CN113355556A - Preparation method of free-cutting brass rod and special-shaped brass rod - Google Patents
Preparation method of free-cutting brass rod and special-shaped brass rod Download PDFInfo
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- CN113355556A CN113355556A CN202110584204.4A CN202110584204A CN113355556A CN 113355556 A CN113355556 A CN 113355556A CN 202110584204 A CN202110584204 A CN 202110584204A CN 113355556 A CN113355556 A CN 113355556A
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- 229910001369 Brass Inorganic materials 0.000 title claims abstract description 61
- 239000010951 brass Substances 0.000 title claims abstract description 61
- 238000005520 cutting process Methods 0.000 title claims abstract description 41
- 238000002360 preparation method Methods 0.000 title claims description 12
- 239000011701 zinc Substances 0.000 claims abstract description 5
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 4
- 239000012535 impurity Substances 0.000 claims abstract description 3
- 238000000137 annealing Methods 0.000 claims description 30
- 238000010438 heat treatment Methods 0.000 claims description 25
- 238000001125 extrusion Methods 0.000 claims description 24
- 239000002245 particle Substances 0.000 claims description 24
- 238000004519 manufacturing process Methods 0.000 claims description 18
- 229910052797 bismuth Inorganic materials 0.000 claims description 12
- 238000005266 casting Methods 0.000 claims description 12
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 claims description 11
- 238000004321 preservation Methods 0.000 claims description 10
- 238000003723 Smelting Methods 0.000 claims description 9
- 238000009749 continuous casting Methods 0.000 claims description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 6
- 239000010949 copper Substances 0.000 claims description 6
- 229910052802 copper Inorganic materials 0.000 claims description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 abstract description 5
- 229910045601 alloy Inorganic materials 0.000 abstract description 5
- 239000000956 alloy Substances 0.000 abstract description 5
- 239000011135 tin Substances 0.000 abstract description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052782 aluminium Inorganic materials 0.000 abstract description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 2
- 230000000694 effects Effects 0.000 abstract description 2
- 229910052742 iron Inorganic materials 0.000 abstract description 2
- 229910052759 nickel Inorganic materials 0.000 abstract description 2
- 229910052718 tin Inorganic materials 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 37
- 239000002253 acid Substances 0.000 description 28
- 238000005406 washing Methods 0.000 description 24
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 15
- 239000000243 solution Substances 0.000 description 14
- 238000005554 pickling Methods 0.000 description 10
- 238000002791 soaking Methods 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 8
- 238000001816 cooling Methods 0.000 description 8
- 238000004513 sizing Methods 0.000 description 5
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 4
- 230000006698 induction Effects 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 208000034656 Contusions Diseases 0.000 description 2
- 208000034526 bruise Diseases 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 229910000881 Cu alloy Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 206010052428 Wound Diseases 0.000 description 1
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910002056 binary alloy Inorganic materials 0.000 description 1
- 238000010622 cold drawing Methods 0.000 description 1
- TVZPLCNGKSPOJA-UHFFFAOYSA-N copper zinc Chemical compound [Cu].[Zn] TVZPLCNGKSPOJA-UHFFFAOYSA-N 0.000 description 1
- 210000003464 cuspid Anatomy 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000003958 fumigation Methods 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C9/00—Alloys based on copper
- C22C9/04—Alloys based on copper with zinc as the next major constituent
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
- B21C37/04—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of bars or wire
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/08—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of copper or alloys based thereon
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Metal Extraction Processes (AREA)
Abstract
The invention discloses a free-cutting brass bar, which is characterized in that: the brass comprises the following components in percentage by mass: 57-60.5 wt%; pb: 1.8 to 4 wt% or Bi: 0.9 to 2 weight percent; sn: 0.2-0.4 wt%; fe: 0.1-0.3 wt%; ni: 0.1-0.3 wt%; the balance of zinc and inevitable impurities. The invention achieves the microalloying effect by adding alloy elements such as aluminum, tin, iron, nickel and the like, adjusts the morphology and the proportion of alpha-phase and beta-phase structures and ensures the cutting performance of products.
Description
Technical Field
The invention belongs to the technical field of copper alloy, and particularly relates to a preparation method of a free-cutting brass rod and a brass profiled rod.
