CN110343976B - Sulfur-containing phosphorus-containing free-cutting steel and production method thereof - Google Patents
Sulfur-containing phosphorus-containing free-cutting steel and production method thereof Download PDFInfo
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- CN110343976B CN110343976B CN201910744568.7A CN201910744568A CN110343976B CN 110343976 B CN110343976 B CN 110343976B CN 201910744568 A CN201910744568 A CN 201910744568A CN 110343976 B CN110343976 B CN 110343976B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
Abstract
A sulfur-containing and phosphorus-containing free-cutting steel and a production method thereof belong to the field of free-cutting steel preparation methods. The invention comprises the following components: 0.09-0.12 wt% of C, 0.20-0.25 wt% of Si, 0.85-0.90 wt% of Mn, 0.10-0.14 wt% of P, 0.13-0.17 wt% of S, 0.008-0.015 wt% of Al and the balance of iron, wherein the mass ratio of Mn to S is 5.5-6.0: 1. the sulfur-containing and phosphorus-containing free-cutting steel produced by the invention has the characteristics of smooth cutting, excellent material quality, stable processing, good metallographic structure, stable chemical composition, small deviation, difficulty in damaging cutters and the like; the cutting is very easy to be carried out on a lathe, the service life of the cutter and the production efficiency are both improved by 40 percent; the product cost is greatly reduced; the surface finish of the workpiece after turning is good.
Description
Technical Field
The invention belongs to the field of a preparation method of free-cutting steel; in particular to a sulfur-containing and phosphorus-containing free-cutting steel and a production method thereof.
Background
The free-cutting steel is alloy steel which is added with a certain amount of one or more free-cutting elements such as sulfur, phosphorus, lead, calcium, selenium, tellurium and the like to improve the machinability. With the automation, high speed and precision of cutting, it is very important to require a steel material having good free-cutting properties, and such a steel is mainly used for machining on automatic cutting machines. The sulfur forms MnS inclusion with Mn in the steel, which can interrupt the continuity of the matrix, make the chip easy to brittle fracture and reduce the contact area of the chip and the cutter. Sulfur also has the function of reducing friction, so that cutting chips are not adhered to the cutting edge. Phosphorus and sulfur are added into steel in a composite mode, phosphorus is dissolved in ferrite in a solid mode, hardness and strength are improved, toughness is reduced, chips are easy to break and remove, and good machining surface roughness is achieved.
Disclosure of Invention
The invention aims to provide a sulfur-containing phosphorus-containing free-cutting steel and a production method thereof.
The invention is realized by the following technical scheme:
a sulfur-containing, phosphorus-containing free-cutting steel, said sulfur-containing, phosphorus-containing free-cutting steel comprising the following components: 0.09-0.12 wt% of C, 0.20-0.25 wt% of Si, 0.85-0.90 wt% of Mn, 0.10-0.14 wt% of P, 0.13-0.17 wt% of S, 0.008-0.015 wt% of Al and the balance of iron, wherein the mass ratio of Mn to S is 5.5-6.0: 1.
the invention relates to a sulfur-containing and phosphorus-containing free-cutting steel, which comprises the following components: 0.11 wt% of C, 0.22 wt% of Si, 0.86 wt% of Mn, 0.13 wt% of P, 0.15 wt% of S, 0.011 wt% of Al and the balance of iron, wherein the mass ratio of Mn to S is 5.73: 1.
the invention relates to a production method of sulfur-containing and phosphorus-containing free-cutting steel, which comprises the following production processes: electric furnace smelting, LF furnace refining → soft blowing, ladle suspension → steel ingot casting → delayed heat transfer or cover cooling → steel ingot heating → steel ingot cogging → cold stacking → steel billet cleaning → flaw detection → steel billet heating → small bar rolling → cold stacking → straightening → flaw detection → grinding → tip pressing → billet heating → acid washing → cold drawing → polishing → inspection → upward.
