CN115652205B - Non-quenched and tempered crankshaft steel not easy to crack and surface quality control method - Google Patents
Non-quenched and tempered crankshaft steel not easy to crack and surface quality control method Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 76
- 239000010959 steel Substances 0.000 title claims abstract description 76
- 238000003908 quality control method Methods 0.000 title abstract description 10
- 238000005096 rolling process Methods 0.000 claims abstract description 162
- 238000010438 heat treatment Methods 0.000 claims abstract description 139
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 16
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 8
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 7
- 238000009749 continuous casting Methods 0.000 claims description 73
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 36
- 238000005422 blasting Methods 0.000 claims description 30
- 238000004513 sizing Methods 0.000 claims description 30
- 230000007547 defect Effects 0.000 claims description 25
- 238000001514 detection method Methods 0.000 claims description 18
- 229910052742 iron Inorganic materials 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 13
- 229910052760 oxygen Inorganic materials 0.000 claims description 13
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 12
- 229910001208 Crucible steel Inorganic materials 0.000 claims description 12
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 12
- 238000005266 casting Methods 0.000 claims description 12
- 238000005520 cutting process Methods 0.000 claims description 12
- 239000003546 flue gas Substances 0.000 claims description 12
- 238000007689 inspection Methods 0.000 claims description 12
- 239000006247 magnetic powder Substances 0.000 claims description 12
- 239000002184 metal Substances 0.000 claims description 12
- 229910052751 metal Inorganic materials 0.000 claims description 12
- 239000001301 oxygen Substances 0.000 claims description 12
- 238000010079 rubber tapping Methods 0.000 claims description 12
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 9
- 239000011574 phosphorus Substances 0.000 claims description 9
- 241000007534 Acacia tetragonophylla Species 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 6
- 239000000498 cooling water Substances 0.000 claims description 6
- 230000003647 oxidation Effects 0.000 claims description 6
- 238000007254 oxidation reaction Methods 0.000 claims description 6
- 230000002441 reversible effect Effects 0.000 claims description 6
- 230000011218 segmentation Effects 0.000 claims description 6
- 238000010008 shearing Methods 0.000 claims description 6
- 238000005336 cracking Methods 0.000 claims description 3
- 238000010583 slow cooling Methods 0.000 abstract description 3
- 239000000463 material Substances 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Abstract
The invention discloses non-quenched and tempered crankshaft steel not easy to crack and a surface quality control method, relates to the technical field of special steel processing in the metallurgical industry, and aims to solve the technical problems that the surface of a product is stressed and cracked due to improper control of slow cooling, heating, dephosphorization and rolling processes of a blank in the prior art, and the surface quality of the product is affected. The non-quenched and tempered crankshaft steel comprises the following components in percentage by mass: c:0.42-0.45%, si:0.6-0.7%, mn:1.4-1.5%, P is less than or equal to 0.015%, S:0.02-0.035%, cu less than or equal to 0.2%, ni less than or equal to 0.15%, cr:0.2-0.25%, mo less than or equal to 0.05%, al:0.01-0.03%, N:0.014-0.020%, B less than or equal to 0.0005%, V:0.15-0.17%, ti:0.01-0.02%, 0.ltoreq.18 ppm, the balance being Fe and unavoidable impurities. The non-quenched and tempered crankshaft steel and the surface quality control method can improve the strength and toughness of the non-quenched and tempered steel, improve the fatigue strength of the non-quenched and tempered crankshaft steel, avoid generating stress cracks and ensure the surface quality of products.
Description
Technical Field
The invention belongs to the technical field of special steel processing in the metallurgical industry, and particularly relates to non-quenched and tempered crankshaft steel not easy to crack and a surface quality control method.
Background
The crankshaft works under the combined action of reciprocating and rotating inertia force and moment under the continuously and periodically changed load, and the crankshaft material has higher tensile strength, fatigue strength, higher hardness and wear resistance, so that the crankshaft adopts non-quenched and tempered steel, thereby being beneficial to energy conservation, emission reduction and environmental protection.
N can improve the strength and toughness of non-quenched and tempered steel, N is an element which can form and stabilize austenite, N and Ti, nb, V and other elements have strong affinity, extremely stable interstitial phase can be formed, nitride and carbide can be mutually dissolved to form carbonitride, nitride can be mutually dissolved to form composite nitride, the compounds usually exist in tiny particles to generate dispersion strengthening effect, the strength of steel is improved, alN, tiN, nbN and the like can effectively prevent austenite grains from coarsening, tiny ferrite grains are obtained, the toughness of the steel is improved, si can improve the fatigue strength of the non-quenched and tempered steel, a crankshaft of an automobile can bear long-period load effects of multidirectional alternating compressive stress, tensile stress, bending stress and the like in an engine, therefore, the fatigue life of materials for the crankshaft is required to be higher, the requirements on the fatigue life of materials for the crankshaft are different along with the different requirements of the automobile on the fatigue life of the materials for the crankshaft at present, the requirements on the fatigue life of the materials for the steel to be higher trend, and the addition of Si of 0.5-0.7% of Si is beneficial to improve the fatigue life of the non-tempered steel. However, when the N content is more than or equal to 0.01%, if the control of the slow cooling, heating and rolling processes of the blank is improper, stress cracks are generated on the surface of the product, and when Si is added into the steel for the quenched and tempered crankshaft, the iron scale is difficult to remove due to the improper control of the heating and dephosphorizing processes, and the surface quality of the product is affected.
Therefore, in order to solve the problems of stress cracking and poor surface quality of the non-quenched and tempered crankshaft steel, it is necessary to solve the problems so as to improve the use scene of the non-quenched and tempered crankshaft steel.
