CN101397634B - Atmospheric corrosion resistant 08CrNiCu low-alloy high intensity non-annealed cold-forging steel and production process - Google Patents

Abstract

The invention pertains to the metal material technical field, and particularly relates to 08CrNiCu cold heading steel and production technology thereof, which has atmospheric corrosion-resistance, low alloy, high strength and non-annealing and is suitable to manufacture metal fasteners. The invention is characterized in that it is calculated by weight percentage and the chemical constituents ratio is as follows: C: 0.5 to 0.90 percent, Si: 0.15 to 0.25 percent, Mn: 0.55 to 0.65 percent, P: 0.005 to 0.025 percent, S: 0.005 to 0.02 percent, Cr: 0.65 to 0.75 percent, Ni: 0.25 to 0.30 percent, Cu: 0.35 to 0.40 percent, and Fe and inevitable impurity as the rest. The invention has the advantages of oxidation resistance, corrosion resistance, relatively long service life, being directly cold heading and molded without quenching, technology without softening and annealing before cold processing, dramatically reducing the consumption of energy, less consumption of metal, shortening productioncycle and high working efficiency. The adding amount of alloy is reduced, thereby reducing the cost, but the strength is high; therefore, the steel can be used for processing 8.8-level bolts and matched nuts. Compared with the common cold heading steel with middle or high strength, the content of carbon in the steel is reduced, and the steel has excellent weldability.

Description

The 08CrNiCu low-alloy high-strength of atmospheric corrosion resistance is exempted from annealed cold-forging steel and production technique

Technical field

The invention belongs to the metallic substance technical field, the 08CrNiCu low-alloy high-strength that particularly relates to a kind of atmospheric corrosion resistance of suitable making metal fastenings is exempted from annealed cold-forging steel and production technique.

Background technology

Data reflection according to the relevent statistics, in some industrially developed country, the annual financial loss that causes due to the topsoil corrosion accounts for 2-4% of national economy total output value, the annual metal of scrapping due to the topsoil corrosion accounts for 10-40% of annual production, and in the loss that corrosion causes, 30-40% is avoidable.Therefore protection against corrosion is as an important subject, more and more caused the people's concern, aspect the research of anticorrosive, two kinds of methods of general employing, the one, the corrosion resistance nature of raising material matrix, the secondth, adopt process for treating surface, namely apply in the metallic surface or the method for anticorrosion layer.

In Investment in fastener industry, anticorrosion technique is also mainly to adopt above two kinds of methods, as: the one, adopting stainless steel is that material is made fastening piece, but its cost is expensive, and product lacks the market competitiveness; Another kind of the combination of coated layer and metal was easily lost efficacy in order to adopt Coating layer treatment process, after key coat is destroyed, matrix was produced corrosion, caused reduce work-ing life, and cut in plating process in transit, easily produced secondary environmental pollution; Conventional fastener is because carbon content is medium high carbon, or alloy content is high, and under normal temperature, hardness is high, cold working again after general employing is first quenched, or adopt thermal processing method, this method energy consumption is high, metal loss is large, the production cycle is long, cost is high.

Summary of the invention

The objective of the invention is to develop a kind of atmospheric corrosion resistance, save energy, the 08CrNiCu low-alloy high-strength of the atmospheric corrosion resistance that metal consumption is low is exempted from annealed cold-forging steel.

Purpose of the present invention adopts following technical proposals to realize: a kind of 08CrNiCu low-alloy high-strength of atmospheric corrosion resistance is exempted from annealed cold-forging steel, it is characterized in that by weight percentage, and the chemical composition proportioning is:

C：?0.05~0.90%，?Si：0.15~0.25%，?Mn：0.55~0.65%，?P：0.005~0.025%，

S:0.005 ~ 0.02%, Cr:0.65 ~ 0.75%, Ni: 0.25 ~ 0.30%, Cu:0.35 ~ 0.40%, all the other are Fe and inevitable impurity.

The chemical composition of the present invention's design, the mechanism of its each composition is as follows:

Adopt the comprehensive microalloying Composition Design of Ni+Cr+Cu, improve erosion resistance and the intensity of material; Ni+Cr+Cu 〉=1.25%;

Cu is the most effective element in atmospheric corrosion resistance low alloy steel, and general content is 0.2 ~ 0.5%, and this steel grade is controlled (0.35 ~ 0.40%) by the middle upper limit;

Cr improves the obdurability of steel, improves atmospheric corrosion resistance, and Cr and Cu fiting effect are particularly remarkable; This steel grade is in w(Cr): w(Cu)=2: 1 ratio, Cr is controlled at 0.65 ~ 0.75%;

Ni improves obdurability, improves the atomospheric corrosion performance, coordinates with chromium, is controlled at 0.25 ~ 0.30%;

P is also the element that improves atmospheric corrosion resistance, due to its cold short impact on material, is controlled at by low

0.005~0.025%，；

S: inevitable impurity, its upper limit is controlled at 0.02%;

C: guarantee the necessary element of intensity of steel, be controlled at 0.05 ~ 0.90%,