According to the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the mass fraction of C is 0.05-0.08 wt% during electric furnace smelting, and the tapping temperature is 1600-1640 ℃.
The invention relates to a production method of sulfur-containing and phosphorus-containing free-cutting steel, wherein 0.5m/t of aluminum wire is fed into an LF furnace during refining, the amount of medium manganese is 5-6 kg/t and aluminum particles are 1-1.5 kg/t during precipitation deoxidation, silicon powder and carbon powder are used for diffusion deoxidation, the amount of silicon powder is 1-1.5 kg/t and the amount of carbon powder is 0.6-0.8 kg/t during precipitation deoxidation, the steel is uniformly mixed and then used, medium-low alkalinity slag is adopted, and the mass ratio of alkaline oxide calcium oxide to acidic oxide silicon dioxide is 2-2.5: 1, the content of aluminum oxide is 10-15 wt%, the refining time of the white slag is 20-30 min, and after the white slag is achieved, the P component is adjusted to be 0.10-0.14 wt% according to the specification requirement.
The invention relates to a production method of sulfur-containing and phosphorus-containing free-cutting steel, which is characterized in that sulfur wires are fed into soft blowing according to 100% recovery rate to adjust the S component to 0.13-0.17 wt%, then a heat insulating agent is added to carbonize 50-55 kg of rice hulls per furnace, the soft blowing time is 15-20 min, the slag surface is slightly moved, the molten steel is not exposed, and the oxygen content in the steel is 20-60 ppm.
According to the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the temperature of a ladle in the production method of the sulfur-containing and phosphorus-containing free-cutting steel is 1575-1580 ℃.
According to the production method of the sulfur-containing and phosphorus-containing free-cutting steel, disclosed by the invention, in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the pouring speed of a steel ingot pouring ingot body is 300-400S, and the pouring speed of a riser is 240-300S.
The production method of the sulfur-containing and phosphorus-containing free-cutting steel comprises the steps of heating a steel billet at a first heating stage of 1000-1120 ℃, controlling the first heating stage for 40-60 min, controlling the second heating stage at 1220-1260 ℃, controlling the second heating stage for 25-30 min, controlling the temperature at a soaking stage of 1210-1250 ℃, controlling the time at a soaking stage for 2-3 h, controlling the tapping temperature at 1210-1250 ℃, controlling the water pressure of a high-pressure water descaler at 220-240 bar after the steel billet is taken out of a furnace, and removing scale on the surface of the steel billet.
According to the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the billet shape of a small bar in the production method of the sulfur-containing and phosphorus-containing free-cutting steel is 230 square, the rolling temperature is 1150-1250 ℃, and after high-temperature fast rolling, two ends of the billet are cut by flame.
The invention relates to a method for producing sulfur-containing and phosphorus-containing free-cutting steel, in general, sulfur is a harmful element in steel and is an impurity which cannot be completely removed in steel making. Sulfur has low solubility in solid iron and can form FeS with low melting point (1190 ℃ C.) with iron. The melting point of the FeS-bound Fe eutectic is lower (989 ℃). Such eutectic crystals with low melting points are generally distributed in the form of dissimilarity eutectics on the grain boundaries. When hot working (forging, rolling) is performed on steel, the heating temperature is usually 1000 ℃ or higher, and the FeS + Fe eutectic on the grain boundary is melted, resulting in cracking of the steel during hot working. This phenomenon is referred to as "hot shortness" or "red shortness" of the steel. When the oxygen content of the steel is high, Fe, FeS and FeO eutectic crystals with lower melting points are formed, so that the hot brittleness tendency is higher. The sulfur-containing and phosphorus-containing free-cutting steel prepared by the invention has the advantages that the hot brittleness and cold brittleness of the steel are not generated, and the surface of the steel has no cracks.
