CN102296246B - Ultrahigh strength cast steel and preparation method as well as welding process thereof - Google Patents
Ultrahigh strength cast steel and preparation method as well as welding process thereof Download PDFInfo
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Abstract
The invention relates to ultrahigh strength cast steel and a preparation method as well as a welding process thereof. The ultrahigh strength cast steel comprises the following chemical components in percentage by weight: 0.15-0.21 percent of C, 0.17-0.37 percent of Si, 0.7-0.9 percent of Mn, 0.6-0.8 percent of Cr, 0.25-0.35 percent of Mo, 1.2-1.5 percent of Ni, 0.02-0.04 percent of Ti, 0.01-0.02 percent of residual Re, 0.03-0.05 percent of residual Al, less than or equal to 0.03 percent of S, less than or equal to 0.03 percent of P and the balance of Fe. Through the ultrahigh strength cast steel disclosed by the invention, the contents of Cr, Mo and Ni are increased, the contents of Si and Mn are kept unchanged, elements Ti and RE are added, a normalizing treatment process is increased compared with the conventional industrial heat treatment, the comprehensive mechanical performance can be obviously improved, the welding performance is superior, the comprehensive cost is low, and the service requirements of a cast steel material for a large-mining-height hydraulic support can be completely met.
Description
Technical field
The present invention relates to a kind of cast steel and preparation method thereof and weldprocedure, relate in particular to a kind of superhigh strength cast steel and preparation method thereof and weldprocedure.
Background technology
At present, the colliery industry all adopts steel casting with some component such as column-fossa, connecting joint class, guide rail on the hydraulic support.Because support will bear the alternating shock load that falls to causing from the vertical pressure of top board and a large amount of coal, stone in when work, therefore, requires the column-fossa steel casting will have preferably comprehensive mechanical performance and well welding property.
Needs along with market, coal machine profession is all being greatly developed high-end large mining height hydraulic support, because fully-mechanized mining working is high, supporting intensity requires also correspondingly greatly to improve, this adopts a large amount of high tensile steel plates with regard to Structure of need spare, the intensity rank of hydraulic support steel develops into 100kg, 110kg by 50kg, 60kg, even to the 120kg level.
The armor plate strength of structural part improves, and the intensity of column-fossa steel casting also will be complementary with it, and the yield strength of existing two kinds of material ZG27SiMn commonly used and ZG30Cr06, tensile strength is low R all
EL, R
m＜1000MPa can not satisfy product to the requirement of material mechanical performance.
Therefore need the again high-strength cast steel material of development of new, its mechanical property mainly is requirement tensile strength R
m＞1000MPa.Through inquiring about domestic and international concerned countries standard and cast steel standard data of the same trade, relatively the Hi-Stren steel near above-mentioned performance has forged steel AISI8620 (AISI standard A ISIA29/A29M-2005), but because its C and Cr constituent content are lower, therefore its intensity is not high, and because the performance of cast steel is poorer than the forged steel with sample ingredient, therefore it can not satisfy the needs of use properties, still need on its basis further to improve.
Summary of the invention
The present invention is directed to the existing lower deficiency of cast steel intensity, a kind of superhigh strength cast steel and preparation method thereof and weldprocedure are provided.
The technical scheme that the present invention solves the problems of the technologies described above is as follows: a kind of trade mark is that ZG18CrNiMnMoRe is that the chemical component weight per-cent of superhigh strength cast steel is: C 0.15%～0.21%, Si 0.17%～0.37%, Mn 0.7%～0.9%, Cr 0.6%～0.8%, Mo 0.25%～0.35%, Ni 1.2%～1.5%, and Ti 0.02%～0.04%, rare earth element Re
Residual0.01%～0.02%, Al
Residual0.03～0.05%, S≤0.03%, P≤0.03%, surplus is Fe.
On the basis of technique scheme, the present invention can also do following improvement.
Further, described rare earth element Re is to add with the form of rare earth ferrosilicon alloy, the described rare earth ferrosilicon alloy trade mark is FeSiRe23, FeSiRe26, FeSiRe29, FeSiRe32-A, FeSiRe32-B, FeSiRe35-A or FeSiRe35-B, wherein, Re is for mainly comprising the mixture of cerium, lanthanum and yttrium.
