CN113046535A - Method for controlling rolling hardness of medium-bar gear round steel - Google Patents
Method for controlling rolling hardness of medium-bar gear round steel Download PDFInfo
- Publication number
- CN113046535A CN113046535A CN202110283652.0A CN202110283652A CN113046535A CN 113046535 A CN113046535 A CN 113046535A CN 202110283652 A CN202110283652 A CN 202110283652A CN 113046535 A CN113046535 A CN 113046535A
- Authority
- CN
- China
- Prior art keywords
- rolling
- temperature
- medium
- round steel
- hardness
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
Abstract
The invention provides a rolling hardness control method for medium-bar gear round steel, and belongs to the field of ferrous metallurgy processing. The control method comprises the steps of preheating, two-section heating, soaking and multi-pass rolling after soaking, wherein the initial rolling temperature T1 is about 980-1000 ℃, the final rolling temperature T2 is that the final rolling temperature is controlled at 750-790 ℃, and the final rolling is carried out and then air-cooled to room temperature to form a delivery state, wherein the temperature is not less than 1.16 ℃/s (T1-T2)/T1 is not more than 1.92 ℃/s; 29.58 ℃/h is less than or equal to (T2-T0)/T2 is less than or equal to 35.91 ℃/h; wherein T0 is the ambient temperature at room temperature during rolling, and T1 is the time consumed during rolling; t2 is the time consumed by cooling to the ambient temperature after finish rolling, and the hardness of the round steel of the medium-bar gear in the delivery state is in the range of 170-195 HBW.
Description
Technical Field
The invention relates to a rolling hardness control method for medium-bar gear round steel, belonging to the field of ferrous metallurgy processing.
Background
Gear or shaft machining raw materials generally adopt round gear steel as raw materials to form gear or shaft blanks, and then various finished products are manufactured through a mechanical machining means. At present, the round steel with the diameter less than or equal to 80mm is generally cut and blanked. Shearing unloading requires that round steel hot rolling attitude hardness is moderate, if round steel hardness is high, except causing the unloading machines loss to increase, still can cause the unloading piece fracture, cave in to finally influence forging size and surface quality, if round steel hardness is low, cause gear round steel to appear gluing the sword phenomenon in the course of working, cause the processing difficulty. Most gear or shaft processing plants want the hardness of the steel gear products with the specification of the middle rod phi of 20-80 mm to be controlled within the range of 170-195 HBW.
Generally, gear round steel is used as a gear or shaft processing raw material, when the gear round steel is delivered to downstream enterprises from a steel mill, in order to meet the processing requirements of the downstream enterprises, the rolled gear round steel needs to be subjected to heat treatment delivery, but the steel subjected to heat treatment delivery needs to be added with procedures such as straightening and finishing, so that the production cost is increased and the delivery date is prolonged.
Disclosure of Invention
The invention aims to provide a production process of gear round steel with proper processing performance, and particularly relates to a rolling-state hardness control method of medium-bar gear round steel.
A rolling-state hardness control method for a medium-bar gear round steel comprises the following components in percentage by mass: c: 0.19 to 0.21%, Si: 0.22 to 0.27%, Mn: 1.14-1.17%, P is less than or equal to 0.020%, S: not more than 0.015 percent, not more than 1.13 to 1.18 percent of Cr, not more than 0.05 percent of Cu, Al: 0.010-0.025%, Ti: 0.042-0.050%, B is less than or equal to 0.0003%, O is less than or equal to 10ppm, and N: 30-60 ppm, H is less than or equal to 2ppm, and the balance is Fe and inevitable impurities, the control method comprises preheating, two-stage heating, soaking and multi-pass rolling after soaking, wherein the initial rolling temperature T1 of the multi-pass rolling is about 980-1000 ℃, the final rolling temperature T2 is the final rolling temperature which is controlled at 750-790 ℃, and the final rolling is air-cooled to room temperature and then is in a delivery state, wherein:
1.16℃/s≤(T1-T2)/t1≤1.92℃/s；
29.58℃/h≤(T2-T0)/t2≤35.91℃/h；
wherein T0 is the ambient temperature at room temperature during rolling, and T1 is the time consumed during rolling; t2 is the time consumed by cooling to the ambient temperature after finish rolling, and the hardness of the round steel of the middle-rod gear in the delivery state is within the range of 170-195 HBW; the process does not include a carburizing step, and the process does not include heat treatment, polishing, chamfering and straightening steps in a delivery state after air cooling to room temperature.
