CN103911485B - Obtain the deoxidization technique of close grain 20Cr steel - Google Patents
Obtain the deoxidization technique of close grain 20Cr steel Download PDFInfo
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Abstract
The invention discloses a kind of deoxidization technique obtaining close grain 20Cr steel, it comprises the following steps: (1) desulfurizing iron and smelting; (2) molten steel after step (1) pre-deoxidation is sent to the refining of argon station; (3) LF refining; (4) billet continuous casting.The present invention adopts suitable aluminium deoxidation by controlling endpoint carbon content of converter and working in coordination with, avoid molten steel oxygen and aluminium too high levels, make in 20Cr steel, to generate appropriate AlN particle, dystectic AlN particle is utilized to hinder the grow up tendency of crystal grain in heat-processed, reach the object improving purity of steel and grain fineness number, and the present invention does not need extra investment, can implement on existing, investment and running cost low and effectively can reduce the consumption of smelting process oxygen and aluminium, there is good economic benefit, thus realize the target of low cost scale operation inherent fine grain 20Cr steel.
Description
Technical field
The present invention relates to and belong to steelmaking technical field, specifically refer to a kind of deoxidization technique obtaining close grain 20Cr steel.
Background technology
20Cr steel is most typical basic silkworm race in chromium alloy structure iron, market demand is huge, be widely used in the manufacturing such as automobile, mining machinery, for the manufacture of higher, the surperficial taking up wear of heart portion requirement of strength, sectional dimension is at below 30mm or shape is more complicated and the carburized parts that load is little, as gear, gear shaft, cam, wrist pin, worm screw etc.; For requiring the part of the little and high-wearing feature of heat treatment deformation, after carburizing, high-frequency surface hardening can be carried out; Also can be used as working speed large and bear the modified part of medium impact load, play an important role in Chinese national economy and national defense construction.
Along with socioeconomic development, user requires more and more higher to 20Cr Steel Properties, but simple, the cheap 20Cr of technique is essential coarse-grained steel, in normal temperature cementation process, in the autstenitic grain size short period of time, easily alligatoring causes grain fineness number in steel to exceed standard, remarkable reduction steel mechanics performance, welding property and fatigue property etc., have a strong impact on usability and the security of 20Cr steel.Therefore, need to develop a kind of technology simple and with low cost, to grow up tendency to reduce grain fineness number in 20Cr steel.Practical application shows close grain 20Cr steel, can not only avoid the problems that coarse grains brings, and effectively can also promote 20Cr steel quality, better meet the requirement that market is more and more harsh, have good Social benefit and economic benefit.
In the face of the difficult problem that 20Cr crystalline grain of steel is easily thick, strong reductor aluminium is adopted to carry out deoxidation, generating appropriate AlN particle while reducing oxygen content in steel, utilize dystectic AlN particle to hinder crystal grain growing up in heat-processed, is produce close grain, the effective method of high-quality 20Cr steel.Converter and electrosmelting process are oxidizing reactions, mainly reaction between carbon and oxygen, by bath lancing, reaches the object removed prime element, reduce carbon content and lifting molten steel temperature, easily cause the problems such as molten steel carbon content is too low, too high oxygen level, to follow-up deoxidation, alloying build-up of pressure.For head it off, traditional technology often adopts a large amount of aluminium deoxidation and adds carburelant, but this not only can strengthen the consumption of aluminium and carburelant, and too much dystectic aluminium deoxidation product also easily produces the problems such as the smooth and purity of steel reduction of continuous casting, adds smelting cost and makes steel performance worsen.
Summary of the invention
The object of the invention is to develop a kind of deoxidization technique obtaining close grain 20Cr steel, to overcome the easily thick difficult problem of 20Cr crystalline grain of steel, thus reach the object of low cost, high efficiency production close grain 20Cr steel.