The present invention also provides a kind of technical scheme that solves the problems of the technologies described above as follows: a kind of preparation method of superhigh strength cast steel may further comprise the steps:
Step 10: feed intake by each chemical composition proportioning except rare earth element and aluminium element in the chemical composition of above-mentioned superhigh strength cast steel, carry out melting and slagging-off processing;
Step 20: add end-deoxidizer Al and mixed rare-earth elements in the casting ladle bottom before molten steel is come out of the stove, stir, then molten steel is come out of the stove, and again leaves standstill in casting ladle and drags for slag, and at last cast forms workpiece;
Step 30: adopt successively annealing, normalizing and modified technological process that workpiece is heat-treated.
Further, described step 10 comprises: at first, with steel scrap and scrap iron prepare burden after and carry out melting, smelting temperature is 1550 ℃～1580 ℃; Then, after steel scrap and scrap iron melt fully, add again ferrochrome, ferro-molybdenum and sheet nickel, and before coming out of the stove 7min～10min, carry out deslagging and process; Then, add again ferro-silicon and manganeseirom, and before coming out of the stove 2min～3min, add ferro-titanium, then come out of the stove.
Further, mixed rare-earth elements is rare earth ferrosilicon alloy in the described step 10, the described rare earth ferrosilicon alloy trade mark is FeSiRe23, FeSiRe26, FeSiRe29, FeSiRe32-A, FeSiRe32-B, FeSiRe35-A or FeSiRe35-B, wherein, Re is for mainly comprising the mixture of cerium, lanthanum and yttrium.
Further, the temperature of the molten steel after coming out of the stove in the described step 20 is 1630 ℃～1660 ℃.
Further, the add-on of end-deoxidizer Al accounts for 0.08～0.12% of Metal Weight in the described step 20, and the add-on of described mixed rare-earth elements accounts for 0.15%～0.2% of Metal Weight.
Further, described step 20 comprises: at first, put into end-deoxidizer Al and rare earth ferrosilicon alloy in the casting ladle bottom, stir, then molten steel is come out of the stove, and the block size of described rare earth ferrosilicon alloy is less than 5mm, and described rare earth ferrosilicon alloy carries out the baking of 1h～2h before adding; Then, the molten steel after coming out of the stove is transferred in the casting ladle, until molten steel leaves standstill 1 minute～3 minutes in casting ladle after, drags for slag, pour into a mould the formation workpiece at 1570 ℃～1600 ℃ again.
Further, described step 30 comprises:
The process of anneal is at 890 ℃～910 ℃ lower insulation 200min, pulls out naturally cooling when temperature in the stove drops to 500 ℃;
The process of normalizing treatment is to cool off in air behind 890 ℃～910 ℃ lower insulation for some time t1;
The modifier treatment process is shrend behind 870 ℃～890 ℃ lower insulation for some time t1;
The time t1=α kD of described insulation, wherein, α is soaking time coefficient (relevant with stove), for steel alloy, heats in box-type furnace or pit furnace, α gets 1.2min/mm～1.5min/mm; K is workpiece shove charge coefficient, and it is determined according to what of batch, when batch is large, the K value also should obtain larger, is generally determined by experiment, and here K gets 1.8～2.0, D is the net thickness (mm) of workpiece, the calculating of D: right cylinder cut-off footpath, square sectional is got the length of side, and it is long that minor face is got in the rectangle cross section, plate is got thickness of slab, the sleeve type workpiece is got wall thickness, and cone is got the 2/3 length place diameter from the microcephaly, and spheroid is got 0.6 times of sphere diameter;
And then shrend behind 530 ℃～550 ℃ lower insulation for some time t2, described soaking time t2=Bn+AnKnD, wherein, Bn is additional period, is generally 10～20min; An is heating coefficient, the heating coefficient of pit furnace is 1.0min/mm～1.5min/mm, the heating coefficient of box-type furnace is 2.0min/mm～2.5min/mm, but in actual production, what and charging mode according to batch, also to add a shove charge adjusted coefficient K n, get the net thickness that 1.0～1.5, D remains workpiece.
