CN101168824A - Leadless easy-cutting steel for medium-hard tooth face heavy load gear wheel and preparation method thereof - Google Patents
Leadless easy-cutting steel for medium-hard tooth face heavy load gear wheel and preparation method thereof Download PDFInfo
- Publication number
- CN101168824A CN101168824A CNA200710019067XA CN200710019067A CN101168824A CN 101168824 A CN101168824 A CN 101168824A CN A200710019067X A CNA200710019067X A CN A200710019067XA CN 200710019067 A CN200710019067 A CN 200710019067A CN 101168824 A CN101168824 A CN 101168824A
- Authority
- CN
- China
- Prior art keywords
- steel
- forging
- temperature
- rare earth
- free cutting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Landscapes
- Forging (AREA)
Abstract
The invention discloses non-lead easily-cut steel for a middle hard gear surface heavy loading gear. The invention is composed of base steel and easily-cut elements, and the components comprise the contents that: C occupies 0.32 to 0.38 percent, Si occupies 0.20 to 0.40 percent, Mn occupies 1.00 to 1.30 percent, Mo occupies 0.25 to 0.35 percent, Cr occupies 0.9 to 1.1 percent, S occupies 0.08 to 0.10 percent, B occupies 0.001 to 0.005 percent, Re occupies 0.04 to 0.08 percent, Ti occupies 0.01 to 0.03 percent, and the residual is Fe. The invention also discloses the preparation method of the easily-cut steel, when being melted, rare earth and titanium elements are added into the melted steel before the steel is discharged, the steel discharging temperature is controlled at 1630 plus or minus 10 DEG C, the casting temperature is controlled at 1580 plus or minus 10 DEG C, and the melted steel is cast into ingot. Then the forging process of the forging ratio lower than or equal to 6 is performed, the forging starting temperature of the steel ingot is 1150 to 1200 DEG C, and the final forging temperature is 870 to 900 DEG C. Finally, oil quenching at 850 plus or minus 20 DEG C and tempering at 560 plus or minus 20 DEG C are performed, to obtain the easily-cut steel of the invention. The production cost of the easily-cut steel of the invention is reduced, and all the mechanical properties reach the using requirements.
Description
Technical field
The invention belongs to metallurgical technology field, relate to the unleaded free cutting steel of a kind of middle hard gear-face heavy-duty gear, also relate to this kind middle hard gear-face heavy-duty gear with preparation and processing methodes such as the melting of unleaded free cutting steel, forging, thermal treatments.
Background technology
Since free-cutting steel comes out, have the history in more than 80 year so far, its speed of development is very surprising.At present the whole world has the consumption of 5,000,000 tons of free-cutting steels every year approximately, and major part all consumes in developed country, and wherein over half produced by the U.S. and Japan.China just produces free-cutting steel since the fifties, output by every year several kilotons be increased to tens0000 tons of present every year.But on quantity and the kind all with the big gap of external existence, therefore annual all will be from a large amount of free cutting steel material of external import, the cost of import is very high.
Present slush pump heavy-duty gear mainly uses leaded free cutting steel material, and the main technical requirements that commute is cut steel is that tooth face hardness reaches HB270～320.Domesticly once developed a kind of leaded free cutting steel, satisfied requirement to material cutting ability and mechanical property aspect, yet the leaded free cutting steel of this kind all shows toxicity in steel-making, forging and mechanical workout, health to producers has directly constituted threat, finally makes the R﹠D and production of this leaded free-cutting steel be forced to stop.Then gear steel is used the 42CrMoT material again instead, if complete mechanical property requirement according to drawing, then the machining difficulty is very big, production efficiency reduces, have to reduce tooth face hardness (being generally HB180～220) for this reason, this has caused the early stage spot corrosion of gear again, can cause gear to be scrapped when serious.Therefore select for use 42CrMoT quenched and tempered steel to produce the also requirement of the actual use of incompatibility modern production of slush pump gear, it is good to press for a kind of machinability, can satisfy the new steel grade of mechanical property requirements again.
Summary of the invention
The objective of the invention is to develop the unleaded free cutting steel of a kind of middle hard gear-face heavy-duty gear, it is big to solve existing unleaded free cutting steel machining difficulty, the serious problem of early stage spot corrosion of gear reaches and makes the unleaded free cutting steel of this kind have good cutting ability and hot workability.
Another object of the present invention provides melting, forging, heat treated preparation technology's method of above-mentioned unleaded free cutting steel.
The technical solution used in the present invention is, the unleaded free cutting steel of a kind of middle hard gear-face heavy-duty gear, composed of the following components by mass percentage: C is 0.32～0.38%, Si is 0.20～0.40%, Mn is 1.00～1.30%, Mo is 0.25～0.35%, Cr is 0.9～1.1%, S is 0.08～0.10%, B is 0.001～0.005%, Re is 0.04～0.08%, Ti is 0.01～0.03%, and all the other are Fe.
Another technical solution used in the present invention is, a kind of method for preparing above-mentioned unleaded free cutting steel, and this method is carried out according to the following steps:
Step 1: melting technology, adopt corresponding furnace charge and melting loss of elements rate to carry out charge calculation, take by weighing the quality of each component of iron alloy, rare earth, boron are with the form of rare earth ferrosilicon and ferro-boron, before tapping, directly add in the molten steel in the stove, when adding rare earth processing molten steel, want violent stirring, tapping immediately, tapping temperature is controlled at 1630 ℃ ± 10 ℃, teeming temperature is controlled at 1580 ℃ ± 10 ℃, pour into a mould by " low temperature waters soon " principle, add insulating covering agent, molten steel is not exposed;
Step 2: forging process, the resulting steel ingot of step 1 is carried out the forging processing of forging ratio≤6, opening and forging temperature is 1150 ℃～1200 ℃, and final forging temperature is 870 ℃～900 ℃, and type of heating is the air furnace heating;
Step 3: thermal treatment process, the steel ingot that obtains after step 2 forged keeps quenching temperature to be: 850 ± 20 ℃ of oil quenchings, tempering temperature is: 560 ± 20 ℃, both.
In the described step 1, the adding mode of element sulphur adopts and increases S in the stove, and adds with the form of Iron sulfuret.
The invention has the beneficial effects as follows, make unleaded free cutting steel of the present invention have good cutting ability and hot workability, it is big to have solved existing unleaded free cutting steel machining difficulty, the serious problem of early stage spot corrosion of gear.