For achieving the above object, the invention provides a kind of deoxidization technique obtaining close grain 20Cr steel, it is characterized in that: it comprises the following steps:
1) by the requirement of 20Cr steel grades, carry out conventional desulfurizing iron and converter or electrosmelting, converter or electrosmelting tapping control terminal C >=0.08%, when the tap of converter tapping reaches 22% ~ 26% of total tap, add aluminium block carry out pre-deoxidation by 0.6 ~ 0.8kg/ ton steel;
2) by step 1) molten steel after pre-deoxidation is sent to the refining of argon station, and by 1.25 ~ 1.3m/ ton steel feeding aluminum steel after Argon process 2 ~ 5min, continue Argon process and also stir 3 ~ 6min;
3) by step 2) molten steel after ar blowing refining is sent to LF stove and carries out conventional refinery, adds Al ball and SiC powder carries out top of the slag deoxidation after having changed slag, and the Al s mass percent controlled in molten steel is 0.02% ~ 0.05%;
4) by step 3) molten steel deliver to continuous casting working procedure, continuous casting becomes steel billet.
Preferably, described step 1) in, when the tap of converter tapping reaches 25% of total tap, add aluminium block by 0.7 ~ 0.8kg/ ton steel and carry out pre-deoxidation;
Described step 2) in, press 1.25m/ ton steel feeding aluminum steel after Argon process 2 ~ 3min, continue Argon process and stir 3 ~ 5min;
Described step 3) in, the Als mass percent controlled in molten steel is 0.025% ~ 0.04%.
As another preferred version, described step 1) in, when the tap of converter tapping reaches 25% of total tap, add aluminium block by 0.8kg/ ton steel and carry out pre-deoxidation.
As another preferred version, described step 2) in, press 1.25m/ ton steel feeding aluminum steel after Argon process 2min, continue Argon process and stir 3min.
As another preferred version, described step 3) in, the Als mass percent controlled in molten steel is 0.035%.
Further, described step 2) in, the aluminum steel specification of feeding is diameter 10mm, and every meter of weight is 205g, and by percentage to the quality containing 99.75%Al, 0.05%Mg, all the other are Fe and inevitable impurity.
In smelting molten steel of the present invention there is equilibrium relationship in C and O, the low O of C then high, C hyperoxia is then low, therefore controls suitable C content in steel and can reduce the pressure of follow-up deoxidation, control terminal C >=0.08% of tapping, oxygen level suitable in steel and AlN content can be ensured, thus reach the object improving grain fineness number.
The invention has the advantages that: the present invention adopts suitable aluminium deoxidation by controlling endpoint carbon content of converter and working in coordination with, avoid molten steel oxygen and aluminium too high levels, make in 20Cr steel, to generate appropriate AlN particle, dystectic AlN particle is utilized to hinder the grow up tendency of crystal grain in heat-processed, reach the object improving purity of steel and grain fineness number, and the present invention does not need extra investment, can implement on existing, investment and running cost low and effectively can reduce the consumption of smelting process oxygen and aluminium, there is good economic benefit, thus realize the target of low cost scale operation inherent fine grain 20Cr steel.
Embodiment
Below in conjunction with specific embodiment, the present invention is described in further detail.
Embodiment 1:
A, by the requirement of 20Cr steel grades, carry out conventional desulfurizing iron and converter or electrosmelting.It is 0.08% that converter tapping controls terminal C, and tap reaches 22% of total tap and adds aluminium block by 0.6kg/ ton steel and carry out pre-deoxidation;
B, the molten steel of steps A is sent to argon station, presses 1.3m/ ton feeding aluminum steel after Argon 2min, continue Argon and stir 3min;
Aluminum steel specification: diameter 10mm, weight 205g/m, containing 99.75%Al, 0.05%Mg, all the other are Fe and other inevitable impurity.
C, the molten steel of step B is sent to LF stove carries out conventional refinery, add appropriate Al ball after having changed slag and SiC powder carries out top of the slag deoxidation, control Als 0.02% in molten steel.
D, the molten steel of step C is sent to continuous casting working procedure, continuous casting becomes base.
Embodiment 2:
A, by the requirement of 20Cr steel grades, carry out conventional desulfurizing iron and converter or electrosmelting.It is 0.10% that converter tapping controls terminal C, and tap reaches 26% of total tap and adds aluminium block by 0.8kg/ ton steel and carry out pre-deoxidation;
B, the molten steel of steps A is sent to argon station, presses 1.25m/ ton feeding aluminum steel after Argon 5min, continue Argon and stir 6min;
Aluminum steel specification: diameter 10mm, weight 205g/m, containing 99.75%Al, 0.05%Mg, all the other are Fe and other inevitable impurity.
