Summary of the invention
The present invention is exactly in order to solve above-mentioned problem, and wire rod susceptibility, anti-defective of the defective of a kind of reduction to taking place in hot rolling wire carrying or the secondary processing process is provided.
Main points of the present invention are as follows.
(1) the direct patenting wire rod of high strength is characterized in that, is the above high carbon steel of carbon content 0.7 quality %, is below the Hv:390 by its surface to the Vickers' hardness of the layer of at least 300 μ m, above-mentioned layer is become be difficult to generate the layer of martensitic stucture of rubbing.
(2) the direct patenting wire rod of high strength, it is characterized in that, being the above high carbon steel of carbon content 0.7 quality %, is below 0.97 times of full face mean carbon content by its surface to the mean carbon content of the layer of at least 300 μ m, above-mentioned layer is become be difficult to generate the layer of martensitic stucture of rubbing.
(3) the direct patenting wire rod of high strength, it is characterized in that, be the above high carbon steel of carbon content 0.7 quality %, by its surface at least 300 μ m layer Vickers' hardness be below the Hv:390, and the mean carbon content of above-mentioned layer is below 0.97 times of full face mean carbon content, makes above-mentioned layer become the layer that is difficult to generate the friction martensitic stucture by this.
(4) the direct patenting wire rod of each described high strength of above-mentioned (1)~(3) is characterized in that, the average wafer spacing in the above-mentioned layer is from being more than the 95nm.
(5) the direct patenting wire rod of each described high strength of above-mentioned (1)~(3) is characterized in that the composition of steel of above-mentioned high carbon steel is counted with quality %,
C:0.7~1.2%,
Si:0.1~1.5%,
Mn:0.1~1.0%,
All the other are made up of iron and unavoidable impurities.
(6) the direct patenting wire rod of each described high strength of above-mentioned (1)~(3) is characterized in that the composition of steel of above-mentioned high carbon steel contains in quality %
C:0.7~1.2%,
Si:0.1~1.5%,
Mn:0.1~1.0% also contains
Cr:0.1~0.5%,
V:0.001~0.2%,
Ni:0.05~1.0%,
Mo:0.1~0.5%,
Cu:0.05~0.8%,
W:0.05~0.8%,
La:0.0005~0.01%,
Ce:0.0005~0.01%,
Al:0.001~0.06%,
B:0.0005~0.06%,
Ti:0.001~0.06%,
A kind of in Nb:0.001~0.06% or more than 2 kinds.
(7) manufacture method of the direct patenting wire rod of high strength, it is characterized in that, with the high carbon steel more than the carbon content 0.7 quality % in the wire rod process furnace with after 1000~1200 ℃ of heating, carry out hot rolling, make diameter become 4~16mm, in the above-mentioned hot rolling that terminates of the temperature more than 850 ℃, 15 seconds with internal cooling to 750~830 ℃, be immersed at once then in 400~570 ℃ the molten salt bath, make the pearlitic transformation termination.
(8) manufacture method of the direct patenting wire rod of high strength, it is characterized in that, with the high carbon steel more than the carbon content 0.7 quality % in the wire rod process furnace with after 1000~1200 ℃ of heating, carry out hot rolling, make diameter become 4~16mm, the above-mentioned hot rolling of termination is immersed in 400~570 ℃ the molten salt bath then at once under 750~830 ℃ temperature, makes the pearlitic transformation termination.
(9) manufacture method of the direct patenting wire rod of above-mentioned (8) described high strength is characterized in that, carries out above-mentioned hot rolling, batches under 750~830 ℃ temperature with interior in 15 seconds then, is immersed at once then in 400~570 ℃ the molten salt bath.
(10) manufacture method of the direct patenting wire rod of above-mentioned (8) described high strength is characterized in that, carries out air-cooledly above-mentionedly flooding in 400~570 ℃ molten salt bath replacing, and makes the pearlitic transformation termination.
(11) manufacture method of the direct patenting wire rod of high strength, it is characterized in that, with more than the carbon content 0.7 quality % and by its surface at least 300 μ m the layer mean carbon content be the high carbon steel of full face mean carbon content below 0.97 times in the wire rod process furnace with after 1000~1200 ℃ of heating, carry out hot rolling, make diameter become 4~16mm, in the above-mentioned hot rolling that terminates of the temperature more than 750 ℃, be immersed at once then in 400~570 ℃ the molten salt bath, make the pearlitic transformation termination.
