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CN-121976030-A - Seamless steel tube for hollow anchor rod and strength regulating and controlling method thereof

CN121976030ACN 121976030 ACN121976030 ACN 121976030ACN-121976030-A

Abstract

The application provides a seamless steel pipe for a hollow anchor rod and a strength regulation method thereof, wherein an alloy steel round steel is heated and then thermally perforated to prepare a hollow pipe blank, the hollow pipe blank is subjected to spheroidizing annealing treatment and then cooled to obtain a first treated steel pipe, wherein the ferrite grain size of the first treated steel pipe is calculated to be D 1 according to a spheroidizing annealing grain size model, the first treated steel pipe is subjected to cold finish rolling forming and cleaning to obtain a second treated steel pipe, the effective ferrite grain size of the second treated steel pipe is calculated to be D def according to a cold deformation grain refinement model, the second treated steel pipe is subjected to recrystallization annealing to obtain a seamless steel pipe, the ferrite grain size of the seamless steel pipe is calculated to be D 2 according to a recrystallization grain evolution model, and the yield strength of the seamless steel pipe is calculated to be R p0.2 according to a strength model.

Inventors

  • JIANG PENGFEI
  • Wang Jiakuo
  • WANG ZIYUE
  • LUO CHAO
  • GUO JICHANG
  • LIU YIJIE
  • REN WANG
  • WANG LIQUAN

Assignees

  • 中煤科工(天津)岩层智控科技有限公司

Dates

Publication Date
20260505
Application Date
20260403

Claims (10)

  1. 1. The method for regulating and controlling the strength of the seamless steel tube for the hollow anchor rod is characterized by comprising the following steps of: Heating the alloy steel round steel and then performing hot piercing to prepare a hollow tube blank; Performing spheroidizing annealing treatment on the hollow tube blank, and cooling to obtain a first treated steel tube, wherein the ferrite grain size of the first treated steel tube is calculated to be D 1 according to a spheroidizing annealing grain size model; Wherein the spheroidizing annealed grain size model is D 1 =11.5+k 1 ×(T 1 -810); d 1 is the ferrite grain size of the first treated steel pipe, μm, T 1 is spheroidizing annealing temperature, DEG C, k 1 is spheroidizing annealing temperature coefficient, μm/DEGC, and the value is 0.25; The first treated steel pipe is subjected to cold finish rolling forming and cleaning to obtain a second treated steel pipe, and the effective ferrite grain size of the second treated steel pipe is calculated to be D def according to a cold deformation grain refinement model; D def =D 1 /1.918, wherein D def is the effective ferrite grain size of the second treated steel pipe, mum, D 1 is the ferrite grain size of the first treated steel pipe, mum, and the cold finish rolling true strain parameter is 1.03; Performing recrystallization annealing on the second treated steel tube to obtain a seamless steel tube, and straightening and sizing the seamless steel tube, wherein the ferrite grain size of the seamless steel tube is calculated to be D 2 according to a recrystallization grain evolution model, and the yield strength of the seamless steel tube is calculated to be R p0.2 according to a strength model; D 2 =D def × (1+γ), wherein D def is the ferrite effective grain size of the second treated steel pipe, μm, D 2 is the ferrite grain size of the seamless steel pipe, μm, γ is the ferrite grain size change rate due to the recrystallization annealing of the second treated steel pipe; R p0.2 =σ 0 +k y ·D 2 -1/2 , wherein D 2 is ferrite grain size of the seamless steel pipe, mu m, k y is Hall-Peltier coefficient, MPa & mu m 1/2 takes 900-1000, sigma 0 is lattice friction stress, MPa and sigma 0 takes 225-255, and R p0.2 is yield strength of the seamless steel pipe, MPa.
  2. 2. The method of claim 1, wherein the round steel alloy is a round steel 40Cr alloy.
  3. 3. The method according to claim 1, wherein the spheroidizing annealing temperature T 1 is 810 to 830 ℃; And/or, the heat preservation time of spheroidizing annealing is 14-16 h at t 1 ;t 1 .
  4. 4. A control method according to claim 3, wherein the ferrite grain size D 1 of the first treated steel pipe is in a linear relationship with the spheroidizing annealing temperature T 1 .
  5. 5. The control method according to claim 1, wherein the recrystallization annealing temperature of the second treated steel tube is T 2 , the heat preservation time is T 2 ;T 2 at 620-660 ℃, and the heat preservation time T 2 at 3.5-4.5h.
  6. 6. The control method according to claim 5, wherein when |γ| is not more than 0.03, the ferrite grain size D 2 of the seamless steel pipe is calculated as D 2 =D def , wherein D def is the ferrite effective grain size of the second treated steel pipe, μm, and D 2 is the ferrite grain size of the seamless steel pipe, μm.
  7. 7. The control method according to claim 1, wherein the alloy steel round steel has a size of an outer diameter of 52mm and a wall thickness of 8mm, and the seamless steel pipe processed has a size of an outer diameter of 25mm and a wall thickness of 7mm.
  8. 8. A control method according to claim 3, characterized in that the yield strength R p0.2 of the seamless steel pipe is equal to or greater than 550MPa by adjusting the spheroidizing annealing temperature T 1 .
  9. 9. A seamless steel tube for hollow bolts, characterized in that it is obtained by the control method according to any one of claims 1 to 8.
  10. 10. The seamless steel pipe according to claim 9, wherein the yield strength R p0.2 is not less than 550MPa, the tensile strength R m is not less than 640MPa, the elongation A is not less than 16% and the breaking force F is not less than 240kN.