Background
The brass is a copper-zinc binary alloy with copper and zinc as main components, and has excellent heat-conducting property, mechanical property, processability and corrosion resistance. The cutting performance of brass can be improved by adding lead or bismuth into the brass, but the cutting performance of the existing lead brass or bismuth brass still needs to be further improved, and the strength and the stress corrosion cracking resistance of the brass also need to be further improved according to different use environments.
According to the characteristics of brass, the special-shaped brass rod is widely applied to various deep-drawing and production-manufacturing supporting parts, such as split pins, bolts, sealing rings, nuts, pressure gauges, stainless steel screens, heat pipe radiating parts and the like.
The traditional production of the special-shaped brass bar generally comprises the steps of preparation of an ingot, extrusion into a proper special-shaped wire coil, pickling, special-shaped stretching, intermediate annealing, pickling and combined drawing, and the problems of long production period, high production cost and the like are caused due to the fact that the traditional process is complex in operation and many in working procedures, so that the traditional production process is not in accordance with the national advocated energy conservation and emission reduction. In addition, because the extrusion blank is a special-shaped wire coil, the poor problems of scratch, bruise, damage and the like easily occur in the processing, conveying and intermediate annealing processes, and the yield and the surface quality of the product are influenced. Annealing is carried out for many times in the production process, so that the crystal grains of the product are coarse, the cutting performance of the finished product is influenced, and the requirement for precision parts machined by a high-speed lathe cannot be met.
The invention patent CN103667782A discloses a production process of a brass round bar, which adopts the process of smelting → horizontal continuous casting → cold drawing → straightening, and the technology has the advantages of short process flow and low production cost. However, the brass bar obtained by the process has uneven tissue distribution, low beta phase proportion and larger grain size, and is not beneficial to the cutting performance of the material.
Therefore, further improvement is needed for the existing preparation method of the brass rod and the special-shaped brass rod.
Disclosure of Invention
The invention aims to solve the first technical problem of providing a free-cutting brass bar with excellent comprehensive performance.
The technical scheme adopted by the invention for solving the first technical problem is as follows: a free-cutting brass bar, which is characterized in that: the brass comprises the following components in percentage by mass: 57-60.5 wt%; pb: 1.8 to 4 wt% or Bi: 0.9 to 2 weight percent; sn: 0.2-0.4 wt%; fe: 0.1-0.3 wt%; ni: 0.1-0.3 wt%; the balance of zinc and inevitable impurities.
Preferably, the brass rod has a grain size of 5 to 20 μm. The grain size in the range can ensure that plastic deformation can be dispersed in more grains, so that the more uniform the plastic deformation is, the higher the strength and the hardness are; and the more the opportunity of the crystal grains to interdigitate with the intermediate canine teeth of the crystal grains, the more the propagation and the development of cracks are hindered, and the strength and the toughness are improved. Whereas the strength and hardness of materials with grain sizes > 20 μm are greatly affected.
Preferably, the brass has a microstructure containing 15 to 30% of a beta phase by area. The beta phase is hard and brittle, and when the beta phase is less than 15%, the cutting performance of the material is poor, and the cutter winding is easy to occur; when the beta phase is more than 30%, the material shaping is greatly reduced, and the subsequent processing use is influenced.
Preferably, the brass has a microstructure of 1mm2The number of the lead particles is more than 15000 or 1mm2The number of the upper bismuth particles is more than 8000. The lead particles and the bismuth particles are distributed in the solid solution in free particles, have the characteristics of lubrication and friction reduction, and can effectively improve the cutting performance of the material, and the quantity of the lead particles and the bismuth particles is the degree of improving the cutting performance. The number of lead particles of the conventional lead brass product subjected to intermediate annealing is less than 10000, and the number of bismuth particles of the bismuth brass product is less than 5000.
Preferably, the brass is added with 1.8-4 wt% of Pb, and lead particles with the size less than or equal to 1 μm in the microstructure of the brass account for more than 70% of the total number of the lead particles. The lead particles can effectively improve the cutting performance of the brass, the smaller the size of the lead particles is, the larger and more uniform the distribution area of the lead particles is, and the lead particles with the size less than or equal to 1 mu m in the microstructure account for more than 70 percent of the total lead particles and can effectively ensure the excellent cutting performance of the brass.