Disclosure of Invention
(1) Technical problem to be solved
Aiming at the defects of the prior art, the invention aims to provide non-quenched and tempered crankshaft steel and a surface quality control method which are not easy to generate cracks, and aims to solve the technical problems that the surface quality of a product is affected due to stress cracks generated on the surface of the product caused by improper control of slow cooling, heating, dephosphorization and rolling processes of blanks in the prior art.
(2) Technical proposal
In order to solve the technical problems, the invention provides non-quenched and tempered crankshaft steel which is not easy to crack, and the non-quenched and tempered crankshaft steel comprises the following components in percentage by mass: c:0.42-0.45%, si:0.6-0.7%, mn:1.4-1.5%, P is less than or equal to 0.015%, S:0.02-0.035%, cu less than or equal to 0.2%, ni less than or equal to 0.15%, cr:0.2-0.25%, mo less than or equal to 0.05%, al:0.01-0.03%, N:0.014-0.020%, B less than or equal to 0.0005%, V:0.15-0.17%, ti:0.01-0.02%, 0.ltoreq.18 ppm, the balance Fe and unavoidable impurities, the steps are as follows:
step one: slowly cooling the continuous casting blank: the initial temperature in the pit is more than or equal to 600 ℃, the surface temperature of the casting blank is more than or equal to 650 ℃, the casting blank is capped and naturally cooled, and the time of the continuous casting blank in the pit is more than or equal to 48 hours;
step two: heating: according to the different furnace-entering temperatures of the continuous casting billets, corresponding continuous casting billet furnace temperature control and continuous casting billet time control are carried out: if the furnace temperature of the continuous casting blank is less than 200 ℃, the furnace temperature control parameters of the continuous casting blank are as follows: the first heating section is less than or equal to 870 ℃, the second heating section is 850-1100 ℃, the third heating section is 1050-1250 ℃, the fourth heating section is 1180-1240 ℃, the tapping temperature is 1220+/-10 ℃, and the continuous casting time control parameters are as follows: the first heating section is more than or equal to 95 minutes, the second heating section is more than or equal to 60 minutes, the high temperature section is 145-350 minutes, and the total heating time is more than or equal to 300 minutes; if the furnace temperature of the continuous casting billet is more than or equal to 200 ℃ and less than 400 ℃, the furnace temperature control parameters of the continuous casting billet are as follows: the first heating section is less than or equal to 910 ℃, the second heating section is 850-1130 ℃, the third heating section is 1050-1250 ℃, the fourth heating section is 1180-1240 ℃, and the tapping temperature is: 1220+/-10 ℃, and the control parameters of the continuous casting billet time are as follows: the first heating section is more than or equal to 80 minutes, the second heating section is more than or equal to 50 minutes, the high temperature section is 115-350 minutes, and the total heating time is more than or equal to 245 minutes;
step three: removing phosphorus by using high-pressure water to remove iron scales on the surface of the steel billet;
step four: cogging: rolling the steel sheet in a two-roller reversible rolling mill phi 1100 x 2500 to obtain a rolled blank, wherein the rolling is carried out for 9 passes, and the cooling water flow of a rolling groove is controlled to be 70% of the water flow of a conventional steel grade;
step five: finishing a rolling blank:
a, a No. 1 hydraulic shear head, wherein the length of the shear head is more than or equal to 100mm, and the defect of the end part of a rolling blank is removed;
b, carrying out single-length or multi-length shearing segmentation on the No. 1 hydraulic shear;
c. a hot saw is used for sizing and sectioning, and a metal saw is used for sawing and sectioning after sizing by a sizing machine;
d. hot sawing tail, cutting the tail length to be more than or equal to 100mm, and cutting off the tail defect of the rolled blank;
e. performing shot blasting and intermediate billet magnetic powder inspection, namely performing full-surface shot blasting on a rolled billet in the direction 210 by using a billet shot blasting machine, performing surface magnetic powder inspection on the shot-blasted billet by adopting cast steel with the diameter of phi of 1.2mm, marking the found surface quality defect, and performing point grinding or peeling to remove the surface quality defect;
step six: heating: the 210 side rolling blank is charged into a furnace at normal temperature, and the heating temperature control parameters are as follows: the first heating section is less than or equal to 880 ℃, the second heating section is 600-1100 ℃, the third heating section is 800-1150 ℃, the surface temperature of the outlet section is 1120 ℃, the fourth heating section is 1060-1120 ℃, the outlet temperature is 1100 ℃, and the control parameters of the heating time of the 210-side rolling billet are as follows: the high temperature period is 60-150 minutes, and the total furnace time is more than or equal to 130 minutes;
step seven: high-pressure water descaling: installing a descaling centering device in front of a high-pressure water descaling device, adjusting the opening degree of a guide wheel according to the size of a cross section of 210 square, and removing iron scales on the surface of a steel billet by utilizing high-pressure water;
step eight: rolling:
a. turning over the steel billet by 90 degrees by using a cogging mill pushing bed, and reducing the scale remained on the surface of the steel billet by using vibration;
b. the rolling reduction of the first pass of the cogging mill is 5mm, the rolling reduction of the second pass of the cogging mill is turned over by 90 degrees to remove the residual iron oxide scales on the surface of the billet by small reduction;
c. and (3) middle rolling: the middle rolling 6 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill is composed of phi 750x6 and is a fifth generation short stress rolling mill, a dephosphorization procedure is added in the middle rolling process, a dephosphorization device is arranged at the outlet of the 2V rolling mill, and dephosphorization is carried out in the middle rolling process so as to eliminate oxidized iron scales generated by secondary oxidation;
d. finish rolling: the finish rolling 4 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill group is phi 550x4, and the rolling mills are all fifth-generation short-stress rolling mills;
step nine: finishing:
a. sawing the segments by a metal saw after sizing by a sizing machine;
b. chamfering the end by using an on-line chamfering device;
c. collecting, bundling and entering a product warehouse;
d. straightening by a two-roller straightener;
e. performing full-surface shot blasting by using a shot blasting machine, wherein phi 1mm cast steel is adopted as the shot;
f. surface flaw detection, magnetic leakage standard: 0.3mm deep;
g. full section flaw detection, exceeding the detection standard, namely full section GB/T4162-2008 grade A;
step ten: bundling, marking and warehousing.