Description of drawings
Fig. 1 is the inclusion shape appearance figure of unleaded free cutting steel as cast condition of the present invention and forging attitude, and wherein, a is as cast condition inclusion morphology figure, and b forges attitude inclusion morphology figure;
Fig. 2 is that unleaded free cutting steel of the present invention stretches and the impact fracture shape appearance figure, and wherein, a is tension specimen fracture apperance figure, and b is impact specimen fracture apperance figure;
Fig. 3 is the comparison diagram that concerns of unleaded free cutting steel of the present invention and 42CrMo steel main cutting force Fz and cutting speed V;
Fig. 4 is the graph of a relation of unleaded free cutting steel of the present invention and 42CrMo steel cutting temperature T and cutting speed V;
Fig. 5 is the heat-treated sturcture shape appearance figure of unleaded free cutting steel of the present invention, and wherein a is the annealed structure shape appearance figure of steel, and b is the quenching structure shape appearance figure, and c is quenched and tempered organization's shape appearance figure;
Fig. 6 is the influence figure of the tempering temperature of unleaded free cutting steel of the present invention to hardness;
Fig. 7 is the embodiment transverse impact fractograph figure of unleaded free cutting steel of the present invention, wherein, a is the low power scanned photograph organization chart of the horizontal fracture of sample, and b is the shear lip aone organization chart for fracture surface of sample, c is a dimple columnar fracture organization chart, and d is a dimple columnar fracture organization chart;
Fig. 8 is the embodiment impact of collision fractograph figure of unleaded free cutting steel of the present invention, wherein, a is a fracture surface of sample low power scanned photograph organization chart, b is that fracture surface of sample is being the rock-candy structure organization chart near gap portions, c is that the tough break organization chart is appearring in sample away from gap portions, and d is that the tough break organization chart is appearring in sample away from gap portions.
Embodiment
The present invention is described in detail below in conjunction with the drawings and specific embodiments.
It is the contrast steel grade that unleaded free cutting steel of the present invention is deferred to the 42CrMo steel, suitably the sulphur content in the raising steel is to improve cutting ability, add rare earth, titanium elements carries out modification to inclusion to be handled, and fine setting carbon, manganese content and interpolation boron improve the thought of hot workability, the steel-making of employing vacuum oven, the air steel-making of intermediate frequency furnace, forge, thermal treatment, research step such as cutting ability and measuring mechanical property, optimize cutting ability, the new steel grade that mechanical property and hot workability are good-----unleaded 35CrMnMoRS free cutting steel (hereinafter to be referred as unleaded free cutting steel) carries out productivity steel-making by factory's electric arc furnace again, forge, thermal treatment and gear cutting processing experiment.
The concrete composition of unleaded free cutting steel of the present invention sees Table 1.The composition that adds in molten steel is by basic ingredient and easily be cut into branch two portions and form.The basic ingredient that adds guarantees the intensity and the hot workability of steel, interpolation be cut into easily that branch guarantees steel easily cut performance.
The moiety content that table 1 unleaded free cutting steel of the present invention adds
| Composition | C | Si | Mn | Mo | Cr | S | B | Re | Ti |
| Content % | 0.32 ～ 0.38 | 0.20 ～ 0.40 | 1.00 ～ 1.30 | 0.25 ～ 0.35 | 0.9 ～ 1.1 | 0.08 ～ 0.10 | 0.001 ～ 0.005 | 0.04 ～ 0.08 | 0.01 ～ 0.03 |
(annotate: this table is the element of each interpolation, and all the other are Fe)
The basic ingredient and the function analysis of unleaded free cutting steel of the present invention are as follows:
Carbon: the key element of proof strength, hardness and plasticity, flexible good combination.In the unleaded free cutting steel composition design of the present invention, carbon quenched and tempered steel in still adopting.Carbon content C:0.38% in the national standard in the 42CrMo steel～0.45% is because the content of the alloying element in the unleaded free cutting steel of the present invention has improved intensity than basic steel height.Therefore, can suitably reduce the carbon content of unleaded free cutting steel of the present invention, the difficulty in the time of can reducing on the one hand steel ingot and forge is improved the toughness of steel alloy, and it is 0.32%～0.38% that definite carbon content accounts for total mass.
Manganese: manganese element not only can improve the obdurability of steel, and raising sulphur is the cutting ability of free cutting steel.Consider that from steel highly malleablized angle manganese and iron form the Solid solution tissue, improve ferritic hardness and intensity in the steel.Manganese is again carbide forming element, forms the intensity that alloyed cementite improves steel.Manganese reduces the perlite critical transition temperature, plays the effect of refine pearlite tissue, improves perlite intensity.Consider that from the cutting ability angle manganese element and sulphur are that sulphur generates the manganese sulfide inclusion thing in the free cutting steel, improve the cutting ability of steel.Steel grade of the present invention is to be used to make heavy-duty gear, requires hardening capacity to be higher than 42CrMo steel or fair with the 42CrMo steel, and the content that increases manganese can also increase the hardening capacity of steel.Manganese element in steel with reinforced ferrite, increase hardening capacity and easily cut element and add, manganese content accounts for total mass and is defined as 1.00%～1.30%.
Chromium: the chromium element adds mainly as the reinforced ferrite element, and is not obvious to the cutting ability influence of steel grade, so keep the Cr content among the former steel grade 42CrMo, Cr content accounts for total mass and is defined as 0.9%～1.1%.
Molybdenum: molybdenum element not only can improve the hardening capacity of steel, but also can eliminate or reduce detrimentally affect such as the thick and temper brittleness sensitivity of crystal grain that material causes because of the manganese too high levels.Its content accounts for total mass and is decided to be 0.25%～0.35%.
Boron: trace B has significant effect again to the hardening capacity of steel, substitutes expensive elements such as part molybdenum, chromium with cheap boron, reaches to reduce cost, save two purposes of alloying element.The outstanding role of boron is can the be multiplied hardening capacity of steel of the boron of trace.When the add-on of boron was 0.0025%, its effect was best, and the boron too high levels no longer influences hardening capacity, was decided to be 0.001%～0.005% so in design its content is accounted for total mass.
Silicon: add the intensity that element silicon can improve Solid solution on the one hand, increase the hardening capacity of steel; On the other hand, silicon is a kind of deoxidant element, often is attended by SiO in steel
2, silicate inclusion generates, this type impurity generally has high fusing point and high hardness, aggravates tool wear in the Tool in Cutting process.Because the furnace charge that adds in the steel-making all contains higher silicone content, in the time of particularly will adding rare earth ferrosilicon, inevitably introduces element silicon, the content of silicon is accounted for total mass be defined as 0.20%～0.40%.
