High-boron low-carbon abrasion resistant cast steel and heat treatment method thereof
Technical field
The invention belongs to steel material technical field, be specifically related to a kind of High-boron low-carbon abrasion resistant cast steel and heat treatment method thereof.
Background technology
Wearing and tearing are topmost modes in three kinds of failure modes of engineering component (wearing and tearing, burn into fracture), whole world every year because of wearing and tearing cause with a toll of hundreds billion of dollars, have great economic implications so research is worn and torn and continually developed the better high-abrasive material of performance.At present, high-abrasive material is concluded 3 classes: (1) Hadfield Steel, virgin state is an austenite, under extraneous intense impact and high pressure stress, austenite takes place to be strengthened to martensitic transformation, the top layer has very high hardness, and inside has good toughness, and good wear resistance and reliability are arranged.(2) low-alloy wear-resistant steel by rational chemical proportioning and thermal treatment, can obtain preferable over-all properties, and alloying element is used Cr, Mo, Ni, Nb, Mn and Si etc. always, adopt usually martensitic transformation, second mutually means such as reinforcement improve wear resistance.(3) rich chromium cast iron belongs to hard brittle material, contains Cr amount high (usually greater than 15%), by M
7C
3The type carbide improves wear resistance.In the above-mentioned materials, at present will high mangaenese steel as main high-abrasive material, but under middle or small impact load, because based on cutting abrasion, so high mangaenese steel is difficult to elicit latent faculties.And in the low alloy steel since do not have wear-resisting hard mutually or the hard phase amount very little, wear resistance is not high yet.Although high-chromium white cast iron hardness height, wear resistance are good, there be safety in utilization difference and the high deficiency of production cost under the big and impact load of fragility.
In order to improve the wear resistance of cast material, Chinese invention patent CN1560311 discloses a kind of wearable cast steel and preparation method thereof.Wearable cast steel contains C0.2~0.35%, Si0.6~1.0%, Mn0.8~1.2%, Ni 0.2~0.6%, Cr 0.6~1.2%, Mo 0.15~0.35%.Its method for making comprises smelting, casting and thermal treatment.Smelt: dissolve at molten steel and put into chromium, nickel, molybdenum at 1/5~2/5 o'clock, come out of the stove and dropped into manganese, silicon in preceding 5~15 minutes, drop into reductor then; Thermal treatment: 910~930 ℃ of casting foundry goods normalizings, be incubated 2 hours air coolings of coming out of the stove, 860~900 ℃ of insulations of the quenching shrend of coming out of the stove after 1.5 hours, water temperature is below 30 ℃, and 210~230 ℃ of tempering are incubated 2~2.5 hours, the air cooling of coming out of the stove.Owing to no wear-resisting hard phase, hardness is low in this invention wearable cast steel, and wear resistance is relatively poor.Chinese invention patent CN1600889 also discloses a kind of wearable cast steel in microalloy martensite and manufacture method, its chemical ingredients is wt%:C0.25~0.34, Si 0.3~0.7, Mn 1.15~1.65, Cr 0.5~1.0, B 0.0005~0.005, Ti 0.01~0.06, Ce 0.01~0.045, La 0.01~0.035, Al 0.01~0.1, S≤0.035, P≤0.035, its microalloying treatment process is earlier to add TiFe in 1600~1610 ℃ in smelting furnace, adds in casting ladle or is inclining to molten steel drop into RESiFe and BFe alloy simultaneously in casting ladle.The advantage of this invention is not use valuable alloying elements such as Mo, Ni, but reaches highly malleablized and hard malleableize purpose by microalloying, thereby manufacturing cost is lower.But also exist hardness low, the deficiency that wears no resistance.