Further, the N is preferably 0.015-0.017% by mass.
Further, the Si is preferably 0.64 to 0.7 mass%.
Further, the blank is: 320×425×9000 continuous casting billets.
Further, in the second step, the residual oxygen content of the flue gas is controlled to be 2-4%.
Further, the dephosphorization water pressure in the third step is more than or equal to 21.5MPa.
Further, the reduction of each pass in the fourth step is 30-60mm.
Further, in the step six, residual oxygen in the flue gas is controlled to be 1-3%.
Further, the curvature after straightening in the step nine is less than or equal to 1mm/m.
(3) Advantageous effects
Compared with the prior art, the invention has the beneficial effects that: according to the non-quenched and tempered crankshaft steel and the surface quality control method, the strength and toughness of the non-quenched and tempered steel can be improved through the addition of N, the fatigue strength of the non-quenched and tempered crankshaft steel can be improved through Si, different heating temperatures and different heating times are respectively set according to different continuous casting blank charging temperatures, the heating process is controlled more accurately, oxidized iron scales are effectively removed through multiple dephosphorization operations, the rolling is controlled by a fifth generation short stress rolling mill in a whole line without torsion, micro tension or tension, the possibility of improper control in the rolling process is reduced, stress cracks are not generated on the surface of a product, and the surface quality of the product is ensured.
Detailed Description
The specific embodiment is non-quenched and tempered crankshaft steel not easy to crack, and comprises the following components in percentage by mass: c:0.42-0.45%, si:0.6-0.7%, mn:1.4-1.5%, P is less than or equal to 0.015%, S:0.02-0.035%, cu less than or equal to 0.2%, ni less than or equal to 0.15%, cr:0.2-0.25%, mo less than or equal to 0.05%, al:0.01-0.03%, N:0.014-0.020%, B less than or equal to 0.0005%, V:0.15-0.17%, ti:0.01-0.02%, 0.ltoreq.18 ppm, the balance Fe and unavoidable impurities, the steps are as follows:
step one: slowly cooling the continuous casting blank: the initial temperature in the pit is more than or equal to 600 ℃, the surface temperature of the casting blank is more than or equal to 650 ℃, the casting blank is capped and naturally cooled, and the time of the continuous casting blank in the pit is more than or equal to 48 hours;
step two: heating: according to the different furnace-entering temperatures of the continuous casting billets, corresponding continuous casting billet furnace temperature control and continuous casting billet time control are carried out: if the furnace temperature of the continuous casting blank is less than 200 ℃, the furnace temperature control parameters of the continuous casting blank are as follows: the first heating section is less than or equal to 870 ℃, the second heating section is 850-1100 ℃, the third heating section is 1050-1250 ℃, the fourth heating section is 1180-1240 ℃, the tapping temperature is 1220+/-10 ℃, and the continuous casting time control parameters are as follows: the first heating section is more than or equal to 95 minutes, the second heating section is more than or equal to 60 minutes, the high temperature section is 145-350 minutes, and the total heating time is more than or equal to 300 minutes; if the furnace temperature of the continuous casting billet is more than or equal to 200 ℃ and less than 400 ℃, the furnace temperature control parameters of the continuous casting billet are as follows: the first heating section is less than or equal to 910 ℃, the second heating section is 850-1130 ℃, the third heating section is 1050-1250 ℃, the fourth heating section is 1180-1240 ℃, and the tapping temperature is: 1220+/-10 ℃, and the control parameters of the continuous casting billet time are as follows: the first heating section is more than or equal to 80 minutes, the second heating section is more than or equal to 50 minutes, the high temperature section is 115-350 minutes, and the total heating time is more than or equal to 245 minutes;
step three: removing phosphorus by using high-pressure water to remove iron scales on the surface of the steel billet;
step four: cogging: rolling the steel sheet in a two-roller reversible rolling mill phi 1100 x 2500 to obtain a rolled blank, wherein the rolling is carried out for 9 passes, and the cooling water flow of a rolling groove is controlled to be 70% of the water flow of a conventional steel grade;
step five: finishing a rolling blank:
a, a No. 1 hydraulic shear head, wherein the length of the shear head is more than or equal to 100mm, and the defect of the end part of a rolling blank is removed;
b, carrying out single-length or multi-length shearing segmentation on the No. 1 hydraulic shear;
c. a hot saw is used for sizing and sectioning, and a metal saw is used for sawing and sectioning after sizing by a sizing machine;
d. hot sawing tail, cutting the tail length to be more than or equal to 100mm, and cutting off the tail defect of the rolled blank;
e. performing shot blasting and intermediate billet magnetic powder inspection, namely performing full-surface shot blasting on a rolled billet in the direction 210 by using a billet shot blasting machine, performing surface magnetic powder inspection on the shot-blasted billet by adopting cast steel with the diameter of phi of 1.2mm, marking the found surface quality defect, and performing point grinding or peeling to remove the surface quality defect;
step six: heating: the 210 side rolling blank is charged into a furnace at normal temperature, and the heating temperature control parameters are as follows: the first heating section is less than or equal to 880 ℃, the second heating section is 600-1100 ℃, the third heating section is 800-1150 ℃, the surface temperature of the outlet section is 1120 ℃, the fourth heating section is 1060-1120 ℃, the outlet temperature is 1100 ℃, and the control parameters of the heating time of the 210-side rolling billet are as follows: the high temperature period is 60-150 minutes, and the total furnace time is more than or equal to 130 minutes;