Further, the preheating temperature of the soaking section is 550-650 ℃; the temperature of the first stage heating of the two-stage heating is 1070 to 1100 ℃; the temperature of the second section heating is 1120-1150 ℃; the temperature of the soaking section is 1135-1145 ℃; wherein the total heating time consisting of preheating, two-stage heating and soaking is 4.5 h-5.5 h, and the soaking time is 90-140 min.
Further, the rolling temperature T1 is T0+ 940-T0 +980 ℃; the finishing temperature T2 is T0+ 710-T0 +760 ℃.
Further, the microstructure of the round steel in a rolled state is ferrite and pearlite.
Furthermore, the rolled microstructure of the round steel is a ferrite structure with the volume ratio of 60-72%, and the balance is a pearlite structure.
Further, the diameter of the central rod is between 20mm and 80mm, and preferably, the diameter of the central rod is between 40mm and 80 mm.
Further, the temperature T0 is between 0 ℃ and 40 ℃.
Further, the time t1 is between 120 and 180 s.
Further, the time t2 is between 22 and 24 hours.
Further, the application protects a round steel rolling state medium-rod gear round steel, which is obtained by adopting the control method of the rolling state hardness of the medium-rod gear round steel.
According to the rolling state hardness control method for the medium-bar gear round steel, provided by the invention, the special component characteristics of the gear round steel are combined, the round steel with moderate hardness is obtained through reasonable process control, the requirements of downstream customers on processing can be well met, air cooling is carried out after the process is finally rolled, a slow cooling pit is not needed, annealing of the round steel is also not needed after the round steel is cooled to room temperature, the round steel is bent and deformed due to general round steel annealing, finishing procedures such as polishing, chamfering, straightening and the like are also additionally added, the cost of the round steel is increased, and the delivery period of the steel is prolonged.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a microstructure diagram of a medium bar rolled state obtained after rolling according to the process of example 1;
FIG. 2 is a microstructure view of a medium bar rolled state obtained after rolling according to the process of example 2;
FIG. 3 is a microstructure view of a medium bar rolled state obtained after rolling according to the process of example 3;
FIG. 4 is a microstructure view of a medium bar rolled state obtained after rolling according to the process of example 4;
FIG. 5 is a view showing a microstructure of a medium bar rolled state obtained after rolling according to the process of comparative example 1;
fig. 6 is a microstructure view of a medium bar rolled state obtained after rolling according to the process of comparative example 2.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The first purpose of the invention is that the method for producing the medium-bar gear round steel with proper hardness by air cooling after rolling is adopted, the medium-bar gear round steel with proper hardness can be obtained only by slow cooling or heat treatment after rolling, and the annealed round steel can meet the requirements of downstream customers by additionally adding finishing processes such as chamfering, straightening and the like.
The second purpose of the invention is to roll the gear round steel with the middle rod with the diameter of 20-80 mm, when the general rod is rolled and formed, the finishing temperature needs to be reduced as much as possible, so that the sizes of the microscopic grains of the rod after finishing rolling are proper, and the microstructure presents ferrite and pearlite structures, so that the rod with proper hardness can be produced, therefore, the water cooling is needed to reduce the finishing rolling temperature before finishing rolling, the temperature difference between the surface of the rod and the core part in the cooling process is large due to the fact that the size of the middle rod with the diameter of more than 20mm, particularly, the size of the middle rod with the diameter of 40-80 mm is large, and the bending deformation is generated, namely, the middle rod with the diameter of 40-80 mm can not pass water, and the water passing operation is difficult if the size is large. The invention can realize that the medium-bar gear round steel with proper hardness can be obtained by direct finish rolling on the premise of not penetrating water.