The present invention also provides a kind of technical scheme that solves the problems of the technologies described above as follows: a kind of weldprocedure of above-mentioned superhigh strength cast steel is included in carries out weld preheating and adopts shielded welding and high-strength low hydrogen welding wire to carry out welded seam in the heat treatment furnace; wherein; interlayer temperature is controlled at 150 ℃～200 ℃ during welding; welding current 230A～260A; weldingvoltage 26V～28V; welding speed 350mm/min～450mm/min, manual heat input 15KJ/cm～18KJ/cm.
Further, the step back of described welded seam also is included in the step of carrying out after welding treatment in the heat treatment furnace.
Further, described weld preheating be in heat treatment furnace under 190 ℃～210 ℃, according to the difference of weldment net thickness, the insulation for some time t3; The welding condition of described welded seam is: adopt 82%Ar+18%CO
2The high-strength low hydrogen welding wire welding of 90 feather weight is adopted in argon-rich gas shielded weldering; After the welding fully, weldment is put into heat treatment furnace carry out postweld heat treatment, be specially and between 250 ℃～350 ℃, carry out the postwelding hydrogen that disappears and process, according to the difference of weldment net thickness, insulation for some time t4, and the temperature of weldment after coming out of the stove＜200 ℃.
Further, when weldment net thickness≤20mm, soaking time t3 is 0.5 hour, and soaking time t4 is 2 hours; When 20mm＜weldment net thickness≤60mm, soaking time t3 is 1 hour, and soaking time t4 is 3 hours; When 60mm＜weldment net thickness≤100mm, soaking time t3 is 2 hours, and soaking time t4 is 4 hours.
The invention has the beneficial effects as follows: superhigh strength cast steel of the present invention has improved the content of Cr, Mo and Ni, keep the content of Si and Mn constant, and element ti and RE have been added, and than conventional industrialization thermal treatment process Duoed one the step normalizing treatment, compare with the ZG30Cr06 cast steel material with existing ZG27SiMn, comprehensive mechanical performance is significantly increased, and welding property is excellent, comprehensive cost is not high, can satisfy the service requirements that large mining height hydraulic support is used cast steel material fully.
Description of drawings
Fig. 1 is the metallographic structure figure after the superhigh strength cast steel thermal treatment of the present invention;
Fig. 2 is the structural representation that the present invention welds test block;
The structural representation of Fig. 3 Y type of the present invention test block;
The structural representation of Fig. 4 welding piece of the present invention.
Embodiment
Below in conjunction with accompanying drawing principle of the present invention and feature are described, institute gives an actual example and only is used for explaining the present invention, is not be used to limiting scope of the present invention.
Cr can significantly improve intensity, hardness and wear resistance in the superhigh strength cast steel of the present invention, can obviously reduce toughness but add too much, therefore the content that needs to improve Ni improves toughness; Mo can make the grain refining of steel, improves hardening capacity, the temper brittleness that is caused by Cr and Ni in the steel alloy in the time of can also suppressing tempering; Too much all can significantly reduce welding property because Cr, Mo and Ni add, improve welding property therefore need to add Ti, and all right crystal grain thinning of carbide Ti and precipitation strength, cast steel intensity improved; Rare earth (Re) but crystal grain thinning and improve form and the distribution of non-metallic inclusion then significantly improve the toughness of steel and improve the welding property of steel; And the purpose that adds a step normalizing in the heat treatment process is in order to make these alloying elements can be with tiny compound particle Precipitation from sosoloid, and play simultaneously the effect of crystal grain thinning, carrying the high-intensity while, plasticity and the toughness of steel have suitably been improved, to reach best over-all properties.
The trade mark of the present invention is that the superhigh strength cast steel of ZG18CrNiMnMoRe is: tempered sorbite+tempering troostite through the metallographic structure of gained after the modifier treatment.Perlite synusia group such as is at the axle shape, size is tiny and be evenly distributed, shown in Fig. 1 (a), be uniform-distribution with granuliform carbide at the ferrite that waits the axle shape, and cementite particle difficult resolution under opticmicroscope, shown in Fig. 1 (b), both grain fineness numbers all reach (approximately 15 μ m) more than 9 grades.
By test, the trade mark of producing according to the present invention is that the superhigh strength cast steel of ZG18CrNiMnMoRe and the mechanical property of existing ZG27SiMn, ZG30Cr06 and AISI8620 contrast as shown in table 1.