step seven: high-pressure water descaling: installing a descaling centering device in front of a high-pressure water descaling device, adjusting the opening degree of a guide wheel according to the size of a cross section of 210 square, and removing iron scales on the surface of a steel billet by utilizing high-pressure water;
step eight: rolling:
a. turning over the steel billet by 90 degrees by using a cogging mill pushing bed, and reducing the scale remained on the surface of the steel billet by using vibration;
b. the rolling reduction of the first pass of the cogging mill is 5mm, the rolling reduction of the second pass of the cogging mill is turned over by 90 degrees to remove the residual iron oxide scales on the surface of the billet by small reduction;
c. and (3) middle rolling: the middle rolling 6 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill is composed of phi 750x6 and is a fifth generation short stress rolling mill, a dephosphorization procedure is added in the middle rolling process, a dephosphorization device is arranged at the outlet of the 2V rolling mill, and dephosphorization is carried out in the middle rolling process so as to eliminate oxidized iron scales generated by secondary oxidation;
d. finish rolling: the finish rolling 4 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill group is phi 550x4, and the rolling mills are all fifth-generation short-stress rolling mills;
step nine: finishing:
a. sawing the segments by a metal saw after sizing by a sizing machine;
b. chamfering the end by using an on-line chamfering device;
c. collecting, bundling and entering a product warehouse;
d. straightening by a two-roller straightener;
e. performing full-surface shot blasting by using a shot blasting machine, wherein phi 1mm cast steel is adopted as the shot;
f. surface flaw detection, magnetic leakage standard: 0.3mm deep;
g. full section flaw detection, exceeding the detection standard, namely full section GB/T4162-2008 grade A;
step ten: bundling, marking and warehousing.
Further, the N is preferably 0.015-0.017% by mass.
Further, the Si is preferably 0.64 to 0.7 mass%.
Further, the blank is: 320×425×9000 continuous casting billets.
Further, in the second step, the residual oxygen content of the flue gas is controlled to be 2-4%.
Further, the dephosphorization water pressure in the third step is more than or equal to 21.5MPa.
Further, the reduction of each pass in the fourth step is 30-60mm.
Further, in the step six, residual oxygen in the flue gas is controlled to be 1-3%.
Further, the curvature after straightening in the step nine is less than or equal to 1mm/m.
Example 1
The non-quenched and tempered crankshaft steel not easy to crack comprises the following components in percentage by mass: c:0.42%, si:0.64%, mn:1.5%, P:0.014%, S:0.025%, cu: 18%, ni:0.13%, cr:0.2%, mo:0.04%, al:0.01%, N:0.017%, B:0.0004%, V:0.15%, ti:0.01%, 0:16ppm, the balance Fe and unavoidable impurities.
The surface quality control method of the non-quenched and tempered crankshaft steel not prone to crack comprises the following steps of:
step one: slowly cooling the continuous casting blank: the initial temperature in the pit is more than or equal to 600 ℃, the surface temperature of a casting blank is more than or equal to 650 ℃, the casting blank is capped and naturally cooled, the time of the continuous casting blank in the pit is more than or equal to 48 hours, and the blank is: 320×425×9000 continuous casting billets;
step two: heating: according to the different furnace-entering temperatures of the continuous casting billets, corresponding continuous casting billet furnace temperature control and continuous casting billet time control are carried out: if the furnace temperature of the continuous casting blank is less than 200 ℃, the furnace temperature control parameters of the continuous casting blank are as follows: the first heating section is less than or equal to 870 ℃, the second heating section is 950 ℃, the third heating section is 1100 ℃, the fourth heating section is 1200 ℃, the tapping temperature is 1220+/-10 ℃, and the continuous casting time control parameters are as follows: the first heating section is more than or equal to 95 minutes, the second heating section is more than or equal to 60 minutes, the high temperature section is 200 minutes, and the total heating time is more than or equal to 300 minutes; if the furnace temperature of the continuous casting billet is more than or equal to 200 ℃ and less than 400 ℃, the furnace temperature control parameters of the continuous casting billet are as follows: the first heating section is less than or equal to 910 ℃, the second heating section 930 ℃, the third heating section 1150 ℃, the fourth heating section 1210 ℃ and the tapping temperature: 1220+/-10 ℃, and the control parameters of the continuous casting billet time are as follows: the first heating section is more than or equal to 80 minutes, the second heating section is more than or equal to 50 minutes, the high temperature section is more than or equal to 280 minutes, the total heating time is more than or equal to 245 minutes, and the residual oxygen content of the flue gas is controlled to be 2.5 percent;
step three: removing phosphorus by using high-pressure water, wherein the pressure of the phosphorus removing water is more than or equal to 21.5MPa;
step four: cogging: rolling the steel blank by a two-roller reversible rolling mill phi 1100 x 2500 in a rolling direction of 210, rolling 9 passes, wherein the reduction of each pass is 40mm, and controlling the cooling water flow of a rolling groove to be 70% of the water flow of a conventional steel grade to obtain a rolling blank;
step five: finishing a rolling blank:
a, a No. 1 hydraulic shear head, wherein the length of the shear head is more than or equal to 100mm, and the defect of the end part of a rolling blank is removed;
b, carrying out single-length or multi-length shearing segmentation on the No. 1 hydraulic shear;
c. a hot saw is used for sizing and sectioning, and a metal saw is used for sawing and sectioning after sizing by a sizing machine;
d. hot sawing tail, cutting the tail length to be more than or equal to 100mm, and cutting off the tail defect of the rolled blank;