Preferably, the brass rods are profiled.
The invention aims to solve the second technical problem of providing a preparation method of the free-cutting special-shaped brass rod.
The technical scheme adopted by the invention for solving the second technical problem is as follows: a preparation method of the free-cutting brass rod is characterized by comprising the following steps: the preparation method comprises the following preparation steps: casting-extrusion-pickling-combined drawing-annealing-pickling-straightening
1) Continuous casting: smelting and casting the components according to a ratio to obtain an ingot;
2) extruding: heating the cast ingot, and extruding the cast ingot by an extruder to form an extruded round bar blank, wherein the extrusion temperature is 630-710 ℃;
3) and (3) combined drawing: performing combined drawing on the round bar blank through a special-shaped die to obtain a finished product special-shaped bar;
4) annealing: and annealing the special-shaped bar, wherein the annealing temperature is 200-400 ℃, and the heat preservation time is 1-5 h.
The traditional special-shaped bar process flow is to extrude a special-shaped round bar blank, and then the finished special-shaped bar is obtained through multi-pass drawing, the poor problems of scratch, bruise and the like easily occur in the processing and carrying and intermediate annealing processes of the special-shaped round bar blank, and the product yield and the surface quality are affected. Through low-temperature annealing, the residual stress of the product is eliminated, the product performance is ensured to be uniform, and the risk of ammonia fumigation cracking is reduced.
Preferably, in order to ensure that the extruded round bar blank deforms fully in the drawing process, the requirements between the round bar blank in the step 2) and the finished special-shaped bar in the step 3) are preferably as follows:
wherein a is the edge distance of the finished special-shaped rod, and D is the diameter of the extrusion blank. The excellent cutting performance of the product is ensured by regulating and controlling the extrusion temperature and controlling the drawing processing rate.
Preferably, in the step 2), when the extrusion temperature of the cast ingot with the copper content less than or equal to 58.5% is 630-660 ℃, the extrusion temperature of the cast ingot with the copper content larger than 58.5% is 660-710 ℃, end point values of 660 are not included, in the step 3), the drawing rate is 18-30%, and the drawing speed is 60-90 m/min. The grain size of the copper bar is 5-20 mu m, the beta phase proportion is 15-30%, and the unit area is (1 mm)2) The brass special-shaped bar with the number of lead particles larger than 15000 or the number of bismuth particles larger than 8000 has excellent cutting performance and short process flow.
In order to ensure that the subsequent drawing with large processing rate is smoothly carried out, preferably, the specification of the extruded round bar blank in the step 2) is phi 4.5-18 mm, and the head-to-tail difference value is less than or equal to 0.1 mm.
Compared with the prior art, the invention has the advantages that: 1) the invention achieves the microalloying effect by adding alloy elements such as aluminum, tin, iron, nickel and the like, adjusts the morphology and the proportion of alpha-phase and beta-phase structures and ensures the cutting performance of products. Wherein, the trace Sn element can improve the strength, the hardness and the like of the material; the addition of trace Fe element can play a role in refining grains so as to improve the uniform property of the material structure; the trace Pb or Bi element can be dispersed in the alpha phase boundary in a soft point form by adding, so that the cutting processing performance of the material is further improved; the addition of trace Ni element can improve the strength and stress corrosion cracking resistance of the material.
2) According to the invention, the finished product of the special-shaped bar is directly drawn after the round bar is extruded, the finished product has excellent performance, the hardness can reach 150-175 HV5, the tensile strength is not less than 500MPa, and the cutting performance is excellent.
Drawings
FIG. 1 is a microstructure of a brass bar of example 1 of the present invention;
FIG. 2 is a photograph of chips obtained in example 1 of the present invention;
FIG. 3 is a photograph of a cutting chip of comparative example 1 of the present invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
The invention provides 4 examples and 2 comparative examples, the specific components of which are shown in Table 1. 4 examples were prepared according to the preparation method of the present invention.