The control method comprises preheating, two-stage heating, soaking and multi-pass rolling after soaking, wherein the initial rolling temperature T1 is about 980-1000 ℃, the final rolling temperature T2 is that the final rolling temperature is controlled at 750-790 ℃, and the final rolling is in a delivery state after air cooling to room temperature, wherein:
1.16℃/s≤(T1-T2)/t1≤1.92℃/s；
29.58℃/h≤(T2-T0)/t2≤35.91℃/h；
through the practice of the inventor, the ideal medium bar material with good rolling hardness cannot be stably obtained by simply controlling the initial rolling temperature and the final rolling temperature. Especially in summer, because the room temperature is higher and sometimes reaches 40 ℃, if the rolling is carried out according to the designed initial rolling temperature and final rolling temperature in winter, the hardness of the produced medium bar is unstable, some batches are higher, and some batches are lower; similarly, when the initial rolling temperature and the final rolling temperature meeting the requirements are designed in summer, the hardness of the produced medium bar is unstable, and some batches are higher and some batches are lower during rolling in winter. The inventor finds that rolling can not be carried out according to the start rolling temperature and the finish rolling temperature which are unified in one year, the inventor properly increases the start rolling temperature and the finish rolling temperature when the room temperature is higher, and properly reduces the start rolling temperature and the finish rolling temperature when the room temperature is lower, then the inventor finds that the medium bar with stable and satisfactory rolling hardness is obtained, and finds that the room temperature condition during combined production is that not only the start rolling temperature T1 is strictly controlled to be within the range of 980-1000 ℃, the finish rolling temperature T2 is the finish rolling temperature controlled to be within the range of 750-790 ℃, and the split rolling temperature and the finish rolling temperature are controlled to be within the range of (T1-T2)/T1 to be less than or equal to 1.92 ℃/s according to 1.16 ℃/s; 29.58 ℃/h is less than or equal to (T2-T0)/T2 is less than or equal to 35.91 ℃/h; in the temperature range, when the room temperature is higher, the initial rolling temperature and the final rolling temperature are relatively higher. When strict process control is carried out according to the requirements, the rolling hardness can be controlled within the range of 170-195 HBW, and the range can well meet the requirements of downstream customers. Because the hardness range is moderate, the machined tool is not damaged; if the hardness is higher than the upper limit value of the hardness, the loss of a blanking machine is increased and even a blanking piece is cracked and cracked due to the overhigh hardness of the bar; if the hardness is lower than the lower limit value of the hardness, the hardness of the bar is lower, so that the cutter is stuck in the working process of the blanking machine.
The invention not only controls the rolling temperature and the finishing temperature, but also strictly controls (T1-T2)/T1 and (T2-T0)/T2. Wherein, the control of the rolling temperature and the finishing temperature is mainly considered by controlling the forming capability of crystal grains and the processing capability of equipment through thermodynamics. The initial rolling temperature T1 is in the range of 980-1000 ℃, preferably in the range of 985-998 ℃, more preferably in the range of 990 ℃ and 996 ℃. When the initial rolling temperature is higher than 1000 ℃, the initial rolling temperature is too high, so that the micro crystal grains in the medium bar rolling state are too coarse, and when the initial rolling temperature is lower than 980 ℃, the initial rolling temperature is relatively low, so that the rolling deformation is difficult, and the micro crystal grains in the medium bar rolling state are not uniform. The finishing temperature T2 is 750-790 ℃, preferably 760-780 ℃, more preferably 765-780 ℃, and most preferably 770 ℃ and 781 ℃. When the finish rolling temperature is higher than 790 ℃, the final rolling temperature is too high, so that the rolling microscopic grains of the medium bar are too coarse, and when the final rolling temperature is lower than 750 ℃, the subsequent air cooling time is relatively shortened due to the relatively low final rolling temperature, for the round steel with a relatively large medium bar size, the core cooling and the edge cooling cannot achieve uniform and consistent microscopic structures, so that the hardness of the medium bar gear round steel cannot be within the range of 170-195 HBW, and even the medium bar is bent due to internal stress.
Combining the effects of rolling deformation and post-rolling cooling power on grain formation, the invention creatively controls (T1-T2)/T1 and (T2-T0)/T2 strictly, mainly controls the microstructure inside the grains through kinetics and thermodynamics, controls (T1-T2)/T1 within the range of 1.16 ℃/s ≦ T1-T2)/T1 ≦ 1.92 ℃/s, preferably, 1.38 ℃/s ≦ T1-T2)/T1 ≦ 1.75 ℃/s, optimally, 1.48 ℃/s ≦ T1-T1)/T1 ≦ 1.55 ℃/s, and (T1-T1)/T1 within the range of 1 ℃/h ≦ T1/T1 ≦ 35.91 ℃/h, preferably, 30.20 ℃/h)/T1 ≦ T1 ℃/h, optimally 32.60 ℃/h is less than or equal to (T2-T0)/T2 is less than or equal to 35.90 ℃/h. By strictly controlling (T1-T2)/T1 and (T2-T0)/T2, a desired distribution of ferrite and pearlite structures can be obtained, and when (T1-T2)/T1 and (T2-T0)/T2 are higher, the formed pearlite is higher, which results in a higher hardness in the medium bar rolled state, while when (T1-T2)/T1 and (T2-T0)/T2 are lower, the formed pearlite ratio is relatively lower, which results in a lower hardness in the medium bar rolled state.
