The content of the invention
The present invention provides one kind aiming at above-mentioned defect, and the present invention provides a kind of high life bearing steel, steel
The composition design and manufacture method of trade mark XWGCr15A, by redesigning, optimizing and revising the content of each element in bearing steel, adds
Trace element is added to carry out microalloying, effective to ensure that bearing steel has a high cleanliness factor, high stability and antifatigue
Performance, has reached the requirement of high life.
A kind of high life bearing steel and its manufacture method technical solution of the present invention is that the bearing composition of steel includes:Carbon
0.95~1.03%, silicon 0.25~0.30%, manganese 0.30~0.40%, chromium 1.48~1.58%, aluminium 0.010~0.035%, phosphorus
≤ 0.012%, sulphur≤0.010%, titanium≤0.0015%, oxygen≤0.0006%, nitrogen≤0.0040%, arsenic≤0.03%, lead≤
0.002%, calcium≤0.001%, trace element:Nickel 0.04~0.07%, molybdenum 0.03~0.05%, copper 0.02~0.06%.This
Invention ensures that high life bearing steel has more preferable, more stable performance by unique composition design.
Preferably, the bearing composition of steel includes:Carbon 0.96~0.98%, silicon 0.26~0.28%, manganese 0.34~
0.36%, chromium 1.51~1.55%, aluminium 0.018~0.025%, phosphorus≤0.008%, sulphur≤0.006%, titanium≤0.0015%,
Oxygen≤0.0006%, nitrogen≤0.0040%, arsenic≤0.012%, lead≤0.002%, calcium≤0.001%, trace element:Nickel 0.04
~0.06%, molybdenum 0.03~0.05%, copper 0.02~0.04%.
The effect of micro- Ni:The addition of nickel can improve the intensity of steel, and keep steel good plasticity and toughness.
Nickel can reduce the brittle transition temperature of steel low temperature, improve the low-temperature flexibility of steel.Nickel has acid, alkaline environment higher corrosion-resistant
Ability, there is antirust and temperature capacity at high temperature.Therefore, the addition 0.04%-0.07% of nickel in steel is designed.
The effect of micro- Mo:Molybdenum can make the crystal grain refinement of steel, improve quenching degree and thermostrength, keep at high temperature
Enough intensity and creep resisting ability, it is possible to increase the mechanical performance of steel, can also suppress crisp caused by the quenching of steel
Property.
The effect of micro- Cu:Copper can improve the weather-resistance of steel, and be conducive to improve steel intensity,
Wearability and yield tensile ratio.
Effective control carbon segregation.Composition design is by reducing the scope of carbon, compared to the requirement of national standard, upper limit drop
Low 0.02%, the effective index for controlling carbon segregation.
The B classes of the bearing steel, D type impurities are controlled at≤0.5 grade;DS type impurities are controlled at≤0.5 grade, are only allowed
Occur 1 time.
Banded structure≤2.0 grade of the bearing steel, liquation≤1.0 grade.
A kind of manufacture method of high life bearing steel, comprises the following steps:
S1, by just refining, refining process control Oxygen Content of Bearing Steel≤0.0006%, Ti content≤0.0015%;
S2, using primary sedimentation deoxidation mode, with reference to refining slag system and vacuum is kept and soft blow step, realizes high life axis
Hold the high-cleanness, high design requirement of steel;Basicity refining slag system during refining slag system uses, basicity of slag R=4-7, according to 85 tons of tap
Calculate, refining lime is incorporated 400 kilograms -800 kilograms/stove, high alkalinity high alumina 300 kilograms/stove of refining slag is public with addition of 30-50
Jin carborundum.
S3, homogenized technology (abbreviation PMO) using pulse magneto vibration solidification, significantly improves Center Equiaxial Crystal area,
Equiaxial crystal ratio reaches 50~90%, and crystallite dimension is significantly refined, and strand macrostructure significantly improves, and eliminates shrinkage cavity;Drop
Low carbon segregation index, high life bearing steel strand carbon segregation index are controlled in 0.93-1.06.
After S4, heating continuous casting billet, once rolling and slow cooling are carried out to continuous casting billet;Rolling requirements steel temperature control system is 1150
℃-1220℃.After being rolled into the specification required by secondary rolling, it need to ensure that 600 DEG C -650 DEG C of blank enters to cheat slow cooling, go out to cheat temperature
150 DEG C of <.By a heating rolling, the presence of primary carbide, proeutectoid carbide is eliminated, coordinates high temperature heavy reduction to roll
System, eliminates core tissue defects, improves the interior tissue of steel.Handled, be met by slow cooling, finishing after the completion of rolling
A rolling steel billet required by follow-up secondary rolling.