The mechanical property of table 1 Hi-Stren steel
Correlation data can be found out from table 1, cast steel ZG18CrNiMnMoRe material hardness and existing three kinds of materials that the present invention produces are similar, intensity has reached the performance index of forged steel AISI8620, but will specific tenacity and plasticity and toughness all are significantly improved mutually with ZG27SiMn and ZG30Cr06.
The raw materials cost contrast of table 2 Hi-Stren steel
| The trade mark | Raw materials cost (yuan/ton) |
| ZG27SiMn | 3930 |
| ZG30Cr06 | 3915 |
| AISI8620 | 4890 |
| ZG18CrNiMnMoRe | 6132 |
Can find out from the cost analysis of table 2, although ZG18CrNiMnMoRe compares with AISI8620, product material cost per ton has only increased by 1200 yuan, comparing with ZG30Cr06 with ZG27SiMn has increased by 2200 yuan/tons, but and the ultrahigh-strength steel of external import easily several ten thousand yuan/tons cost ratio get up to want cheap a lot, the market advantage is very large.
After superhigh strength cast steel thermal treatment of the present invention is finished, in actual production, also need strictly to control the welding procedure parameter, avoid producing welding cold cracking and thermal crack, affect the reliability of product.So, also to carry out the welding property test to cast steel ZG18CrNiMnMoRe, test-results sees Table 3.
The welding property of table 3 ZG18CrNiMnMoRe
| The crackle kind | The surface crack rate | The section crack rate |
| Numerical value | 0％ | 0％ |
As can be seen from Table 3, after postweld heat treatment, the welding property of ZG18CrNiMnMoRe is fine.
In sum, the cast steel ZG18CrNiMnMoRe that the present invention produces has excellent mechanical property, excellent welding property and raw materials cost hangs down three large advantages, can satisfy the service requirements of hydraulic support cast steel material fully.
The below does further detailed description to the trade mark of the present invention as the superhigh strength cast steel of ZG18CrNiMnMoRe take three embodiment.
Embodiment 1
The method of preparation and use of superhigh strength cast steel comprises following smelting, cast, thermal treatment and welding procedure, and its concrete technology parameter is:
(1) smelting technology
Carry out melting in the 200Kg intermediate frequency furnace,＜0.03% Q235 I-shaped steel scrap and the Q10 pig iron are smelted as raw material respectively to choose sulphur, phosphorus content.Melt first most steel scrap 186.38kg and scrap iron 3.78kg, smelting temperature is 1550 ℃, after wholeization of aniseed are clear, add again 1.90kg low carbon ferrochromium FeCr69C0.25,1.36kg ferro-molybdenum FeMo60-A, 2.8kg sheet nickel carries out melting, front 10min comes out of the stove, carrying out deslagging processes, add again 0.65kg ferrosilicon FeSi75Al1.0-A, 2.45kg mid-carbon fe-mn FeMn78C2.0, the front 3min that comes out of the stove adds 0.37kg ferrotianium FeTi30-A, puts into 0.24kg end-deoxidizer Al and 0.29kg rare earth ferrosilicon alloy FeSiRE23 in the casting ladle bottom at last, end-deoxidizer Al is the fine aluminium sheet, rare earth ferrosilicon alloy is broken into bulk, and size＜5mm is with front baking 2h.
(2) pouring technology
The tapping temperature of the molten steel height of trying one's best is 1660 ℃, until molten steel leaves standstill 2min in casting ladle after, 1590 ℃ of welding test blocks that pour into standard as shown in Figure 2 with the test block of Y type as shown in Figure 3.
(3) thermal treatment process
Behind the test block castable, put into RT type bench vehicle type electrical resistance furnace and heat-treat.Adopt annealing+normalizing+modified heat treatment process, at 890 ℃ of lower insulation 200min, when temperature in the stove drops to 500 ℃, pull out naturally cooling; The normalizing treatment temperature is 910 ℃, cools off in air behind the insulation 120min; Modifier treatment is shrend behind 890 ℃ of lower insulation 120min, and then shrend behind 540 ℃ of lower insulation 180min (calculating t1=α KD, α gets 1.3min/mm, k gets 1.8, D gets 50mm, and t1=1.3min/mm * 1.8 * 50mm=117min is therefore get t1=120min; Calculate t2=Bn+AnKnD, Bn gets 20min, and An gets 2.3mm/min, and Kn gets 1.4, D and gets 50mm, and t2=20min+2.3mm/min * 2.3mm/min * 1.4=181min is therefore get t2=180min).