e. performing shot blasting and intermediate billet magnetic powder inspection, namely performing full-surface shot blasting on a rolled billet in the direction 210 by using a billet shot blasting machine, performing surface magnetic powder inspection on the shot-blasted billet by adopting cast steel with the diameter of phi of 1.2mm, marking the found surface quality defect, and performing point grinding or peeling to remove the surface quality defect;
step six: heating: the 210 side rolling blank is charged into a furnace at normal temperature, and the heating temperature control parameters are as follows: the first heating section is equal to or less than 880 ℃, the second heating section is 800 ℃, the third heating section is 950 ℃, the surface temperature of the outlet section is 1120 ℃, the fourth heating section is 1080 ℃, the outlet temperature is 1100 ℃, and the control parameters of the heating time of the 210-side rolling billet are as follows: the high temperature period is 90 minutes, the total furnace time is more than or equal to 130 minutes, and the residual oxygen of the flue gas is controlled at 1.5 percent;
step seven: high-pressure water descaling: installing a descaling centering device in front of a high-pressure water descaling device, adjusting the opening degree of a guide wheel according to the size of a cross section of 210 square, and removing iron scales on the surface of a steel billet by utilizing high-pressure water;
step eight: rolling:
a. turning over the steel billet by 90 degrees by using a cogging mill pushing bed, and reducing the scale remained on the surface of the steel billet by using vibration;
b. the rolling reduction of the first pass of the cogging mill is 5mm, the rolling reduction of the second pass of the cogging mill is turned over by 90 degrees to remove the residual iron oxide scales on the surface of the billet by small reduction;
c. and (3) middle rolling: the middle rolling 6 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill is composed of phi 750x6 and is a fifth generation short stress rolling mill, a dephosphorization procedure is added in the middle rolling process, a dephosphorization device is arranged at the outlet of the 2V rolling mill, and dephosphorization is carried out in the middle rolling process so as to eliminate oxidized iron scales generated by secondary oxidation;
d. finish rolling: the finish rolling 4 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill group is phi 550x4, and the rolling mills are all fifth-generation short-stress rolling mills;
step nine: finishing:
a. sawing the segments by a metal saw after sizing by a sizing machine;
b. chamfering the end by using an on-line chamfering device;
c. collecting, bundling and entering a product warehouse;
d. straightening by a two-roller straightener, wherein the curvature after straightening is less than or equal to 1mm/m;
e. performing full-surface shot blasting by using a shot blasting machine, wherein phi 1mm cast steel is adopted as the shot;
f. surface flaw detection, magnetic leakage standard: 0.3mm deep;
g. full section flaw detection, exceeding the detection standard, namely full section GB/T4162-2008 grade A;
step ten: bundling, marking and warehousing.
Example 2
The non-quenched and tempered crankshaft steel not easy to crack comprises the following components in percentage by mass: c: 0.45%, si:0.65%, mn:1.5%, P:0.013%, S:0.035%, cu:0.17 % Ni:0.12%, cr:0.2%, mo:0.035%, al:0.03%, N:0.016%, B:0.00045%, V:0.16%, ti:0.01%, 0:16ppm, the balance Fe and unavoidable impurities.
The surface quality control method of the non-quenched and tempered crankshaft steel not prone to crack comprises the following steps of:
step one: slowly cooling the continuous casting blank: the initial temperature in the pit is more than or equal to 600 ℃, the surface temperature of a casting blank is more than or equal to 650 ℃, the casting blank is capped and naturally cooled, the time of the continuous casting blank in the pit is more than or equal to 48 hours, and the blank is: 320×425×9000 continuous casting billets;
step two: heating: according to the different furnace-entering temperatures of the continuous casting billets, corresponding continuous casting billet furnace temperature control and continuous casting billet time control are carried out: if the furnace temperature of the continuous casting blank is less than 200 ℃, the furnace temperature control parameters of the continuous casting blank are as follows: the first heating section is less than or equal to 870 ℃, the second heating section is 850 ℃, the third heating section is 1050 ℃, the fourth heating section is 1180 ℃, the tapping temperature is 1220+/-10 ℃, and the continuous casting time control parameters are as follows: the first heating section is more than or equal to 95 minutes, the second heating section is more than or equal to 60 minutes, the high temperature section is 280 minutes, and the total heating time is more than or equal to 300 minutes; if the furnace temperature of the continuous casting billet is more than or equal to 200 ℃ and less than 400 ℃, the furnace temperature control parameters of the continuous casting billet are as follows: the first heating section is less than or equal to 910 ℃, the second heating section 950 ℃, the third heating section 1050 ℃, the fourth heating section 1180 ℃, and the tapping temperature: 1220+/-10 ℃, and the control parameters of the continuous casting billet time are as follows: the first heating section is more than or equal to 80 minutes, the second heating section is more than or equal to 50 minutes, the high temperature section is 150 minutes, the total heating time is more than or equal to 245 minutes, and the residual oxygen content of the flue gas is controlled to be 2 percent;
step three: removing phosphorus by using high-pressure water, wherein the pressure of the phosphorus removing water is more than or equal to 21.5MPa;
step four: cogging: rolling the steel blank by a two-roller reversible rolling mill phi 1100 x 2500 in a rolling direction of 210, rolling 9 passes, wherein the reduction of each pass is 30mm, and controlling the cooling water flow of a rolling groove to be 70% of the water flow of a conventional steel grade to obtain a rolling blank;
step five: finishing a rolling blank:
a, a No. 1 hydraulic shear head, wherein the length of the shear head is more than or equal to 100mm, and the defect of the end part of a rolling blank is removed;