After S5, a heating rolling steel billet, secondary rolling and secondary slow cooling are carried out to a rolling steel billet.Specific steps
For:Blank surface is cleared up, checked after going out hole, carry out reheating after qualified to steel billet, steel billet temperature after reheating
Control is at 1050 DEG C -1100 DEG C;Rolling need to regulate and control it into trip temperature when completing, i.e., cools down as early as possible after finish to gauge, make its temperature
Spend prompt drop to 700 DEG C or so, then carry out it is secondary enter to cheat slow cooling, go out to cheat 100 DEG C of temperature <.
It is different from and once heats, reheating rolls the problems such as emphasis solves carbide three times and skin decarburization, by prolonging
When rolling, control finishing temperature, optimization retarded cooling process, finishing detection etc. means, obtain final bar.
S2 is specifically, with reference to CaO-SiO2-Al2O3Ternary slag system diagram, by CaO/Al2O3Control is realized 1.2~2.0
Oxygen content≤0.0006%;Under the molten steel environment of hypoxemia, by the irregular Al in molten steel2O3Class oxidation category inclusion modification
To ball-type 12CaO7Al2O3Easy to float, it is achieved thereby that the high-cleanness, high of molten steel;The vacuum retention time is 25-30min;It is soft
It is 20-25min to blow the time.
PMO technologies are that pulse current is imported to the coil being wrapped on the outside of strand in S3, so as to be produced in solid liquid interface forward position
Raw electromagnetic induction effect, achievees the purpose that thinning solidification structure.
Equipment is mainly made of the pulse power, PMO coils, crystallizer.Steel billet with wick-containing is worn after crystallizer disengaging
PMO coils are crossed, after pulling rate stabilization, unbalanced pulse power supply carries out pulse magneto oscillation treatment.The current peak used is 102Ki
A, discharge frequency are 247hi Hz, and pulse width is 34bi ms (Ki, hi, bi are related with power supply natures).
When a heating time is small no less than 9 in S4;Latter end, 1230 DEG C -1250 DEG C of soaking zone temperature are heated, wherein preceding four
The more conventional product drafts of passage improves 15mm-20mm;Such as the first passage routine drafts is 115mm, then when producing the steel grade
Drafts control in 120mm or so, and so on to four-pass, to ensure penetrating for roll-force.Dry in the air after ending base to 1020
Finish rolling is carried out after DEG C -1050 DEG C;Slow cooling is cold using cheating, when temperature retention time is small no less than 48.
Reheating time control is when 5.5 is small or so in S5;Heat latter end, 950 DEG C -1000 DEG C of soaking zone temperature;Eventually
Roll 850 DEG C -920 DEG C of temperature;Slow cooling, which enters, cheats temperature >=400 DEG C, when temperature retention time is small no less than 60.
Beneficial effects of the present invention are:The high life bearing steel of the present invention, steel trade mark XWGCr15A, passes through the weight to component
New design and micro- alloying, and every control measure in manufacturing process so that the bearing steel produced has more
High cleanliness factor, more stable mechanical property, more preferable wearability, realizes the fatigue life of higher, made using the technology
The high speed performance index D n values for the bearing made can reach 3.3 × 106。
Figure of description:
Fig. 1 show CaO-SiO2-Al2O3Ternary slag system diagram;
Fig. 2 show Al2O3 type impurity patterns;
Fig. 3 show 12CaO7Al2O3 type impurity patterns;
Fig. 4 show B type impurity patterns;
Fig. 5 show D type impurity patterns;
Fig. 6 show carbide strip pattern;
Fig. 7 show carbide liquid-extraction pattern.
Embodiment 1
(1) high life bearing steel composition design and control
The high life bearing steel designed in the present embodiment, it specifically includes following component:
Carbon 0.95~1.03%, silicon 0.25~0.30%, manganese 0.30~0.40%, chromium 1.48~1.58%, aluminium 0.010~
0.035%, phosphorus≤0.012%, sulphur≤0.010%, titanium≤0.0015%, oxygen≤0.0006%, nitrogen≤0.0040%, arsenic≤
0.03%, lead≤0.002%, calcium≤0.001%, trace element:Nickel 0.04~0.07%, molybdenum 0.03~0.05%, copper 0.02
~0.06%.
Therefore, the composition more than designs, and the Composition Control measured value in implementation process is shown in Table 1:
Table 1 surveys chemical Composition Control scope %
During high life bearing steel is manufactured, process capability control characteristic Cpk >=1.67 of actual control composition, reach
It is horizontal to A+ grades, reach design requirement, specific heat (batch) number component of testing is shown in Table 2.
Table 2 surveys chemical Composition Control scope %
(2) manufacture method of high life bearing steel
S1, using different metal redox principle, by accurate first refining, refining operation, realizes high life bearing steel
Oxygen content≤0.0006%, Ti content≤0.0015%.
