Method for manufacturing low-cost ultrafine grain dual-phase steel seamless tube on line

An ultra-fine-grain, dual-phase steel technology, applied in the field of steel pipe preparation, can solve the problems that the idler table cannot ensure the uniform rotation of the steel pipe, cannot produce large-scale and length steel pipes, and limits the product specifications of the steel pipes, achieving low cost, Improves strong plasticity and prevents crack growth

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

[0004] At present, the heating methods for heat treatment of steel pipes are still mainly gas heating and resistance heating. Most of them put the whole steel pipe into the heating furnace for heating. In this way, the length of the processed steel pipe is limited by the size of the heating furnace body, so it cannot produce large-scale and Longer steel pipes limit the product specifications of the steel pipes; in addition, the temperature rises slowly during the heating process with this device, the oxide layer on the surface of the steel pipes is serious, and the work efficiency is low; moreover, the roller table in the furnace body The uniform rotation of the steel pipe in the heating furnace cannot be guaranteed, and its heating is uneven, which can lead to bending of the steel pipe

Method used

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  • Method for manufacturing low-cost ultrafine grain dual-phase steel seamless tube on line
  • Method for manufacturing low-cost ultrafine grain dual-phase steel seamless tube on line
  • Method for manufacturing low-cost ultrafine grain dual-phase steel seamless tube on line

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] The chemical composition of the steel used in this example is C: 0.20%, Si: 0.8%, Mn: 1.90%, Nb: 0.04%, P: 0.006%, S: 0.024%, and the balance is Fe and smelting conditions Impurities produced below. Its A is measured from the thermal expansion curve c1 and A c3 705 and 882°C, respectively.

[0040] 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 5 passes to obtain a seamless cold-drawn steel tube with a wall thickness of 1.5 mm and an outer diameter of 46 mm.

[0041] The seamless cold-drawn steel pipe was subjected to 3 cycles of heating + quenching treatment with an intermediate frequency heating induction coil. The specific annealing process parameters are shown in Table 1. The heating rate is about 300 °C / s, and the annealing temperat...

Embodiment 2

[0051] The chemical composition of the steel used in this example is C: 0.16%, Si: 0.5%, Mn: 1.54%, V: 0.05%, P: 0.019%, S: 0.016%, and the balance is Fe and smelting conditions Impurities produced below. Its A is measured from the thermal expansion curve c1 and A c3 728 and 865°C, respectively.

[0052] 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 1250°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 3.2 mm and an outer diameter of 54 mm.

[0053] The seamless cold-drawn steel pipe is subjected to 3 cycles of heating + quenching treatment with an intermediate frequency heating induction coil. The specific annealing process parameters are shown in Table 2. The heating rate is about 300 °C / s, and the annealing temperature ...

Embodiment 3

[0059] The chemical composition of the steel used in this example is C: 0.11%, Si: 0.14%, Mn: 1.81%, P: 0.015%, S: 0.01%, and the balance is Fe and impurities produced under smelting conditions. Its A is measured from the thermal expansion curve c1 and A c3 746 and 854°C, respectively.

[0060] 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 5 passes to obtain a seamless cold-drawn steel tube with a wall thickness of 2.5 mm and an outer diameter of 52 mm.

[0061] The seamless cold-drawn steel pipe is subjected to 3 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 400°C / s, and the annealing temperature (...

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Abstract

The invention belongs to the field of steel tube manufacturing and relates to a method for manufacturing a low-cost ultrafine grain dual-phase steel seamless tube on line. The method comprises the following steps: processing a cast ingot to obtain a seamless cold-drawn steel tube, then carrying out cycle heating for more than three times and quenching by adopting an intermediate frequency heating induction coil, and finally carrying out air cooling, water cooling or natural cooling to room temperature, thus obtaining the ultrafine grain dual-phase steel seamless tube. According to the method disclosed by the invention, the ultrafine grain dual-phase steel seamless tube with favorable comprehensive mechanical performance can be produced by using chemical components of common low-carbon steel, so that the cost is relatively low, the tensile strength is larger than or equal to 790MPa, the yield ratio is less than or equal to 0.53, the ductility is larger than or equal to 24.2 percent, the work-hardening index is larger than or equal to 0.24, the average crystallite size of microscopic structure is less than or equal to 3.0mu m, wherein the martensite volume fraction is within 15.0-26.0 percent.

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 dual-phase 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 and achieve light weight un...

Claims

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Application Information

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