(12) manufacture method of the direct patenting wire rod of above-mentioned (11) described high strength is characterized in that, carries out above-mentioned hot rolling, batches under 750~900 ℃ temperature then, is immersed at once then in 400~570 ℃ the molten salt bath.
(13) manufacture method of above-mentioned (11) or the direct patenting wire rod of (12) described high strength is characterized in that, carries out air-cooledly above-mentionedly flooding in 400~570 ℃ molten salt bath replacing, and makes the pearlitic transformation termination.
Implement best mode of the present invention
At first the qualification reason that steel is formed describes.Composition all is quality %, with weight % synonym.
C is to strengthening effective elements, and in order to obtain high-intensity steel wire, C must be measured is more than 0.7%, but easily separates out proeutectoid cementite when too high, and ductility is reduced, and the stringiness variation, therefore the upper limit is taken as 1.2%.
Si is the bioelement of steel-deoxidizing, and when its content was very few, deoxidation effect was insufficient, therefore adds more than 0.1%.In addition, Si is solid-solubilized in after thermal treatment in the ferritic phase in the perlite of formation, make patenting after intensity improve, harmful to heat-treatability but then, therefore be taken as below 1.5%.
Mn:, must add the Mn more than 0.1% in order to ensure the hardenability of steel.But the ductility the when Mn of interpolation volume also can make galvanizing is replied slack-off, therefore is taken as below 1.0%.
The interpolation of Cr is in order to improve intensity after the patenting and the intensity after the Wire Drawing.Therefore, the addition of Cr be taken as can reach this effect more than 0.1% and can be because of patenting the time phase change delay cause below 0.5% of heat-treatability variation.
The interpolation of V also is in order to improve intensity after the patenting and the intensity after the Wire Drawing.During interpolation, be taken as and show more than 0.001% of this effect, add when excessive, phase transformation is significantly slack-off, and productivity is affected, and therefore is taken as below 0.1%.
The interpolation of Ni also is in order to improve intensity after the patenting and the intensity after the Wire Drawing.During interpolation, be taken as and show more than 0.05% of this effect, add when excessive, phase transformation is significantly slack-off, and productivity is affected, and therefore is taken as below 1.0%.
The interpolation of Mo also is in order to improve intensity after the patenting and the intensity after the Wire Drawing.During interpolation, be taken as and show more than 0.1% of this effect, add when excessive, pearlitic transformation is significantly slack-off, and productivity is reduced, and therefore is taken as and does not cause below 0.5% of this influence.
The interpolation of Cu is in order to improve the resistance to corrosion fatigue characteristic.During interpolation, be taken as and show more than 0.05% of this effect, add when excessive, pearlitic transformation is significantly slack-off, and productivity is reduced, and therefore is taken as and does not cause below 0.8% of this influence.
The interpolation of W also is in order to improve the resistance to corrosion fatigue characteristic.During interpolation, be taken as and show more than 0.05% of this effect, add when excessive, pearlitic transformation is significantly slack-off, and productivity is reduced, and therefore is taken as and does not cause below 0.8% of this influence.More can bring into play effect when these elements compounding are added in addition.
Add (0.0005~0.01%) other La, Ce by trace, can improve the resistance to corrosion fatigue characteristic.
The interpolation of Al is to become fine for the size that makes the perlite thin slice.During interpolation, be taken as and show more than 0.001% of this effect.Addition surpasses 0.06% o'clock Al
2O
3Increase etc. the hard inclusions thing, wire-drawing workability is reduced.
The interpolation of B is to become fine for the size that makes the perlite thin slice.During interpolation, be taken as and show more than 0.0005% of this effect.When addition is too much, make the constant temperature phase change delay, easily produce the fine martensite of hard, therefore be taken as below 0.06%.
The interpolation of Ti is to become fine for the size that makes the perlite thin slice.During interpolation, be taken as and show more than 0.001% of this effect.When addition is too much, make the constant temperature phase change delay, easily produce the fine martensite of hard, therefore be taken as below 0.06%.