Example 1
The embodiment provides a free-cutting special-shaped brass bar, and the manufacturing method comprises the following steps:
1) smelting: carrying out element content formula according to the element proportion in the table 1;
2) a casting procedure: adopting horizontal continuous casting and drawing casting ingot with the specification of
Sawing the cast ingot on a horizontal sawing machine, wherein the sawing length is 1200 mm;
3) an extrusion process: heating the cast ingot in a medium-frequency induction heating furnace, wherein a four-section temperature gradient heating mode is adopted, the first section is heated to 250 ℃, and the heating time is 30 min; heating to 450 deg.C for 20 min; heating to 580 deg.C for 10 min; the fourth stage is heated to 650 deg.C for 15 min. Peeling and extruding the heated cast ingot on a 2200T reverse extruder to obtain an extrusion specification
The shape of the extruded rod blank is a round line, and the number of the extruded rod blanks is 2;
4) acid washing process: connecting the extruded blank, soaking in acid solution containing 20% sulfuric acid for 3min, and washing with high pressure water;
5) a combined drawing process: drawing the acid-washed round bar blank on a 4T combined drawing machine at the drawing speed of 50m/min to obtain a drawing specification S7mm with the processing rate of 28.79%;
6) and (3) annealing: preserving the heat of the drawn profiled bar in a box-type annealing furnace at 300 ℃ for 3h, and cooling along with the furnace after the heat preservation is finished;
7) acid washing process: pickling the product by an online pickling device, wherein the advancing speed of a crawler belt is 5m/min, and the acid solution is phosphoric acid solution;
8) straightening: straightening the product under a two-roller straightening machine at a straightening speed of 50 m/min;
9) and (5) sizing, and inspecting and warehousing finished products.
Example 2
The embodiment provides a free-cutting special-shaped brass bar, and the manufacturing process comprises the following steps:
1) a smelting process: carrying out element content formula according to the element proportion in the table 1;
2) a casting procedure: adopting horizontal continuous casting and drawing casting ingot with the specification of
Sawing the cast ingot on a horizontal sawing machine, wherein the sawing length is 800 mm;
3) an extrusion process: heating the cast ingot in a medium-frequency induction heating furnace by adopting a four-section temperature gradient heating mode, wherein the first section is heated to 300 ℃ for 30 min; heating to 450 deg.C for 20 min; heating to 550 deg.C for 10 min; and heating to 670 deg.C for 15 min. Peeling and extruding the heated cast ingot on a 2200T reverse extruder, wherein the extrusion specification is phi 8.7mm, the shape of an extruded rod blank is a round line, and the number of the extruded rod blanks is 2;
4) acid washing process: connecting the extruded blank, soaking in acid solution containing 20% sulfuric acid for 5min, and washing with high pressure water;
5) a combined drawing process: drawing the acid-washed round bar blank on an 8T combined drawing machine, wherein the drawing speed is 55m/min, the drawing specification is S11mm, and the processing rate is 18.76%;
6) and (3) annealing: preserving the heat of the drawn profiled bar in a box-type annealing furnace at 280 ℃ for 3h, and cooling along with the furnace after the heat preservation is finished;
7) acid washing process: pickling the product by an online pickling device, wherein the advancing speed of a crawler belt is 7m/min, and the acid solution is phosphoric acid solution;
8) straightening: straightening the product under a two-roller straightening machine at a straightening speed of 50 m/min;
9) and (5) sizing, and inspecting and warehousing finished products.