The invention relates to a method for producing sulfur-containing and phosphorus-containing free-cutting steel, which uses manganese for desulfurization, and preferentially forms manganese sulfide and reduces iron sulfide by utilizing the fact that the affinity of manganese and sulfur is greater than that of iron and sulfur. The manganese sulfide has high melting point (1600 ℃), has certain plasticity at high temperature, and can not cause the steel to generate hot brittleness.
The invention relates to a method for producing sulfur-containing and phosphorus-containing free-cutting steel, which utilizes phosphorus to improve the strength of the steel in the steel with lower mass fraction of carbon, and the phosphorus can also improve the corrosion resistance of the steel in the atmosphere, thereby inhibiting the cold brittleness of the phosphorus under the condition of ensuring that a fine grain structure is obtained, improving the tensile strength and the yield strength and simultaneously keeping the low-temperature toughness at the required level.
According to the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the proper oxygen content is adjusted to promote MnS in the steel to be spindle-shaped or ellipsoidal, so that the cutting performance is improved. However, the higher the oxygen content in free-cutting steel is, the better the oxygen content is, the higher the oxygen content is, the surface quality of a casting blank is affected, subcutaneous bubbles are generated, and the high content of oxide inclusions is unfavorable for abrasion and finally the product performance is also affected.
According to the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the produced sulfur-containing and phosphorus-containing free-cutting steel has the characteristics of smooth cutting, excellent material quality, stable processing, good metallographic structure, stable chemical composition, small deviation, difficulty in damaging a cutter and the like; the cutting is very easy to be carried out on a lathe, the service life of the cutter and the production efficiency are both improved by 40 percent; the product cost is greatly reduced; the surface finish of the workpiece after turning is good.
Compared with the prior art, the production method of the sulfur-containing and phosphorus-containing free-cutting steel solves the problems of hot brittleness and cold brittleness of the free-cutting steel and simultaneously ensures the cutting processing performance of the steel. Compared with the prior art, the production cost is reduced, 60 yuan/t, no vacuum pumping is needed, and the cutting machining performance is good.
Detailed Description
The first embodiment is as follows:
a sulfur-containing, phosphorus-containing free-cutting steel, said sulfur-containing, phosphorus-containing free-cutting steel comprising the following components: 0.11 wt% of C, 0.22 wt% of Si, 0.86 wt% of Mn, 0.13 wt% of P, 0.15 wt% of S, 0.011 wt% of Al and the balance of iron, wherein the mass ratio of Mn to S is 5.73: 1.
the production method of the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment comprises the following production processes: electric furnace smelting, LF furnace refining → soft blowing, ladle suspension → steel ingot casting → delayed heat transfer or cover cooling → steel ingot heating → steel ingot cogging → cold stacking → steel billet cleaning → flaw detection → steel billet heating → small bar rolling → cold stacking → straightening → flaw detection → grinding → tip pressing → billet heating → acid washing → cold drawing → polishing → inspection → upward.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment, the mass fraction of C is 0.08 wt% during electric furnace smelting, and the tapping temperature is 1640 ℃.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel, 0.5m/t of aluminum wire is fed into an LF furnace during refining, during precipitation deoxidation, the medium manganese dosage is 6kg/t, the aluminum particles are 1kg/t, silicon powder and carbon powder are used for diffusion deoxidation, the silicon powder dosage is 1.5kg/t, the carbon powder dosage is 0.6kg/t, the steel is uniformly mixed and used, low-alkalinity slag is adopted, and the mass ratio of alkaline oxide calcium oxide to acidic oxide silicon dioxide is 2.5: 1, the content of aluminum oxide is 15 wt%, the refining time of the white slag is 20min, and after the white slag is achieved, the P component is adjusted to be 0.14 wt% according to the specification requirement.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel, sulfur wires are fed into the soft blowing according to 100% recovery rate to adjust the S component to 0.17 wt%, then a heat insulating agent is added to carbonize the rice hulls to 50 kg/furnace, the soft blowing is carried out for 15min, the slag surface is slightly moved, the molten steel is not exposed, and the oxygen content in the steel is 60 ppm.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment, the temperature of the ladle in the production method of the sulfur-containing and phosphorus-containing free-cutting steel is 1580 ℃.