The interpolation of Nb is to become fine for the size that makes the perlite thin slice.During interpolation, be taken as and show more than 0.001% of this effect.When addition is too much, make the constant temperature phase change delay, easily produce the fine martensite of hard, therefore be taken as below 0.06%.
P generates the embrittlement tissue easily because of segregation, and S then is the element that easily forms inclusion, therefore wish to be taken as respectively detrimentally affect little below 0.02%.
Below manufacture method of the present invention is described.
Be adjusted to the steel of above-mentioned composition of steel, be continuously cast into large-scale square billet or middle-size and small-size square billet after the melting.The steel of making large-scale square billet is rolled into middle-size and small-size square billet by the square billet blooming mill.Middle-size and small-size square billet with 1000 ℃ to 1200 ℃ heating, makes the tissue of steel become austenite in the wire rod process furnace.In order in hot rolling, not to be reduced to below the austenitizing temperature, be necessary this temperature is heated to more than 900 ℃ at least.In addition, during over-heating, rolling final rolling temperature uprises, and can promote the growth of austenite crystal, therefore gets the temperature below 1200 ℃.Then, the heated square billet of hot rolling becomes the shape of diameter 4~16mm, in the hot rolling of the termination of the temperature more than 800 ℃.
At this moment, final rolling temperature is taken as occasion more than 850 ℃, diminishes, be necessary to cool off at once, with interior coiling temperature is adjusted between 750 ℃ to 830 ℃ in 15 seconds for making near the austenite crystal diameter the wire rod top layer.When above, easily cause grain growing in 15 seconds, therefore should adjust with interior at least 15 seconds.
In addition,, heterogeneity is spent greatly, wire-drawing workability is reduced, so be taken as more than 750 ℃ because cooled temperature begins phase transformation during less than 750 ℃.In addition, when surpassing 830 ℃, it is big that the austenite structure on top layer becomes, and makes the surface made with interior tissue at least 300 μ m to be difficult to produce that friction is martensitic, the tissue of wafer spacing more than 95nm becomes is difficult.
Then, be impregnated at once in 530 ℃~570 ℃ the molten salt bath, make the pearlitic transformation termination, thereby will organize adjustment to become wafer spacing from the perlite more than the 95nm or below the Vickers' hardness Hv390.The temperature of molten salt bath is during less than 530 ℃, with wafer spacing from making the difficulty that becomes more than the 95nm.And intensity is low excessively when getting more than 570 ℃, therefore wishes to be taken as below 570 ℃.In addition, above-mentioned final rolling temperature is taken as 750~830 ℃ occasion, adopts in the molten salt bath that is impregnated into 400~570 ℃ after the finish rolling at once, make the technology of pearlitic transformation termination, also can obtain the goods of same characteristic.In addition, the cooling after batching adopt air-cooled, spraying is cold etc. also can obtain same effect.
Cause the reason of fracture of wire to be narrated when then, imperfect tape being gone into wire rod.
Be brought into the degree of depth of the defective on the wire rod, big is 100 μ m degree.At this moment, why influence most fracture of wire,, be because the martensitic existence of hard that the heat that takes place when bringing defective into forms on the top layer.In order to make the martensitic generation that causes fracture of wire innoxious, be necessary and will be adjusted to below the Hv390 by the Vickers' hardness of surface at least 300 μ m, perhaps will by the surface at least 300 μ m the layer average wafer spacing from being adjusted into more than the 95nm.By this, the martensite that forms when bringing defective into is not taken place or be thinned to harmless degree.
In addition, in the present invention, the steel that is adjusted to above-mentioned composition of steel is continuously cast into large-scale square billet or middle-size and small-size square billet after melting.The pure iron that nearby adds of the crystallizer in casting mold makes by the surface and becomes below 0.97 times of average carbon density to the carbon concentration of at least 300 μ m by when casting.When surpassing 0.97 times, be that coiling temperature batches the back, is immersed in the occasion that obtains pearlitic structure in the molten salt bath with 400~530 ℃ temperature more than 850 ℃ with general manufacturing process, can not make by the surface to the Vickers' hardness of at least 300 mu m ranges below Hv390, perhaps average wafer spacing is from more than 95nm.Thereby being necessary to make by the surface is below 0.97 times of all mean concnss of section to the carbon amount of at least 300 μ m.