It is as follows easily to cut elemental composition and function analysis in the unleaded free cutting steel of the present invention:
Sulphur: element sulphur is the most frequently used easy cutting element, and is nontoxic.Based on the sulphur and the compound series free-cutting steel of sulphur of cutting ability, sulphur content is between 0.20%～0.40%; Based on mechanical property, cutting ability is the free-cutting steel of assisting, and sulphur content is 0.04%～0.07%; Important structure part sulphur content optional 0.08%～0.13%.In order to guarantee the mechanical property of steel, its sulphur content is accounted for total mass be decided to be 0.08%～0.10%.
Titanium: add the titanium elements of trace in the resulfurizing series free cutting steel, can further improve the cutting ability of steel.Titanium series free-cutting steel is a kind of novel easy-to-cut steel and since the titanium refinement crystal grain, and increased hardening capacity, effect is remarkable improving aspect the Machinability of Stainless Steel.Its shortcoming is that slow cutting is not good.It is that free cutting steel can improve the mechanical property of steel and the thought of cutting ability that the present invention adopts Re-S, Ti-S, adds the trace amount of titanium element, and it is 0.01%～0.03% that its content accounts for total mass.
Re: add type and the form that rare earth element can change inclusion (particularly sulfide) in the steel.Add in the steel and make behind the cerium sulfide that distributes along crystal boundary change into the spherical sulfide that is distributed in intracrystalline, perhaps make block sulfide (III class) change into spherical sulfide (I class).Rare earth changes the formula of oxide morphology in the steel, i.e. Re/S 〉=1.5 o'clock, and the form that can control sulfide is entirely spherical.Determine that in view of the above it is 0.04%～0.08% that rare earth Re content accounts for total mass.
The preparation method of unleaded free cutting steel of the present invention implements according to the following steps,
Step 1, melting technology.In free cutting steel, the composition of inclusion, form, distribution and volume fraction have fundamental influence to the cutting ability and the mechanical property of steel grade.The smelting technology of steel influences the formation of inclusion.Unleaded free cutting steel of the present invention can adopt vacuum induction furnace melting, the melting of air induction furnace or air-arc furnace melting.
Will note when preparing burden in the melting technology of the present invention: the first, in order to guarantee batching accurately, furnace charge should not have oily few the rust, few steel cuttings amount of using.The second, understand fully the chemical ingredients of furnace charge, when using the steel alloy furnace charge, avoid introducing and the irrelevant impurity element of this steel grade.Three, reduce the scaling loss of alloying element, guarantee recovery rate, the suitable joining day of various alloys and the rate of receipts should take into full account.
Unleaded free cutting steel of the present invention is in fusion process, and the adding of alloying element does not have particular requirement, can add refining by the melting mode of general steel alloy, and key is the adding mode and the rational joining day of rare earth element, calcium and element sulphur.Because the avidity of rare earth element and oxygen is very strong, makes the adding method of steel middle-weight rare earths become a problem with unique meaning.Rare earth adds in the steel and following point: Re generally occurs
2O
3, Re
2O
2S proportion and molten steel are close or high slightly, easily form the awl segregation in the bottom; The secondary oxidation problem occurs, sulphur is reduced in the molten steel, II class sulfide might occur in process of setting, and the rare earth behind the secondary oxidation no longer has Denaturation; Rate of recovery instability.Therefore, when adding rare earth processing molten steel, should guarantee low oxygen level, want violent stirring when adding rare earth, make the little and uniform distribution of reaction product.Rare earth element add to adopt rare earth ferrosilicon alloy or norium, adopts in the bag to be pressed into, to hang in the mould etc.When adding rare earth, can add the Si-Ca alloy simultaneously, the effect of calcium is the unlikely oxidation of protection rare earth, helps rare earth and dissolve decomposition in steel, improves rare earth yield.The adding mode of element sulphur adopts and increases S in the stove, and adds with the form of Iron sulfuret, to guarantee recovery rate.
Unleaded free cutting steel of the present invention is controlled tapping temperature at 1630 ℃ ± 10 ℃ in casting cycle, pouring temperature is controlled at 1580 ℃ ± 10 ℃, the warm teeming speed of strict control casting, and teeming speed is answered held stationary, and speed governing should be not too urgent, prevents that steel ingot from producing transverse fissure.
Step 2, forging process because unleaded free cutting steel of the present invention contains S amount height, belong to heavy froging again, and forging ratio is big, must strict control forging process.Forging process is that steel ingot is opened and forged temperature is 1150 ℃～1200 ℃, 870 ℃～900 ℃ of final forging temperatures.Type of heating is an air furnace, presses the forging size dimension heat-up time and determines.Because the final forging temperature of unleaded free cutting steel of the present invention is higher, might make grain coarsening, for crystal grain thinning, can carry out one annealing operation after the forging.
Step 3, thermal treatment process, the blank that has forged just will heat-treated before the mechanical workouts such as car, gear shaping.Thermal treatment is little to the influence of inclusion, and only need the control quenching temperature to be in the technology: 850 ± 20 ℃ of oil quenchings are incubated two hours; Tempering temperature is: 560 ± 20 ℃, be incubated 3 hours, both.
The mechanics property analysis of unleaded free cutting steel of the present invention:
In order relatively unleaded free cutting steel of the present invention and 42CrMo to be carried out the forging of same forging ratio and the thermal treatment of same process, carry out conventional mechanical property respectively and detect.Tensile property carries out according to GB GB228-76, and impact property adopts the V-notch sample and carries out according to GB GB2106-80, has tested the horizontal and impact of collision toughness of two kinds of materials respectively.Table 2 be two kinds of steel performance relatively, unleaded free cutting steel mechanical property of the present invention as can be seen and 42CrMo steel very approaching can substitute the 42CrMo steel from mechanical property and hot workability aspect.