b, carrying out single-length or multi-length shearing segmentation on the No. 1 hydraulic shear;
c. a hot saw is used for sizing and sectioning, and a metal saw is used for sawing and sectioning after sizing by a sizing machine;
d. hot sawing tail, cutting the tail length to be more than or equal to 100mm, and cutting off the tail defect of the rolled blank;
e. performing shot blasting and intermediate billet magnetic powder inspection, namely performing full-surface shot blasting on a rolled billet in the direction 210 by using a billet shot blasting machine, performing surface magnetic powder inspection on the shot-blasted billet by adopting cast steel with the diameter of phi of 1.2mm, marking the found surface quality defect, and performing point grinding or peeling to remove the surface quality defect;
step six: heating: the 210 side rolling blank is charged into a furnace at normal temperature, and the heating temperature control parameters are as follows: the first heating section is equal to or less than 880 ℃, the second heating section is 700 ℃, the third heating section is 850 ℃, the surface temperature of the outlet section is 1120 ℃, the fourth heating section is 1060 ℃, the outlet temperature is 1100 ℃, and the control parameters of the heating time of the 210-side rolling billet are as follows: the high-temperature period is 60 minutes, the total furnace time is more than or equal to 130 minutes, and the residual oxygen of the flue gas is controlled at 1 percent;
step seven: high-pressure water descaling: installing a descaling centering device in front of a high-pressure water descaling device, adjusting the opening degree of a guide wheel according to the size of a cross section of 210 square, and removing iron scales on the surface of a steel billet by utilizing high-pressure water;
step eight: rolling:
a. turning over the steel billet by 90 degrees by using a cogging mill pushing bed, and reducing the scale remained on the surface of the steel billet by using vibration;
b. the rolling reduction of the first pass of the cogging mill is 5mm, the rolling reduction of the second pass of the cogging mill is turned over by 90 degrees to remove the residual iron oxide scales on the surface of the billet by small reduction;
c. and (3) middle rolling: the middle rolling 6 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill is composed of phi 750x6 and is a fifth generation short stress rolling mill, a dephosphorization procedure is added in the middle rolling process, a dephosphorization device is arranged at the outlet of the 2V rolling mill, and dephosphorization is carried out in the middle rolling process so as to eliminate oxidized iron scales generated by secondary oxidation;
d. finish rolling: the finish rolling 4 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill group is phi 550x4, and the rolling mills are all fifth-generation short-stress rolling mills;
step nine: finishing:
a. sawing the segments by a metal saw after sizing by a sizing machine;
b. chamfering the end by using an on-line chamfering device;
c. collecting, bundling and entering a product warehouse;
d. straightening by a two-roller straightener, wherein the curvature after straightening is less than or equal to 1mm/m;
e. performing full-surface shot blasting by using a shot blasting machine, wherein phi 1mm cast steel is adopted as the shot;
f. surface flaw detection, magnetic leakage standard: 0.3mm deep;
g. full section flaw detection, exceeding the detection standard, namely full section GB/T4162-2008 grade A;
step ten: bundling, marking and warehousing.
Example 3
The non-quenched and tempered crankshaft steel not easy to crack comprises the following components in percentage by mass: c: 0.45%, si:0.68%, mn:1.4%, P:0.013%, S:0.035%, cu: 18%, ni:0.13%, cr:0.2%, mo:0.045%, al:0.03%, N:0.017%, B:0.00048%, V:0.17%, ti:0.01%, 0:17ppm, the balance being Fe and unavoidable impurities.
The surface quality control method of the non-quenched and tempered crankshaft steel not prone to crack comprises the following steps of:
step one: slowly cooling the continuous casting blank: the initial temperature in the pit is more than or equal to 600 ℃, the surface temperature of a casting blank is more than or equal to 650 ℃, the casting blank is capped and naturally cooled, the time of the continuous casting blank in the pit is more than or equal to 48 hours, and the blank is: 320×425×9000 continuous casting billets;
step two: heating: according to the different furnace-entering temperatures of the continuous casting billets, corresponding continuous casting billet furnace temperature control and continuous casting billet time control are carried out: if the furnace temperature of the continuous casting blank is less than 200 ℃, the furnace temperature control parameters of the continuous casting blank are as follows: the first heating section is less than or equal to 870 ℃, the second heating section is 950 ℃, the third heating section is 1050 ℃, the fourth heating section is 1220 ℃, the tapping temperature is 1220+/-10 ℃, and the continuous casting time control parameters are as follows: the first heating section is more than or equal to 95 minutes, the second heating section is more than or equal to 60 minutes, the high temperature section is 180 minutes, and the total heating time is more than or equal to 300 minutes; if the furnace temperature of the continuous casting billet is more than or equal to 200 ℃ and less than 400 ℃, the furnace temperature control parameters of the continuous casting billet are as follows: the first heating section is less than or equal to 910 ℃, the second heating section is 85 ℃, the third heating section is 1050 ℃, the fourth heating section is 1180 ℃, and the tapping temperature is: 1220+/-10 ℃, and the control parameters of the continuous casting billet time are as follows: the first heating section is more than or equal to 80 minutes, the second heating section is more than or equal to 50 minutes, the high temperature section is 145 minutes, the total heating time is more than or equal to 245 minutes, and the residual oxygen content of the flue gas is controlled to be 2%;
step three: removing phosphorus by using high-pressure water, wherein the pressure of the phosphorus removing water is more than or equal to 21.5MPa;
