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Preparation method for manufacturing low-cost ultrafine grain transformation-induced plastic steel seamless tube online

A technology of phase change induced plasticity and ultra-fine grain, which is applied in the field of steel pipe preparation, can solve the problems of no further detailed analysis of the mechanical properties of grain ultra-fine, difficult process control, complex process, etc., to achieve low cost, Process stability and the effect of increasing the grain boundary area

Active Publication Date: 2014-06-18
LAIWU IRON & STEEL GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although this method successfully achieves ultra-fine grains of alloy structural steel, it has the following disadvantages: (1) It is only suitable for materials with C≥0.35% and containing high content of precious alloying elements such as Cr and Mo; (2 ) There is no further detailed analysis of the impact of grain ultra-refinement on mechanical properties; (3) The manufacturing process is longer, the process is more complicated, and the process control is more difficult

Method used

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  • Preparation method for manufacturing low-cost ultrafine grain transformation-induced plastic steel seamless tube online
  • Preparation method for manufacturing low-cost ultrafine grain transformation-induced plastic steel seamless tube online
  • Preparation method for manufacturing low-cost ultrafine grain transformation-induced plastic steel seamless tube online

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] The chemical composition of the steel used in this embodiment is C: 0.101%, Si: 1.80%, Mn: 1.09%, P: 0.002%, S: 0.005%, and the balance is Fe. Its A is measured from the thermal expansion curve c1 and A c3 721 and 849°C, respectively. said A c1 is the starting temperature of ferrite to austenite transformation during annealing heating process, A c3 It is the end temperature of ferrite to austenite transformation during the annealing heating process. Due to the different composition of steel (such as changes in carbon content, silicon content, etc.) and changes in process parameters (such as heating rate), A c1 ﹑A c3 will change accordingly. The steel that the present invention adopts records its A by thermal expansion curve c1 and A c3 .

[0048] The smelted ingot is forged into a bar, and the bar is turned to remove wrinkles and defects on the outer surface to form a tube blank. The tube blank is heated to 1100°C and kept for 2 hours before piercing, and then ...

Embodiment 2

[0058] The chemical composition of the steel used in this embodiment is C: 0.16%, Si: 1.35%, Mn: 1.51%, P: 0.005%, S: 0.007%, and the balance is Fe. Its A is measured from the thermal expansion curve c1 and A c3 735 and 870°C, respectively.

[0059] The smelted ingot is forged into a bar, and the bar is turned to remove wrinkles and defects on the outer surface to form a tube blank. The tube blank is heated to 1100°C and kept for 2 hours before piercing, and then cooled to room temperature. The tube blank is cold-drawn for 4 passes to obtain a seamless cold-drawn steel tube with a wall thickness of 2.1 mm and an outer diameter of 53 mm.

[0060] The seamless cold-drawn steel pipe is subjected to 4 cycles of heating + quenching treatment with a medium-frequency heating induction coil. The specific annealing process parameters are shown in Table 2. The heating rate is about 400 °C / s, and the annealing temperature (A c3 -40℃)~(A c3 +10℃), the annealing time is 5~15s. Cool th...

Embodiment 3

[0067] The chemical composition of the steel used in this embodiment is C: 0.184%, Si: 1.00%, Mn: 1.87%, P: 0.006%, S: 0.003%, and the balance is Fe. Its A is measured from the thermal expansion curve c1 and A c3 730 and 850°C, respectively.

[0068] The smelted ingot is forged into a bar, and the bar is turned to remove wrinkles and defects on the outer surface to form a tube billet. The tube billet is heated to 1200°C and kept for 2 hours before piercing, and then cooled to room temperature. The tube blank is cold-drawn for 4 passes to obtain a seamless cold-drawn steel tube with a wall thickness of 1.20 mm and an outer diameter of 43 mm.

[0069] The seamless cold-drawn steel pipe is subjected to 4 cycles of heating + quenching treatment with an intermediate frequency heating induction coil. The specific annealing process parameters are shown in Table 3, in which the heating rate is about 300°C / s, and the annealing temperature (A c3 -40℃)~(A c3 +10℃), the annealing time...

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Abstract

The invention relates to a preparation method for manufacturing a low-cost ultrafine grain transformation-induced plastic steel seamless tube online. The method comprises the following steps: forging, turning, heating, perforating and coldly drawing a cast ingot to obtain a seamless cold-drawn steel tube; then carrying out circulating heating and quenching treatment for over three times by adopting a medium-frequency heating induction coil; finally, air cooling, water cooling or naturally cooling to room temperature, so as to obtain the low-cost ultrafine grain transformation-induced plastic steel seamless tube. Chemical components of common low-carbon steel are utilized, so that the cost is relatively low, the tensile strength is greater than or equal to 900 MPa, the yield ratio is smaller than or equal to 0.64, the ductility is greater than or equal to 24.0%, the work hardening index is greater than or equal to 0.23, the anisotropic index is greater than or equal to 1.01, the average grain size of a microscopic structure is smaller than or equal to 3mum, and the volume fraction of the retained austenite is 11.5-19.5%.

Description

technical field [0001] The invention belongs to the field of steel pipe preparation, and in particular relates to a preparation method for on-line manufacturing of low-cost ultrafine grain phase transformation-induced plastic steel seamless pipes. Background technique [0002] In recent years, issues such as climate change and energy shortage have had an increasingly serious impact on the development of modern industry and people's daily lives. Energy saving, emission reduction, low-carbon environmental protection have become urgent problems to be solved in the industrial development of various countries today. As the symbol and symbol of modern industry, the automobile industry is not only a pillar industry that stimulates the development of the national economy, but also a key industry that consumes a lot of energy, emits high emissions, and causes environmental pollution. The primary problem to be solved. [0003] In order to meet the needs of environmental protection a...

Claims

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Application Information

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IPC IPC(8): C22C38/14C22C38/12C22C38/04C21D8/10
Inventor 侯晓英王业勤许荣昌
Owner LAIWU IRON & STEEL GRP
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