C, the molten steel of step B is sent to LF stove carries out conventional refinery, add appropriate Al ball after having changed slag and SiC powder carries out top of the slag deoxidation, control Als 0.03% in molten steel.
D, the molten steel of step C is sent to continuous casting working procedure, continuous casting becomes base.
Embodiment 3:
A, by the requirement of 20Cr steel grades, carry out conventional desulfurizing iron and converter or electrosmelting.It is 0.12% that converter tapping controls terminal C, and tap reaches 25% of total tap and adds aluminium block by 0.7kg/ ton steel and carry out pre-deoxidation;
B, the molten steel of steps A is sent to argon station, presses 1.25m/ ton feeding aluminum steel after Argon 3min, continue Argon and stir 5min;
Aluminum steel specification: diameter 10mm, weight 205g/m, containing 99.75%Al, 0.05%Mg, all the other are Fe and other inevitable impurity.
C, the molten steel of step B is sent to LF stove carries out conventional refinery, add appropriate Al ball after having changed slag and SiC powder carries out top of the slag deoxidation, control Als 0.04% in molten steel.
D, the molten steel of step C is sent to continuous casting working procedure, continuous casting becomes base.
Embodiment 4:
A, by the requirement of 20Cr steel grades, carry out conventional desulfurizing iron and converter or electrosmelting.It is 0.15% that converter tapping controls terminal C, and tap reaches 25% of total tap and adds aluminium block by 0.8kg/ ton steel and carry out pre-deoxidation;
B, the molten steel of steps A is sent to argon station, presses 1.25m/ ton feeding aluminum steel after Argon 2min, continue Argon and stir 3min;
Aluminum steel specification: diameter 10mm, weight 205g/m, containing 99.75%Al, 0.05%Mg, all the other are Fe and other inevitable impurity.
C, the molten steel of step B is sent to LF stove carries out conventional refinery, add appropriate Al ball after having changed slag and SiC powder carries out top of the slag deoxidation, control Als 0.05% in molten steel.
D, the molten steel of step C is sent to continuous casting working procedure, continuous casting becomes base.
Embodiment 5:
A, by the requirement of 20Cr steel grades, carry out conventional desulfurizing iron and converter or electrosmelting.It is 0.09% that converter tapping controls terminal C, and tap reaches 25% of total tap and adds aluminium block by 0.8kg/ ton steel and carry out pre-deoxidation;
B, the molten steel of steps A is sent to argon station, presses 1.25m/ ton feeding aluminum steel after Argon 5min, continue Argon and stir 5min;
Aluminum steel specification: diameter 10mm, weight 205g/m, containing 99.75%Al, 0.05%Mg, all the other are Fe and other inevitable impurity.
C, the molten steel of step B is sent to LF stove carries out conventional refinery, add appropriate Al ball after having changed slag and SiC powder carries out top of the slag deoxidation, control Als 0.03% in molten steel.
D, the molten steel of step C is sent to continuous casting working procedure, continuous casting becomes base.
Each embodiment processing parameter is in table 1.
Comparative example 1:
(processing step is with embodiment 1) difference is:
A, by the requirement of 20Cr steel grades, carry out conventional desulfurizing iron and converter or electrosmelting; It is 0.07% that converter tapping controls terminal C;
B, the molten steel of steps A is sent to argon station, carries out deoxidation and continue Argon making composition and homogeneous temperature;
C, the molten steel of step B is sent to LF stove carries out conventional refinery, add appropriate Al ball after having changed slag and SiC powder carries out top of the slag deoxidation, control Als 0.01% in molten steel.
D, the molten steel of step C is sent to continuous casting working procedure, continuous casting becomes base.
Comparative example 2:
(processing step is with embodiment 1) difference is:
A, by the requirement of 20Cr steel grades, carry out conventional desulfurizing iron and converter or electrosmelting; It is 0.05% that converter tapping controls terminal C;
B, the molten steel of steps A is sent to argon station, carries out deoxidation and continue Argon making composition and homogeneous temperature;
C, the molten steel of step B is sent to LF stove carries out conventional refinery, add appropriate Al ball after having changed slag and SiC powder carries out top of the slag deoxidation, control Als 0.009% in molten steel.