Chinese invention patent CN1385549 then discloses a kind of middle carbon multi-member low alloy grinding-tolerant steel material Chemical Composition and content, wherein: C0.38~0.45%, Si0.90~1.30%, Mn1.2~2.0%, Cr 1.0~1.7%, Mo0.3~0.5%, V0.1~0.2%, B0.001~0.003%, Re0.01~0.03%, S≤0.04%, P≤0.045%, all the other are Fe.Final metallographic structure is: tempered martensite+bainite+carbide+small portion of residual austenite.This steel not only has higher hardness, and has toughness preferably, and thermal treatment process simply is easy to grasp, and manufacturing cost is lower, can be widely used in wearing pieces such as ball grinding machine lining board, crusher tooth plate, backplate, tup.The raising of carbon content causes hardness to increase, and wear resistance makes moderate progress, but owing to contain expensive molybdenum element, causes production cost to increase.Russ P RU2288294-C2 also discloses a kind of casting wear-resistant steel, and its chemical constitution is 0.80~0.95%C, 0.20~0.40%Si, 8.50~10.0%Mn, 0.50~0.85%Ni, 0.10~0.30%W, 0.025~0.045%N, 0.05~0.10%V and 0.10~0.30%Mo.Owing to add elements such as expensive nickel, molybdenum, cause production cost to increase.
In order to improve the cast steel wear resisting property, Chinese invention patent CN100999803 discloses a kind of high boron wear-resisting casting steel, it is characterized in that the chemical ingredients and the weight percent thereof of this high boron wear-resisting casting steel of making is: C:0.10%~0.50%; B:0.8%~5.0%; Cu:0.3%~0.6%; Mn:0.8%~2.0%; Cr:1.0%~2.5%; Si<1.5%; Ti:0.08%~0.20%; Ce:0.04%~0.12%; Mg:0.02%~0.18%; N:0.06%~0.18%; S<0.05%; P<0.05%; Surplus is Fe and inevitable trace impurity.With ferrotianium, cerium base magnesium-rare earth and nitrogenous substances molten steel is carried out composite inoculating and handle, cooling is fast carried out low-temperaturetempering subsequently and is eliminated stress after high temperature austeniteization.Contain more high rigidity boride in this cast steel, wear resistance is better, but matrix is a martensite, and fragility is bigger.Chinese invention patent CN1804091 then discloses a kind of toughening method of casting high-boron wear-resistant alloy, the chemical ingredients that it is characterized in that casting high-boron wear-resistant alloy is: 0.3~0.35wt%C, 1~1.5wt%B, 0.6~0.8wt%Si, 0.8~1.0wt%Mn, S<0.04wt%, P<0.04wt%, all the other are Fe, Ti and unavoidable impurities element, and wherein Ti is brought into by the alterant ferrotianium; Concrete preparation process is: carry out the molten steel melting earlier, after the aluminium final deoxygenation is finished and is inserted in the molten steel melting, add the processing of going bad of alterant ferro-titanium, treating poured into a mould after skimming clearly, carry out malleableize thermal treatment behind the casting complete, the malleableize thermal treatment temp is 1020~1050 ℃, and soaking time is 2~3 hours, quench or normalizing last tempering then; Alterant ferro-titanium consumption satisfies: wherein the consumption of titanium is 0.75~1.0wt% of casting high-boron wear-resistant alloy; Molten steel adds boron and adopts ferro-boron, adds after ferro-boron adds when the molten steel melting or the agent ferrotianium adds on the turn again.The eutectic boride of the sand mold casting high-boron wear-resistant alloy after the process patent is isolated shape and is distributed in the matrix.The absorption merit A of 10mm * 10mm * 55mm standard impact specimen
kReach 12.5J, impelling strength strengthens.Because matrix is still martensite, fragility is still bigger.
Summary of the invention
The objective of the invention is to solve the problems of the prior art, and a kind of hardness height is provided, wear resistance, plasticity and good toughness, cost is low, the High-boron low-carbon abrasion resistant cast steel and heat treatment method thereof of not nickeliferous and molybdenum element.