Description

Seamless steel tube for hollow anchor rod and strength regulating and controlling method thereof Technical Field The application relates to the technical field of seamless steel tube processing, in particular to a seamless steel tube for a hollow anchor rod and a strength regulating and controlling method thereof. Background Hollow anchor rods are used as key components for supporting tunnels, mines and slopes, and the rod bodies of the hollow anchor rods are usually made of seamless steel tubes. The 40Cr alloy steel is a common material for manufacturing medium-high strength anchor rods due to good hardenability, high strength and proper toughness. A typical production process flow of the seamless steel pipe comprises hot punching blank making, spheroidizing annealing, cold finish rolling, recrystallization annealing and straightening sizing, wherein in the process, the spheroidizing annealing and the recrystallization annealing are two most critical heat treatment processes, and the heat treatment processes jointly determine the grain size and the mechanical property of the final seamless steel pipe. However, the prior art has the problems that the intensity regulation and control of the seamless steel pipe depends on experience, lacks scientific quantitative basis, and usually only adjusts the final recrystallization annealing temperature singly by experience or simply changes spheroidizing annealing parameters when the intensity level of the seamless steel pipe needs to be adjusted, and the adjustment method leads to low intensity regulation and control precision of the seamless steel pipe, long adjustment period and large fluctuation of the performances among batches. In addition, the matching relation between the strength and the plasticity of the seamless steel pipe is difficult to control, in the traditional process, when the strength of the seamless steel pipe is improved, the plasticity performance of the seamless steel pipe is reduced, and meanwhile, when the plasticity of the seamless steel pipe needs to be improved, the strength of the seamless steel pipe is easy to be reduced, so that the prior process cannot realize quantitative prediction and accurate regulation of the grain size of the seamless steel pipe. Disclosure of Invention In order to solve the problems in the prior art, the application provides a seamless steel pipe for a hollow anchor rod and a strength regulating method thereof, wherein the method realizes reverse design of the yield strength of the seamless steel pipe and simultaneously ensures good plasticity of the seamless steel pipe by establishing a physical metallurgical model with consistent dimensions of technological parameters, grain size and yield strength. According to a first aspect of the present application, an embodiment provides a method for adjusting and controlling the strength of a seamless steel tube for a hollow anchor rod, including the following steps: Heating the alloy steel round steel and then performing hot piercing to prepare a hollow tube blank; Performing spheroidizing annealing treatment on the hollow tube blank, and cooling to obtain a first treated steel tube, wherein the ferrite grain size of the first treated steel tube is calculated to be D 1 according to a spheroidizing annealing grain size model; Wherein the spheroidizing annealed grain size model is D 1=11.5+k1×(T1 -810); d 1 is the ferrite grain size of the first treated steel pipe, μm, T 1 is spheroidizing annealing temperature, DEG C, k 1 is spheroidizing annealing temperature coefficient, μm/DEGC, and the value is 0.25; The first treated steel pipe is subjected to cold finish rolling forming and cleaning to obtain a second treated steel pipe, and the effective ferrite grain size of the second treated steel pipe is calculated to be D def according to a cold deformation grain refinement model; D def=D1/1.918, wherein D def is the effective ferrite grain size of the second treated steel pipe, mum, D 1 is the ferrite grain size of the first treated steel pipe, mum, and the cold finish rolling true strain parameter is 1.03; Performing recrystallization annealing on the second treated steel tube to obtain a seamless steel tube, and straightening and sizing the seamless steel tube, wherein the ferrite grain size of the seamless steel tube is calculated to be D 2 according to a recrystallization grain evolution model, and the yield strength of the seamless steel tube is calculated to be R p0.2 according to a strength model; d 2=Ddef × (1+γ), wherein D def is the ferrite effective grain size of the second treated steel pipe, μm, D 2 is the ferrite grain size of the seamless steel pipe, μm, γ is the ferrite grain size change rate caused by the recrystallization annealing of the second treated steel pipe, wherein γ >0 represents grain growth, γ <0 represents incomplete recrystallization resulting in grain refinement, and the grain size change is negligible in this process window when |γ| is less t