CN104962817A - Simple annealing cold heading steel hot rolled wire rod for high-strength fastener and production method of simple annealing cold heading steel hot rolled wire rod - Google Patents

Abstract

The invention discloses a simple annealing cold heading steel hot rolled wire rod for a high-strength fastener and a production method of the simple annealing cold heading steel hot rolled wire rod. The simplified annealing cold heading steel hot rolled wire rod comprises, by weight, 0.30-0.40% of C, 0.15-0.25% of Si, 0.60-0.85% of Mn, 0.90-1.10% of Cr, 0.15-0.30% of Mo, smaller than or equal to 0.02% of P, smaller than or equal to 0.025% of S and the balance Fe and micro-impurities. According to the method, due to the fact that the design of alloy components is optimized and the controlled-rolling and controlled-cooling technology is optimized, simple annealing is achieved, and the annealing cost is reduced; energy is saved, pollution is reduced, the production efficiency is improved, and the hot rolled wire rod can be directly formed in a cold heading mode after simple annealing under the premise that the basic technical index of products is met. According to the simple annealing cold heading steel hot rolled wire rod for the high-strength fastener and the production method of the simple annealing cold heading steel hot rolled wire rod, the production cost is not increased, existing equipment and technologies are fully utilized, and the purposes of simplifying the annealing technology and reducing the production cost in the deep machining process of downstream users are achieved. The performance of the produced 12.9-grade finished bolt products meet various index requirements, the rod passing stability is good, and the obvious effects of energy conservation, consumption reduction and environmental friendliness are achieved.

Description

High-intensity fasteners is with simplifying annealed cold-forging steel gren rod and production method thereof

Technical field

The present invention relates to a kind of hot rolling wire, especially a kind of 12.9 grade high-strength fasteners simplify annealed cold-forging steel gren rod and production method thereof.

Background technology

Chinese Automobile Industry ' is fast-developing, Chinese automobile output in 2009 has surmounted the U.S. becomes the maximum producing country in the whole world and country of consumption, but the automobile popularity of China also has very large gap compared with developed countries, so in a very long time from now on, the production of Chinese automobile will continuous prosperity.Wherein the research and development of the bolt cold heading steel such as automobile 12.9 stage motor connecting rods, cylinder cap, wheel hub are particularly urgent.

Along with the increase of production cost and the pressure of environment protection; downstream deep processing enterprise is for saving the energy, decreasing pollution and cost; enhance productivity; when producing 12.9 grade high-strength fastener; carry out simplification annealing; because this increasing the requirement to cold heading steel gren rod, high strength and high-ductility index need be taken into account.Therefore the status of 12.9 grades of fastening piece simplification annealed cold-forging steel gren rods manifests gradually.So, in " severe winter " of current steel industry, steel industry is by the transition of steelmaker to material service business, the comprehensive lifting market competitiveness, gain a place in world market with keen competition, cater to the requirement that client reduces costs, develop the proprietary technology producing simplification annealing product particularly important.

Have some producers to produce both at home and abroad at present and exempt from annealing or simplify annealing wire rod, but most method is for adopting thermo-mechanical rolling.Application number CN201210408163.4 discloses for " one exempts from annealed low carbon steel wire rod and production method thereof ", it comprises convertor deacidification control, refining carburetting control, oiler temperature control, roller table speed control, but mainly for low-carbon cold heading steel, use field is also only limitted to General fasteners.Patent No. CN200410103089.0 discloses for " production methods of 8.8 grade high-strength cold forging steel hot-rolling anneal-free coil rods ", it comprises the middle carbon anneal-free coil rod utilizing the high-speed rod-rolling mill production with thermo-mechanical rolling function to exempt from annealing, and be only production 8.8 grades of fastening pieces, need to carry out online upgrading to high line production line, increase the facility investments such as super-heavy load finishing train, nearly about 1,000,000,000 need be invested.