The chemical ingredients of a kind of high-boron low-carbon abrasion resistant cast steel provided by the present invention and mass percent thereof are: C:0.15~0.30%, B:1.5~2.5%, Si:2.6~3.0%, Cr:1.4~1.8%, Mn:0.5~0.8%, Ce:0.05~0.12%, V:0.03~0.15%, Ti:0.03~0.15%, P<0.05%, S<0.05%, surplus are Fe, wherein 0.10%<V+Ti<0.25%.
The heat treating method of a kind of high-boron low-carbon abrasion resistant cast steel provided by the present invention may further comprise the steps:
1) with steel scrap, ferro-boron, ferrosilicon, ferrochrome, ferromanganese, Graphite Electrodes or the pig iron, cerium base rare earth, ferrotianium and vanadium iron according to target in the product chemical component weight per-cent get the raw materials ready C:0.15~0.30%, B:1.5~2.5%, Si:2.6~3.0%, Cr:1.4~1.8%, Mn:0.5~0.8%, Ce:0.05~0.12%, V:0.03~0.15%, Ti:0.03~0.15%, P<0.05%, S<0.05%, surplus is Fe, wherein 0.10%<V+Ti<0.25%;
2) with steel scrap, ferro-boron, ferrosilicon, ferrochrome and ferromanganese, put into electric furnace after adjusting its carbon content with the Graphite Electrodes or the pig iron, molten steel fusing, stokehold be adjusted to branch qualified after, temperature is risen to 1580~1600 ℃, add the aluminium deoxidation that accounts for steel quality 0.15%~0.30%, then come out of the stove;
3) cerium base rare earth, ferrotianium and vanadium iron are crushed to the fritter of granularity less than 12mm, after 180~200 ℃ of oven dry, place casting ladle bottom, with pouring method to step 2 in the bag) in the processing of molten steel composite inoculating;
4) after rotten the processing pouring molten steel is become foundry goods;
5) foundry goods is in 880~920 ℃, behind austenitizing 1~3h, directly carries out isothermal quenching in temperature is 250~300 ℃ isothermal salt bath furnace, soaking time 2~4h, and air cooling promptly gets the good high-boron low-carbon abrasion resistant cast steel of obdurability and wear resistance to room temperature subsequently.
The performance of alloy material is by the metallographic structure decision, and certain tissue depends on chemical ingredients and thermal treatment process, and the chemical ingredients of cast steel of the present invention is to determine like this:
Carbon: carbon is to guarantee that steel obtains one of efficient hardening element of high strength, high rigidity, and it can significantly improve the intensity and the hardness of steel, prevents to occur in the quenching structure ferrite.Add-on is too much, and matrix fragility increases, plasticity descends, and suitable carbon content should be controlled at 0.15~0.30%.
Boron: boron is the main alloy element in the high-boron cast steel, adds the iron boron compound that easily forms high rigidity in the steel, obviously improves the cast steel wear resistance, and part of boron is dissolved in matrix, can improve matrix hardening capacity.The boron add-on is too much, causes the fragility boride to increase, and the intensity of cast steel and toughness are obviously descended, and therefore the boron add-on is controlled at 1.5~2.5%.
Silicon: silicon also is the main alloy element in the high-boron low-carbon abrasion resistant cast steel, and be non-carbide forming element, can increase the activity of carbon in austenite, in the bainite ferrite process of growth, unnecessary carbon can be arranged in the contiguous austenite of interface one side, separates out because silicon hinders cementite, causes the rich carbon of austenite on every side, make between the bainite ferrite slip or slip in rich carbon retained austenite stabilization, form carbide-free Bainite.The temperature range that silicon also makes the first kind temper brittleness of steel occur raises, and makes steel eliminate quenching stress more in tempering under the comparatively high temps.In addition, silicon also can make the TTT of steel or the CCT curve moved and improved bainite hardening capacity from steel to the lower right and toughness.During silicone content lower (<2.6%), because a little less than the effect that silicon inhibition carbide is separated out, promote that the effect of bainite transformation is not strong yet, in isothermal transformation, at first separate out bainite at austenite grain boundary, and the austenite that does not change changes martensite in process of cooling subsequently, its microstructure is made up of bainite ferrite, martensite and small portion of residual austenite, have high intensity, hardness, and impelling strength and fracture toughness property are lower; When silicone content brings up to 2.6~3.0%, silicon suppresses the carbide effect of separating out significantly to be strengthened, the carbon enrichment of discharging when bainite is grown up is in austenite, improved the stability of supercooled austenite, its microstructure is typical Ao-Bei tissue, promptly by the bainite ferrite of lath-shaped and the residual austenite of the rich carbon that distributes therebetween form the good obdurability of material tool.Bring up to 3.0% when above when the silicone content in the steel, occurred a large amount of not transformation austenite structures in the tissue, cause the hardness of material to descend.Take all factors into consideration, selecting silicone content is 2.6~3.0%.