In the method for producing the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment, the ingot casting speed of a steel ingot is 300S, and the riser casting speed is 240S.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the first heating section of heating a steel billet is controlled at 1120 ℃, the first heating section is controlled for 60min, the second heating section is controlled at 1260 ℃, the second heating section is controlled for 25min, the soaking section is controlled at 1250 ℃, the soaking section is controlled for 2h, the tapping temperature is 1210 ℃, the water pressure of a high-pressure water descaler is 220-240 bar after the steel billet is taken out of a furnace, and the iron scale on the surface of the steel billet is removed.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment, a billet of a small rod in the production method of the sulfur-containing and phosphorus-containing free-cutting steel is rolled at 230 square, the rolling temperature is 1150 ℃, and after high-temperature fast rolling, the billet is subjected to flame cutting at two ends.
In the method for producing a sulfur-containing, phosphorus-containing free-cutting steel according to the present embodiment, the performance parameters of the prepared sulfur-containing, phosphorus-containing free-cutting steel are shown in table 1:
TABLE 1 comparison of Properties and parameters of free-cutting steels containing sulfur and phosphorus
The sulfur-containing and phosphorus-containing free-cutting steel produced by the method for producing sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment has a tensile strength of 615N/mm2The elongation is 20.5 percent, the hardness reaches 185HB, and the comprehensive performance is superior to that of the prior art.
The second embodiment is as follows:
a sulfur-containing, phosphorus-containing free-cutting steel, said sulfur-containing, phosphorus-containing free-cutting steel comprising the following components: 0.09 wt% of C, 0.20 wt% of Si, 0.85 wt% of Mn, 0.10 wt% of P, 0.15 wt% of S, 0.008 wt% of Al and the balance of iron, wherein the mass ratio of Mn to S is 5.6: 1.
the production method of the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment comprises the following production processes: electric furnace smelting, LF furnace refining → soft blowing, ladle suspension → steel ingot casting → delayed heat transfer or cover cooling → steel ingot heating → steel ingot cogging → cold stacking → steel billet cleaning → flaw detection → steel billet heating → small bar rolling → cold stacking → straightening → flaw detection → grinding → tip pressing → billet heating → acid washing → cold drawing → polishing → inspection → upward.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment, the mass fraction of C is 0.05 wt% during electric furnace smelting, and the tapping temperature is 1600 ℃.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel, 0.5m/t of aluminum wire is fed into an LF furnace during refining, during precipitation deoxidation, the medium manganese dosage is 5kg/t, the aluminum particles are 1kg/t, silicon powder and carbon powder are used for diffusion deoxidation, the silicon powder dosage is 1kg/t, the carbon powder dosage is 0.6kg/t, the steel is uniformly mixed and used, medium-low alkalinity slag is adopted, and the mass ratio of alkaline oxide calcium oxide to acidic oxide silicon dioxide is 2: 1, the content of aluminum oxide is 10 wt%, the refining time of the white slag is 20min, and after the white slag is achieved, the component P is adjusted to be 0.10 wt% according to the specification requirement.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel, sulfur wires are fed into the soft blowing according to 100% recovery rate to adjust the S component to 0.13 wt%, then a heat insulating agent is added to carbonize the rice hulls in a furnace, the soft blowing is carried out for 15min, the slag surface is slightly moved, the molten steel is not exposed, and the oxygen content in the steel is 20 ppm.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment, the ladle temperature is 1575 ℃.