Further, the temperature of the preheating section of the soaking section is 550-650 ℃; the temperature of the first stage heating of the two-stage heating is 1070 to 1100 ℃; the temperature of the second section heating is 1120-1150 ℃; the temperature of the soaking section is 1135-1145 ℃; wherein the total heating time is 4.5-5.5 h, and the soaking time is 90-140 min.
Further, the rolling temperature is T0+ 940-T0 +980 ℃, preferably, the rolling temperature is T0+ 960-T0 +980 ℃; the finishing temperature is T0+ 710-T0 +760 ℃, preferably T0+ 745-T0 +760 ℃, and preferably T0+750 ℃. Experiments show that the initial rolling temperature and the final rolling temperature are dynamically adjusted by combining the actual room temperature environment during local rolling process operation, and the rolling hardness of the round steel of the medium-bar gear is ensured to meet the performance requirements of downstream manufacturers on the round steel of the medium-bar gear by controlling the (T1-T2)/T1 and the (T2-T0)/T2.
Further, the microstructure of the round steel in a rolled state is ferrite and pearlite.
Furthermore, the rolled microstructure of the round steel is a ferrite structure with the volume ratio of 60-72%, and the balance is a pearlite structure.
Further, the diameter of the middle rod is between 20mm and 80mm, preferably the diameter of the middle rod is between 40mm and 70mm, preferably the diameter of the middle rod is between 55mm and 65mm, and most preferably the diameter of the middle rod is 60 mm.
Further, the temperature T0 is between 0 ℃ and 40 ℃.
Further, the time t1 is between 120 and 180 s.
Further, the time t2 is between 22 and 24 hours.
In conclusion, according to the rolling-state hardness control method for the medium-bar gear round steel, provided by the invention, the round steel with moderate hardness is obtained by combining the specific component characteristics of the gear round steel and reasonable process control, the requirements of downstream customers on processing can be well met, air cooling is carried out after the process is finished, a slow cooling pit is not needed, annealing on the round steel is not needed after the round steel is cooled to room temperature, the round steel is not required to be annealed, the round steel is bent and deformed due to general round steel annealing, finishing procedures such as grinding chamfering and straightening are also required to be additionally added, the cost of the round steel is increased, and the delivery period of the steel is prolonged.
Example 1: a rolling-state hardness control method for a medium-bar gear round steel comprises the following components in percentage by mass: c: 0.20%, Si: 0.24%, Mn: 1.15%, P: 0.007%, S: 0.005%, Cr: 1.15%, Cu: 0.02%, Al: 0.021%, Ti: 0.045%, B: 0.0001%, O: 4.3ppm, N: 41.4ppm, 0.6ppm H, and the balance Fe and inevitable impurities.
Smelting according to the components, continuously casting a square billet with the billet shape of 200 multiplied by 200mm, and then rolling, wherein the rolling control method comprises preheating, two-section heating, a soaking section and multi-pass rolling after soaking, and the temperature of the preheating section is 591 ℃; heating to a first temperature of 1080 ℃; the temperature of the second heating section is 1145 ℃; the temperature of the soaking section is 1143 ℃, the soaking time is 119min, and the total heating time is 4.86 h. The initial rolling temperature T1 is 996 ℃, the final rolling temperature T2 is the final rolling temperature which is 787 ℃, and the finish rolling is carried out, air-cooled to room temperature and then in a delivery state, wherein:
(T1-T2)/T1 is 1.161 ℃/s;
(T2-T0)/T2 is 33.733 ℃/h;
wherein T0 is 28 ℃, T1 is 180 s; t2 is 22.5h, the hardness of the round steel of the medium-rod gear in the delivery state is 192HBW (measured according to Brinell hardness test standard shown in national standard GB/T231.1-2018 of the people's republic of China, the same below), and the size of the medium rod is 20 mm; the process does not include a carburizing step, and the process does not include heat treatment, polishing, chamfering and straightening steps after air cooling to room temperature and in a delivery state. The microstructure was found to be a fine ferrite plus pearlite structure, as shown in fig. 1, wherein the proportion of the ferrite structure was 65.31% and the proportion of the pearlite structure was 34.69%.
Example 2: mainly the same as the embodiment 1, except that the medium-bar gear round steel comprises the following components in percentage by mass: c: 0.21%, Si: 0.24%, Mn: 1.16%, P: 0.009%, S: 0.006%, Cr: 1.14%, Cu: 0.02%, Al: 0.020%, Ti: 0.046%, B: 0.0001%, O: 6.1ppm, N: 46.0ppm, H:0.8ppm, the balance being Fe and inevitable impurities.