Example 3
The embodiment provides a free-cutting special-shaped brass bar, and the manufacturing process comprises the following steps:
1) a smelting process: carrying out element content formula according to the element proportion in the table 1;
2) a casting procedure: adopting horizontal continuous casting and drawing casting ingot with the specification of
Sawing the cast ingot on a horizontal sawing machine, wherein the sawing length is 900 mm;
3) an extrusion process: heating the cast ingot in a medium-frequency induction heating furnace by adopting a four-section temperature gradient heating mode, wherein the first section is heated to 300 ℃ for 30 min; heating to 500 deg.C for 20 min; heating to 600 deg.C for 10 min; the fourth stage is heated to 680 deg.C for 20 min. Peeling and extruding the heated cast ingot on a 2200T reverse extruder, wherein the extrusion specification is phi 8.7mm, the shape of an extruded rod blank is a round line, and the number of the extruded rod blanks is 2;
4) acid washing process: connecting the extruded blank, soaking in acid solution containing 20% sulfuric acid for 3min, and washing with high pressure water;
5) a combined drawing process: drawing the acid-washed round bar blank on an 8T combined drawing machine, wherein the drawing speed is 45m/min, the drawing specification is S12mm, and the processing rate is 24.66%;
6) and (3) annealing: preserving the heat of the drawn profiled bar in a box-type annealing furnace at 310 ℃ for 3h, and cooling along with the furnace after the heat preservation is finished;
7) acid washing process: pickling the product by an online pickling device, wherein the advancing speed of a crawler belt is 6m/min, and the acid solution is phosphoric acid solution;
8) straightening: straightening the product under a two-roller straightening machine at a straightening speed of 45 m/min;
9) and (5) sizing, and inspecting and warehousing finished products.
Example 4
The embodiment provides a free-cutting special-shaped brass bar, and the manufacturing process comprises the following steps:
1) a smelting process: carrying out element content formula according to the element proportion in the table 1;
2) a casting procedure: adopting horizontal continuous casting and drawing casting ingot with the specification of
Sawing the cast ingot on a horizontal sawing machine, wherein the sawing length is 1250 mm;
3) an extrusion process: heating the cast ingot in a medium-frequency induction heating furnace, wherein a four-section temperature gradient heating mode is adopted, the first section is heated to 250 ℃, and the heating time is 30 min; heating to 450 deg.C for 20 min; heating to 580 deg.C for 10 min; the fourth stage is heated to 650 deg.C for 20 min. Peeling and extruding the heated cast ingot on a 2200T reverse extruder, wherein the extrusion specification is phi 8.7mm, the shape of an extruded rod blank is a round rod blank, and the number of the extruded rod blanks is 2;
4) acid washing process: connecting the extruded blank, soaking in acid solution containing 20% sulfuric acid for 3min, and washing with high pressure water;
5) a combined drawing process: drawing the acid-washed round bar blank on an 8T combined drawing machine, wherein the drawing speed is 50m/min, the drawing specification is S9.8mm, and the processing rate is 25.40%;
6) and (3) annealing: preserving the heat of the drawn profiled bar in a box-type annealing furnace at 330 ℃ for 3h, and cooling along with the furnace after the heat preservation is finished;
7) acid washing process: pickling the product by an online pickling device, wherein the advancing speed of a crawler belt is 5m/min, and the acid solution is phosphoric acid solution;
8) straightening: straightening the product under a two-roller straightening machine at a straightening speed of 50 m/min;
9) and (5) sizing, and inspecting and warehousing finished products.
Comparative example 1
The comparative example provides a free-cutting small-size special-shaped brass bar, and the manufacturing process comprises the following steps:
1. a smelting process: carrying out element content formula according to the element proportion in the table 1;
2. a casting procedure: adopting a horizontal continuous casting technology to cast a blank with the specification of
Sawing the cast ingot on a horizontal sawing machine, wherein the sawing length is 900 mm;
3. an extrusion process: peeling and extruding the heated cast ingot on a 2200T reverse extruder, wherein the extrusion specification is phi 8.7mm, the shape of the extruded wire blank is a special-shaped rod, and the number of the extruded wire blanks is 2;
4. acid washing process: connecting the extruded blank, soaking in acid solution containing 20% sulfuric acid for 3min, and washing with high pressure water;
5. a coil drawing process: the pickled special-shaped blank is coiled and pulled in an inverted mode, the coiling and pulling speed is 60m/min, and the outgoing line specification is S8 mm;
6. intermediate annealing: preserving the heat of the coiled and drawn special-shaped blank in a hood-type annealing furnace at 550 ℃ for 3h, and cooling along with the furnace after the heat preservation is finished;
7. acid washing process: soaking the annealed special-shaped blank in acid liquor containing 20% of sulfuric acid for 5min, and washing the blank with high-pressure water;
8. a coil drawing process: the pickled special-shaped blank is coiled and pulled in an inverted mode, the coiling and pulling speed is 70m/min, and the outgoing line specification is S7.3mm;
9. intermediate annealing: preserving the heat of the coiled and drawn special-shaped blank in a hood-type annealing furnace at 550 ℃ for 3h, and cooling along with the furnace after the heat preservation is finished;
10. acid washing process: soaking the annealed special-shaped blank in acid liquor containing 20% of sulfuric acid for 5min, and washing the blank with high-pressure water;
11. a combined drawing process: drawing the acid-washed round wire blank on an 8T combined drawing machine, wherein the drawing speed is 50m/min, the drawing specification is S7mm, and the processing rate is 8.05%;
12. and (5) sizing, and inspecting and warehousing finished products.
