-09-19 | 2009-02-25 | 山西太钢不锈钢股份有限公司 | High vacuum induction furnace nitrogen-containing steel smelting nitrogen pickup method |
| CN101429627A (en) * | 2007-11-06 | 2009-05-13 | 江苏兴海特钢有限公司 | Austenite valve steel and technique for producing the same |
| CN103146875A (en) * | 2012-11-15 | 2013-06-12 | 北京北冶功能材料有限公司 | Method for smelting high nitrogen steel under ordinary pressure |
| CN103667587A (en) * | 2012-09-24 | 2014-03-26 | 江苏申源特钢有限公司 | Smelting method of austenite steel for engine air valve |
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- 2015-04-01 CN CN201510152199.4A patent/CN104694708B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101429627A (en) * | 2007-11-06 | 2009-05-13 | 江苏兴海特钢有限公司 | Austenite valve steel and technique for producing the same |
| CN101372721A (en) * | 2008-09-19 | 2009-02-25 | 山西太钢不锈钢股份有限公司 | High vacuum induction furnace nitrogen-containing steel smelting nitrogen pickup method |
| CN103667587A (en) * | 2012-09-24 | 2014-03-26 | 江苏申源特钢有限公司 | Smelting method of austenite steel for engine air valve |
| CN103146875A (en) * | 2012-11-15 | 2013-06-12 | 北京北冶功能材料有限公司 | Method for smelting high nitrogen steel under ordinary pressure |
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Denomination of invention: Vacuum smelting process of nitrogen-containing austenitic gas valve steel Effective date of registration: 20211213 Granted publication date: 20160824 Pledgee: Commercial Bank of China Yiyuan branch of Limited by Share Ltd Pledgor: SHANDONG ROITIE NEW MATERIAL SCIENCE AND TECHNOLOGY Co.,Ltd. Registration number: Y2021980014746 |
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