D, the molten steel of step C is sent to continuous casting working procedure, continuous casting becomes base.
Comparative example 3:
(processing step is with embodiment 1) difference is:
A, by the requirement of 20Cr steel grades, carry out conventional desulfurizing iron and converter or electrosmelting; It is 0.03% that converter tapping controls terminal C;
B, the molten steel of steps A is sent to argon station, carries out deoxidation and continue Argon making composition and homogeneous temperature;
C, the molten steel of step B is sent to LF stove carries out conventional refinery, add appropriate Al ball after having changed slag and SiC powder carries out top of the slag deoxidation, control Als 0.0015% in molten steel.
D, the molten steel of step C is sent to continuous casting working procedure, continuous casting becomes base.
Each comparative example processing parameter is in table 1.
Embodiment and comparative example effect are in table 2.
Table 1: processing parameter and finished product oxygen content in steel
Table 2:20Cr crystalline grain of steel degree rank
As known from Table 2, adopt 20Cr crystalline grain of steel degree rank >=10 of the present invention, and adopt traditional technology 20Cr crystalline grain of steel degree level≤8, show that the present invention has significant technical superiority and without the need to scrap build or upgrading, thus has good operability and the market competitiveness.
Principle of work of the present invention and parameter designing:
Converter tapping terminal C content, to follow-up deoxidation system important.Reaction between carbon and oxygen is most important chemical reaction in the process of bessemerizing, and its chemical equation is as follows:
Steel-making temperature (1550 ~ 1700 DEG C) scope in and p '
cOduring=100kPa, the reaction equilibrium constant of (1) formula varies with temperature not quite, and carbon oxygen concn amasss and is:
ω[C]·ω[O]≈0.0025 (2)
From (2) formula, endpoint carbon content of converter is relevant with molten steel oxygen level.According to the principle of C-O balance, in steel, C is less than 0.08%, and in converter molten steel, free oxygen level will reach 300-800ppm, and molten steel is in superoxidant state.Therefore, converter tapping of the present invention controls terminal C >=0.08%.
, there is following chemical reaction with during Al deoxidation in Als content:
When Als content is too low, dissolved oxygen content can be increased oxide content in steel is increased, affect the structure property of steel, and do not reach the object of crystal grain thinning; During Als too high levels, although dissolved oxygen can be made to control at lower level and crystal grain thinning, higher Als can increase secondary oxidation during molten steel cast, the Al of generation
2o
3be mingled with to be trapped in steel and affect steel performance.Therefore, Als of the present invention controls 0.020% ~ 0.050%.
Present invention process deoxidizing capacity is strong, and the finished product 20Cr oxygen content in steel adopting the present invention to produce can be controlled in 15 ~ 25ppm, the crystal grain thinning degree Be very effective of finished product 20Cr steel, 20Cr crystalline grain of steel degree rank all >=10 grades; And this process costs is cheap, be easy to large-scale promotion, without the need to extra investment, under prior art equipment condition, just can realize scale operation inherent fine grain 20Cr steel.
In content of the present invention other some illustrate:
Injection feeding technology (wirefeecling): density is less, the curative agent of easily oxidation makes wire rod, is dropped into molten steel depths, molten steel is carried out to a kind of method of external refining by feeding wire machine.
Aluminum steel injection feeding technology: this method reasons for its use be carbon aluminium-killed steel produce in the urgent need to.The requirement of carbon aluminium-killed steel to aluminium content is harsher.Aluminium content is too low, and reduce the non-ageing of steel, the plasticity of steel is declined, and punching performance is poor; Aluminium too high levels, then can form again the Al of a large amount of tufted in steel
2o
3be mingled with, plate surface quality degenerated, processing difficulties, and Al high in molten steel
2o
3be mingled with the blocking that also can cause the casting mouth of a river.Adopt and traditional add aluminium method, as aluminium block method, ferro-aluminum method, aluminium case method etc., the recovery rate of aluminium is low, the more important thing is that the hit rate of dissolved aluminum content in Finished Steel is too low, can not meet the requirement that deep drawing steel is produced.Adopting injection feeding technology to add aluminium, by controlling aluminum steel diameter and velocity of projection, can accurately control to add aluminum amount.Meanwhile, select suitable aluminum steel feeding position and the degree of depth, make aluminum steel stir strong position fusing in molten steel depths, the oxidational losses of aluminium can be reduced, the recovery rate of aluminium is improved and favorable reproducibility, thus accurately can control aluminium content in steel.
