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A kind of directly cutting high-strength and tough hot-rolled round steel and its preparation method

A round steel, direct technology, applied in the direction of heat treatment equipment, manufacturing tools, heat treatment furnace, etc., can solve the problems of high material cost and low production efficiency, achieve the effect of improving production rhythm, reducing waiting time and promoting refinement

Active Publication Date: 2021-09-28
JIANGSU VALIN XIGANG SPECIAL STEEL +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] Patent application CN 201711100874 discloses a non-quenched and tempered steel and its preparation method, the non-quenched and tempered steel of the invention, by weight percentage, C: 0.46-0.55%, Si: 0.20-0.60%, Mn: 1.20-1.60% , Cr: 0.00-0.30%, Al: 0.010-0.030%, Ni: 0.10-0.30%, Cu: 0.00-0.20%, P: 0.000-0.030%, S: 0.020-0.050%, V: 0.050-0.250%, Nb: 0.020-0.050%, Ti: 0.010-0.030%, B: 0.0005-0.0030, N: 0.012-0.020%, the balance is Fe, the patent application product contains higher alloys Mn, V, Nb, Ti, B , the cost of materials is high, and it needs to be finished at 780-850°C for final rolling, and the production efficiency is low

Method used

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  • A kind of directly cutting high-strength and tough hot-rolled round steel and its preparation method
  • A kind of directly cutting high-strength and tough hot-rolled round steel and its preparation method
  • A kind of directly cutting high-strength and tough hot-rolled round steel and its preparation method

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Experimental program
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Effect test

Embodiment 1

[0039] The diameter of the hot-rolled round steel in this embodiment is 60mm, and its chemical composition is calculated by mass percentage: C: 0.45%, Si: 0.25%, Mn: 0.75%, Cr: 0.25%, Al: 0.008%, S: 0.015% , Nb: 0.020%, V: 0.030%, N: 0.0120%, and the balance is iron and unavoidable impurity elements.

[0040] The above round steel is successively smelted by electric furnace and LF refined to produce molten steel; the molten steel is poured into a 250*250mm continuous casting billet with a low superheat of 15-30°C under full argon protection, and the continuous casting billet is slowly cooled in the pit for 32 hours; The cast billet is heated to 1200°C, held for 3 hours and released from the furnace; after descaling by high-pressure water once, it returns to the original path, and performs second descaling by high-pressure water to remove all surface oxide scales and promote cooling; Air cooling on the road and waiting for temperature. During the waiting period, the turning mac...

Embodiment 2

[0042] The diameter of the round steel involved in this embodiment is 60mm, and its chemical composition is calculated by mass percentage: C: 0.45%, Si: 0.30%, Mn: 1.55%, Cr: 0.20%, Al: 0.010%, S: 0.028%, Nb: 0.025%, V: 0.035%, N: 0.0120%, and the balance is iron and unavoidable impurity elements.

[0043] The above-mentioned round steel is sequentially smelted by converter and LF refined to produce molten steel; the molten steel is poured into a 300*340mm continuous casting billet with a low superheat of 15-30°C under argon protection throughout the whole process, and the continuous casting billet is slowly cooled in the pit for 32 hours; The cast billet is heated to 1200°C, held for 3 hours and released from the furnace; after descaling by high-pressure water once, it returns to the original route, and performs second descaling by high-pressure water to remove all surface oxide scales and promote cooling; then turn over in the reciprocating billet opener The roller table is ...

Embodiment 3

[0045] The diameter of the round steel involved in this embodiment is 60mm, and its chemical composition is calculated by mass percentage: C: 0.36%, Si: 0.30%, Mn: 1.35%, Cr: 0.20%, Al: 0.012%, S: 0.035%, Ti: 0.012%, Nb: 0.028%, V: 0.038%, N: 0.0150%, and the balance is iron and unavoidable impurity elements.

[0046] The above-mentioned round steel is sequentially smelted by converter and LF refined to produce molten steel; the molten steel is poured into a 250*250mm continuous casting billet with low superheat of 15-30°C under argon protection throughout the whole process, and the continuous casting billet is slowly cooled in the pit for 32 hours; The cast billet is heated to 1200°C, held for 3 hours and released from the furnace; after descaling by high-pressure water once, it returns to the original route, and performs second descaling by high-pressure water to remove all surface oxide scales and promote cooling; then turn over in the reciprocating billet opener The roller...

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Abstract

The invention relates to a high-strength and tough hot-rolled round steel that can be directly cut and a preparation method thereof. The round steel elements contain microalloys such as Nb and V, which help to refine crystal grains and improve strength. Two stages of billet rolling and continuous rolling are adopted. Before the two rollings, air-cooling is carried out to wait for temperature. During the first air-cooling and waiting for temperature, the billet is turned over 180° by the billet opening machine. The steel billet is roughly rolled into an intermediate billet; the intermediate billet is air-cooled for the second time before continuous rolling, and the intermediate billet is heated to the initial temperature of 800-950°C for continuous rolling. After the second heating, the intermediate billet is continuously Rolled into round steel, the final rolling temperature is 780-900°C; when the temperature of the hot-rolled round steel is lower than Ar3, spray + air cooling is used to comprehensively cool the round steel, and after cooling to 600°C, turn to pile cooling to obtain fine flakes Microstructure of pearlite + a small amount of ferrite.

Description

technical field [0001] The invention belongs to the technical field of iron-based alloys, and in particular relates to a hot-rolled round steel that can be directly cut without quenching and tempering treatment. Background technique [0002] Hot-rolled round steel for direct cutting is widely used to replace 45, 40Cr, 42CrMo and other quenched and tempered steels to produce injection molding machine tie rods, engineering vehicle cylinder piston rods and other various rod parts. Compared with traditional quenched and tempered steel, because the heat treatment after rolling is omitted in the process, the production cycle is shorter and the production cost is lower, so as to achieve the production goals of energy saving, cost reduction, emission reduction and efficiency increase. However, this type of hot-rolled round steel generally needs to be warmed during rolling to achieve low-temperature rolling; in addition, in order to ensure higher strength and toughness, a higher cont...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/24C22C38/26C22C38/28C22C38/38C22C38/60C21D6/00C21D8/06C21D9/00C22C33/04
CPCC21D6/002C21D6/005C21D6/008C21D8/065C21D9/0075C21D2211/005C21D2211/009C22C33/04C22C38/001C22C38/002C22C38/02C22C38/04C22C38/06C22C38/24C22C38/26C22C38/28C22C38/38C22C38/60
Inventor 冀鸰高助忠郑亚明
Owner JIANGSU VALIN XIGANG SPECIAL STEEL
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