Specifically, first with manufacture at first furnace initial stage high alkalinity, high oxidative, with reference to low temperature feature early period, will just refine
The Ti content of stove tapping is controlled≤0.0005%;With reference to metal oxidation reduction principle, root different metal oxidation sequencing, turns
Stove tapping process settles alloy at one go with steel stream, and upper line traffic control in pressing, utilizes " oxygen-enriched gesture ", [O] > 200ppm, by molten steel and
Titanium elements in alloy are oxidized to TiO2, and blow floating with BOTTOM ARGON BLOWING to the top of the slag.
Before LF refining starts, first carry out deslagging or take off Slag treatment, TiO will be contained2Slag once exclude;Again slag making, will
Deoxidier is once added to position, avoids the later stage from adding, and keeps the Argon of whole refining process;When vacuum refining process keeps vacuum
Between stablize in 25-30min, soft blow time 20-25min, it is achieved thereby that high life bearing steel Ti content≤0.0015%, oxygen contain
Amount≤0.0006%.
S2, it is the refining slag system being well combined and the holding of enough vacuum and soft blow time, real with primary sedimentation deoxidation mode
The high-cleanness, high design requirement of high life bearing steel is showed.
Specifically, with reference to the deoxidation mode in step S1, the one-time-reach-place amount of deoxidier Al is controlled in 0.055%-
0.065%, the later stage carries out top of the slag diffusive deoxidation using 20-30 kilograms of carborundum;With reference to CaO-SiO2-Al2O3Ternary slag system phase
The deoxidation ideal zone (see Figure of description Fig. 1) of aluminum killed steel in figure, by A values (CaO/Al2O3) control 1.2~2.0,
Realize oxygen content≤0.0006%.Under the molten steel environment of hypoxemia, by the irregular Al in molten steel2O3Class aoxidizes type impurity
It is denatured ball-type 12CaO7Al2O3Easy to float (see Figure of description Fig. 2), it is achieved thereby that the high-cleanness, high of molten steel.
By the realization of step S1 and S2, the inclusion behavior of actual measurement high life bearing steel is shown in Table 3, specific metallographic pattern
See Figure of description Fig. 3.
3 high life of table bearing steel measured value
S3, is homogenized technology (abbreviation PMO) using pulse magneto vibration solidification, significantly improves Center Equiaxial Crystal area,
Equiaxial crystal ratio reaches 50~90%, and crystallite dimension is significantly refined, and strand macrostructure significantly improves, and eliminates shrinkage cavity;Drop
Low carbon segregation index, high life bearing steel strand carbon segregation index are controlled in 0.93-1.06.
Pulse magneto vibration (abbreviation PMO) is that pulse current is imported to the coil being wrapped on the outside of strand, so that in solid-liquid
Interface forward position produces specific electromagnetic induction effect, achievees the purpose that thinning solidification structure.Pulse current is in continuous casting billet solid-liquid circle
In front along formation inductive impulse magnetic field;Magnetic field causes molten steel to be subcooled, and promotes forming core;Nucleus takes off under electromagnetic force and gravity
Fall, sink, formed " crystalline rain ", so as to smash original nucleation mode, expand the area of equiax crystal, reduce carbon segregation
Index.Carbon segregation value is carried out by using carbon sulphur instrument to strand to analyze, the control of high life bearing steel strand carbon segregation index
In 0.93-1.06.
After S4, heating continuous casting billet, once rolling and slow cooling are carried out to continuous casting billet.
Heating rolling uses high-temperature diffusion process, i.e., when heating time is small no less than 9, heating latter end, soaking temperature
1230 DEG C -1250 DEG C, coordinate high temperature heavy reduction split rolling method, eliminate the presence of primary carbide, proeutectoid carbide, eliminate
Core tissue defects, improve the interior tissue of steel.
Handled after the completion of rolling by slow cooling, finishing, a rolling steel billet being met required by follow-up secondary rolling.
After S5, a heating rolling steel billet, secondary rolling and secondary slow cooling are carried out to a rolling steel billet.It is different from once
The problems such as heating, reheating rolling emphasis solves carbide three times and skin decarburization, pass through the rolling that is delayed, control finish to gauge temperature
The means such as degree, optimization retarded cooling process, finishing detection, obtain final bar.
The high life bearing steel of the present invention, steel trade mark XWGCr15A, is closed by the redesign to component and trace element
Every control measure in aurification, and manufacturing process so that the bearing steel produced has the cleanliness factor of higher, more stable
Mechanical property, more preferable wearability realize fatigue life of higher, and the high speed performance using the bearing manufactured by the technology refers to
Number Dn values can reach 3.3 × 106。