By above technique, can prepare superhigh strength cast steel ZG18CrNiMnMoRe, the mass percent of its contained element consists of: C 0.19%, and Si 0.30%, and Mn 0.71%, and Cr 0.62%, and Mo 0.31%, and Ni 1.38%, and Ti 0.022%, Re
Residual0.015%, Al
Residual0.05%, S 0.030%, and P 0.019%; All the other are ferro element.
Make superhigh strength cast steel of the present invention, the mechanical property of cast steel is: tensile strength 1035MPa, yield strength 892MPa, unit elongation 16%, relative reduction in area 40%, impact absorbing energy 51J, impelling strength 62J/cm
2, hardness 302HB.
After superhigh strength cast steel thermal treatment of the present invention is finished, in actual production, also need strictly to control the welding procedure parameter, avoid producing welding cold cracking and thermal crack, affect the reliability of product.As shown in Figure 4, the weldprocedure of test specimen comprises weld preheating, welded seam, three processes of after welding treatment, and weld preheating refers to preheating in heat treatment furnace, at 200 ℃ of lower insulation 60min; Welding condition is: adopt 82%Ar+18%CO
2The high-strength low hydrogen welding wire welding of 90 feather weight is adopted in argon-rich gas shielded weldering, and interlayer temperature is controlled at 150 ℃, welding current 250A, weldingvoltage 27V, welding speed 400mm/min, manual heat input 16.8KJ/cm; The postwelding hydrogen that disappears is processed, and at 300 ℃ of lower insulation 180min, is cooled to below 200 ℃, pulls out the fire door cooling.Surface crack rate and section crack rate that the welding property test obtains all are 0%.
Embodiment 2
The method of preparation and use of superhigh strength cast steel comprises following smelting, cast, thermal treatment and welding procedure, and its concrete technology parameter is:
(1) smelting technology
Carry out melting in the 200Kg intermediate frequency furnace,＜0.03% Q235 I-shaped steel scrap and the Q10 pig iron are smelted as raw material respectively to choose sulphur, phosphorus content.Melt first most steel scrap 185.65kg and scrap iron 3.58kg, smelting temperature is 1580 ℃, after wholeization of aniseed are clear, add again 2.30kg medium carbon ferrochrome FeCr69C1.0,1.05kg ferro-molybdenum FeMo70,2.9kg sheet nickel carries out melting, come out of the stove front 7, carrying out deslagging processes, add again 0.76kg ferrosilicon FeSi75-A, 2.79kg mid-carbon fe-mn FeMn82C1.5, the front 2min that comes out of the stove adds 0.52kg ferrotianium FeTi40-A, puts into 0.22kg end-deoxidizer Al and 0.23kg rare earth ferrosilicon alloy FeSiRE26 in the casting ladle bottom at last, end-deoxidizer Al is the fine aluminium sheet, rare earth ferrosilicon alloy is broken into bulk, and size＜5mm is with front baking 2h.
(2) pouring technology
The tapping temperature of the molten steel height of trying one's best is 1650 ℃, until molten steel leaves standstill 3min in casting ladle after, 1580 ℃ of welding test blocks that pour into standard as shown in Figure 2 with the test block of Y type as shown in Figure 3.
(3) thermal treatment process
Behind the test block castable, put into RT type bench vehicle type electrical resistance furnace and heat-treat.Adopt annealing+normalizing+modified heat treatment process, at 900 ℃ of lower insulation 200min, when temperature in the stove drops to 500 ℃, pull out naturally cooling; The normalizing treatment temperature is 900 ℃, cools off in air behind the insulation 120min; Modifier treatment is shrend behind 880 ℃ of lower insulation 120min, and then shrend behind 550 ℃ of lower insulation 180min (calculating t1=α KD, α gets 1.3min/mm, k gets 1.8, D gets 50mm, and t1=1.3min/mm * 1.8 * 50mm=117min is therefore get t1=120min; Calculate t2=Bn+AnKnD, Bn gets 20min, and An gets 2.3mm/min, and Kn gets 1.4, D and gets 50mm, and t2=20min+2.3mm/min * 2.3mm/min * 1.4=181min is therefore get t2=180min).