The mechanical property of table 2, unleaded free cutting steel of the present invention and 42CrMo steel relatively
| Material | σb (MPa) | σs (MPa) | δ ％ | ψ ％ | akv J/cm2 | HB | |
| 35CrMnMoRS 42CrMo | 994 1097 | 850 894 | 12.5 13.8 | 53 57 | Vertically | Laterally | 332 328 |
| 95 107 | 63 76 | ||||||
Annotate: forging ratio is 6,850 ℃ of oil quenchings, 560 ℃ of tempering
As shown in Figure 1, be unleaded free cutting steel as cast condition of the present invention and forging attitude (forging ratio is 6) inclusion morphology figure.Shown in a, the as cast condition inclusion is based on manganese sulfide, and elements such as iron content, rare earth are with spherical, spot distribution.Shown in the b, forge the big inclusion of back small part and be elongated, point-like inclusion still keeps original form.This good shapes has guaranteed higher transverse impact performance.
As shown in Figure 2, be the stretching and the impact fracture shape appearance figure of the unleaded free cutting steel kind of the present invention.Wherein a is the tension specimen fracture apperance of the unleaded free cutting steel kind of the present invention; B is the impact specimen fracture apperance of the unleaded free cutting steel kind of the present invention.The fracture of two kinds of fracture modes is plastic fracture, is the uneven typical dimple pattern of size, the big visible Spherical Inhomogeneity thing in dimple bottom.Fracture apperance shows that unleaded free cutting steel alloying of the present invention is rational.
Unleaded free cutting steel cutting ability of the present invention is analyzed:
Cutting test is to carry out the dried external cutting test of cutting on C620-1 type lathe.Other is equipped with anistree ring type dynamometry frame, resistance dynamic strain meter, x-y function recording instrument, electron potentiometer etc.
Test is YT15 with cutter, geometric parameter:
γ0＝60，α0＝α0/＝60，λs＝60，κr＝750，κr/＝150。
The cutting parameter is: amount of feed f=2mm/r, the shape that depth of cut ap=2mm. observation different rotating speeds cuts down, color etc.
Test unleaded free cutting steel cutting ability of the present invention, and compare with cutting ability under the 42CrMo steel equal state.
As shown in Figure 3, be the graph of a relation between above-mentioned two kinds of material cutting force and the cutting speed, Fig. 3 shows that the main cutting force of unleaded free cutting steel of the present invention (S-R) is starkly lower than the main cutting force of 42CrMo, cutting speed scope at 10m/min～80 m/min, unleaded free cutting steel main cutting force of the present invention changes mild, shows good easy cutting characteristic.
As shown in Figure 4, be to characterize the cutting temperature of temperature and the graph of a relation of cutting speed with the thermopair output voltage, unleaded free cutting steel of the present invention (S-R) is in the lower cutting temperature (than the little potential difference reading of 42CrMo) of cutting speed scope performance.What reflect unleaded free cutting steel of the present invention easily cuts characteristic.
Owing to the introducing of sulphur and rare earth element, improved the machinability of unleaded free cutting steel of the present invention.From the result of cutting experiment, situations such as the cutting force of unleaded free cutting steel of the present invention, cutting temperature, chip breaking all are better than former steel grade 42CrMo.
Embodiment 1
The vacuum furnace charge is all adopted in vacuum metling, starting material, and ingot casting is of a size of 140～ 120 * 300 frustums, undertaken by following step,
Step 1: melting technology, adopt corresponding furnace charge and melting loss of elements rate to carry out charge calculation, take by weighing the quality of each component of iron alloy, rare earth, boron directly add in the molten steel in the stove with the form of rare earth ferrosilicon and ferro-boron before tapping, tapping immediately, tapping temperature is controlled at 1620 ± 20 ℃, and pouring temperature is controlled at 1570 ± 10 ℃, pours into a mould by " low temperature waters soon " principle, add insulating covering agent, molten steel is not exposed.
Step 2: forging process, the resulting steel ingot of step 1 is carried out the forging processing of forging ratio≤6, opening and forging temperature is 1150 ± 20 ℃, and final forging temperature is 870 ± 10 ℃, and type of heating is the air furnace heating.
Step 3: thermal treatment process, the steel ingot that obtains after step 2 forged keeps quenching temperature to be: 830 ± 10 ℃ of oil quenchings, tempering temperature is: 540 ± 10 ℃, both.
The design mix of steel and steel-making end composition of steel result of laboratory test see Table 3 when feeding intake.As can be seen, the actual constituent of steel reaches design requirements substantially.It should be noted that owing to adopted vacuum furnace charge and vacuum metling, the chemical examination composition of food ingredient and ingot casting is very approaching, but the rare earth element difference is bigger.For the forging condition of simulation bull gear, select the forging ratio (forging ratio is 6) in the actual production for use, steel ingot is forged, be swaged into the garden bar of 50, do not find defectives such as crackle in the forging.
The unleaded free cutting steel design composition and the result of laboratory test of present embodiment during table 3 vacuum metling
| Chemical ingredients | C | Si | Mn | Cr | Mo | S | B | Re | Ti |
| Design | 0.38 | 0.20 | 1.3 | 0.9 | 0.25 | 0.08 | 0.005 | 0.08 | 0.01 |
| Scope, % result of laboratory test, % | 0.36 | 0.20 | 1.29 | 0.87 | 0.23 | 0.065 | 0.004 | 0.05 | 0.01 |
The unleaded free cutting steel of the present embodiment that is swaged into carries out modifier treatment with 42CrMo steel (commercial), and hardness reaches HB320～340.Contrast cutting test qualitatively, find that the 42CrMo steel is difficult to cutting under this hardness, and the unleaded free cutting steel of present embodiment shows good cutting ability.
The vacuum metling of the unleaded free cutting steel of present embodiment, forging, heat treatment performance are good, and no particular requirement can be satisfied the production reality of factory; Under the identical situation of other condition, the unleaded free cutting steel of present embodiment is under the hardness of HB340, and its cutting ability obviously is better than the 42CrMo steel.
Embodiment 2
The steel-making of intermediate frequency air furnace, air-arc furnace steel-making commonly used directly contacted with air during consideration was produced, and for the realistic working condition of free cutting steel composition energy that vacuum oven is determined, we adopt the 50kg medium-frequency induction furnace to carry out air furnace steel-making test.Furnace charge all is the air furnace charge, and the concrete trade mark of master alloy sees Table 4, and the master alloy composition sees Table 5, and adopts rare earth, titanium to carry out modification and handle, undertaken by following step,
Step 1: melting technology, adopt corresponding furnace charge and melting loss of elements rate to carry out charge calculation, take by weighing the quality of each component of iron compound, rare earth, boron directly add in the molten steel in the stove with the form of rare earth ferrosilicon and ferro-boron before tapping, tapping immediately, tapping temperature is controlled at 1610 ± 20 ℃, and pouring temperature is controlled at 1570 ± 10 ℃, pours into a mould by " low temperature waters soon " principle, add insulating covering agent, molten steel is not exposed.
