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CN-121992297-A - Steel for hot-rolled ultrahigh-strength welded pipe for automobile and production method thereof

CN121992297ACN 121992297 ACN121992297 ACN 121992297ACN-121992297-A

Abstract

The invention provides steel for a hot-rolled ultrahigh-strength welded pipe for an automobile and a production method thereof, wherein the steel comprises the main chemical components in percentage by weight of ：C：0.04~0.08%,Si：0.2~0.35%,Mn：1.2~2.0%,Ti：0.07~0.12%,Cr：0.2~0.8%,Nb：0.01~0.05%：S≤0.006%,N≤0.008%,P≤0.020%,, C+Nb+Ti is more than or equal to 0.16 and less than or equal to 0.24,1.6, cr+Mn is more than or equal to 2.5, and the balance of Fe and unavoidable impurities. The production method comprises the steps of heating, namely, heating at 1230-1300 ℃ for 140-200 min, rough rolling, namely, rough rolling a casting blank to an intermediate blank, wherein the rough rolling outlet temperature is 1030-1080 ℃, finish rolling, namely, the finish rolling temperature is 840-880 ℃, and coiling, namely, the coiling temperature is 500-580 ℃. Wherein the heating temperature is 1230-1270 ℃ and the heating time is 150-180 min. The invention can solve the problem of large transverse and longitudinal strength fluctuation of the existing steel for the hot-rolled ultrahigh-strength welded pipe for the automobile.

Inventors

  • CAI ZHEN
  • LIU YONGQIAN
  • JIANG NAN
  • HU JUN
  • SUN YIQIANG
  • LIU CHANGMING
  • LIU YANG

Assignees

  • 武汉钢铁有限公司

Dates

Publication Date
20260508
Application Date
20260123

Claims (10)

  1. 1. A steel for a hot-rolled ultrahigh-strength welded pipe for an automobile is characterized by comprising the main chemical components in percentage by weight of ：C：0.04~0.08%,Si：0.2~0.35%,Mn：1.2~2.0%,Ti：0.07~0.12%,Cr：0.2~0.8%,Nb：0.01~0.05%：S≤0.006%,N≤0.008%,P≤0.020%,, C+Nb+Ti not less than 0.16 and not more than 0.24,1.6, cr+Mn not more than 2.5, and the balance of Fe and unavoidable impurities.
  2. 2. The steel for hot rolled ultrahigh-strength welded pipe for automobile as claimed in claim 1, wherein the weight percentage of C is 0.06-0.08%.
  3. 3. The steel for automotive ultrahigh-strength welded pipe according to claim 1, wherein the weight percentage of Mn is 1.6 to 2.0%.
  4. 4. The steel for a hot rolled ultrahigh-strength welded pipe for automobiles according to claim 1, wherein the weight percentage of Ti is 0.07 to 0.10%.
  5. 5. The steel for automotive ultrahigh-strength welded pipe according to claim 1, wherein the weight percentage of Cr is 0.5 to 0.8%.
  6. 6. The steel for a hot rolled ultrahigh-strength welded pipe for automobiles according to claim 1, wherein the weight percentage of Nb is 0.01 to 0.03%.
  7. 7. A method for producing a steel for a hot rolled ultra high strength welded pipe for automobiles according to any one of claims 1 to 6, comprising: Heating, namely heating at 1230-1300 ℃ for 140-200 min; Rough rolling, namely rough rolling a casting blank to an intermediate blank, wherein the outlet temperature of rough rolling is 1030-1080 ℃; finish rolling, namely, finish rolling, wherein the finish rolling temperature is 840-880 ℃; and coiling, wherein the coiling temperature is 500-580 ℃.
  8. 8. The method for producing a steel for a hot rolled ultra-high strength welded pipe for automobiles according to claim 7, wherein the heating temperature is 1230 to 1270 ℃ and the heating time is 150 to 180 minutes.
  9. 9. The method for producing a steel for automotive ultrahigh-strength welded pipes as claimed in claim 7, wherein the finish rolling temperature is 840 to 860 ℃.
  10. 10. The method for producing a steel for a hot-rolled ultrahigh-strength welded pipe for automobiles according to claim 7, wherein the coiling temperature is 500 to 540 ℃.