Si: improve the corrosion resistance nature of steel, improve the cold deformation drag, be controlled at 0.15 ~ 0.25%,

Mn: improve the necessary element of obdurability of steel, be controlled at 0.55 ~ 0.65%,

The invention has the advantages that, under atmosphere and water surrounding, the corrosion of material surface resistance to oxidation has long work-ing life; The direct cold pier moulding of exempting to quench, technique need not be by the softening annealing operation before cold working, and energy consumption significantly reduces, and metal consumption is little, and the production cycle shortens, high efficiency; Reduce because alloy addition reduces cost, but intensity is high, can be used for processing 8.8 grade bolts and matching nut; With common middle high intensity cold pier steel ratio, carbon content reduces greatly, has good welding property.

Embodiment

The production technique of steel of the present invention adopts the EAF stove just to refine-LF refining-billet continuous casting-high-speed wire rolling operational path: the purity that adopts sial deoxidation smelting technology to control; Obtain the rational microstructure of wire rod by Controlled Rolling And Controlled Cooling, guarantee good cold-workability, its concrete smelting technology is as follows:

The EAF stove just refines: all steel-making starting material must keep dry, to reduce hydrogen richness in steel; During tapping carburetting, adopt low nitrogen carburelant, to reduce nitrogen in steel content; The molten aluminium of acid controls 0.01 ~ 0.02%;

LF refining: feed the CaSi line concise latter stage and carry out the calcium processing, and soft stirring was greater than 3 minutes;

Billet continuous casting: continuous casting tundish target superheating temperature: 20 ~ 25 ℃;

High-speed wire rolling: single stove is rolling, must not organize and criticize; For improving product surface quality, after coming out of the stove, blank must carry out dephosphorize by high pressure water; Start rolling temperature is controlled at 1000 ± 20 ℃; 890 ~ 900 ℃ of laying temperatures;

Stelmo line adopts the delaying type process for cooling.

The 08CrNiCu low-alloy high-strength of atmospheric corrosion resistance of the present invention is exempted from annealed cold-forging steel, by weight percentage, the chemical composition proportioning is: C:0.05 ~ 0.90%, Si:0.15 ~ 0.25%, Mn:0.55 ~ 0.65%, P:0.005 ~ 0.025%, S:0.005 ~ 0.02%, Cr:0.65 ~ 0.75%, Ni: 0.25 ~ 0.30%, Cu:0.35 ~ 0.40%, all the other are Fe and inevitable impurity; Ni+Cr+Cu 〉=1.25% wherein; W(Cr): w(Cu)=2: 1 ratio.

Performance index of the present invention require: size of the present invention, profile and permissible variation are pressed the accuracy requirement of GB/714981-94 standard B group and are carried out, and surface quality is carried out according to GB/T3077-1999 standard 6.6 clauses; Every batch of 08CrNiCu hot rolling dish all must carry out 1/3 cold forging test, and the cold forging test result is intact can dispatching from the factory as salable product; Be the cold-forming property of assurance 08CrNiCu hot-rolled state wire rod, its hot-rolled state mechanical property requirements Rm 520Mpa, Z 50%, and HARDNESS OF HOT-ROLLED HBW 130.

Claims (1)

1. the 08CrNiCu low-alloy high-strength of atmospheric corrosion resistance is exempted from the production technique of annealed cold-forging steel, the 08CrNiCu low-alloy high-strength of described atmospheric corrosion resistance is exempted from annealed cold-forging steel by weight percentage, the chemical composition proportioning is: C:0.05%, Si:0.15 ~ 0.25%, Mn:0.55 ~ 0.65%, P:0.005 ~ 0.025%, S:0.005 ~ 0.02%, Cr:0.65 ~ 0.75%, Ni: 0.25 ~ 0.30%, Cu:0.35 ~ 0.40%, all the other are Fe and inevitable impurity; Production technique adopts the EAF stove just to refine-LF refining-billet continuous casting-high-speed wire rolling operational path: it is characterized in that this production technique adopts sial deoxidation smelting technology to control purity; Obtain the rational microstructure of wire rod by Controlled Rolling And Controlled Cooling, guarantee good cold-workability, its concrete smelting technology is as follows:

The EAF stove just refines: all steel-making starting material must keep dry, to reduce hydrogen richness in steel; During tapping carburetting, adopt low nitrogen carburelant, to reduce nitrogen in steel content; The molten aluminium of acid controls 0.01 ~ 0.02%;

The LF refining: refining hello CaSi line in latter stage carries out calcium to be processed, and soft stirring was greater than 3 minutes;

Billet continuous casting: continuous casting tundish target superheating temperature: 20 ~ 25 ℃;

High-speed wire rolling: single stove is rolling, must not organize and criticize; After coming out of the stove, blank must carry out dephosphorize by high pressure water; Start rolling temperature is controlled at 1000 ± 20 ℃; 890 ~ 900 ℃ of laying temperatures; Stelmo line adopts the delaying type process for cooling.