Chromium: adding an amount of chromium in the high-boron cast steel, mainly is in order to improve the hardening capacity of steel, and the tissue of refinement steel adds an amount of chromium in addition, helps reducing boride fragility, the embrittlement of boride in preventing to use.Its suitable add-on should be controlled at 1.4~1.8%.
Manganese: adding an amount of manganese in the high-boron cast steel, mainly is in order to improve the hardening capacity of steel, and add-on is too much, and tissue that will the alligatoring steel increases the hot cracking tendency of high-boron cast steel, takes all factors into consideration, and its content is controlled at 0.5~0.8%.
Cerium: in high-boron cast steel, the adding Ce elements can be used as crystallization nuclei and comes crystal grain thinning, thereby improves the toughness of steel, and suitable cerium add-on is 0.05~0.12%.
Vanadium and titanium: in high-boron cast steel, add an amount of vanadium and titanium, can be used for thinning solidification structure, all right in addition refinement boride, promote the suspension and isolated distribution of boride network, help improving the intensity and the toughness of high-boron cast steel, suitable vanadium add-on is 0.03~0.15%, and suitable titanium add-on is 0.03~0.15Ti, and 0.10%<V+Ti<0.25%.
The performance of high-boron cast steel also has direct relation with thermal treatment process, and it is worked out according to being:
Along with the raising of austenitizing temperature, carbon and the alloying element distributing homogeneity in austenite improves, and has reduced isothermal and has been decomposed to form the speed of bainite and rich carbon austenitic, thereby increased austenitic stability relatively.Therefore, under the constant situation of isothermal transformation temperature and time, along with the raising of austenitizing temperature, stabilization of austenite increases, and the quantity of residual austenite increases after the isothermal transformation, and material hardness is descended, and impelling strength improves.If but austenitizing temperature is too high, austenite crystal is grown up and is made the bainite structure that forms after the isothermal transformation thick, causes mechanical property to reduce.
In addition, when austempering temperature is low, phase driving force is bigger, bainite is given birth to nuclear with the poor carbon district in supercooled austenite in a large number along habit plane, but, cause carbon can not in austenite, do the long-range diffusion, therefore under lower austempering temperature because temperature is low, bainite transformation is more abundant, organizes more tiny.When isothermal temperature is elevated to 300 ℃, the lower bainite chap, residual austenite content increases, and at this moment the hardness of steel has decline slightly, and impelling strength improves.Foundry goods directly carries out isothermal quenching in temperature is 250~300 ℃ isothermal salt bath furnace behind 880~920 ℃ * (1~3) h austenitizing, soaking time 1~3h, and air cooling can obtain obdurability and the good high-boron low-carbon abrasion resistant cast steel of wear resistance subsequently.