In the method for producing the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment, the ingot casting speed of a steel ingot is 300S, and the riser casting speed is 240S.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the first heating section of heating a steel billet is controlled at 1000 ℃, the first heating section is controlled for 40min, the second heating section is controlled at 1220 ℃, the second heating section is controlled for 25min, the soaking section is controlled at 1210 ℃, the soaking section is controlled for 2h, the tapping temperature is 1210 ℃, the water pressure of a high-pressure water descaler is 220-240 bar after the steel billet is taken out of a furnace, and the iron scale on the surface of the steel billet is removed.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment, a billet of a small rod in the production method of the sulfur-containing and phosphorus-containing free-cutting steel is rolled at 230 square, the rolling temperature is 1150 ℃, and after high-temperature fast rolling, the billet is subjected to flame cutting at two ends.
In the method for producing a sulfur-containing, phosphorus-containing free-cutting steel according to the present embodiment, the performance parameters of the prepared sulfur-containing, phosphorus-containing free-cutting steel are shown in table 2:
TABLE 2 comparison of Properties and parameters of sulfur-and phosphorus-containing free-cutting steels
The sulfur-containing and phosphorus-containing free-cutting steel produced by the method for producing sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment has a tensile strength of 604N/mm2The elongation is 18.5 percent, the hardness reaches 179HB, and the comprehensive performance is superior to the prior art.
The third concrete implementation mode:
a sulfur-containing, phosphorus-containing free-cutting steel, said sulfur-containing, phosphorus-containing free-cutting steel comprising the following components: 0.12 wt% of C, 0.25 wt% of Si, 0.90 wt% of Mn, 0.14 wt% of P, 0.163 wt% of S, 0.015 wt% of Al and the balance of iron, wherein the mass ratio of Mn to S is 5.52: 1.
the production method of the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment comprises the following production processes: electric furnace smelting, LF furnace refining → soft blowing, ladle suspension → steel ingot casting → delayed heat transfer or cover cooling → steel ingot heating → steel ingot cogging → cold stacking → steel billet cleaning → flaw detection → steel billet heating → small bar rolling → cold stacking → straightening → flaw detection → grinding → tip pressing → billet heating → acid washing → cold drawing → polishing → inspection → upward.
In the method for producing a sulfur-and phosphorus-containing free-cutting steel according to the present embodiment, the mass fraction of C during electric furnace smelting is 0.1 wt%, and the tapping temperature is 1620 ℃.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel, 0.5m/t of aluminum wire is fed into an LF furnace during refining, the medium manganese dosage is 5.5kg/t and aluminum particles are 1.2kg/t during precipitation deoxidation, silicon powder and carbon powder are used for diffusion deoxidation, the silicon powder dosage is 1.2kg/t and the carbon powder dosage is 0.7kg/t, the mixture is uniformly mixed and used, medium-low alkalinity slag is adopted, and the mass ratio of alkaline oxide calcium oxide to acidic oxide silicon dioxide is 2.3: 1, the content of aluminum oxide is 12 wt%, the refining time of the white slag is 25min, and after the white slag is achieved, the P component is adjusted to be 0.12 wt% according to the specification requirement.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel, sulfur wires are fed into the soft blowing according to 100% recovery rate to adjust the S component to 0.16 wt%, then a heat insulating agent is added to carbonize rice hulls 52 kg/furnace, and the soft blowing is carried out for 20min, wherein the slag surface is slightly moved, the molten steel is not exposed, and the oxygen content in the steel is 40 ppm.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment, the temperature of the ladle in the production method of the sulfur-containing and phosphorus-containing free-cutting steel is 1580 ℃.
In the method for producing the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment, the ingot body casting speed of a steel ingot is 350S, and the riser casting speed is 260S.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the first heating section of heating a steel billet is controlled at 1100 ℃ for 50min, the second heating section is controlled at 1250 ℃, the second heating section is controlled at 25min, the soaking section is controlled at 1220 ℃ for 3h, the tapping temperature is 1210 ℃, the water pressure of a high-pressure water descaler is 220-240 bar after the steel billet is taken out of a furnace, and scale on the surface of the steel billet is removed.