Adopt medium carbon cold heading steel gren rod in deep-processing process, simplify the demand of the annealing process before drawing for downstream client, how on the basis not increasing wire rod investment of production equipment, according to the production technology characteristic of downstream manufacturing concern, realize downstream by the technology of steel mill self and capacity of equipment and simplify annealing production and become a problem demanding prompt solution.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of 12.9 grade high-strength fasteners making full use of existing installation and simplifies annealed cold-forging steel gren rod and production method thereof.

For solving the problems of the technologies described above, the weight percentage of present component is: C 0.30 ~ 0.40%, Si 0.15 ~ 0.25%, Mn 0.60 ~ 0.85%, Cr 0.90 ~ 1.10%, Mo 0.15 ~ 0.30%, P≤0.025%, S≤0.025%, and all the other are iron and trace impurity.

The inventive method is: its by steel billet through heating, rolling, weave silk and refrigerating work procedure, obtain described gren rod; The weight percentage of described steel billet composition is described above;

Described heating process: the Heating temperature of steel billet 1000 ~ 1100 DEG C, soaking time 70 ~ 130min;

Described rolling process: enter final rolling temperature 800 ~ 850 DEG C;

Described operation of weaving silk: laying temperature 800 ~ 820 DEG C;

Described refrigerating work procedure: phase transformation leading portion rate of cooling 0.5 ~ 0.8 DEG C/s.

In heating process described in the inventive method, the steel billet dephosphorize by high pressure water after insulation; Dephosphorization temperature 980 ~ 1080 DEG C, hydraulic pressure >=10MPa.

The principle that the inventive method adopts is: the optimization design of carrying out chemical composition, reduces the solution strengthening of C element, reduces the elements such as P, S, avoids material fragility, improve the indexs such as material cold working hardening rate; Adjustment steel billet austenitizing temperature, makes austenite crystal fully grow up; Low temperature rolling, is conducive to the accumulation storing energy, and increases dislocation desity, thus improve ferrite nuclear driving force, promote ferrite transformation, thus improve the plasticity of wire rod; Reduce laying temperature, extend austenite to ferritic fringe time, promote ferrite forming core and grow up, improving ferritic grain fineness number simultaneously; Roller table speed reduces, and reduces speed of cooling in phase transition process, effectively prevent the generation of excessive condensate depression, facilitate ferritic eutectoid transformation, and fully changed; Cooling rate reduces, and the temperature drop of heart portion and edge is balanced, effectively prevent thermograde, makes the austenite cooling transformation synchronism of heart portion and edge.

The beneficial effect that produces of technique scheme is adopted to be: to the present invention is directed to down-stream enterprise when producing 12.9 grade high-strength fastener, existing weaponry and equipment is utilized to the requirement realizing simplifying annealing process before the drawing of cold heading steel gren rod, by optimized alloy Composition Design, optimize cooling controlling and rolling controlling process, realize simplifying annealing, reduce annealing cost; Save the energy, decreasing pollution, enhance productivity, gren rod, can direct cold-heading molding after simplifying annealing under the prerequisite meeting product basic technical indicator.The inventive method does not increase production cost, makes full use of existing installation and technique, the object realize simplifying annealing process in downstream user deep-processing process, reducing cost; The 12.9 grade bolt end properties produced meet indices requirement, and poker has good stability, and have the effect of significant energy-saving and cost-reducing environmental protection.

Microtexture of the present invention is made up of ferrite+perlite, tensile strength 830 ~ 850MPa, reduction of area 48 ~ 53%, reaches the requirement simplifying annealing product.

Embodiment

Below in conjunction with specific embodiment, the present invention is further detailed explanation.

Embodiment 1: this high-intensity fasteners simplification annealed cold-forging steel gren rod adopts following explained hereafter to form.

(1) to smelt and continuous casting working procedure: smelting molten steel continuous casting becomes steel billet, its composition is by weight percentage: C 0.30%, Si 0.20%, Mn 0.85%, Cr 1.10%, Mo 0.30%, P 0.013%, S 0.025%, and all the other are iron and trace impurity.