Embodiment 1
Table 1 shows the chemical ingredients of the steel of the present invention of test usefulness.Chemical ingredients with comparative steel is shown in same table 1 in addition.With converter melting steel of the present invention and comparative steel, cast the large-scale square billet of 500mm * 300mm then through continuous casting, reusable heat rolls into the small-sized square billet of 122mm side.With after 1100~1200 ℃ of heating, be rolled into the wire rod of diameter 5.5mm to 13mm then.
Table 2 shows based on the creating conditions of the temperature after the wire rolling termination, with the wafer spacing on the hardness on the top layer that resulting wire rod has been shown in the table 2 and top layer from.
Steel 1~15 of the present invention is adjusted the chemical ingredients and the microstructure of steel according to the present invention.
Comparative steel 16, the composition of its steel is identical with steel of the present invention, and the final rolling temperature in the hot rolling is 900 ℃, is cooled to 850 ℃ then, than steel height of the present invention.
Comparative steel 17, the composition of its steel is identical with steel of the present invention, and final rolling temperature in the hot rolling and coiling temperature thereafter are in scope of the present invention, but it is slow to reach the cooling of coiling temperature, and the time ratio the present invention who carries out is long.
Comparative steel 18, the composition of its steel is identical with steel of the present invention, does not cool off after the finish rolling in the hot rolling, and coiling temperature reaches 840 ℃, than the present invention height.
Comparative steel 19, the composition of its steel is identical with steel of the present invention, but Heating temperature is low, and coiling temperature is lower than the present invention.
Comparative steel 20, the composition of its steel is identical with steel of the present invention, the Heating temperature height, but the cooling during finish rolling is strong, and coiling temperature is lower than the present invention.
Use these wire rods, manually invest defective, measure the martensitic thickness that forms under the defective.In addition, 2 tons of coils of wire of these wire rods are carried 30 times repeatedly, made the hook and the wire rod friction of fork truck, investigate the fracture of wire number of times in the drawing process then.These be the results are shown in table 2.
Made in accordance with the present invention 1~15, martensitic thin thickness demonstrates the few good result of fracture of wire number of times.
On the other hand, the martensite thickness of comparative steel 11~13 is thick, and the fracture of wire number of times is than steel height of the present invention.Though and comparative steel 14~15 martensite thin thickness, the relative reduction in area shown in the table 1 is low, the fracture of wire number of times shown in the table 2 is than the present invention height.
The chemical ingredients of table 1 steel of the present invention (mass%)
| | C | Si | Mn | P | S | Cr | V | Ni | Mo | Cu | W | Al | B | Ti | Nb |
Steel of the present invention | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | 0.72 0.82 0.82 0.83 0.86 1.02 0.98 0.82 0.92 0.84 0.84 0.82 0.86 0.92 1.15 | 0.20 0.21 0.20 0.21 0.71 0.21 1.20 0.20 0.21 0.21 0.15 0.20 0.20 0.80 0.20 | 0.51 0.71 0.48 0.62 0.72 0.30 0.29 0.92 0.29 0.72 0.33 0.50 0.39 0.99 0.32 | 0.016 0.014 0.012 0.013 0.012 0.008 0.013 0.013 0.012 0.008 0.016 0.013 0.008 0.012 0.004 | 0.008 0.010 0.006 0.008 0.006 0.008 0.006 0.003 0.009 0.011 0.012 0.013 0.011 0.011 0.012 | 0.21 - - - 0.21 0.10 0.21 - 0.40 - 0.10 - - 0.12 - | 0.01 - - 0.10 - - 0.01 0.001 - - - - 0.10 - - | - - - 0.80 - 0.30 - - - - 0.05 - 0.10 - - | 0.10 - - 0.10 - 0.50 - - - - 0.10 - - - - | 0.10 - - - - - - 0.80 - - - - - - - | - - - - - 0.05 - - - - - - 0.80 - - | - 0.028 0.034 - - - - - - - - 0.041 - - - | 0.005 - - - - - - 0.01 - - - - - - - | - - - - 0.005 - - - - 0.01 - - - - - | - 0.005 - - - - 0.06 - - - - - - - - |