In the production method of the sulfur-containing and phosphorus-containing free-cutting steel according to the embodiment, a billet of a small rod in the production method of the sulfur-containing and phosphorus-containing free-cutting steel is rolled at a starting rolling temperature of 1200 ℃, and after high-temperature fast rolling, the billet is subjected to flame cutting at two ends.
In the method for producing a sulfur-containing, phosphorus-containing free-cutting steel according to the present embodiment, the performance parameters of the prepared sulfur-containing, phosphorus-containing free-cutting steel are shown in table 3:
TABLE 3 comparison of Properties and parameters of sulfur-and phosphorus-containing free-cutting steels
The sulfur-containing phosphorus-containing free-cutting steel produced by the method of producing sulfur-containing phosphorus-containing free-cutting steel according to the embodiment has a tensile strength of 609N/mm2The elongation is 19.2 percent, the hardness reaches 181HB, and the comprehensive performance is superior to that of the prior art.
The fourth concrete implementation mode:
a sulfur-containing, phosphorus-containing free-cutting steel, said sulfur-containing, phosphorus-containing free-cutting steel comprising the following components: 0.09-0.12 wt% of C, 0.20-0.25 wt% of Si, 0.85-0.90 wt% of Mn, 0.10-0.14 wt% of P, 0.13-0.17 wt% of S, 0.008-0.015 wt% of Al and the balance of iron, wherein the mass ratio of Mn to S is 5.5-6.0: 1.
the fifth concrete implementation mode:
the production method of the sulfur-containing and phosphorus-containing free-cutting steel comprises the following production processes: electric furnace smelting, LF furnace refining → soft blowing, ladle suspension → steel ingot casting → delayed heat transfer or cover cooling → steel ingot heating → steel ingot cogging → cold stacking → steel billet cleaning → flaw detection → steel billet heating → small bar rolling → cold stacking → straightening → flaw detection → grinding → tip pressing → billet heating → acid washing → cold drawing → polishing → inspection → upward.
In the method for producing a sulfur-containing, phosphorus-containing free-cutting steel according to the present embodiment, sulfur is a harmful element in steel in general, and is an impurity that cannot be completely removed in steel making. Sulfur has low solubility in solid iron and can form FeS with low melting point (1190 ℃ C.) with iron. The melting point of the FeS-bound Fe eutectic is lower (989 ℃). Such eutectic crystals with low melting points are generally distributed in the form of dissimilarity eutectics on the grain boundaries. When hot working (forging, rolling) is performed on steel, the heating temperature is usually 1000 ℃ or higher, and the FeS + Fe eutectic on the grain boundary is melted, resulting in cracking of the steel during hot working. This phenomenon is referred to as "hot shortness" or "red shortness" of the steel. When the oxygen content of the steel is high, Fe, FeS and FeO eutectic crystals with lower melting points are formed, so that the hot brittleness tendency is higher. The sulfur-containing and phosphorus-containing free-cutting steel prepared by the invention has the advantages that the hot brittleness and cold brittleness of the steel are not generated, and the surface of the steel has no cracks.
In the method for producing the sulfur-containing phosphorus-containing free-cutting steel according to the embodiment, manganese is used for desulfurization, and manganese sulfide is preferentially formed and iron sulfide is reduced by utilizing the fact that the affinity of manganese to sulfur is higher than that of iron to sulfur. The manganese sulfide has high melting point (1600 ℃), has certain plasticity at high temperature, and can not cause the steel to generate hot brittleness.
In the method for producing a sulfur-containing, phosphorus-containing free-cutting steel according to the present embodiment, phosphorus is used to increase the strength of the steel in a steel having a relatively low carbon content by mass fraction, and phosphorus also improves the corrosion resistance of the steel in the atmosphere, so that the cold embrittlement of phosphorus is suppressed under the condition that a fine grain structure is obtained, and the low-temperature toughness is maintained at a desired level while the tensile strength and yield strength are improved.