step four: cogging: rolling the steel blank by a two-roller reversible rolling mill phi 1100 x 2500 in a rolling direction of 210, rolling 9 passes, wherein the reduction of each pass is 35mm, and controlling the cooling water flow of a rolling groove to be 70% of the water flow of a conventional steel grade to obtain a rolling blank;
step five: finishing a rolling blank:
a, a No. 1 hydraulic shear head, wherein the length of the shear head is more than or equal to 100mm, and the defect of the end part of a rolling blank is removed;
b, carrying out single-length or multi-length shearing segmentation on the No. 1 hydraulic shear;
c. a hot saw is used for sizing and sectioning, and a metal saw is used for sawing and sectioning after sizing by a sizing machine;
d. hot sawing tail, cutting the tail length to be more than or equal to 100mm, and cutting off the tail defect of the rolled blank;
e. performing shot blasting and intermediate billet magnetic powder inspection, namely performing full-surface shot blasting on a rolled billet in the direction 210 by using a billet shot blasting machine, performing surface magnetic powder inspection on the shot-blasted billet by adopting cast steel with the diameter of phi of 1.2mm, marking the found surface quality defect, and performing point grinding or peeling to remove the surface quality defect;
step six: heating: the 210 side rolling blank is charged into a furnace at normal temperature, and the heating temperature control parameters are as follows: the first heating section is not more than 880 ℃, the second heating section is 600 ℃, the third heating section is 800 ℃, the surface temperature of the outlet section is 1120 ℃, the fourth heating section is 1060 ℃, the outlet temperature is 1100 ℃, and the control parameters of the heating time of the 210-side rolling billet are as follows: the high-temperature period is 80 minutes, the total furnace time is more than or equal to 130 minutes, and the residual oxygen of the flue gas is controlled at 1 percent;
step seven: high-pressure water descaling: installing a descaling centering device in front of a high-pressure water descaling device, adjusting the opening degree of a guide wheel according to the size of a cross section of 210 square, and removing iron scales on the surface of a steel billet by utilizing high-pressure water;
step eight: rolling:
a. turning over the steel billet by 90 degrees by using a cogging mill pushing bed, and reducing the scale remained on the surface of the steel billet by using vibration;
b. the rolling reduction of the first pass of the cogging mill is 5mm, the rolling reduction of the second pass of the cogging mill is turned over by 90 degrees to remove the residual iron oxide scales on the surface of the billet by small reduction;
c. and (3) middle rolling: the middle rolling 6 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill is composed of phi 750x6 and is a fifth generation short stress rolling mill, a dephosphorization procedure is added in the middle rolling process, a dephosphorization device is arranged at the outlet of the 2V rolling mill, and dephosphorization is carried out in the middle rolling process so as to eliminate oxidized iron scales generated by secondary oxidation;
d. finish rolling: the finish rolling 4 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill group is phi 550x4, and the rolling mills are all fifth-generation short-stress rolling mills;
step nine: finishing:
a. sawing the segments by a metal saw after sizing by a sizing machine;
b. chamfering the end by using an on-line chamfering device;
c. collecting, bundling and entering a product warehouse;
d. straightening by a two-roller straightener, wherein the curvature after straightening is less than or equal to 1mm/m;
e. performing full-surface shot blasting by using a shot blasting machine, wherein phi 1mm cast steel is adopted as the shot;
f. surface flaw detection, magnetic leakage standard: 0.3mm deep;
g. full section flaw detection, exceeding the detection standard, namely full section GB/T4162-2008 grade A;
step ten: bundling, marking and warehousing.
Table 1 shows the performance details of each example of the non-quenched and tempered crankshaft steel.
Claims (9)
1. The non-quenched and tempered crankshaft steel which is not easy to crack is characterized by comprising the following components in percentage by mass: c:0.42-0.45%, si:0.6-0.7%, mn:1.4-1.5%, P is less than or equal to 0.015%, S:0.02-0.035%, cu less than or equal to 0.2%, ni less than or equal to 0.15%, cr:0.2-0.25%, mo less than or equal to 0.05%, al:0.01-0.03%, N:0.014-0.020%, B less than or equal to 0.0005%, V:0.15-0.17%, ti:0.01-0.02%, O is less than or equal to 18ppm, and the balance is Fe and unavoidable impurities, and the steps are as follows:
step one: slowly cooling the continuous casting blank: the initial temperature in the pit is more than or equal to 600 ℃, the surface temperature of the casting blank is more than or equal to 650 ℃, the casting blank is capped and naturally cooled, and the time of the continuous casting blank in the pit is more than or equal to 48 hours;
step two: heating: according to the different furnace-entering temperatures of the continuous casting billets, corresponding continuous casting billet furnace temperature control and continuous casting billet time control are carried out: if the furnace temperature of the continuous casting blank is less than 200 ℃, the furnace temperature control parameters of the continuous casting blank are as follows: the first heating section is less than or equal to 870 ℃, the second heating section is 850-1100 ℃, the third heating section is 1050-1250 ℃, the fourth heating section is 1180-1240 ℃, the tapping temperature is 1220+/-10 ℃, and the continuous casting time control parameters are as follows: the first heating section is more than or equal to 95 minutes, the second heating section is more than or equal to 60 minutes, the high temperature section is 145-350 minutes, and the total heating time is more than or equal to 300 minutes; if the furnace temperature of the continuous casting billet is more than or equal to 200 ℃ and less than 400 ℃, the furnace temperature control parameters of the continuous casting billet are as follows: the first heating section is less than or equal to 910 ℃, the second heating section is 850-1130 ℃, the third heating section is 1050-1250 ℃, the fourth heating section is 1180-1240 ℃, and the tapping temperature is: 1220+/-10 ℃, and the control parameters of the continuous casting billet time are as follows: the first heating section is more than or equal to 80 minutes, the second heating section is more than or equal to 50 minutes, the high temperature section is 115-350 minutes, and the total heating time is more than or equal to 245 minutes;