Step 2: forging process, the resulting steel ingot of step 1 is carried out the forging processing of forging ratio≤6, opening and forging temperature is 1170 ± 10 ℃, and final forging temperature is 880 ± 20 ℃, and type of heating is the air furnace heating.
Step 3: thermal treatment process, the steel ingot that obtains after step 2 forged keeps quenching temperature to be: 850 ± 10 ℃ of oil quenchings, tempering temperature is: 560 ± 10 ℃, both.
Table 4, the master alloy trade mark
| Title | Low carbon ferromanganese | Low carbon ferrochromium | Molybdenum-iron | Ferro-boron | Rare earth ferrosilicon |
| The trade mark | Low carbon ferromanganese | Low carbon ferrochromium | FeMo55-B | FeB235C0.05 | FeSiRE30 |
The composition of table 5 master alloy
| Master alloy | Alloying constituent, % (surplus is an iron) | ||||||||
| C | Si | Mn | Cr | Mo | S | B | Re | Ti | |
| 35 steel low carbon ferromanganese low carbon ferrochromium molybdenum-iron ferro-boron rare earth ferrosilicon titanium valve Iron sulfurets | 0.33 0.7 0.21 | 0.25 1.1 0.6 1.5 2.0 40 | 0.59 82 4.0 | 67.5 | 55 | 0.014 0.15 0.01 36.4 | 24 | 30 | 3.5 99 |
Concrete batching is undertaken by table 6 and table 7.Wherein the recovery rate of FeS is with 100%, and the titanium valve recovery rate is by 50%, rare earth be the recovery rate of rare earth ferrosilicon with 60～80%, total amount of rare earth 30%, Ce content are 15% to prepare burden, all the other each elements are joined by technology.Smelting temperature is 1630 ℃ ℃, the sand mo(u)ld casting, and 1580 ℃ of temperature, casting dimension is the garden rod of 130.
Table 6 present embodiment steel-making allocation sheet (35kg always prepares burden)
| Furnace charge | 35 steel | Ferromanganese | Molybdenum-iron | Ferrochrome | Sulphur iron | Ferro-boron | Rare earth ferrosilicon | Titanium valve |
| Weight (kg) | 33.6 | 0.35 | 0.184 | 0.59 | 0.03 | 0.009 | 0.04 | 0.01 |
The food ingredient of table 7 present embodiment and result of laboratory test
| Chemical ingredients | C | Si | Mn | Cr | Mo | S | B | Re | Ti |
| Food ingredient, % steel ingot chemical examination composition, % | 0.32 0.34 | 0.40 0.37 | 1.0 1.05 | 1.1 1.04 | 0.35 0.31 | 0.1 0.086 | 0.001 0.000 | 0.04 0.01 | 0.03 0.02 |
Listed steel ingot chemical examination composition in the table 7, as can be seen, steel ingot composition and food ingredient basically identical, unleaded free cutting steel composition according to the invention requirement.
Steel ingot is forged, and opening and forging temperature is 1170 ± 10 ℃, 880 ± 20 ℃ of final forging temperatures, and 120 minutes heat-up times, the box-type furnace heating, 50 tons air hammer flat-die forging is swaged into Φ 55, and forging ratio is 6.The unleaded free cutting steel forgeability of the present embodiment of smelting in the air furnace is good.
The present embodiment sample of Φ 55 and the 42CrMo of Φ 55 are carried out modifier treatment, and its quenching temperature is 850 ℃ ± 10 ℃ oil quenchings, is incubated 1 hour, and 560 ℃ ± 10 ℃ of tempering temperatures are incubated 3 hours, air cooling.
Hardness after the unleaded free cutting steel of present embodiment is handled is HB330,42CrMo is 340, tensile strength is 975MPa, and near the 1150MPa of 42CrMo steel, unit elongation is 11.3%, 12% suitable with the 42CrMo steel, impact of collision toughness is 7.6kgfm/cm2, and is approaching with 8.6 kgfm/cm2 of 42CrMo steel, and transverse impact toughness is 4.8kgfm/cm2, poor than 42CrMo steel, but meet the requirement that sulphur is free cutting steel.The 42CrMo steel is difficult to cut under HB340 hardness, for this carries out 600 ℃ ± 10 ℃ tempering to it, its hardness is reduced to HB260 carry out cutting test, and the result is shown in table 8 and table 9.As seen the unleaded free cutting steel of present embodiment still has characteristics such as cutting force is little, cutting temperature is low under high rigidity.
Table 8,42CrMo (φ 50mm) cutting force test result
| Test event | Test value under the corresponding rotating speed | ||||||
| Cutting speed (m/min) | 11.8 | 20.0 | 25.0 | 38.5 | 47.9 | 63.5 | 79.2 |
| Cutting force Fz (N) | 1332.8 | 1254.4 | 1176.0 | 1215.2 | 1176.0 | 1136.8 | 1058.4 |
| Cutting temperature (mV) | 5.8 | 6.3 | 8.2 | 9.1 | 9.4 | 10.9 | 12.8 |
The unleaded free cutting steel of table 9, present embodiment (φ 50) cutting force test result
| Test event | Test value under the corresponding rotating speed | ||||||
| Cutting speed (m/min) | 11.8 | 20.0 | 25.0 | 38.5 | 47.9 | 63.5 | 79.2 |
| Cutting force Fz (N) | 940.8 | 940.8 | 901.6 | 862.4 | 823.2 | 784 | 744.8 |
| Cutting temperature (mV) | 5.2 | 6.2 | 6.9 | 7.4 | 7.8 | 10.0 | 13.0 |
The unleaded free cutting steel of present embodiment is fit to air furnace to be smelted, and forges, heat treatment performance is good, and mechanical property and 42CrMo steel are approaching, show good easily cutting property.