The rolling control method comprises preheating, two-section heating, soaking and multi-pass rolling after soaking, wherein the temperature of the preheating section is 583 ℃; heating to a first temperature of 1091 ℃; the temperature of the second heating section is 1136 ℃; the temperature of the soaking section is 1141 ℃, the soaking time is 125min, and the total heating time is 4.82 h. The initial rolling temperature T1 is 998 ℃, the final rolling temperature T2 is the final rolling temperature which is 789 ℃, and the finish rolling is carried out, air-cooled to room temperature and then in a delivery state, wherein:
(T1-T2)/T1 is 1.393 ℃/s;
(T2-T0)/T2 is 32.826 ℃/h;
wherein T0 is 34 ℃, and T1 is 150 s; t2 is 23h, the hardness of the round steel of the gear with the middle rod in the delivery state is 188HBW, and the size of the middle rod is 45 mm; the process does not include a carburizing step, and the process does not include heat treatment, polishing, chamfering and straightening steps after air cooling to room temperature and in a delivery state. The microstructure obtained is ferrite plus pearlite, as shown in fig. 2, wherein the proportion of ferrite is 67.86%, and the proportion of pearlite is 32.14%.
Example 3: mainly the same as the embodiment 1, except that the medium-bar gear round steel comprises the following components in percentage by mass: c: 0.20%, Si: 0.23%, Mn: 1.16%, P: 0.010%, S: 0.009%, Cr: 1.14%, Cu: 0.01%, Al: 0.021%, Ti: 0.046%, B: 0.0001%, O: 5.6ppm, N: 50.8ppm, 0.8ppm H, and the balance Fe and inevitable impurities.
The rolling control method comprises preheating, two-section heating, soaking and multi-pass rolling after soaking, wherein the temperature of the preheating section is 596 ℃; heating to a temperature of 1088 ℃; the temperature of the heating second section is 1129 ℃; the temperature of the soaking section is 1142 ℃, the soaking time is 128min, and the total heating time is 4.78 h. The initial rolling temperature T1 is 984 ℃, the final rolling temperature T2 is the final rolling temperature which is controlled at 756 ℃, and the rolled steel is in a delivery state after being air-cooled to room temperature after being finally rolled, wherein:
(T1-T2)/T1 is 1.628 ℃/s;
(T2-T0)/T2 is 32.938 ℃/h;
wherein T0 is 5 ℃, and T1 is 140 s; t2 is 22.8h, the hardness of the round steel of the middle-rod gear in the delivery state is 186HBW, and the size of the middle rod is 60 mm; the process does not include a carburizing step, and the process does not include heat treatment, polishing, chamfering and straightening steps after air cooling to room temperature and in a delivery state. The microstructure of ferrite plus pearlite was obtained, as shown in fig. 3, in which the proportion of ferrite structure was 68.45% and the proportion of pearlite structure was 31.55%.
Example 4: mainly the same as the embodiment 1, except that the medium-bar gear round steel comprises the following components in percentage by mass: c: 0.20%, Si: 0.25%, Mn: 1.17%, P: 0.008%, S: 0.007%, Cr 1.12%, Cu 0.02%, Al: 0.022%, Ti: 0.045%, B: 0.0001%, O:5.9ppm, N: 40.3ppm, 1.0ppm H, and the balance Fe and inevitable impurities.
The rolling control method comprises preheating, two-section heating, soaking and multi-pass rolling after soaking, wherein the temperature of the preheating section is 587 ℃; heating to a temperature of 1085 ℃; the temperature of the second heating section is 1133 ℃; the temperature of the soaking section is 1139 ℃, the soaking time is 121min, and the total heating time is 5.01 h. . The initial rolling temperature T1 is 982 ℃, the final rolling temperature T2 is the final rolling temperature which is controlled at 753 ℃, and the steel is in a delivery state after air cooling to room temperature after final rolling, wherein:
(T1-T2)/T1 is 1.908 ℃/s;
(T2-T0)/T2 at 31.250 ℃/h;
wherein T0 is 3 ℃, and T1 is 120 s; t2 is 24h, the hardness of the round steel of the gear with the middle rod in the delivery state is 179HBW, and the size of the middle rod is 80 mm; the process does not include a carburizing step, and the process does not include heat treatment, polishing, chamfering and straightening steps after air cooling to room temperature and in a delivery state. The microstructure obtained was ferrite plus pearlite, as shown in fig. 4, wherein the proportion of ferrite was 71.20% and the proportion of pearlite was 28.80%.
