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Super fine crystal microalloyed medium carbon steel coil and its producing method

A production method and technology for steel wire rods, applied in the field of metal materials, can solve the problems of increasing the chance of decarburization on the surface of the bolt, affecting the quality stability of the bolt, and complicated procedures, so as to improve the quality and production efficiency of the bolt, save annealing and quenching and tempering. Treatment cost, effect of reducing environmental pollution

Inactive Publication Date: 2006-11-08
MAANSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Chinese Invention Patent: Patent No. 99115353.7 Spheroidizing annealing process of high-speed and large-deformation hot-rolled cold heading steel carbide; although the traditional spheroidizing annealing process has been improved and the annealing time has been shortened, offline spheroidizing annealing is still required
The spheroidizing annealing and quenching and tempering heat treatment (quenching + high temperature tempering) process is cumbersome, consumes a lot of energy, costs a lot, also causes metal loss, pollutes the environment, and increases the chance of decarburization of the bolt surface, and the manufacture of slender fasteners , easy to produce heat treatment deformation, affecting the quality stability of bolts
The slender fasteners must be quenched and tempered in a medium-high frequency furnace, and the operation rate is low.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Implementation example 1: MFT8 ultra-fine grain non-quenched and tempered cold heading steel Φ6.5mm wire, alloy elements are C-0.19% Si-0.15% Mn-1.30% P-0.016% S-0.012%, V, Nb, Ti, Al A small amount is added, and the rest is Fe; the steel mill is refined and continuously cast into a 140 billet; The unit and the reducing and sizing machine are finished rolling at 800°C to form wire rods, and the cumulative area reduction rate is 80%. After spinning, the coils are loosened and the cover is blown to cool for about 2-3 minutes. After cooling to below 500°C, the coils are collected, cooled naturally and bundled. , the properties of the wire are listed in Table 1. In a fastener factory, 30 tons of wire rods were directly pickled and drawn without annealing, and were remade into 5.6mm process materials. They were made into M6× 20 semi-finished hex bolts, then through stabilization treatment - galvanized, made into 8.8 grade M6 bolts, the appearance quality is very good, no cr...

Embodiment 2

[0020] Implementation example 2: MFT8 ultra-fine grain non-quenched and tempered cold heading steel Φ11mm wire, alloy elements are C-0.21% Si-0.18% Mn-1.40% P-0.020% S-0.008%, V, Nb, Ti, Al are added in small amounts , the rest is Fe; the steel mill is refined and continuously cast into 140 billets; The reducing and sizing machine is finished rolling at 760°C to form wire rods, and the cumulative area reduction rate is 65%. After spinning, the coils are loosened and the cover is blown to cool for about 2-3 minutes. After cooling to below 500°C, the coils are collected, cooled naturally and bundled. Properties are listed in Table 1. In a fastener factory, 10 tons of wire rods were directly pickled and pulled without annealing, and were remade into 9.5mm process materials. They were made into M10 with a low-speed multi-position cold heading machine at a cold heading speed of 75 pcs / min. The semi-finished outer hexagonal bolts of ×65 are stabilized and galvanized to make 8.8-gra...

Embodiment 3

[0021] Implementation example 3: MFT10 ultra-fine grain non-quenched and tempered cold heading steel Φ16mm wire, alloy elements are C-0.24% Si-0.30% Mn-1.50% P-0.015% S-0.005%, V, Nb, Ti, Al are added in small amounts , the rest is Fe; the steel mill is refined and continuously cast into 140 billets; The reducing and sizing machine is finished rolling at 760°C to form wire rods, and the cumulative area reduction rate is 60%. After spinning, the coils are loosened and the cover is blown to cool for about 2-3 minutes. After cooling to below 500°C, the coils are collected, cooled naturally and bundled. Properties are listed in Table 1. 10 tons of wire, in a fastener factory, directly pickled and drawn without annealing, remade into 15.5mm process material, cut and rolled to make M16×800mm long 10.9 grade screw fasteners, 100% Qualified, the bolt properties are listed in Table 2.

[0022] Tensile strength (MPa)

[0023] Tensile load (KN)

[0024] It can b...

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PUM

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Abstract

The present invention relates to metal material, and especially cold forging steel coil for fastener and its production process. The superfine crystal microalloyed medium carbon steel coil has the alloy elements including: C 0.10-0.25 wt%, Si not more than 0.08 wt%, Mn 0.80-1.70 wt%, P not more than 0.035 wt%, S not more than 0.035 wt%, V, Nb, Ti and Al trace quantity, and Fe for the rest. Its production process includes the following steps: smelting in a converter, external refining, casting blank; heating to 1100 deg.c in a heating furnace; rolling at 750-830 deg.c, finish rolling in a TMCP process and rolling in a two phase region and great deformation quantity; controlled cooling and spinning; cooling and bundling at temperature lower than 500 deg.c. The cold forging steel coil is used in producing fastener directly in a cold header, has simple technological process, low cost, less pollution and raised production efficiency.

Description

technical field [0001] The invention belongs to metal materials, in particular to cold heading steel for fasteners, and also to a production method of the cold heading steel. Background technique [0002] There are many types and specifications of fasteners, which are widely used and require a large amount. The fasteners such as small-sized bolts and screws currently used, especially the fasteners with specifications below M24, mostly use hot-rolled wire rods as raw materials. Formed by law. Low-strength cold heading steel wire rod is easy to process and form, but the processed fasteners have low strength, which affects the use. More and more fasteners of grade 8.8 and above are used, and low-strength fasteners are gradually eliminated. At present, fastener manufacturing enterprises widely use high-quality carbon steel or alloy steel wire rods with a carbon equivalent of 0.35%-0.55%, and medium carbon alloy steel wire rods. It is drawn and transformed into cold heading pro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/14B21B1/18C21D7/13C21D9/56C22C33/04
Inventor 胡孝三华刚宋强孙维于同仁许建
Owner MAANSHAN IRON & STEEL CO LTD
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