Embodiment 3
The productivity electric arc furnace smelting is smelted on the successful basis of enforcement, at the composition and the production technique of unleaded free cutting steel of the present invention at vacuum, intermediate frequency furnace, the moiety that provides according to table 1, in conjunction with concrete working condition make steel, forging, thermal treatment and Gear Processing, implement according to the following steps
Step 1: melting technology, adopt corresponding furnace charge and melting loss of elements rate to carry out charge calculation, take by weighing the quality of each component of iron alloy, rare earth, boron directly add in the molten steel in the stove with the form of rare earth ferrosilicon and ferro-boron before tapping, tapping immediately, tapping temperature is controlled at 1620 ± 20 ℃, and pouring temperature is controlled at 1570 ± 20 ℃, pours into a mould by " low temperature waters soon " principle, add insulating covering agent, molten steel is not exposed.
Step 2: forging process, the resulting steel ingot of step 1 is carried out the forging processing of forging ratio≤6, opening and forging temperature is 1180 ± 20 ℃, and final forging temperature is 880 ± 20 ℃, and type of heating is the air furnace heating.
Step 3: thermal treatment process, the steel ingot that obtains after step 2 forged keeps quenching temperature to be: 860 ± 10 ℃ of oil quenchings, tempering temperature is: 570 ± 10 ℃, both.
Present embodiment adopts arc melting, and unleaded free cutting steel of the present invention is a carbon quenched and tempered steel in a kind of microalloy, and trace alloying element and the easily adding of cutting element have increased the melting difficulty.The melting technology main points mainly contain: normal running as in the past before fusing, oxidation, reduction bits bleach; Keep white slag about 20 minutes, sampling analysis is pulled out 2/3rds alkaline reduction slags, adds sulphur iron according to the residual S amount of sample in stove, add firebrick piece macrobead magnesia immediately and make inferior acid slag, push away slag and stir, continue reduction with the carbon silica flour, after the slag flavescence, adjust composition, continue reduction; Tapped preceding about 3 minutes, and added Si-Fe, Si-Al-Ba pushes away slag and stirs; Add rare earth on request in stove before the tapping, Ti-Fe stirs, and presses 0.3kg/T B-Fe (content 18.8%) is inserted in the molten steel in the stove, tapping immediately.Tapping temperature is controlled at 1620 ± 20 ℃, and teeming temperature is controlled at 1570 ± 20 ℃, pours into a mould by " low temperature waters soon " principle, adds insulating covering agent, and molten steel is not exposed as far as possible.About the ingredients principle of alloying element, Cr, Mn content add by the middle upper limit, and firebrick piece, macrobead magnesia are pressed the 6:4 proportioning, and S-Fe content is by 50%, and recovery rate presses 90%, B-Fe, and the Ti-Fe recovery rate is by 50%.Before in rare earth element adds stove, the S content of stokehold chemical examination reaches the upper limit of composition design, and the add-on of rare earth is according to 0.09% content adding, the rate of recovery of testing S and rare earth element successively.After above-mentioned measure melting, the chemical ingredients process chemical examination to steel ingot find that the content of elements such as its alloying element B, Ti has reached design requirements, and the content of S is 0.033%, and content of rare earth is 0.04%.Think, rare earth element adopts in the stove and adds, because the S constituent content in the molten steel is than the height of ordinary steel, thereby very easily generating the Re2S3 inclusion, this inclusion proportion is light than molten steel, in processes such as the tapping of molten steel subsequently, calmness, cast, provide rare-earth sulfide to enter the condition of slag, thereby caused the dual loss of rare earth and S element, the effect of inclusion modification is not played in the adding of rare earth element, and what play a part on the contrary is cleaning molten steel, go out sulphur.Therefore, for the content that makes sulphur in the steel can reach design requirements, must increase the add-on of S-Fe.Result of laboratory test to the ingot casting composition is as shown in table 10.
Table 10, present embodiment food ingredient and productivity chemical examination composition are relatively
| Alloying element | C | Si | Mn | Mo | Cr | S | B | Re | Ti |
| Food ingredient, % | 0.37 | 0.37 | 1.22 | 0.30 | 1.05 | 0.095 | 0.004 | 0.05 | 0.025 |
| Chemical examination content, % | 0.36 | 0.37 | 1.24 | 0.29 | 1.02 | 0.106 | 0.003 | ＜0.01 | 0.022 |
From the chemical examination composition as can be seen, S, B, Ti microalloy element all reach the requirement of design mix, and the adding method that these three kinds of elements are described is feasible in actual production.But regrettably rare-earth element modified content is far below design mix, this mainly is that directly the form with rare earth ferrosilicon charges in the molten steel rare earth element in the melting later stage, in steel, mainly play a part deoxidation, desulfurization, the modifying function of inclusion is reduced, make that the content of rare earth is very low.
The forging process of the unleaded free cutting steel of present embodiment
The existence that lot of F eS is mingled with causes the hot-short of steel.The unleaded free cutting steel S element of present embodiment is the form adding with alloying element, plays a part to improve cutting ability, increases the difficulty of steel ingot at forging process.But because the adding of Mn, Ti, rare earth element has changed the composition and the form of inclusion, thereby has avoided the hot-short generation of steel.In actual forging process, improve the final forging temperature of steel, can reduce the forging deformation stress increase that steel occurs in the cryogenic forging process, form big stress concentration at inclusion and basal body interface, thus the germinating crackle, on the other hand, improve final forging temperature, also can play the anisotropy of improving steel mechanical property, so in forging process, its final forging temperature is decided to be 880 ± 20 ℃.
Concrete forging process is 1180 ± 20 ℃ for opening the forging temperature, and final forging temperature is 880 ± 20 ℃, and forging process roughly is divided into chamfered edge → otch → jumping-up → punching → reaming → dehydrogenation, has carried out 3 heating altogether, and forging ratio is 5.As seen, the forging ratio of the unleaded free cutting steel of present embodiment is bigger, but owing to adopted the technology of jumping-up pulling, has improved the horizontal plastic property and the toughness of steel.From forging process, defective or crackle all do not appear in forged three samples simultaneously, illustrate that the unleaded free cutting steel of present embodiment has good forgeability.
The thermal treatment process of the unleaded free cutting steel of present embodiment
The unleaded free cutting steel of present embodiment at the end often obtains thick and uneven recrystal grain in forging, autstenitic grain size is generally at 3～4 grades, this be on the one hand since when forging the each several part distortion inhomogeneous, forging can not be swaged into by a fire on the other hand, need carry out heating for multiple times, forging.In order to guarantee that forging has the favorable mechanical performance, obtain tiny and uniform crystal grain is important condition.So, to note the refinement and the homogenizing problem of crystal grain in thermal treatment.During dehydrogenation, can prevent on the one hand the generation of white point, but thinning microstructure also on the other hand.In addition, for easy to process and carried out the effect that annealing process also can play structure refinement.