The present invention compared with prior art has the following advantages:
(1) high-boron low-carbon abrasion resistant cast steel of the present invention is a main alloy element with the rich boron of China, adds elements such as cheap silicon, manganese, chromium in addition, valuable alloying elements such as not nickeliferous, molybdenum, and the starting material source is abundant, low production cost;
(2) in the high-boron low-carbon abrasion resistant cast steel of the present invention, add more boron, can form the iron boron compound of high rigidity, can obviously improve cast steel hardness and improve the cast steel wear resistance;
(3) the present invention adopts isothermal quenching, can obtain carbide-free Bainite, and matrix has good plasticity and toughness;
(4) the present invention adopts stove to add trace rare-earth, ferrotianium and vanadium iron composite inoculating and handles thinning solidification structure, adopts isothermal quenching subsequently, obtains hardness greater than 58HRC, tensile strength sigma
b〉=850Mpa, impelling strength α
k〉=18J/cm
2, fracture toughness property K
IC〉=35MPa.m
1/2High-boron low-carbon abrasion resistant cast steel;
(5) high-boron low-carbon abrasion resistant cast steel of the present invention is applied to the wearing and tearing field, wear resistance improves 2~3 times than high mangaenese steel, improve more than 1 times than low alloy steel, suitable with high-chromium white cast iron, and it is big to have overcome high-chromium white cast iron fragility, easily fragmentation and the deficiency that ruptures in the use, and production cost reduces more than 35% than high-chromium white cast iron.
The invention will be further described below in conjunction with embodiment.
Embodiment
Embodiment 1
With 500 kilograms of medium-frequency induction furnace melting high-boron low-carbon abrasion resistant cast steels, its manufacturing technology steps is:
1) with steel scrap, ferro-boron, ferrosilicon, ferrochrome, ferromanganese batching, adjust carbon content with the barren rock electrode ink, molten steel fusing, stokehold be adjusted to branchs qualified after, temperature is risen to 1592 ℃, adding accounts for the aluminium deoxidation of steel quality 0.24%, then comes out of the stove;
2) cerium base rare earth, ferrotianium and vanadium iron are crushed to the fritter of granularity less than 12mm, after 180~200 ℃ of oven dry, place the casting ladle bottom, the molten steel composite inoculating is handled with pouring method in the bag;
3) after rotten the processing pouring molten steel is become foundry goods;
4) foundry goods is behind 900 ℃ * 2h austenitizing, directly carries out isothermal quenching in temperature is 280 ℃ isothermal salt bath furnace, soaking time 3h, and air cooling can obtain the good high-boron low-carbon abrasion resistant cast steel of obdurability and wear resistance to room temperature subsequently.The cast steel chemical ingredients sees Table 1, and mechanical properties of cast steel sees Table 2.
Element |
C |
B |
Si |
Cr |
Mn |
Ce |
Content |
0.27 |
2.14 |
2.78 |
1.60 |
0.73 |
0.08 |
Element |
V |
Ti |
V+Ti |
S |
P |
Fe |
Content |
0.09 |
0.08 |
0.17 |
0.027 |
0.039 |
Surplus |
Table 1 cast steel chemical ingredients and content thereof (quality %)
Hardness/HRC |
Tensile strength/MPa |
Impelling strength/J.cm
-2 |
Fracture toughness property/MPa.m
1/2 |
58.9 |
880.6 |
19.6 |
37.2 |
Table 2 mechanical properties of cast steel
Embodiment 2
With 500 kilograms of medium-frequency induction furnace melting high-boron low-carbon abrasion resistant cast steels, its manufacturing technology steps is:
1) with steel scrap, ferro-boron, ferrosilicon, ferrochrome, ferromanganese batching, adjust carbon content with the pig iron, molten steel fusing, stokehold be adjusted to branchs qualified after, temperature is risen to 1598 ℃, adding accounts for the aluminium deoxidation of steel quality 0.30%, then comes out of the stove;
2) cerium base rare earth, ferrotianium and vanadium iron are crushed to the fritter of granularity less than 12mm, after 180-200 ℃ of oven dry, place the casting ladle bottom, the molten steel composite inoculating is handled with pouring method in the bag;
3) after rotten the processing pouring molten steel is become foundry goods;
4) foundry goods is behind 920 ℃ * 1h austenitizing, directly carries out isothermal quenching in temperature is 250 ℃ isothermal salt bath furnace, soaking time 4h, and air cooling can obtain the good high-boron low-carbon abrasion resistant cast steel of obdurability and wear resistance to room temperature subsequently.The cast steel chemical ingredients sees Table 3, and mechanical properties of cast steel sees Table 4.