Comparative example 1: a rolling-state hardness control method for a medium-bar gear round steel comprises the following components in percentage by mass: c: 0.19%, Si: 0.25%, Mn: 1.08%, P: 0.011%, S: 0.008%, Cr 1.17%, Cu 0.02%, Al: 0.019%, Ti: 0.044%, B: 0.0001%, O:8.7ppm, N: 75.5ppm, 0.7ppm of H and the balance of Fe and inevitable impurities, wherein the control method comprises preheating, two-stage heating, soaking and multi-pass rolling after soaking, and the temperature of the preheating stage is 512 ℃; heating to a first temperature of 998 ℃; the temperature of the second section is 1192 ℃; the temperature of the soaking section is 1223 ℃, the soaking time is 85min, and the total heating time is 3.92 h. The initial rolling temperature T1 is 1098 ℃, the final rolling temperature T2 is the final rolling temperature which is controlled at 913 ℃, the finish rolling is carried out, the air cooling is carried out after the finish rolling is carried out, and the finish rolling is in a delivery state after the air cooling is carried out to the room temperature, wherein:
(T1-T2)/T1 is 1.03 ℃/s;
(T2-T0)/T2 is 37.96 ℃/s;
wherein T0 is 21 ℃, and T1 is 180 s; t2 is 23.5h, the hardness of the round steel of the gear with the middle rod in the delivery state is 264HBW, and the size of the middle rod is 20 mm; the process does not include a carburizing step, and the process does not include heat treatment, polishing, chamfering and straightening steps after air cooling to room temperature and in a delivery state. The microstructure obtained is ferrite + bainite + pearlite (a small amount), and is shown in figure 5, wherein the proportion of ferrite structure is 6.33%, the proportion of bainite structure is 90.11%, and the proportion of pearlite structure is 3.56%.
Comparative example 2: a rolling-state hardness control method for a medium-bar gear round steel comprises the following components in percentage by mass: c: 0.21%, Si: 0.25%, Mn: 1.06%, P: 0.011%, S: 0.008%, Cr 1.09%, Cu 0.01%, Al: 0.022%, Ti: 0.045%, B: 0.0001%, O:4.0ppm, N: 68.4ppm, 1.0ppm of H and the balance of Fe and inevitable impurities, wherein the control method comprises preheating, two-stage heating, soaking and multi-pass rolling after soaking, and the temperature of the preheating stage is 529 ℃; heating to a temperature of 973 ℃; the temperature of the second stage of heating is 1216 ℃; the temperature of the soaking section is 1214 ℃, the soaking time is 84min, and the total heating time is 3.83 h. . The initial rolling temperature T1 is 1106 ℃, the final rolling temperature T2 is the final rolling temperature which is controlled at 923 ℃, and the product is in a delivery state after air cooling to room temperature after final rolling, wherein:
(T1-T2)/T1 is 0.90 ℃/s;
(T2-T0)/T2 is 36.44 ℃/h;
wherein T0 is 30 ℃, and T1 is 120 s; t2 is 24.5h, the hardness of the round steel of the gear with the middle rod in the delivery state is 247HBW, and the size of the middle rod is 75 mm; the process does not include a carburizing step, and the process does not include heat treatment, polishing, chamfering and straightening steps after air cooling to room temperature and in a delivery state. The microstructure obtained is ferrite + bainite + pearlite (a small amount), and is shown in figure 6, wherein the proportion of ferrite structure is 11.67%, the proportion of bainite structure is 76.48%, and the proportion of pearlite structure is 11.85%.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A control method for rolling hardness of medium-bar gear round steel is characterized by comprising the following steps: the medium-bar gear round steel comprises the following components in percentage by mass: c: 0.19 to 0.21%, Si: 0.22 to 0.27%, Mn: 1.14-1.17%, P is less than or equal to 0.020%, S: not more than 0.015 percent, not more than 1.13 to 1.18 percent of Cr, not more than 0.05 percent of Cu, Al: 0.010-0.025%, Ti: 0.042-0.050%, B is less than or equal to 0.0003%, O is less than or equal to 10ppm, and N: 30-60 ppm, less than or equal to 2ppm of H, and the balance of Fe and inevitable impurities; the control method comprises preheating, two-section heating and soaking, wherein multi-pass rolling is carried out after soaking, the initial rolling temperature T1 of the multi-pass rolling is about 980-1000 ℃, the final rolling temperature T2 is that the final rolling temperature is controlled at 750-790 ℃, and the final rolling is carried out after air cooling to room temperature and then is in a delivery state, wherein:
1.16℃/s≤(T1-T2)/t1≤1.92℃/s；
29.58℃/h≤(T2-T0)/t2≤35.91℃/h；
wherein T0 is the ambient temperature at room temperature during rolling, and T1 is the time consumed during rolling; t2 is the time consumed by cooling to the ambient temperature after finish rolling, and the hardness of the round steel of the middle-rod gear in the delivery state is within the range of 170-195 HBW; the process does not include a carburizing step, and the process does not include heat treatment, polishing, chamfering and straightening steps in a delivery state after air cooling to room temperature.