Multinomial research points out that the inclusion in the steel is very little to the Heat Treatment Of Steel performance impact.Therefore, in industrial experimentation, the unleaded free cutting steel thermal treatment process of present embodiment is consistent with the 42CrMoT steel fully, and its quenching temperature is 860 ± 10 ℃, be incubated two hours, and heat-eliminating medium is that zero number diesel cycle is cooled off.570 ± 10 ℃ of tempering temperatures are incubated 3 hours.After measured, the hardness after modified is 320HB with this technology.
As shown in Figure 5, be the conventional heat-treated sturcture shape appearance figure of test steel, wherein a is the annealed structure shape appearance figure of steel, and b is the quenching structure shape appearance figure, and c is quenched and tempered organization's shape appearance figure.
As shown in Figure 6, for the tempering temperature of test steel to the figure that influences of hardness.As can be seen from Figure, this steel has good anti-temper resistance when 560 ℃ ± tempering below 10 ℃, and when surpassing 560 ℃ ± 10 ℃, hardness obviously reduces.The slush pump heavy-duty gear requires at 270～340HB, so this steel is to be advisable 550 ℃ ± 10 ℃ left and right sides tempering with the tooth face hardness of steel at present.
The unleaded free cutting steel of present embodiment has reduced the horizontal mechanical property of the mechanical property, particularly steel of steel because the content of S element is higher.Table 12 is mechanics performance determining data, except transverse impact toughness a little less than (a the design requirements
Kv＞48J/cm
2), other mechanical performance index is all above the design safety requirement.The decline of lateral performance, closely related with the form of inclusion.
The Mechanics Performance Testing result of the unleaded free cutting steel test example of table 12, present embodiment
| Material | σ b(Mpa) | σ s(Mpa) | δ ％ | ψ ％ | a kv J/cm 2 | HB | |
| Vertically | Laterally | ||||||
| 35CrMnMoRS | 900 | 755 | 15 | 51 | 65 | 37 | 300 |
As shown in Figure 7, laterally test the impact fracture organization chart for sample.Wherein scheming a is the low power scanned photograph of horizontal fracture sample, and figure b arrow points b point is the shear lip aone of fracture, corresponding b, at the fracture dimple not of uniform size that distributing, rectangular MnS is mingled with and is distributed in the dimple, and fracture is tough break, the corresponding arrow points c of figure c point, in this zone, existing dimple columnar fracture appearance has accurate cleavage again, the toughness of material variation, the corresponding arrow points d of figure d point, the pattern of ordering with c is identical.
As shown in Figure 8, figure a is the vertically impact fracture organization chart of experiment of sample.Wherein scheme the low power scanned photograph of a for the impact fracture sample of vertical experiment, arrow points b point is being rock-candy structure for fracture near gap portions among the figure b, arrow points c point tough break occurring away from gap portions among the figure c, and arrow points d point tough break occurring away from gap portions among the figure d.Different is, sample inclusion longitudinally is spherical distribution, and MnS compares with strip, has increased the resistance of crack propagation, and corresponding notched bar impact strength is also higher.It should be noted that the inclusion among the figure c has been carried out energy spectrum analysis, show that this inclusion mostly is the symbiosis inclusion of manganese oxide and ferric oxide.
From embodiment, illustrate that unleaded free cutting steel of the present invention can accomplish scale production.The melting of unleaded free cutting steel of the present invention, forgeability excellence, cutting ability obviously is better than the 42CrMoT steel, and this will enhance productivity and economic benefit greatly.According to the forging practice of unleaded free cutting steel of the present invention, can consider final forging temperature is dropped to 860 ℃ ± 10 ℃.Gear is after modifier treatment, carry out gear-shaping processing, concrete complete processing is according to the technology of 42CrMoT steel, through on-the-spot test, unleaded free cutting steel of the present invention is when quenching and tempering hardness reaches the HB320 left and right sides, its cutting ability is better than the 42CrMoT steel, and gear surface smooth finish improves a grade, and cutter life improves at least one times.
Three bull gear slush pump heavy-duty gear test samples making of unleaded free cutting steel of the present invention are in the field test use, and the tracking situation shows that these three bull gear slush pump heavy-duty gear working orders are good.These all prove absolutely, the unleaded free cutting steel of 35CrMnMoRS of the present invention meets national environmental protection, policy efficiently, can be widely used in the heavy-duty gear of industries such as oil, sugaring, steel rolling.
Claims (3)
1. unleaded free cutting steel of middle hard gear-face heavy-duty gear, it is characterized in that: by total mass per-cent, composed of the following components, C is 0.32～0.38%, Si is 0.20～0.40%, Mn is 1.00～1.30%, Mo is 0.25～0.35%, Cr is 0.9～1.1%, S is 0.08～0.10%, B is 0.001～0.005%, Re is 0.04～0.08%, Ti is 0.01～0.03%, and all the other are Fe.
, a kind of method for preparing the described unleaded free cutting steel of claim 1, it is characterized in that: this method is carried out according to the following steps,
Step 1: melting technology, adopt corresponding furnace charge and melting loss of elements rate to carry out charge calculation, take by weighing the quality of each component of iron compound, rare earth, boron are with the form of rare earth ferrosilicon and ferro-boron, before tapping, directly add in the molten steel in the stove, when adding rare earth processing molten steel, want violent stirring, tapping immediately, tapping temperature is controlled at 1630 ℃ ± 10 ℃, teeming temperature is controlled at 1580 ℃ ± 10 ℃, pour into a mould by " low temperature waters soon " principle, add insulating covering agent, molten steel is not exposed;
Step 2: forging process, the resulting steel ingot of step 1 is carried out the forging processing of forging ratio≤6, opening and forging temperature is 1150 ℃～1200 ℃, and final forging temperature is 870 ℃～900 ℃, and type of heating is the air furnace heating;
Step 3: thermal treatment process, the steel ingot that obtains after step 2 forged keeps quenching temperature to be: 850 ± 20 ℃ of oil quenchings, tempering temperature is: 560 ± 20 ℃, both.