Comparative example 2
The comparative example provides a free-cutting special-shaped brass bar, and the manufacturing process comprises the following steps:
1. a smelting process: carrying out element content formula according to the element proportion in the table 1;
2. a casting procedure: adopting a horizontal continuous casting technology to cast a blank with the specification of
Sawing the cast ingot on a horizontal sawing machine, wherein the sawing length is 1050 mm;
3. an extrusion process: peeling and extruding the heated cast ingot on a 2200T reverse extruder, wherein the extrusion specification is phi 8.7mm, the shape of the extruded wire blank is a special-shaped rod, and the number of the extruded wire blanks is 2;
4. acid washing process: connecting the extruded blank, soaking in acid solution containing 20% sulfuric acid for 3min, and washing with high pressure water;
5. a coil drawing process: the acid-washed special-shaped blank is coiled and pulled in an inverted mode, the coiling and pulling speed is 70m/min, and the outgoing line specification is S8.7mm;
6. intermediate annealing: preserving the heat of the coiled and drawn special-shaped blank in a hood-type annealing furnace at 550 ℃ for 3h, and cooling along with the furnace after the heat preservation is finished;
7. acid washing process: soaking the annealed special-shaped blank in acid liquor containing 20% of sulfuric acid for 6min, and washing the blank with high-pressure water;
8. a coil drawing process: the pickled special-shaped blank is coiled and pulled in an inverted mode, the coiling and pulling speed is 70m/min, and the outgoing line specification is S8 mm;
9. intermediate annealing: keeping the coiled and drawn special-shaped blank at 530 ℃ in a hood-type annealing furnace for 3h, and cooling along with the furnace after the heat preservation is finished;
10. acid washing process: soaking the annealed special-shaped blank in acid liquor containing 20% of sulfuric acid for 6min, and washing the blank with high-pressure water;
11. a combined drawing process: and drawing the acid-washed round wire blank on an 8T combined drawing machine, wherein the drawing speed is 50m/min, the drawing specification is S7.6mm, and the processing rate is 9.75%.
The machinability was defined as 100% of the machinability of example 1, and the other was defined as a ratio to the machinability of example 1. As can be seen from table 3, the cutting performance of the inventive example was superior to that of the comparative example.
Fig. 2 is a chip of example 1, and fig. 3 is a chip of comparative example 1. It can be seen from the figure that the chips of example 1 were in the form of powder, and the chips of comparative example 1 were spirally wound. The main reasons are that the steel is drawn directly from a round bar to a special bar after extrusion in example 1, the intermediate annealing is not performed, the grain size is small, the beta phase ratio is high, and the number of lead (bismuth) particles is large. And the comparative example 1 is that after the special-shaped bar is extruded, the middle disc is drawn twice, and the special-shaped bar is drawn to a special-shaped finished product after 2 times of middle annealing. The grain size was large, B phase was low and the number of lead (bismuth) particles was small, and thus example 1 had excellent machinability.
