Rolling method of steel for low-sulfur engineering machinery breaking hammer

Abstract

The invention discloses a rolling method of steel for a low-sulfur engineering machinery breaking hammer. The steel comprises the following chemical components in percentage by mass: 0.18-0.22% of C, 0.20-0.35% of S i, 0.60-0.75% of Mn, less than or equal to 0.020% of P, 0.015-0.030% of S, less than or equal to 0.020% of A l, 0.83-0.90% of Cr, less than or equal to 0.10% of Mo, less than or equal to 0.15% of Cu, less than or equal to 0.20% of N i, less than or equal to 0.05% of V and less than or equal to 2.0 ppm of [H]. [O] < = 20 ppm; and [N] < = 80 ppm. And the balance is Fe and inevitable impurities. By adopting the components and the production process, the produced steel for the breaking hammer of the engineering machinery can meet the requirements of the current market on product components, performance and specification.

Description

Technical Field

[0001] The invention belongs to the technical field of steel rolling, and in particular relates to a rolling method for low-sulfur steel for a breaker hammer of engineering machinery. Background Art

[0002] A breaker hammer is a tool commonly used in excavation projects to break hard materials such as rock and concrete. It consists of a cylinder body, piston, oil cylinder, cam, and drill bit. The cylinder body is a crucial component in the breaker hammer, responsible for supporting the hammer head, transmitting the striking force, and moving up and down around the piston. The cylinder body is typically made of high-strength alloy steel, offering high resistance to pressure, wear, and corrosion. A cam and camshaft are also located within the cylinder body. The rotation of the cam drives the piston up and down within the cylinder body, generating a tremendous striking force. The cylinder body also has a cooling water pipe, which effectively reduces the cylinder body temperature and extends its service life.

[0003] The high-strength steel industry for construction machinery. In recent years, with the expansion of the domestic construction machinery market and the acceleration of industrial upgrading, this industry has ushered in new development opportunities. China's high-strength steel industry for construction machinery has formed a complete industrial chain encompassing raw material supply, manufacturing, product sales, and after-sales service.

[0004] The development trend of steel for construction machinery is towards high strength and toughness, and the demand for high-end steel will continue to increase. With increasing environmental protection requirements and the emergence of new technologies and processes, the construction machinery steel industry will face more stringent regulatory challenges. Companies need to strengthen technological innovation and environmental protection investment to improve product quality and environmental performance. Summary of the Invention

[0005] The purpose of the present invention is to provide a rolling method for low-sulfur steel for engineering machinery breaker hammers. By adopting this composition and production process, the product composition, performance and specification requirements of engineering machinery breaker hammers that can meet the current market demand can be produced, while solving the processing and cutting problems.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention discloses a rolling method for low-sulfur steel for a breaker hammer of engineering machinery. The chemical composition of the steel is as follows by mass percentage: C 0.18-0.22%, Si 0.20-0.35%, Mn 0.60-0.75%, P ≤ 0.020%, S 0.015-0.030%, Al ≤ 0.020%, Cr 0.83-0.90%, Mo ≤ 0.10%, Cu ≤ 0.15%, Ni ≤ 0.20%, V ≤ 0.05%, [H] ≤ 2.0 ppm; [O] ≤ 20 ppm; [N] ≤ 80 ppm. The remainder is Fe and unavoidable impurities.

[0008] The heating process includes: determining the heating system according to the specifications of the continuous casting billet, the preheating section is ≤850℃, the first heating section is 1100~1180℃, the second heating section is 1150~1260℃, and the soaking section is 1150~1240℃. The heating section adopts slow heating, and overburning or overheating is prohibited. At the same time, the soaking time of the continuous casting billet is guaranteed to be ≥60min to ensure uniform temperature inside and outside the continuous casting billet.

[0009] The rolling process includes: the continuous casting billet adopts the rolling process of Ф850 billet opening machine and Ф700mm×3+Ф550mm×4 continuous rolling mill group, the continuous casting billet starting rolling temperature is controlled at 1050~1150℃, the final rolling temperature is controlled at ≥850℃, the cooling bed adopts a close-packed method, and enters the slow cooling pit for slow cooling to ensure that the hot rolling hardness after slow cooling is ≤250HB.

[0010] Furthermore, its chemical composition by mass percentage is: C 0.19%, Si 0.28%, Mn 0.69%, P 0.017%, S 0.018%, Al 0.011%, Cr 0.86%, Mo 0.01%, Cu 0.02%, Ni 0.02%, V 0.01%, [H] 1.2ppm; [O] 18ppm; [N] 56ppm, and the rest is Fe and unavoidable impurities.

[0011] Furthermore, its chemical composition by mass percentage is: C 0.21%, Si 0.22%, Mn 0.72%, P 0.012%, S 0.025%, Al 0.018%, Cr 0.85%, Mo 0.01%, Cu 0.01%, Ni 0.02%, V 0.01%, [H] 1.7ppm; [O] 18ppm; [N] 79ppm, and the rest is Fe and unavoidable impurities.

[0012] Furthermore, its chemical composition by mass percentage is: C 0.22%, Si 0.22%, Mn 0.63%, P 0.014%, S 0.016%, Al 0.018%, Cr 0.82%, Mo 0.01%, Cu 0.02%, Ni 0.01%, V 0.01%, [H] 1.0 ppm; [O] 12 ppm; [N] 66 ppm, and the rest is Fe and unavoidable impurities.

[0013] Furthermore, the specifications of hot-rolled square steel for engineering machinery breaker hammers are 151×198 and 216×274mm. In order to ensure the compression ratio requirements, the continuous casting billet shapes used are 280*380mm and 320*415mm.

[0014] Furthermore, the lower yield strength of the prepared steel for engineering machinery breaker hammer is greater than its tensile strength.

[0015] Furthermore, the prepared steel for engineering machinery breaker hammer meets the yield strength ratio greater than 1.3.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects:

[0017] By adopting this composition and production process, the steel for engineering machinery breakers can be produced to meet the current market demand for product composition, performance and specifications, while solving the processing and cutting problems. DETAILED DESCRIPTION

[0018] The industrial production process is briefly described as follows:

[0019] Ingot heating - high-pressure water dephosphorization - Ф850 ingot opening machine - Ф700mm×3+Ф550mm×4 continuous rolling mill - sawing (sampling) - slow cooling in cooling pit

[0020] More than 50 furnaces have been produced industrially, and the specific process parameters are controlled as follows:

[0021] 1) Heating furnace heating process

[0022] The continuous casting billet is determined according to different specifications based on the thermodynamic formula to determine the reasonable heating time and heating speed.

[0023] Table 1 Heating temperature and soaking time

[0024]

[0025] 2) Rolling process

[0026] To ensure product quality and smooth rolling, uniform rolling is adopted and temperature increase is strictly prohibited. Specific parameters are shown in Table 2.

[0027] Table 2 Starting rolling temperature, finishing rolling temperature and temperature in the slow cooling pit

[0028]

[0029] 3) Surface quality

[0030] The hot-rolled square steel is slowly cooled for more than 48 hours. No surface cracks or other defects are found on the surface of the hot-rolled square steel, which fully meets the requirements of the production technology agreement. The rolled hardness is between 213-246HB.

[0031] 4) Performance test

[0032] According to GB / T 2975, longitudinal φ25mm blank specimens were taken and heat treated with 880℃ oil quenching + 200℃ tempering water quenching. The properties were tested as follows:

[0033] Table 3 Mechanical properties

[0034]

[0035] The chemical composition of 1# is as follows by mass percentage: C 0.19%, Si 0.28%, Mn 0.69%, P 0.017%, S 0.018%, Al 0.011%, Cr 0.86%, Mo 0.01%, Cu 0.02%, Ni 0.02%, V 0.01%, [H] 1.2ppm; [O] 18ppm; [N] 56ppm, and the rest is Fe and unavoidable impurities.

[0036] The chemical composition of 2# is as follows by mass percentage: C 0.21%, Si 0.22%, Mn 0.72%, P 0.012%, S 0.025%, Al 0.018%, Cr 0.85%, Mo 0.01%, Cu 0.01%, Ni 0.02%, V 0.01%, [H] 1.7ppm; [O] 18ppm; [N] 79ppm, and the rest is Fe and unavoidable impurities.

[0037] The chemical composition of 3# is as follows by mass percentage: C 0.22%, Si 0.22%, Mn 0.63%, P 0.014%, S 0.016%, Al 0.018%, Cr 0.82%, Mo 0.01%, Cu 0.02%, Ni 0.01%, V 0.01%, [H] 1.0ppm; [O] 12ppm; [N] 66ppm, and the rest is Fe and unavoidable impurities.