By above technique, can prepare high-strength cast steel ZG18CrNiMnMoRe, the mass percent of its contained element consists of: C 0.18%, and Si 0.35%, and Mn 0.85%, and Cr 0.75%, and Mo 0.28%, and Ni 1.43%, and Ti 0.031%, Re
Residual0.013%, Al
Residual0.04%, S 0.025%, and P 0.022%; All the other are ferro element.
Make superhigh strength cast steel of the present invention, the mechanical property of cast steel is: tensile strength 1045MPa, yield strength 887MPa, unit elongation 17%, relative reduction in area 39%, impact absorbing energy 52J, impelling strength 64J/cm
2, hardness 297HB.
After superhigh strength cast steel thermal treatment of the present invention is finished, in actual production, also need strictly to control the welding procedure parameter, avoid producing welding cold cracking and thermal crack, affect the reliability of product.As shown in Figure 4, the weldprocedure of test specimen comprises weld preheating, welded seam, three processes of after welding treatment, and weld preheating refers to preheating in heat treatment furnace, at 210 ℃ of lower insulation 60min; Welding condition is: adopt 82%Ar+18%CO
2The high-strength low hydrogen welding wire welding of 90 feather weight is adopted in argon-rich gas shielded weldering, and interlayer temperature is controlled at 160 ℃, welding current 260A, weldingvoltage 26V, welding speed 420mm/min, manual heat input 16KJ/cm; The postwelding hydrogen that disappears is processed, and at 320 ℃ of lower insulation 180min, is cooled to below 200 ℃, pulls out the fire door cooling.Surface crack rate and section crack rate that the welding property test obtains all are 0%.
Embodiment 3
The method of preparation and use of superhigh strength cast steel comprises following smelting, cast, thermal treatment and welding procedure, and its concrete technology parameter is:
(1) smelting technology
Carry out melting in the 200Kg intermediate frequency furnace,＜0.03% Q235 I-shaped steel scrap and the Q10 pig iron are smelted as raw material respectively to choose sulphur, phosphorus content.Melt first most steel scrap 183.64kg and scrap iron 3.98kg, smelting temperature is 1560 ℃, after wholeization of aniseed are clear, add again 2.73kg medium carbon ferrochrome FeCr55C100,1.58kg ferro-molybdenum FeMo55-A, 2.84kg sheet nickel carries out melting, front 8min comes out of the stove, carrying out deslagging processes, add again 1.66kg ferrosilicon FeSi65,2.56kg low carbon ferromanganese FeMn84C0.4, the front 3min that comes out of the stove adds 0.59kg ferrotianium FeTi30-B, puts into 0.25kg end-deoxidizer Al and 0.17kg rare earth ferrosilicon alloy FeSiRE29 in the casting ladle bottom at last, end-deoxidizer Al is the fine aluminium sheet, rare earth ferrosilicon alloy is broken into bulk, and size＜5mm is with front baking 2h.
(2) pouring technology
The tapping temperature of the molten steel height of trying one's best is 1640 ℃, until molten steel leaves standstill 1min in casting ladle after, 1600 ℃ of welding test blocks that pour into standard as shown in Figure 2 with the test block of Y type as shown in Figure 3.
(3) thermal treatment process
Behind the test block castable, put into RT type bench vehicle type electrical resistance furnace and heat-treat.Adopt annealing+normalizing+modified heat treatment process, at 910 ℃ of lower insulation 200min, when temperature in the stove drops to 500 ℃, pull out naturally cooling; The normalizing treatment temperature is 890 ℃, cools off in air behind the insulation 120min; Modifier treatment is shrend behind 870 ℃ of lower insulation 120min, and then shrend behind 530 ℃ of lower insulation 180min (calculating t1=α KD, α gets 1.3min/mm, k gets 1.8, D gets 50mm, and t1=1.3min/mm * 1.8 * 50mm=117min is therefore get t1=120min; Calculate t2=Bn+AnKnD, Bn gets 20min, and An gets 2.3mm/min, and Kn gets 1.4, D and gets 50mm, and t2=20min+2.3mm/min * 2.3mm/min * 1.4=181min is therefore get t2=180min).