TABLE 1 chemical composition (wt%) of alloy bars of examples of the invention and comparative examples
| Numbering | Cu | Pb | Fe | Sn | Ni | P | Ca | Bi | Zn |
| Example 1 | 57.85 | 1.63 | 0.15 | 0.28 | 0.11 | - | - | Balance of | |
| Example 2 | 59.41 | 2.11 | 0.08 | 0.11 | 0.04 | 0.03 | 0.02 | Balance of | |
| Example 3 | 58.85 | 3.12 | 0.18 | 0.15 | 0.08 | - | 0.01 | Balance of | |
| Example 4 | 58.42 | ≤0.01 | 0.11 | 0.14 | 0.03 | - | - | 1.89 | Balance of |
| Comparative example 1 | 57.61 | 3.25 | - | - | 0.15 | 0.01 | - | - | Balance of |
| Comparative example 2 | 58.55 | ≤0.01 | - | 0.12 | - | - | 0.02 | 1.82 | Balance of |
TABLE 2 microstructure of alloy bars of examples of the invention and comparative examples
TABLE 3 Properties of alloy bars of examples of the invention and of comparative examples
Claims (10)
1. A free-cutting brass bar, which is characterized in that: the brass comprises the following components in percentage by mass: 57-60.5 wt%; pb: 1.8 to 4 wt% or Bi: 0.9 to 2 weight percent; sn: 0.2-0.4 wt%; fe: 0.1-0.3 wt%; ni: 0.1-0.3 wt%; the balance of zinc and inevitable impurities.
2. The free-cutting brass rod in accordance with claim 1, wherein: the grain size of the brass bar is 5-20 μm.
3. The free-cutting brass rod in accordance with claim 1, wherein: the brass has a microstructure containing 15-30% of a beta phase by area.
4. The free-cutting brass rod in accordance with claim 1, wherein: 1mm in microstructure of the brass2The number of the lead particles is more than 15000 or 1mm2The number of the upper bismuth particles is more than 8000.
5. The free-cutting brass rod in accordance with claim 4, wherein: the brass is added with 1.8-4 wt% of Pb, and lead particles with the size less than or equal to 1 mu m in the microstructure of the brass account for more than 70% of the total number of the lead particles.
6. The free-cutting brass rod defined in any one of claims 1 to 4, wherein: the brass rods are in special shapes.
7. A method of making the free-cutting brass rod of claim 6, characterized in that: the preparation method comprises the following preparation steps:
1) continuous casting: smelting and casting the components according to a ratio to obtain an ingot;
2) extruding: heating the cast ingot, and extruding the cast ingot by an extruder to form an extruded round bar blank, wherein the extrusion temperature is 630-710 ℃;
3) and (3) combined drawing: performing combined drawing on the round bar blank through a special-shaped die to obtain a finished product special-shaped bar;
4) annealing: and annealing the special-shaped bar, wherein the annealing temperature is 200-400 ℃, and the heat preservation time is 1-5 h.
8. The method of making a free-cutting brass rod in accordance with claim 7, wherein: the requirement between the round bar blank in the step 2) and the finished product special-shaped bar in the step 3) is as follows:
wherein a is the edge distance of the finished special-shaped rod, and D is the diameter of the extrusion blank.
9. The method of making a free-cutting brass rod in accordance with claim 7, wherein: in the step 2), when the extrusion temperature of the cast ingot with the copper content less than or equal to 58.5% is 630-660 ℃, the extrusion temperature of the cast ingot with the copper content larger than 58.5% is 660-710 ℃, the end point value of 660 is not included, in the step 3), the drawing rate is 18-30%, and the drawing speed is 60-90 m/min.
10. The method of making a free-cutting brass rod in accordance with claim 7, wherein: the specification of the extruded round bar billet in the step 2) is phi 4.5-18 mm, and the head-to-tail difference value is less than or equal to 0.1 mm.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111304488A (en) * | 2020-03-25 | 2020-06-19 | 宁波金田铜业(集团)股份有限公司 | Stress cracking resistant lead brass bar and preparation method thereof |
| CN111926214A (en) * | 2020-08-18 | 2020-11-13 | 宁波金田铜业(集团)股份有限公司 | Free-cutting lead brass bar with excellent cold machining plasticity and preparation method thereof |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111304488A (en) * | 2020-03-25 | 2020-06-19 | 宁波金田铜业(集团)股份有限公司 | Stress cracking resistant lead brass bar and preparation method thereof |
| CN111926214A (en) * | 2020-08-18 | 2020-11-13 | 宁波金田铜业(集团)股份有限公司 | Free-cutting lead brass bar with excellent cold machining plasticity and preparation method thereof |
Non-Patent Citations (1)
| Title |
|---|
| 李宏磊等: "《铜加工生产技术问答》", 31 January 2008, 冶金工业出版社 * |
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