step three: removing phosphorus by using high-pressure water to remove iron scales on the surface of the steel billet;
step four: cogging: rolling the steel sheet in a two-roller reversible rolling mill phi 1100 x 2500 to obtain a rolled blank, wherein the rolling is carried out for 9 passes, and the cooling water flow of a rolling groove is controlled to be 70% of the water flow of a conventional steel grade;
step five: finishing a rolling blank:
a, a No. 1 hydraulic shear head, wherein the length of the shear head is more than or equal to 100mm, and the defect of the end part of a rolling blank is removed;
b, carrying out single-length or multi-length shearing segmentation on the No. 1 hydraulic shear;
c. a hot saw is used for sizing and sectioning, and a metal saw is used for sawing and sectioning after sizing by a sizing machine;
d. hot sawing tail, cutting the tail length to be more than or equal to 100mm, and cutting off the tail defect of the rolled blank;
e. performing shot blasting and intermediate billet magnetic powder inspection, namely performing full-surface shot blasting on a rolled billet in the direction 210 by using a billet shot blasting machine, performing surface magnetic powder inspection on the shot-blasted billet by adopting cast steel with the diameter of phi of 1.2mm, marking the found surface quality defect, and performing point grinding or peeling to remove the surface quality defect;
step six: heating: the 210 side rolling blank is charged into a furnace at normal temperature, and the heating temperature control parameters are as follows: the first heating section is less than or equal to 880 ℃, the second heating section is 600-1100 ℃, the third heating section is 800-1150 ℃, the surface temperature of the outlet section is 1120 ℃, the fourth heating section is 1060-1120 ℃, the outlet temperature is 1100 ℃, and the control parameters of the heating time of the 210-side rolling billet are as follows: the high temperature period is 60-150 minutes, and the total furnace time is more than or equal to 130 minutes;
step seven: high-pressure water descaling: installing a descaling centering device in front of a high-pressure water descaling device, adjusting the opening degree of a guide wheel according to the size of a cross section of 210 square, and removing iron scales on the surface of a steel billet by utilizing high-pressure water;
step eight: rolling:
a. turning over the steel billet by 90 degrees by using a cogging mill pushing bed, and reducing the scale remained on the surface of the steel billet by using vibration;
b. the rolling reduction of the first pass of the cogging mill is 5mm, the rolling reduction of the second pass of the cogging mill is turned over by 90 degrees to remove the residual iron oxide scales on the surface of the billet by small reduction;
c. and (3) middle rolling: the middle rolling 6 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill is composed of phi 750x6 and is a fifth generation short stress rolling mill, a dephosphorization procedure is added in the middle rolling process, a dephosphorization device is arranged at the outlet of the 2V rolling mill, and dephosphorization is carried out in the middle rolling process so as to eliminate oxidized iron scales generated by secondary oxidation;
d. finish rolling: the finish rolling 4 continuous rolling mills are all arranged in a horizontal-vertical alternating manner, the rolling mill group is phi 550x4, and the rolling mills are all fifth-generation short-stress rolling mills;
step nine: finishing:
a. sawing the segments by a metal saw after sizing by a sizing machine;
b. chamfering the end by using an on-line chamfering device;
c. collecting, bundling and entering a product warehouse;
d. straightening by a two-roller straightener;
e. performing full-surface shot blasting by using a shot blasting machine, wherein phi 1mm cast steel is adopted as the shot;
f. surface flaw detection, magnetic leakage standard: 0.3mm deep;
g. full section flaw detection, exceeding the detection standard, namely full section GB/T4162-2008 grade A;
step ten: bundling, marking and warehousing.
2. The non-quenched and tempered crankshaft steel not prone to cracking according to claim 1, wherein the preferable mass percentage of N is 0.015 to 0.017%.
3. The non-quenched and tempered steel for a crank shaft, which is less likely to crack as claimed in claim 1, wherein the Si is preferably 0.64 to 0.7 mass%.
4. The method for controlling the surface quality of non-quenched and tempered crankshaft steel which is not easy to crack according to claim 1, wherein the blank is: 320×425×9000 continuous casting billets.
5. The method for controlling the surface quality of non-quenched and tempered crankshaft steel which is not easy to crack according to claim 1, wherein the residual oxygen content of the flue gas is controlled to be 2-4% in the second step.
6. The method for controlling the surface quality of non-quenched and tempered crankshaft steel which is not easy to crack according to claim 1, wherein the dephosphorization water pressure in the third step is more than or equal to 21.5MPa.
7. The method for controlling the surface quality of non-quenched and tempered crankshaft steel which is not easy to crack according to claim 1, wherein the reduction per pass in the fourth step is 30-60mm.
8. The method for controlling the surface quality of non-quenched and tempered crankshaft steel which is not easy to crack according to claim 1, wherein the residual oxygen in the flue gas in the step six is controlled to be 1-3%.
9. The method for controlling the surface quality of non-quenched and tempered crankshaft steel not prone to cracking according to claim 1, wherein the degree of curvature after straightening in the step nine is less than or equal to 1mm/m.
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