(2) heating process: by heating steel billet to 1100 DEG C, soaking time 70min; Then dephosphorize by high pressure water, dephosphorization temperature is 1080 DEG C, requires dephosphorization hydraulic pressure 12MPa.

(3) rolling process: the steel billet after dephosphorization is carried out 6+8 passage thick in roll, the pre-finish rolling of 4 passage, 8 passage finish rolling, enter final rolling temperature 800 DEG C, weave silk after finish rolling terminates.

(4) to weave silk operation: laying temperature controls at 820 DEG C.

(5) refrigerating work procedure: enter Stelmor cooling line, regulate air-cooled line stay-warm case to open quantity and blower fan aperture, after weaving silk, wire rod phase transformation leading portion rate of cooling controls at 0.8 DEG C/s.

The cold heading steel gren rod of the Φ 12mm specification of producing by present method, tensile strength 850MPa, reduction of area 53%.Deep processing is carried out through certain fastening parts of automobiles factory, pickling-phosphatization-simplification 11.2mm-that anneals-be drawn to simplifies and to anneal-be drawn to 10.60mm-cold-heading-tempering of quenching, the 12.9 grades of hexagon socket head cap screws made, visual appearance is excellent, qualification rate 100% good without cracking phenomena, processability.

Embodiment 2: this high-intensity fasteners simplification annealed cold-forging steel gren rod adopts following explained hereafter to form.

(1) to smelt and continuous casting working procedure: smelting molten steel continuous casting becomes steel billet, its composition is by weight percentage: C 0.40%, Si 0.15%, Mn 0.60%, Cr 0.90%, Mo 0.15%, P 0.025%, S 0.014%, and all the other are iron and trace impurity.

(2) heating process: by heating steel billet to 1000 DEG C, soaking time 130min; Then dephosphorize by high pressure water, dephosphorization temperature is 980 DEG C, requires dephosphorization hydraulic pressure 10MPa.

(3) rolling process: the steel billet after dephosphorization is carried out 6+8 passage thick in roll, the pre-finish rolling of 4 passage, 8 passage finish rolling, enter final rolling temperature 850 DEG C.

(4) to weave silk operation: laying temperature controls at 800 DEG C.

(5) refrigerating work procedure: enter Stelmor cooling line, regulate air-cooled line stay-warm case to open quantity and blower fan aperture, after weaving silk, wire rod phase transformation leading portion rate of cooling controls at 0.5 DEG C/s.

The cold heading steel gren rod of the Φ 14mm specification of producing by present method, tensile strength 846MPa, reduction of area 51%.Deep processing is carried out through certain fastening parts of automobiles factory, pickling-phosphatization-simplification 13.1mm-that anneals-be drawn to simplifies and to anneal-be drawn to 12.70mm-cold-heading-tempering of quenching, the 12.9 grades of hexagon socket head cap screws made, visual appearance is excellent, qualification rate 100% good without cracking phenomena, processability.

Embodiment 3: this high-intensity fasteners simplification annealed cold-forging steel gren rod adopts following explained hereafter to form.

(1) to smelt and continuous casting working procedure: smelting molten steel continuous casting becomes steel billet, its composition is by weight percentage: C 0.35%, Si 0.25%, Mn 0.72%, Cr 1.00%, Mo 0.20%, P 0.015%, S 0.008%, and all the other are iron and trace impurity.

(2) heating process: by heating steel billet to 1050 DEG C, soaking time 100min; Then dephosphorize by high pressure water, dephosphorization temperature is 1020 DEG C, requires dephosphorization hydraulic pressure 15MPa.

(3) rolling process: the steel billet after dephosphorization is carried out 6+8 passage thick in roll, the pre-finish rolling of 4 passage, 8 passage finish rolling, enter final rolling temperature 830 DEG C.

(4) to weave silk operation: laying temperature controls at 810 DEG C.