Element |
C |
B |
Si |
Cr |
Mn |
Ce |
Content |
0.17 |
2.48 |
2.61 |
1.44 |
0.78 |
0.11 |
Element |
V |
Ti |
V+Ti |
S |
P |
Fe |
Content |
0.04 |
0.15 |
0.19 |
0.028 |
0.040 |
Surplus |
Table 3 cast steel chemical ingredients and content thereof (quality %)
Hardness/HRC |
Tensile strength/MPa |
Impelling strength/J.cm
-2 |
Fracture toughness property/MPa.m
1/2 |
58.5 |
871.8 |
18.1 |
35.7 |
Table 4 mechanical properties of cast steel
Embodiment 3
With 750 kilograms of medium-frequency induction furnace melting high-boron low-carbon abrasion resistant cast steels, its manufacturing technology steps is:
1) with steel scrap, ferro-boron, ferrosilicon, ferrochrome, ferromanganese batching, adjust carbon content with the pig iron, molten steel fusing, stokehold be adjusted to branchs qualified after, temperature is risen to 1581 ℃, adding accounts for the aluminium deoxidation of steel quality 0.15%, then comes out of the stove;
2) cerium base rare earth, ferrotianium and vanadium iron are crushed to the fritter of granularity less than 12mm, after 180-200 ℃ of oven dry, place the casting ladle bottom, the molten steel composite inoculating is handled with pouring method in the bag;
3) after rotten the processing pouring molten steel is become foundry goods;
4) foundry goods is behind 880 ℃ * 3h austenitizing, directly carries out isothermal quenching in temperature is 300 ℃ isothermal salt bath furnace, soaking time 2h, and air cooling can obtain the good high-boron low-carbon abrasion resistant cast steel of obdurability and wear resistance to room temperature subsequently.The cast steel chemical ingredients sees Table 5, and mechanical properties of cast steel sees Table 6.
Element |
C |
B |
Si |
Cr |
Mn |
Ce |
Content |
0.29 |
1.57 |
2.97 |
1.76 |
0.53 |
0.06 |
Element |
V |
Ti |
V+Ti |
S |
P |
Fe |
Content |
0.14 |
0.03 |
0.17 |
0.030 |
0.039 |
Surplus |
Table 5 cast steel chemical ingredients and content thereof (quality %)
Hardness/HRC |
Tensile strength/MPa |
Impelling strength/J.cm
-2 |
Fracture toughness property/MPa.m
1/2 |
58.1 |
857.4 |
18.4 |
36.6 |
Table 6 mechanical properties of cast steel
Get the high-boron low-carbon abrasion resistant cast steel tup and the sieve plate of the present invention preparation, respectively on hammer mill and agglomerate sieve apparatus, the test run(s) of installing, the former is used for broken agglomerate, and the latter is used to sieve agglomerate.The result shows, wear resistance castings with high-boron low-carbon abrasion resistant cast steel manufacturing of the present invention, safe in utilization, non-cracking in the use, broken phenomenon occurs, obviously prolong than common wear resistance castings work-ing life, wherein on hammer mill, high-boron low-carbon abrasion resistant cast steel tup of the present invention improves 2-3 doubly than high mangaenese steel, improve more than 1 times than low alloy steel, on the agglomerate sieve apparatus, the work-ing life and the high-chromium white cast iron of high-boron low-carbon abrasion resistant cast steel sieve plate of the present invention are suitable, and it is big also to have overcome high-chromium white cast iron fragility, easily fragmentation and the deficiency that ruptures in the use, and production cost reduces more than 35% than high-chromium white cast iron.Applying of material of the present invention has remarkable economical and social benefit.