Description

Steel for hot-rolled ultrahigh-strength welded pipe for automobile and production method thereof Technical Field The invention relates to the technical field of hot-rolled ultrahigh-strength welded pipe steel, in particular to hot-rolled ultrahigh-strength welded pipe steel for an automobile and a production method thereof. Background In the current automobile industry, energy conservation, emission reduction and safety performance improvement become two major core development trends. With the enhancement of global environmental awareness and the increasing severity of automobile exhaust emission standards in various countries, the reduction of automobile energy consumption is an urgent task facing automobile manufacturers. Related researches show that the fuel oil can be saved by about 6-8% when the automobile quality is reduced by 10%. Under the background, the steel for the automobile needs to have the advantages of high strength, high toughness and light weight at the same time so as to meet the dual requirements of weight reduction and safety improvement of the automobile. The high-strength steel plate is the most economical and effective solution which can simultaneously realize weight reduction and safety by virtue of the advantages of high weight reduction potential, high fatigue strength and the like. In automotive construction, hot rolled ultrahigh strength welded pipe steels are widely used for critical components such as driveshaft tubes, frames, and the like. Taking a transmission shaft tube as an example, the transmission shaft tube is taken as an important part for transmitting power in an automobile transmission system, and has extremely strict requirements on material performance. On the one hand, the inner surface of the transmission shaft tube is contacted with lubricating oil, the outer surface is contacted with environmental factors such as external atmosphere, water, fog and the like, and the running environment of the automobile is complex and changeable, and different terrains and temperature conditions form challenges to the performance of the transmission shaft tube, so that the transmission shaft tube is required to have good weldability, corrosion resistance and impact resistance. On the other hand, in the trend of pursuing the weight reduction of automobiles under the premise of safety, materials used for the weight reduction can be reduced by adopting ultra-high strength steel, so that the weight reduction of parts is promoted, for example, the wall thickness of a transmission shaft tube is thinned, and the weight reduction aim of the transmission shaft tube of the automobiles is realized. However, the current steel for hot-rolled ultrahigh-strength welded pipes for automobiles still faces a plurality of difficulties in practical application and production processes. In terms of material performance, the industry standard of the electric welding steel pipe for the domestic transmission shaft is up to 550 (the yield strength is more than or equal to 550 MPa), and some enterprises develop the ultra-high strength hot rolled steel strip (the tensile strength is more than or equal to 750 MPa) for the automobile transmission shaft, but the high-strength hot rolled steel strip adopts high-content Nb and Mn components and is added with rare earth and other elements, so that the cost is high, and the production process and control are extremely complex. Foreign countries such as the united states, germany, japan and the like develop researches on the forming technology and welding technology of high-strength automobile transmission shaft tubes with yield strength below 700MPa, and the development of materials with higher strength levels is insufficient. In addition, under the prior art, in the cooling process of the alloyed ultra-high strength steel after hot rolling coiling and coiling, due to different cooling paths, the phenomena of uneven structure and precipitation exist in the longitudinal direction and the transverse direction of a hot rolled steel coil, and further the quality problems of poor coiling, cracking and the like easily occur in the processing process due to the fact that the hot rolled raw material has 100-400MPa in the longitudinal direction and 60-200MPa in the transverse direction. Disclosure of Invention The invention aims to provide hot-rolled ultrahigh-strength welding tube steel for an automobile and a production method thereof, which aim to solve the problem of large transverse and longitudinal strength fluctuation of the existing hot-rolled ultrahigh-strength welding tube steel for the automobile. In order to solve the technical problems, the invention provides hot-rolled ultrahigh-strength welding pipe steel for automobiles, which comprises the main chemical components in percentage by weight of ：C：0.04~0.08%,Si：0.2~0.35%,Mn：1.2~2.0%,Ti：0.07~0.12%,Cr：0.2~0.8%,Nb：0.01~0.05%：S≤0.006%,N≤0.008%,P≤0.020%,, C+Nb+Ti not less than 0.16 and not more than 0.24,1.6 an