According to the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the proper oxygen content is adjusted to promote MnS in the steel to be spindle-shaped or ellipsoidal, and the cutting performance is improved. However, the higher the oxygen content in free-cutting steel is, the better the oxygen content is, the higher the oxygen content is, the surface quality of a casting blank is affected, subcutaneous bubbles are generated, and the high content of oxide inclusions is unfavorable for abrasion and finally the product performance is also affected.
According to the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the produced sulfur-containing and phosphorus-containing free-cutting steel has the characteristics of smooth cutting, excellent material quality, stable processing, good metallographic structure, stable chemical composition, small deviation, difficulty in damaging cutters and the like; the cutting is very easy to be carried out on a lathe, the service life of the cutter and the production efficiency are both improved by 40 percent; the product cost is greatly reduced; the surface finish of the workpiece after turning is good.
Compared with the prior art, the production method of the sulfur-containing and phosphorus-containing free-cutting steel solves the problems of hot brittleness and cold brittleness of the free-cutting steel and ensures the cutting processing performance of the steel. Compared with the prior art, the production cost is reduced, 60 yuan/t, no vacuum pumping is needed, and the cutting machining performance is good.
The sixth specific implementation mode:
according to the production method of the sulfur-containing phosphorus-containing free-cutting steel of the fifth embodiment, the mass fraction of C in the electric furnace smelting is 0.05 to 0.08 wt%, and the tapping temperature is 1600 to 1640 ℃.
The seventh embodiment:
according to the fifth specific embodiment, in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, 0.5m/t of aluminum wire is fed into an LF furnace during refining, during precipitation deoxidation, the using amount of medium manganese is 5-6 kg/t, the using amount of aluminum particles is 1-1.5 kg/t, silicon powder and carbon powder are used for diffusion deoxidation, the using amount of silicon powder is 1-1.5 kg/t, the using amount of carbon powder is 0.6-0.8 kg/t, after uniform mixing, medium-low alkalinity slag is adopted, and the mass ratio of alkaline oxide calcium oxide to acidic oxide silicon dioxide is 2-2.5: 1, the content of aluminum oxide is 10-15 wt%, the refining time of the white slag is 20-30 min, and after the white slag is achieved, the P component is adjusted to be 0.10-0.14 wt% according to the specification requirement.
The specific implementation mode is eight:
according to the production method of the sulfur-containing and phosphorus-containing free-cutting steel, in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, sulfur wires are fed into soft blowing according to 100% recovery rate to adjust the S component to 0.13-0.17 wt%, then the thermal insulating agent is added to carbonize the rice hulls to 50-55 kg/furnace, the soft blowing is carried out for 15-20 min, the slag surface is slightly moved, the steel liquid is not exposed, and the oxygen content in the steel is 20-60 ppm.
The specific implementation method nine:
according to the fifth specific embodiment, in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the temperature of the ladle is 1575-1580 ℃.
The detailed implementation mode is ten:
according to the fifth specific embodiment, in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the pouring speed of a steel ingot pouring ingot body is 300-400S, and the pouring speed of a riser is 240-300S.
The concrete implementation mode eleven:
according to the fifth specific embodiment, in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the first heating section of the heating of the steel billet is controlled to be 1000-1120 ℃, the first heating section is controlled to be 40-60 min, the second heating section is controlled to be 1220-1260 ℃, the second heating section is controlled to be 25-30 min, the temperature of the soaking section is controlled to be 1210-1250 ℃, the time of the soaking section is controlled to be 2-3 h, and the tapping temperature is 1210-1250 ℃.
The specific implementation mode twelve:
according to the production method of the sulfur-containing and phosphorus-containing free-cutting steel, in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the rolled billet shape of a small bar is 230 square, the rolling temperature is 1150-1250 ℃, and after high-temperature fast rolling, the billet is subjected to flame cutting at two ends.