(5) refrigerating work procedure: enter Stelmor cooling line, regulate air-cooled line stay-warm case to open quantity and blower fan aperture, after weaving silk, wire rod phase transformation leading portion rate of cooling controls at 0.6 DEG C/s.

The cold heading steel gren rod of the Φ 16mm specification of producing by present method, tensile strength 840MPa, reduction of area 50%.Deep processing is carried out through certain fastening parts of automobiles factory, pickling-phosphatization-simplification 15.3mm-that anneals-be drawn to simplifies and to anneal-be drawn to 14.80mm-cold-heading-tempering of quenching, the 12.9 grades of hexagon socket head cap screws made, visual appearance is excellent, qualification rate 100% good without cracking phenomena, processability.

Embodiment 4: this high-intensity fasteners simplification annealed cold-forging steel gren rod adopts following explained hereafter to form.

(1) to smelt and continuous casting working procedure: smelting molten steel continuous casting becomes steel billet, its composition is by weight percentage: C 0.36%, Si 0.17%, Mn 0.70%, Cr 1.05%, Mo 0.18%, P 0.013%, S 0.006%, and all the other are iron and trace impurity.

(2) heating process: by heating steel billet to 1060 DEG C, soaking time 110min; Then dephosphorize by high pressure water, dephosphorization temperature is 1040 DEG C, requires dephosphorization hydraulic pressure at least 14MPa.

(3) rolling process: the steel billet after dephosphorization is carried out 6+8 passage thick in roll, the pre-finish rolling of 4 passage, 8 passage finish rolling, enter final rolling temperature 820 DEG C.

(4) to weave silk operation: after finish rolling terminates, laying temperature controls at 800 DEG C.

(5) refrigerating work procedure: enter Stelmor cooling line, regulate air-cooled line stay-warm case to open quantity and blower fan aperture, after weaving silk, wire rod phase transformation leading portion rate of cooling controls at 0.5 DEG C/s.

The cold heading steel gren rod of the Φ 18mm specification of producing by present method, tensile strength 830MPa, reduction of area 48%.Deep processing is carried out through certain fastening parts of automobiles factory, pickling-phosphatization-simplification 17.1mm-that anneals-be drawn to simplifies and to anneal-be drawn to 16.70mm-cold-heading-tempering of quenching, the 12.9 grades of hexagon socket head cap screws made, visual appearance is excellent, qualification rate 100% good without cracking phenomena, processability.

Claims (3)

1. a high-intensity fasteners is with simplifying annealed cold-forging steel gren rod, it is characterized in that, the weight percentage of its composition is: C 0.30 ~ 0.40%, Si 0.15 ~ 0.25%, Mn 0.60 ~ 0.85%, Cr 0.90 ~ 1.10%, Mo 0.15 ~ 0.30%, P≤0.025%, S≤0.025%, and all the other are iron and trace impurity.

2. the high-intensity fasteners production method simplifying annealed cold-forging steel gren rod, is characterized in that: its by steel billet through heating, rolling, weave silk and refrigerating work procedure, obtain described gren rod; The weight percentage of described steel billet composition is: C 0.30 ~ 0.40%, Si 0.15 ~ 0.25%, Mn 0.60 ~ 0.85%, Cr 0.90 ~ 1.10%, Mo 0.15 ~ 0.30%, P≤0.025%, S≤0.025%, and all the other are iron and trace impurity;

Described heating process: the Heating temperature of steel billet 1000 ~ 1100 DEG C, soaking time 70 ~ 130min;

Described rolling process: enter final rolling temperature 800 ~ 850 DEG C;

Described operation of weaving silk: laying temperature 800 ~ 820 DEG C;

Described refrigerating work procedure: phase transformation leading portion rate of cooling 0.5 ~ 0.8 DEG C/s.

3. high-intensity fasteners according to claim 2 simplifies the production method of annealed cold-forging steel gren rod, it is characterized in that: in described heating process, after insulation steel billet dephosphorize by high pressure water; Dephosphorization temperature 980 ~ 1080 DEG C, hydraulic pressure >=10MPa.