2. The method for controlling the rolling hardness of the round steel bar of the medium-bar gear according to claim 1, wherein the preheating temperature is 550-650 ℃; the temperature of the first stage heating of the two-stage heating is 1070 to 1100 ℃; the temperature of the second section heating is 1120-1150 ℃; the temperature of the soaking section is 1135-1145 ℃; wherein the total heating time consisting of preheating, two-stage heating and soaking is 4.5-5.5 h, and the soaking time is 90-140 min.
3. The method for controlling the rolling hardness of the round steel bar of the medium-speed gear according to claim 1, wherein the rolling temperature T1 is T0+ 940-T0 +980 ℃; the finishing temperature T2 is T0+ 710-T0 +760 ℃.
4. The method for controlling the rolled hardness of the round bar of the medium bar gear according to claim 1, wherein the rolled microstructure of the round bar is ferrite and pearlite.
5. The method for controlling the rolled hardness of the round bar of the medium-bar gear according to claim 1, wherein the rolled microstructure of the round bar is 60-72% by volume of ferrite structure, and the balance is pearlite structure.
6. The method for controlling the rolling hardness of the medium-bar gear round steel according to claim 1, wherein the diameter of the medium bar is between 20mm and 80 mm.
7. The method for controlling the rolling hardness of the medium-bar gear round steel according to claim 1, wherein the diameter of the medium bar is between 40mm and 80 mm.
8. The method for controlling the rolling hardness of the medium-bar gear round steel according to claim 1, wherein the temperature T0 is between 0 and 40 ℃.
9. The method for controlling the rolling hardness of the medium-bar gear round steel according to claim 1, wherein the time t1 is 120-180 s; the time t2 is between 22 and 24 hours.
10. A round steel rolling-state medium-rod gear round steel obtained by the method for controlling the rolling-state hardness of the medium-rod gear round steel according to claims 1-9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110283652.0A CN113046535B (en) | 2021-03-16 | 2021-03-16 | Method for controlling rolling hardness of medium-bar gear round steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110283652.0A CN113046535B (en) | 2021-03-16 | 2021-03-16 | Method for controlling rolling hardness of medium-bar gear round steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113046535A true CN113046535A (en) | 2021-06-29 |
| CN113046535B CN113046535B (en) | 2022-11-08 |
Family
ID=76512928
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110283652.0A Active CN113046535B (en) | 2021-03-16 | 2021-03-16 | Method for controlling rolling hardness of medium-bar gear round steel |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113046535B (en) |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004091916A (en) * | 2002-07-10 | 2004-03-25 | Sumitomo Metal Ind Ltd | Wear-resisting steel |
| CN103192012A (en) * | 2013-04-25 | 2013-07-10 | 内蒙古包钢钢联股份有限公司 | Rolling production process of 20CrMnTi gear steel |
| DE102012109692A1 (en) * | 2012-10-11 | 2014-04-17 | Benteler Defense Gmbh & Co. Kg | Use of steel alloy containing carbon, silicon, manganese, phosphor, sulfur, aluminum, chromium, copper, titanium, boron, niobium, nitrogen, cobalt and iron for preparation of tank component e.g. side wall and roof for vehicles |
| US20140261909A1 (en) * | 2013-03-14 | 2014-09-18 | Super Alloy Industrial Co., Ltd. | High-strength aluminum-magnesium silicon alloy and manufacturing process thereof |
| CN106435133A (en) * | 2016-10-26 | 2017-02-22 | 承德建龙特殊钢有限公司 | Method for reducing Brinell hardness of CrMo serial hot-rolled rod |
| DE102017208251A1 (en) * | 2017-05-16 | 2018-11-22 | Thyssenkrupp Ag | Safety steel or wear-resistant steel and use |
| CN108906884A (en) * | 2018-06-22 | 2018-11-30 | 大冶特殊钢股份有限公司 | A kind of zerolling production method of high-performance 20CrMnTi pinion steel |
| JP2019127630A (en) * | 2018-01-25 | 2019-08-01 | Ｊｆｅスチール株式会社 | Clad steel plate and method for producing the same |