3. preparation method according to claim 2 is characterized in that: in the described step 1, the adding mode of element sulphur adopts and increases S in the stove, and adds with the form of Iron sulfuret.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA200710019067XA CN101168824A (en) | 2007-11-15 | 2007-11-15 | Leadless easy-cutting steel for medium-hard tooth face heavy load gear wheel and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA200710019067XA CN101168824A (en) | 2007-11-15 | 2007-11-15 | Leadless easy-cutting steel for medium-hard tooth face heavy load gear wheel and preparation method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101168824A true CN101168824A (en) | 2008-04-30 |
Family
ID=39389589
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA200710019067XA Pending CN101168824A (en) | 2007-11-15 | 2007-11-15 | Leadless easy-cutting steel for medium-hard tooth face heavy load gear wheel and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101168824A (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102703826A (en) * | 2012-06-13 | 2012-10-03 | 安徽工业大学 | Ti-B-R compound micro-alloying high-tenacity bending die steel and preparation method thereof |
| CN102886661A (en) * | 2012-09-11 | 2013-01-23 | 昌利锻造有限公司 | Method for forging spiral bevel gear pinion of automobile rear axle |
| CN102989940A (en) * | 2012-08-22 | 2013-03-27 | 昌利锻造有限公司 | Processing method of positioning hook forge piece |
| CN104668433A (en) * | 2015-02-03 | 2015-06-03 | 江苏金源锻造股份有限公司 | Big gear forging process |
| CN105057559A (en) * | 2015-07-20 | 2015-11-18 | 安徽蓝博旺机械集团精密液压件有限责任公司 | Method for forging fuel feed pump driving gear for forklift |
| CN107177804A (en) * | 2017-04-07 | 2017-09-19 | 江阴兴澄特种钢铁有限公司 | A kind of high tough quenched round steel of Cutting free and its manufacture method |
| CN111850407A (en) * | 2020-07-29 | 2020-10-30 | 成都先进金属材料产业技术研究院有限公司 | 850 MPa-grade titanium-containing free-cutting stainless steel forged bar and preparation method thereof |
| CN112899567A (en) * | 2021-01-18 | 2021-06-04 | 中国科学院金属研究所 | High-purity high-strength-toughness rare earth free-cutting steel |
-
2007
- 2007-11-15 CN CNA200710019067XA patent/CN101168824A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102703826A (en) * | 2012-06-13 | 2012-10-03 | 安徽工业大学 | Ti-B-R compound micro-alloying high-tenacity bending die steel and preparation method thereof |
| CN102989940A (en) * | 2012-08-22 | 2013-03-27 | 昌利锻造有限公司 | Processing method of positioning hook forge piece |
| CN102886661A (en) * | 2012-09-11 | 2013-01-23 | 昌利锻造有限公司 | Method for forging spiral bevel gear pinion of automobile rear axle |
| CN104668433A (en) * | 2015-02-03 | 2015-06-03 | 江苏金源锻造股份有限公司 | Big gear forging process |
| CN105057559A (en) * | 2015-07-20 | 2015-11-18 | 安徽蓝博旺机械集团精密液压件有限责任公司 | Method for forging fuel feed pump driving gear for forklift |
| CN107177804A (en) * | 2017-04-07 | 2017-09-19 | 江阴兴澄特种钢铁有限公司 | A kind of high tough quenched round steel of Cutting free and its manufacture method |
| CN111850407A (en) * | 2020-07-29 | 2020-10-30 | 成都先进金属材料产业技术研究院有限公司 | 850 MPa-grade titanium-containing free-cutting stainless steel forged bar and preparation method thereof |
| CN111850407B (en) * | 2020-07-29 | 2021-10-08 | 成都先进金属材料产业技术研究院有限公司 | 850 MPa-grade titanium-containing free-cutting stainless steel forged bar and preparation method thereof |
| CN112899567A (en) * | 2021-01-18 | 2021-06-04 | 中国科学院金属研究所 | High-purity high-strength-toughness rare earth free-cutting steel |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102703817B (en) | Free-machining pinion steel and production technique thereof | |
| CN102424934B (en) | Manufacturing method of steel forged component of 18CrNiMo7-6 large gear | |
| CN112853211B (en) | Cold forging steel for universal joint fork of passenger vehicle and manufacturing method thereof | |
| CN106661705B (en) | carburized alloy steel and preparation method and application thereof | |
| CN101168824A (en) | Leadless easy-cutting steel for medium-hard tooth face heavy load gear wheel and preparation method thereof | |
| CN105200337A (en) | High-strength wear-resistant steel plate and production method thereof | |
| CN110408845A (en) | A kind of vanadium micro-alloying hot rolling 700MPa grade high-strength reinforcing bar and preparation method thereof | |
| CN103966515B (en) | A kind of method utilizing electric arc furnace to prepare low-alloy high-strength toughness cast steel adding | |
| CN103981449B (en) | A kind of method utilizing electric arc furnace to prepare low-alloy high-ductility abrasion-proof cast steel | |
| CN103556069A (en) | Large-diameter seamless steel tube for high-pressure gas cylinders and manufacturing method thereof | |
| CN102676946B (en) | Segmented hardness low-alloy steel hammer head and manufacturing method thereof | |
| CN110273105B (en) | High-speed tool steel and preparation method thereof | |
| CN103540701A (en) | Smelting process suitable for ultra-high strength gray cast iron | |
| CN109252096A (en) | Economical heavy load truck steering gear rack 43MnCrMoB steel and its production method | |
| CN106367672A (en) | Nodular cast iron and processing technology thereof | |
| WO2022228216A1 (en) | Steel for high-temperature carburized gear shaft and manufacturing method for steel | |
| CN112143970B (en) | High-strength high-toughness non-quenched and tempered front axle steel and production method thereof | |
| CN103993234A (en) | Medium carbon and chromium alloy steel wear resistant liner and making method thereof | |
| CN114058935A (en) | Ultralow-temperature ferrite nodular cast iron and preparation method thereof | |
| CN104911494B (en) | Boron-contained wear-resisting steel casting material and preparation method thereof | |
| CN103966498B (en) | A kind of high chromium white antifriction cast iron high-abrasive material and manufacture method thereof | |
| CN103952632B (en) | Oil drilling and extracting equipment slush pump pressure part cast steel and preparation method | |
| CN101319289B (en) | Smelting method for high manganese steel casting | |
| CN112609134A (en) | Novel austenite free-cutting stainless steel material | |
| CN107675104A (en) | The preparation method and applications of cast steel, cast steel |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C12 | Rejection of a patent application after its publication | ||
| RJ01 | Rejection of invention patent application after publication |
Open date: 20080430 |