Comparative steel | 16 17 18 19 20 | 0.82 0.82 0.82 0.82 0.82 | 0.20 0.21 0.21 0.21 0.21 | 0.71 0.76 0.77 0.82 0.71 | 0.016 0.014 0.013 0.012 0.012 | 0.008 0.010 0.008 0.008 0.009 | - - - - - | - - - - - | - - - - - | - - - - - | - - - - - | - - - - - | 0.032 0.028 0.031 0.034 0.033 | - - - - - | - - - - - | - - - - - |
The complete processing of table 2 hot rolling wire
| | Steel wire diameter (mm) | Heating temperature (℃) | Final rolling temperature (℃) | Coiling temperature (℃) | Cooling time (s) | Controlled chilling | TS (GPa) | RA (%) | Surface~300 μ m portions | The martensite thickness that artificial defect causes (μ m) | Broken string index when landing |
Hardness (Hv) | Wafer spacing is from (nm) |
Steel of the present invention | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | 13 13 13 13 13 13 5.5 7 13 13 13 5.5 13 13 13 | 1100 1100 1100 1100 1100 1000 1100 1100 1100 1100 1100 1100 1100 1100 1100 | 850 850 850 850 850 850 850 850 850 850 780 820 850 850 820 | 810 800 800 800 800 800 800 800 800 800 780 820 790 810 820 | 10 9 10 12 10 10 9 10 10 10 0 0 9 10 0 | DLP DLP DLP DLP DLP DLP DLP DLP DLP DLP DLP DLP DP DP DP | 1.15 1.20 1.20 1.31 1.19 1.19 1.22 1.20 1.16 1.22 1.22 1.10 1.18 1.21 1.13 | 43 48 44 42 45 43 45 44 43 44 43 42 45 44 42 | 380 370 350 360 370 350 360 365 365 365 340 320 330 340 340 | 95 100 120 110 100 120 110 105 105 120 120 110 120 125 110 | 5 3 2 5 3 2 3 2 3 2 4 2 3 2 3 | 2 1 0 0 1 0 5 2 3 3 0 1 0 3 0 |
Comparative steel | 16 17 18 19 20 | 13.0 13.0 13.0 13.0 13.0 | 1100 1100 1100 950 1100 | 900 850 840 720 850 | 850 800 840 720 720 | 10 16 0 0 15 | DLP DLP DLP DLP DLP | 1.20 1.22 1.21 1.21 1.25 | 44 43 44 23 15 | 400 400 410 370 365 | 80 80 75 100 100 | 10 11 12 6 12 | 10 12 13 24 30 |
DLP: patenting in the melting salt
DP: air-cooled patenting
Embodiment 2
Table 3 shows the steel of the present invention of test usefulness and the chemical ingredients of comparative steel.With converter melting steel of the present invention and comparative steel, cast the large-scale square billet of 500mm * 300mm then through continuous casting, reusable heat rolls into the small-sized square billet of 122mm side.With after 1100~1200 ℃ of heating, be rolled into the wire rod of diameter 5.5mm to 13mm then.
Table 4 show with by wire surface to the carbon concentration of 300 μ m divided by the carbon amount of the average carbon amount of the full basal area of wire rod than and creating conditions based on hot rolling termination back temperature.
With the wafer spacing on the surface hardness of gained wire rod and top layer from being shown in same table 4.
Steel 1~15 of the present invention is adjusted the chemical ingredients and the microstructure of steel according to the present invention.On the other hand, the composition of comparative example 16,17 its steel is identical with steel of the present invention with rolling method, but the carbon amount is compared steel height of the present invention.
Use these wire rods, manually invest defective, measure the martensitic thickness that forms under the defective.In addition, 2 tons of coils of wire of these wire rods are carried 30 times repeatedly, made the hook and the wire rod friction of fork truck, investigate the fracture of wire number of times in the drawing process then.These be the results are shown in table 4.
Steel 1~15 of the present invention made in accordance with the present invention, martensitic thin thickness demonstrates the few good result of fracture of wire number of times.On the other hand, the martensite thickness of comparative steel 16~17 is thick, and the fracture of wire number of times is than steel height of the present invention.