| CN111534669A (en) * | 2020-06-16 | 2020-08-14 | 宝钢特钢韶关有限公司 | Method for machining gear part from round gear steel and gear part |
-
2021
- 2021-03-16 CN CN202110283652.0A patent/CN113046535B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004091916A (en) * | 2002-07-10 | 2004-03-25 | Sumitomo Metal Ind Ltd | Wear-resisting steel |
| DE102012109692A1 (en) * | 2012-10-11 | 2014-04-17 | Benteler Defense Gmbh & Co. Kg | Use of steel alloy containing carbon, silicon, manganese, phosphor, sulfur, aluminum, chromium, copper, titanium, boron, niobium, nitrogen, cobalt and iron for preparation of tank component e.g. side wall and roof for vehicles |
| US20140261909A1 (en) * | 2013-03-14 | 2014-09-18 | Super Alloy Industrial Co., Ltd. | High-strength aluminum-magnesium silicon alloy and manufacturing process thereof |
| CN103192012A (en) * | 2013-04-25 | 2013-07-10 | 内蒙古包钢钢联股份有限公司 | Rolling production process of 20CrMnTi gear steel |
| CN106435133A (en) * | 2016-10-26 | 2017-02-22 | 承德建龙特殊钢有限公司 | Method for reducing Brinell hardness of CrMo serial hot-rolled rod |
| DE102017208251A1 (en) * | 2017-05-16 | 2018-11-22 | Thyssenkrupp Ag | Safety steel or wear-resistant steel and use |
| JP2019127630A (en) * | 2018-01-25 | 2019-08-01 | Ｊｆｅスチール株式会社 | Clad steel plate and method for producing the same |
| CN108906884A (en) * | 2018-06-22 | 2018-11-30 | 大冶特殊钢股份有限公司 | A kind of zerolling production method of high-performance 20CrMnTi pinion steel |
| CN111534669A (en) * | 2020-06-16 | 2020-08-14 | 宝钢特钢韶关有限公司 | Method for machining gear part from round gear steel and gear part |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113046535B (en) | 2022-11-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106319378A (en) | Steel for large-diameter thin saw blade substrate and manufacturing method thereof | |
| KR20090125134A (en) | Case-hardened steel pipe excellent in workability and process for production thereof | |
| CN113245365B (en) | Rolling production method for improving toughness of steel on line | |
| CN114134399B (en) | Energy-saving steel wire rod with high bainite content for high alloy tool and manufacturing method thereof | |
| EP2334456B1 (en) | Free-machining powder metallurgy lead-free steel articles and method of making same | |
| KR101977499B1 (en) | Wire rod without spheroidizing heat treatment, and method for manufacturing thereof | |
| JP3474545B2 (en) | Machine parts | |
| CN113046535B (en) | Method for controlling rolling hardness of medium-bar gear round steel | |
| CN111676422A (en) | Cold-rolled high-carbon steel strip for V-saw blade matrix and production method thereof | |
| KR101819431B1 (en) | High-carbon steel wire rod for cold forging, processed good using the same, and methods for manufacturing thereof | |
| JPS6159379B2 (en) | ||
| JP2014070229A (en) | Manufacturing method of band steel for blade | |
| JPH059588A (en) | Production of high carbon steel sheet excellent in formability | |
| JPH09324212A (en) | Production of hot rolled high carbon steel strip excellent in hardenability and cold workability | |
| JP2003073737A (en) | Method for manufacturing coil spring with high tensile strength and yield strength | |
| JP2781296B2 (en) | Manufacturing method of forged steel roll for cold rolling | |
| JPH0213004B2 (en) | ||
| KR20160066570A (en) | Method for manufacturing middle carbon alloy steels wire for cold forging capable of eliminating softening annealing treatment | |
| CN111876664B (en) | Manufacturing method of 50CrVA hot-rolled wide spring steel plate | |
| CN113490756B (en) | Steel sheet, member, and method for producing same | |
| JPH1060540A (en) | Production of high carbon cold rolled steel strip | |
| TWI815504B (en) | Cold-rolled steel plate, steel parts, manufacturing method of cold-rolled steel plate, and manufacturing method of steel parts | |
| JPS6259167B2 (en) | ||
| KR20170110773A (en) | High-carbon steel wire rod for cold forging, processed good using the same, and methods for manufacturing thereof | |
| CN117463770A (en) | 20CrMnTi steel and rolling method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |