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CN-122012886-A - Q690D steel for low-cost coal mine machinery and production method thereof

CN122012886ACN 122012886 ACN122012886 ACN 122012886ACN-122012886-A

Abstract

The invention relates to Q690D steel for low-cost coal mine machinery and a production method thereof, wherein the production method comprises the following steps: primary refining, LF refining, VD treatment, continuous casting, casting blank stacking, cleaning, heating control rolling, online quenching, stacking slow cooling and tempering. Wherein the Q690D steel comprises the following chemical components in percentage by mass ,C：0.16%～0.18%、Si：0.2%～0.4%、Mn：1.45%～1.55%、P：≤0.015%、S：≤0.02%、Cr：0.25%～0.3%、Nb：0.2%～0.3%、Ti：0.01%～0.018%、Al：0.02%～0.043%,B：0.001%～0.0018%, and the balance of Fe and unavoidable impurities. The design of the production method of the invention prevents the addition of noble metals Mo and Ni while guaranteeing the toughness of steel, reduces the cost, reduces the overall heating time on the basis of the traditional online quenching and tempering smelting steel plate, and realizes the efficient and stable production of Q690D steel on the premise that the mechanical property and the low-temperature impact toughness meet the requirements.

Inventors

  • ZOU XINGLU
  • LEI JUNHAO

Assignees

  • 江苏沙钢钢铁有限公司
  • 江苏沙钢集团有限公司
  • 江苏省沙钢钢铁研究院有限公司

Dates

Publication Date
20260512
Application Date
20251223

Claims (10)

  1. 1. A production method of Q690D steel for low-cost coal mine machinery is characterized by comprising the following steps: Primary smelting, namely smelting molten iron to primarily remove impurities to form molten steel; LF refining comprises tundish baking treatment, refining ladle deoxidizing treatment and fine-tuning alloy treatment; VD treatment, including Ca treatment before vacuum and boron treatment at vacuum; Continuous casting, wherein the superheat degree of continuous casting is controlled to be 15-30 ℃, and electromagnetic stirring is adopted for continuous casting blanks of 300mm and 330mm, and molten steel after VD treatment is cast into casting blanks; Casting blank stacking, wherein the stacking time of continuous casting blanks is more than or equal to 48 hours; cleaning to treat surface defects of the casting blank; heating and controlling rolling to improve the structural property of steel; On-line quenching, controlling the water inlet temperature to be more than or equal to 810 ℃ and the reddening temperature to be less than 200 ℃ so as to improve the hardness and strength of the steel; stacking and slow cooling, wherein the stacking time is controlled to be more than or equal to 24 hours so as to eliminate quenching stress; Tempering, wherein the tempering temperature is controlled to be 530-550 ℃, and the tempering time is controlled to be 28.8-72 min/mm, so that the toughness of the steel is adjusted, the internal structure is ensured to be fully transformed, and the Q690D steel plate is obtained.
  2. 2. A method for producing Q690D steel for low-cost coal machinery according to claim 1, wherein the tundish baking treatment is protected by introducing argon gas treatment to control the N content.
  3. 3. The method for producing the Q690D steel for the low-cost coal mine machinery, according to claim 1, wherein in the LF refining, the refining white slag time is controlled to be more than or equal to 25min, and the total refining time is controlled to be more than or equal to 45min.
  4. 4. The method for producing the Q690D steel for the low-cost coal mine machinery according to claim 1, wherein the Al content is controlled to be more than or equal to 0.025% 10min before the LF refining is finished, and Ti iron is added.
  5. 5. The method for producing Q690D steel for low-cost coal mine machinery according to claim 1, wherein argon is kept in a state of being introduced during the fine adjustment alloy treatment, and the Al content is controlled to be 0.12% by adding Al wires.
  6. 6. The method for producing Q690D steel for low-cost coal mine machinery according to claim 1, wherein the boron treatment is performed in vacuum by adding B iron, and the time of adding B iron and the continuity of vacuum pumping are controlled.
  7. 7. The method for producing the Q690D steel for the low-cost coal mine machinery, which is disclosed in claim 1, wherein the vacuum degree is controlled to be less than or equal to 66pa, the continuous casting heat time is controlled to be more than or equal to 15min, and the soft blowing time after vacuum is controlled to be more than or equal to 8min.
  8. 8. The method for producing the Q690D steel for the low-cost coal mine machinery, which is disclosed in claim 1, is characterized in that when the heating control rolling is performed, the highest heating temperature of a billet is controlled to be less than or equal to 1260 ℃, the heating time is 9-10 min/cm, the heat preservation temperature is 1220-1240 ℃, and the heat preservation time of a soaking section is controlled to be more than or equal to 40min.
  9. 9. The production method of the Q690D steel for the low-cost coal mine machinery, which is characterized by adopting two-stage controlled rolling when the heating control rolling is performed, wherein the initial rolling temperature of the first stage is controlled to 1050-1150 ℃, the three-pass reduction is controlled to be more than or equal to 30mm, the steel plate airing thickness is controlled to be 1.5-2.0 times of the steel plate thickness, the initial rolling temperature of the second stage is controlled to 880-900 ℃, and the final rolling temperature is controlled to be 840-850 ℃.
  10. The Q690D steel is prepared by the production method of the Q690D steel for low-cost coal mine machinery according to any one of claims 1-9, and is characterized by comprising the following chemical components in percentage by mass ,C：0.16%～0.18%、Si：0.2%～0.4%、Mn：1.45%～1.55%、P：≤0.015%、S：≤0.02%、Cr：0.25%～0.3%、Nb：0.2%～0.3%、Ti：0.01%～0.018%、Al:0.02%～0.043%,B：0.001%～0.0018%, and the balance of Fe and unavoidable impurities.

Description

Q690D steel for low-cost coal mine machinery and production method thereof Technical Field The invention relates to the technical field of steel material production, in particular to Q690D steel for low-cost coal mine machinery and a production method thereof. Background With the continuous development of the coal machine industry, the field of steel materials is continuously advancing the technical development towards the direction of low cost and light weight. At present, the plate consumption material mainly used in the domestic coal machine industry is Q690D steel, and the steel has two main production process routes, namely, tempering after online quenching and tempering after offline quenching, namely, offline tempering. The offline quenching process has the problems of long production period, high cost and the like, so that a plurality of advanced steel enterprises in China are actively working on developing online quenching and tempering processes. Under the process route, the conventional component system is designed to generally adopt low carbon content and add alloy elements such as Mo, ni and the like with higher price, but the production cost is increased, and the competitive power of the product on the market is weakened, so that a production process is required to be provided, and the addition amount of noble alloy elements such as Mo, ni and the like is reduced on the premise of ensuring the toughness of the Q690D steel, so that the stable production of the Q690D steel under the condition of low cost is realized. Disclosure of Invention In view of the foregoing shortcomings of the prior art, it is an object of the present invention to provide a low cost Q690D steel for coal mine machinery and a method of producing the same, which solve one or more of the problems of the prior art. In order to achieve the above purpose, the technical scheme of the invention is as follows: A method for producing Q690D steel for low-cost coal mine machinery, which comprises the following steps: Primary smelting, namely smelting molten iron to primarily remove impurities to form molten steel; LF refining comprises tundish baking treatment, refining ladle deoxidizing treatment and fine-tuning alloy treatment; VD treatment, including Ca treatment before vacuum and boron treatment at vacuum; Continuous casting, wherein the superheat degree of continuous casting is controlled to be 15-30 ℃, and electromagnetic stirring is adopted for continuous casting blanks of 300mm and 330mm, and molten steel after VD treatment is cast into casting blanks; Casting blank stacking, wherein the stacking time of continuous casting blanks is more than or equal to 48 hours; cleaning to treat surface defects of the casting blank; heating and controlling rolling to improve the structural property of steel; On-line quenching, controlling the water inlet temperature to be more than or equal to 810 ℃ and the reddening temperature to be less than 200 ℃ so as to improve the hardness and strength of the steel; stacking and slow cooling, wherein the stacking time is controlled to be more than or equal to 24 hours so as to eliminate quenching stress; Tempering, wherein the tempering temperature is controlled to be 530-550 ℃, and the tempering time is controlled to be 28.8-72 min/mm, so that the toughness of the steel is adjusted, the internal structure is ensured to be fully transformed, and the Q690D steel plate is obtained. Further, the tundish baking treatment is protected by introducing argon gas to control the N content. Further, in the LF refining, the refining white slag time is controlled to be more than or equal to 25min, and the total refining time is controlled to be more than or equal to 45min. Further, the Al content is controlled to be more than or equal to 0.025% 10min before the LF refining is finished, and Ti iron is added. Further, during the fine adjustment alloy treatment, argon is kept in a state of being introduced, and the Al content is controlled to be 0.12% by adding an Al wire. Further, the boron treatment is carried out in vacuum, B iron is added, and the adding time of the B iron and the continuity of vacuum pumping are controlled. Further, during VD treatment, the vacuum degree is controlled to be less than or equal to 66pa, the continuous casting heat time is controlled to be more than or equal to 15min, and the soft blowing time after vacuum is controlled to be more than or equal to 8min. Further, during heating control rolling, the highest heating temperature of the billet is controlled to be less than or equal to 1260 ℃, the heating time is 9-10 min/cm, the heat preservation temperature is 1220-1240 ℃, and the heat preservation time of the soaking section is controlled to be more than or equal to 40min. Further, during heating control rolling, two-stage control rolling is adopted, the initial rolling temperature in the first stage is controlled to 1050-1150 ℃, the three-pass reduction is controlled to be more tha