By above technique, can prepare superhigh strength cast steel ZG18CrNiMnMoRe, the mass percent of its contained element consists of: C 0.20%, and Si 0.28%, and Mn 0.80%, and Cr 0.71%, and Mo 0.33%, and Ni 1.40%, and Ti 0.035%, Re
Residual0.018%, Al
Residual0.03%, S 0.022%, and P 0.017%; All the other are ferro element.
Make superhigh strength cast steel of the present invention, the mechanical property of cast steel is: tensile strength 1052MPa, yield strength 881MPa, unit elongation 16%, relative reduction in area 42%, impact absorbing energy 54J, impelling strength 65J/cm
2, hardness 295HB.
After superhigh strength cast steel thermal treatment of the present invention is finished, in actual production, also need strictly to control the welding procedure parameter, avoid producing welding cold cracking and thermal crack, affect the reliability of product.As shown in Figure 4, the weldprocedure of test specimen comprises weld preheating, welded seam, three processes of after welding treatment, and weld preheating refers to preheating in heat treatment furnace, at 190 ℃ of lower insulation 60min; Welding condition is: adopt 82%Ar+18%CO
2The high-strength low hydrogen welding wire welding of 90 feather weight is adopted in argon-rich gas shielded weldering, and interlayer temperature is controlled at 180 ℃, welding current 240A, weldingvoltage 28V, welding speed 380mm/min, manual heat input 17.6KJ/cm; The postwelding hydrogen that disappears is processed, and at 280 ℃ of lower insulation 180min, is cooled to below 200 ℃, pulls out the fire door cooling.Surface crack rate and section crack rate that the welding property test obtains all are 0%.
The above only is preferred embodiment of the present invention, and is in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of doing, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (12)
1. the preparation method of a superhigh strength cast steel is characterized in that, described preparation method may further comprise the steps:
Step 10: feed intake by each chemical composition proportioning except mixed rare-earth elements and aluminium element in the chemical composition of superhigh strength cast steel, carry out melting and slagging-off processing, the chemical component weight per-cent of described superhigh strength cast steel is: C0.15%～0.21%, S i0.17%～0.37%, Mn0.7%～0.9%, Cr0.6%～0.8%, Mo0.25%～0.35%, Ni1.2%～1.5%, T i0.02%～0.04%, rare earth elements RE
Residual0.01%～0.02%, Al
Residual0.03～0.05%, S≤0.03%, P≤0.03%, surplus is Fe;
Step 20: add end-deoxidizer Al and mixed rare-earth elements in the casting ladle bottom before molten steel is come out of the stove, stir, then molten steel is come out of the stove, and again leaves standstill in casting ladle and drags for slag, and at last cast forms workpiece;
Step 30: adopt successively annealing, normalizing and modified technological process that workpiece is heat-treated;
Wherein, described step 30 comprises:
The process of anneal is at 890 ℃～910 ℃ lower insulation 200min, pulls out naturally cooling when temperature in the stove drops to 500 ℃;
The process of normalizing treatment is to cool off in air behind 890 ℃～910 ℃ lower insulation for some time t1;
The modifier treatment process is shrend behind 870 ℃～890 ℃ lower insulation for some time t1;
The time t1=α kD of described insulation, wherein, α is the soaking time coefficient, gets 1.2min/mm～1.5min/mm when heating in box-type furnace or pit furnace; K is workpiece shove charge coefficient, gets the net thickness that 1.8～2.0, D is workpiece;
And then shrend behind 530 ℃～550 ℃ lower insulation for some time t2, described soaking time t2=Bn+AnKnD, wherein, Bn is additional period, gets 10min～20min; An is heating coefficient, gets 1.0min/mm～1.5min/mm when heating in pit furnace, gets 2.0min/mm～2.5min/mm when heating in box-type furnace; Kn shove charge correction factor gets 1.0～1.5.
2. the preparation method of superhigh strength cast steel according to claim 1 is characterized in that, described step 10 comprises: at first, with steel scrap and scrap iron prepare burden after and carry out melting, smelting temperature is 1550 ℃～1580 ℃; Then, after steel scrap and scrap iron melt fully, add again ferrochrome, ferro-molybdenum and sheet nickel, and before coming out of the stove 7min～10min, carry out deslagging and process; Then, add again ferro-silicon and manganeseirom, and before coming out of the stove 2min～3min, add ferro-titanium, then come out of the stove.