The chemical ingredients of table 3 steel of the present invention (mass%)
| | C | Si | Mn | P | S | Cr | V | Ni | Mo | Cu | W | Al | B | Ti | Nb | La | Ce |
Steel of the present invention | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | 0.72 0.82 0.84 0.83 0.87 1.00 0.97 0.83 0.92 0.94 0.83 0.82 0.86 0.92 1.15 | 0.21 0.21 0.19 0.29 0.72 0.18 1.17 0.21 0.19 0.21 0.16 0.18 0.19 0.79 0.18 | 0.51 0.72 0.48 0.63 0.72 0.32 0.29 0.81 0.31 0.72 0.32 0.48 0.32 0.86 0.31 | 0.012 0.011 0.014 0.012 0.014 0.010 0.013 0.013 0.012 0.011 0.016 0.013 0.008 0.012 0.005 | 0.009 0.010 0.008 0.009 0.008 0.008 0.006 0.003 0.009 0.006 0.012 0.013 0.011 0.011 0.012 | 0.21 - - - 0.20 0.10 0.21 - 0.40 - 0.10 - - 0.16 - | 0.01 - - 0.10 - - 0.01 0.002 - - - - 0.10 - - | 0.20 - - 0.80 - 0.30 - - - - 0.08 - 0.12 - - | 0.10 - - 0.10 - 0.50 - - - - 0.15 - - - - | 0.10 - - - - 0.13 - 0.75 - - - - - - - | - - - - - 0.05 - - - - - - 0.77 - - | - 0.029 0.032 - - - - - - - - 0.039 - - - | 0.007 - - - - - - 0.02 - - - - - - - | - - - - 0.006 - - - - 0.02 - - - - - | - 0.006 - - - - 0.06 - - - - - - - - | 0.001 - - - - - - - - - - - - - - | - - - - - 0.001 - - - - - - - - - |
Compare copper | 16 17 | 0.81 0.81 | 0.20 0.21 | 0.71 0.76 | 0.016 0.014 | 0.008 0.010 | - - | - - | - - | - - | - - | - - | 0.032 0.028 | - - | - - | - - | - - | - - |
The complete processing of table 4 hot rolling wire
| | Steel wire diameter (mm) | The carbon amount ratio on top layer | Heating temperature (℃) | Final rolling temperature (℃) | Coiling temperature (℃) | Controlled chilling (℃) | TS (GPa | RA (%) | Surface~300 μ m portions | The horse that the Ren Gongquexianshi body thickness causes (μ m) | Broken string index when landing |
Hardness (Hv) | Wafer spacing is from (nm) |
Steel of the present invention | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | 13 13 13 13 13 13 5.5 7 13 13 13 5.5 13 13 13 | 0.95 0.94 0.92 0.93 0.94 0.92 0.94 0.92 0.95 0.94 0.94 0.97 0.97 0.96 0.95 | 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 1100 | 870 870 870 870 870 870 870 870 870 870 870 870 870 870 870 | 850 850 850 850 850 850 850 850 850 850 850 850 850 850 850 | DLP(550) DLP(550) DLP(550) DLP(550) DLP(550) DLP(550) DLP(550) DLP(550) DLP(550) DLP(550) DLP(550) DLP(550) DLP(550) DLP(550) DLP(550) | 1.15 1.20 1.20 1.31 1.19 1.19 1.22 1.20 1.16 1.22 1.22 1.10 1.18 1.21 1.13 | 43 48 44 42 45 43 45 44 43 44 43 42 45 44 42 | 380 370 350 360 370 350 360 365 365 365 340 320 330 340 340 | 95 100 120 110 100 120 110 105 105 120 120 110 120 125 110 | 5 3 2 5 3 2 3 2 3 2 4 2 3 2 3 | 2 1 0 0 1 0 5 2 3 3 0 1 0 3 0 |
Comparative steel | 16 17 | 13 13 | 1.0 1.0 | 1100 1100 | 870 870 | 850 850 | DLP DLP | 1.20 1.22 | 44 43 | 400 400 | 80 80 | 10 11 | 10 12 |
DLP: patenting in the melting salt
DP: air-cooled patenting
Adopt the present invention, can easily obtain the few high-strength wire material of fracture of wire that defective causes.