Claims (6)
1. obtain a deoxidization technique for close grain 20Cr steel, it is characterized in that: it comprises the following steps:
1) by the requirement of 20Cr steel grades, carry out conventional desulfurizing iron and converter or electrosmelting, converter or electrosmelting tapping control terminal C >=0.08%, when the tap of converter tapping reaches 22% ~ 26% of total tap, add aluminium block carry out pre-deoxidation by 0.6 ~ 0.8kg/ ton steel;
2) by step 1) molten steel after pre-deoxidation is sent to the refining of argon station, and by 1.25 ~ 1.3m/ ton steel feeding aluminum steel after Argon process 2 ~ 5min, continue Argon process and also stir 3 ~ 6min;
3) by step 2) molten steel after ar blowing refining is sent to LF stove and carries out conventional refinery, adds Al ball and SiC powder carries out top of the slag deoxidation after having changed slag, and the Als mass percent controlled in molten steel is 0.02% ~ 0.05%;
4) by step 3) molten steel deliver to continuous casting working procedure, continuous casting becomes steel billet.
2. obtain the deoxidization technique of close grain 20Cr steel according to claim 1, it is characterized in that:
Described step 1) in, when the tap of converter tapping reaches 25% of total tap, add aluminium block by 0.7 ~ 0.8kg/ ton steel and carry out pre-deoxidation;
Described step 2) in, press 1.25m/ ton steel feeding aluminum steel after Argon process 2 ~ 3min, continue Argon process and stir 3 ~ 5min;
Described step 3) in, the Als mass percent controlled in molten steel is 0.025% ~ 0.04%.
3. obtain the deoxidization technique of close grain 20Cr steel according to claim 1, it is characterized in that: described step 1) in, when the tap of converter tapping reaches 25% of total tap, add aluminium block by 0.8kg/ ton steel and carry out pre-deoxidation.
4. obtain the deoxidization technique of close grain 20Cr steel according to claim 1, it is characterized in that: described step 2) in, press 1.25m/ ton steel feeding aluminum steel after Argon process 2min, continue Argon process and stir 3min.
5. obtain the deoxidization technique of close grain 20Cr steel according to claim 1, it is characterized in that: described step 3) in, the Als mass percent controlled in molten steel is 0.035%.
6. according to any one of Claims 1 to 5, obtain the deoxidization technique of close grain 20Cr steel, it is characterized in that: described step 2) in, the aluminum steel specification of feeding is diameter 10mm, every meter of weight is 205g, by percentage to the quality containing 99.75%Al, 0.05%Mg, all the other are Fe and inevitable impurity.
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| CN109280740B (en) * | 2018-12-14 | 2020-11-24 | 山东钢铁股份有限公司 | Process method for in-place yellow and white slag of LF (ladle furnace) refining furnace |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102703834A (en) * | 2012-06-29 | 2012-10-03 | 中天钢铁集团有限公司 | Grain-refined gear steel and production process thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102703834A (en) * | 2012-06-29 | 2012-10-03 | 中天钢铁集团有限公司 | Grain-refined gear steel and production process thereof |
Non-Patent Citations (2)
| Title |
|---|
| 20CrMnTi生产工艺的调整;徐华良等;《江苏冶金》;20061031;第34卷(第5期);第63-64页 * |
| 酸溶铝对转炉连铸20CrMnTi钢奥氏体晶粒度的影响;朱玉秀等;《武汉工程职业技术学院学报》;20110930;第23卷(第3期);第23-25、71页 * |
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Effective date of registration: 20170724 Address after: 430083, Hubei Wuhan Qingshan District Factory No. 2 Gate joint stock company organs Patentee after: Wuhan iron and Steel Company Limited Address before: 430080 Wuchang, Hubei Friendship Road, No. A, block, floor 999, 15 Patentee before: Wuhan Iron & Steel (Group) Corp. |