3. the preparation method of superhigh strength cast steel according to claim 1 is characterized in that, mixed rare-earth elements is to add with the form of rare earth ferrosilicon alloy in the described step 10, and wherein, RE is the mixture that comprises cerium, lanthanum and yttrium.
4. the preparation method of superhigh strength cast steel according to claim 1 is characterized in that, the temperature of the molten steel after coming out of the stove in the described step 20 is 1630 ℃～1660 ℃.
5. the preparation method of superhigh strength cast steel according to claim 1 is characterized in that, the add-on of end-deoxidizer Al accounts for 0.08～0.12% of Metal Weight in the described step 20, and the add-on of described mixed rare-earth elements accounts for 0.15%～0.2% of Metal Weight.
6. the preparation method of superhigh strength cast steel according to claim 1, it is characterized in that, described step 20 comprises: at first, put into end-deoxidizer Al and rare earth ferrosilicon alloy in the casting ladle bottom, stir, then molten steel is come out of the stove, and the block size of described rare earth ferrosilicon alloy is less than 5mm, and described rare earth ferrosilicon alloy carries out the baking of 1h～2h before adding; Then, the molten steel after coming out of the stove is transferred in the casting ladle, until molten steel leaves standstill 1 minute～3 minutes in casting ladle after, drags for slag, pour into a mould the formation workpiece at 1570 ℃～1600 ℃ again.
7. superhigh strength cast steel such as the preparation method of each described superhigh strength cast steel of claim 1 to 6 preparation.
8. superhigh strength cast steel according to claim 7 is characterized in that, described rare earth elements RE is to add with the form of rare earth ferrosilicon alloy, and wherein, RE is the mixture that comprises cerium, lanthanum and yttrium.
9. weldprocedure such as claim 7 or 8 described superhigh strength cast steels; it is characterized in that; described weldprocedure is included in carries out weld preheating and adopts shielded welding and high-strength low hydrogen welding wire to carry out welded seam in the heat treatment furnace; wherein; interlayer temperature is controlled at 150 ℃～200 ℃ during welding, welding current 230A～260A, weldingvoltage 26V～28V; welding speed 350mm/min～450mm/min, manual heat input 15KJ/cm～18KJ/cm.
10. the weldprocedure of superhigh strength cast steel according to claim 9 is characterized in that, the step back of described welded seam also is included in the step of carrying out after welding treatment in the heat treatment furnace.
11. the weldprocedure of superhigh strength cast steel according to claim 10 is characterized in that, described weld preheating be in heat treatment furnace under 190 ℃～210 ℃, according to the difference of weldment net thickness, the insulation for some time t3; The welding condition of described welded seam is: adopt 82%Ar+18%CO
2The high-strength low hydrogen welding wire welding of 90 feather weight is adopted in argon-rich gas shielded weldering; After the welding fully, weldment is put into heat treatment furnace carry out postweld heat treatment, be specially and between 250 ℃～350 ℃, carry out the postwelding hydrogen that disappears and process, according to the difference of weldment net thickness, insulation for some time t4, and the temperature of weldment after coming out of the stove＜200 ℃.
12. the weldprocedure of superhigh strength cast steel according to claim 11 is characterized in that, when weldment net thickness≤20mm, soaking time t3 is 0.5 hour, and soaking time t4 is 2 hours; When 20mm＜weldment net thickness≤60mm, soaking time t3 is 1 hour, and soaking time t4 is 3 hours; When 60mm＜weldment net thickness≤100mm, soaking time t3 is 2 hours, and soaking time t4 is 4 hours.
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| CN106185669A (en) * | 2016-08-26 | 2016-12-07 | 常熟中德重机有限公司 | A kind of wear-resisting type hoist roller |
| CN109234640A (en) * | 2018-11-16 | 2019-01-18 | 泉州市恒通机械配件有限公司 | A kind of cast steel and its production technology |
| CN110669986B (en) * | 2019-10-17 | 2021-09-07 | 浦项(张家港)不锈钢股份有限公司 | 310S stainless steel preparation method and 310S stainless steel |
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