[0038] Compared with the inventor's other patent "202210124988.7", the steel type of the present invention has different component systems and uses, and both belong to alloy C steel.

[0039] Table 4 Impact test results (heat treatment) Unit: J

[0040]

[0041] Table 5 Brinell hardness test results (heat treatment) Unit: HB

[0042]

[0043] Table 6 Non-metallic inclusions

[0044] Category A Category B Category C Class D 1# 1.5 1.0 0.5 1.0 2# 1.5 1.0 1.0 1.0 3# 2.0 0.5 0.5 1.0

[0045] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A rolling method for low-sulfur steel for engineering machinery breaker hammer, characterized by: Its chemical composition by mass percentage is: C 0.18-0.22%, Si 0.20-0.35%, Mn0.60-0.75%, P≤0.020%, S 0.015-0.030%, Al≤0.020%, Cr0.83-0.90%, Mo≤0.10%, Cu≤0.15%, Ni≤0.20%, V≤0.05%, [H]≤2.0ppm; [O]≤20ppm; [N]≤80ppm. Others are Fe and unavoidable impurities; The heating process includes: determining the heating system according to the specifications of the continuous casting billet, the preheating section is ≤850℃, the first heating section is 1100~1180℃, the second heating section is 1150~1260℃, and the soaking section is 1150~1240℃. The heating section adopts slow heating, and overburning or overheating is prohibited. At the same time, the soaking time of the continuous casting billet is guaranteed to be ≥60min to ensure uniform temperature inside and outside the continuous casting billet. The rolling process includes: the continuous casting billet adopts the rolling process of Ф850 billet opening machine and Ф700mm×3+Ф550mm×4 continuous rolling mill group, the continuous casting billet starting rolling temperature is controlled at 1050~1150℃, the final rolling temperature is controlled at ≥850℃, the cooling bed adopts a close-packed method, and enters the slow cooling pit for slow cooling to ensure that the hot rolling hardness after slow cooling is ≤250HB.

2. The rolling method of low-sulfur steel for engineering machinery breaker hammer according to claim 1, characterized in that: Its chemical composition by mass percentage is: C 0.19%, Si 0.28%, Mn 0.69%, P 0.017%, S 0.018%, Al 0.011%, Cr 0.86%, Mo 0.01%, Cu 0.02%, Ni 0.02%, V 0.01%, [H] 1.2ppm; [O] 18ppm; [N] 56ppm, and the rest is Fe and unavoidable impurities.

3. The rolling method of low-sulfur steel for engineering machinery breaker hammer according to claim 1, characterized in that: Its chemical composition by mass percentage is: C 0.21%, Si 0.22%, Mn 0.72%, P 0.012%, S 0.025%, Al 0.018%, Cr 0.85%, Mo 0.01%, Cu 0.01%, Ni 0.02%, V 0.01%, [H] 1.7ppm; [O] 18ppm; [N] 79ppm, and the rest is Fe and unavoidable impurities.

4. The rolling method of low-sulfur steel for engineering machinery breaker hammer according to claim 1, characterized in that: Its chemical composition by mass percentage is: C 0.22%, Si 0.22%, Mn 0.63%, P 0.014%, S 0.016%, Al 0.018%, Cr 0.82%, Mo 0.01%, Cu 0.02%, Ni 0.01%, V 0.01%, [H] 1.0ppm; [O] 12ppm; [N] 66ppm, and the rest is Fe and unavoidable impurities.

5. The rolling method of low-sulfur steel for engineering machinery breaker hammer according to claim 1, characterized in that: The specifications of hot-rolled square steel for engineering machinery breakers are 151×198 and 216×274mm. In order to ensure the compression ratio requirements, the continuous casting billet shapes used are 280*380mm and 320*415mm.

6. The rolling method of low-sulfur steel for engineering machinery breaker hammer according to claim 1, characterized in that: The lower yield strength of the prepared steel for engineering machinery breaker hammer is greater than its tensile strength.

7. The rolling method of low-sulfur steel for engineering machinery breaker hammer according to claim 1, characterized in that: The prepared steel for engineering machinery breaker hammer meets the requirement of a yield strength ratio greater than 1.3.

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