Claims (6)
1. A production method of sulfur-containing and phosphorus-containing free-cutting steel is characterized by comprising the following steps: the production process of the production method of the sulfur-containing and phosphorus-containing free-cutting steel comprises the following steps: electric furnace smelting, LF furnace refining → soft blowing, ladle suspension → steel ingot casting → delayed heat delivery or cover cooling → steel ingot heating → steel ingot cogging → cold stacking → steel billet cleaning → flaw detection → steel billet heating → small bar rolling → cold stacking → straightening → flaw detection → grinding → tip pressing → blank fire → acid cleaning → cold drawing → polishing → inspection → upward;
in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, 0.5m/t of aluminum wire is fed in an LF furnace during refining, when precipitation deoxidation is performed, the using amount of medium manganese is 5-6 kg/t, aluminum particles are 1-1.5 kg/t, silicon powder and carbon powder are used for diffusion deoxidation, the using amount of the silicon powder is 1-1.5 kg/t, the using amount of the carbon powder is 0.6-0.8 kg/t, the steel is uniformly mixed and used, medium-low alkalinity slag is adopted, and the mass ratio of alkaline oxide calcium oxide to acidic oxide silicon dioxide is 2-2.5: 1, the content of aluminum oxide is 10-15 wt%, the refining time of white slag is 20-30 min, and after the white slag is obtained, the component P is adjusted to be 0.10-0.14 wt% according to the specification requirement;
in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, sulfur wires are fed into soft blowing according to 100% recovery rate to adjust the S component to 0.13-0.17 wt%, then a heat insulating agent is added to carbonize the rice hulls to 50-55 kg/furnace, the soft blowing is carried out for 15-20 min, the slag surface is slightly moved, the molten steel is not exposed, and the oxygen content in the steel is 20-60 ppm;
the sulfur-containing phosphorus-containing free-cutting steel produced by the production method comprises the following components: 0.09-0.12 wt% of C, 0.20-0.25 wt% of Si, 0.85-0.90 wt% of Mn, 0.10-0.14 wt% of P, 0.13-0.17 wt% of S, 0.008-0.015 wt% of Al and the balance of iron, wherein the mass ratio of Mn to S is 5.5-6.0: 1.
2. the method for producing a sulfur-containing, phosphorus-containing free-cutting steel as set forth in claim 1, wherein: in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the mass fraction of C is 0.05-0.08 wt% during electric furnace smelting, and the tapping temperature is 1600-1640 ℃.
3. The method for producing a sulfur-containing, phosphorus-containing free-cutting steel as set forth in claim 1, wherein: in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the temperature of a ladle is 1575-1580 ℃.
4. The method for producing a sulfur-containing, phosphorus-containing free-cutting steel as set forth in claim 1, wherein: in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the pouring speed of a steel ingot pouring ingot body is 300-400 s, and the pouring speed of a riser is 240-300 s.
5. The method for producing a sulfur-containing, phosphorus-containing free-cutting steel as set forth in claim 1, wherein: in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the first heating section of heating the steel billet is controlled at the temperature of 1000-1120 ℃, the first heating section is controlled for 40-60 min, the second heating section is controlled at the temperature of 1220-1260 ℃, the second heating section is controlled for 25-30 min, the soaking section is controlled at the temperature of 1210-1250 ℃, the soaking section is controlled for 2-3 h, the tapping temperature is 1210-1250 ℃, the water pressure of a high-pressure water descaler is 220-240 bar after the steel billet is tapped from a furnace, and the iron oxide scales on the surface of the steel billet are removed.
6. The method for producing a sulfur-containing, phosphorus-containing free-cutting steel as set forth in claim 1, wherein: in the production method of the sulfur-containing and phosphorus-containing free-cutting steel, the billet shape of a small bar is rolled to be 230 square, the rolling temperature is 1150-1250 ℃, and after high-temperature fast rolling, the billet is subjected to flame cutting at two ends.
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