CN104164628A - High-strength automobile engine cover steel material and manufacturing method thereof - Google Patents

Abstract

The invention discloses a high-strength automobile engine cover steel material and a manufacturing method thereof. The high-strength automobile engine cover steel material comprises, by mass, 0.2-0.5% of carbon, 0.045-0.06% of silicon, 0.2-0.25% of manganese, 0.65-0.7% of cobalt, 0.03-0.05% of copper, 0.03-0.04% of boron, 0.02-0.03% of nickel, 0.001-0.003% of bismuth, 0.06-0.07% of niobium, 0.03-0.04% of tantalum, 0.02-0.05% of titanium, 0.06-0.065% of sulfur, 0.028-0.032% of phosphorus and the balance iron. The manufacturing method comprises that an alloy block is prepared and then is melt and the melt is added with alloy elements and then forms a casting so that toughness of an ultrahigh strength alloy steel forged piece is improved and a decreasing degree of a fatigue strength/tensile strength ratio of the ultrahigh strength alloy steel forged piece is reduced. Through use of rare earth metals such as bismuth, niobium and tantalum in the steel material, alloy wear-resistance and cold working performances are greatly improved.

Description

A kind of high-strength vehicle hood steel and manufacturing process thereof

Technical field

The present invention relates to a kind of steel alloy and manufacture method thereof, particularly a kind of manufacturing process of high-strength vehicle hood steel.

Background technology

The metal kit of automobile not only has higher requirement in structural strength and function, while no less important in mechanical workout, and such requirement is not only and is met the primary condition that automobile uses, and is also the safe and reliable guarantee increasing the service life simultaneously.

In prior art, the steel of producing auto parts machinery are common middle low levels steel alloy, and because these automobile metal accessories are generally moving partss frequently using in function, wear rate is very high, change frequently, have increased maintenance cost; Search out a kind of raising hardness and wear resisting property, it is extremely important that the steel alloy of the middle low levels that piece surface resistance toheat is high simultaneously just shows.

Summary of the invention

The object of the present invention is to provide a kind of manufacturing process of high-strength vehicle hood steel.

The present invention adopts following technical scheme:

High-strength vehicle hood steel, chemical element composition and mass percent thereof that it contains are: carbon 0.2-0.5%, silicon 0.045-0.06%, manganese 0.2-0.25%, cobalt 0.65-0.7%, copper 0.03-0.05%, boron 0.03-0.04%, nickel 0.02-0.03%, bismuth 0.001-0.003%, niobium 0.06-0.07%, tantalum 0.03-0.04%, titanium 0.02-0.05%, sulphur 0.06-0.065%, phosphorus 0.028-0.032%, surplus are iron.

The manufacturing process of high-strength vehicle hood steel, comprises the following steps:

(1) making of alloy block: ferrochrome and scrap iron are dropped in vacuum induction furnace and melted in 2.5-3.5:1 ratio, then add steel scrap, originate as ferrous substrate; Carry out desulfurization, deoxidation; Then add successively carbon, silicon, manganese, copper, boron, tantalum, titanium alloy element alloyed, described silicon, tantalum, titanium alloy element add-on are in its formula separately 3/5 of mass percent, in melting process, adopt refining agent refining, casting, casting postheat treatment etc., make steel billet after cooling;

(2) casting: the steel billet of step (1) is put into electric arc furnace and be melted to molten state, then add wherein silicon, tantalum, the titanium alloy element of residual content, stir, insulation 20-30 minute, add wherein again other remaining set alloying element, stir, at 1340-1550 ℃ of refining 50-55min, after insulation 15-20min, sample, after analysis ingredient, adjusting component, fusing 15-20min, casting, tapping temperature is 1150-1520 ℃;

(3) forging and thermal treatment: the profiled member in step (2) is forged, open forging temperature >=1050 ℃, final forging temperature >=880 ℃, forging deformation amount >=28%, after forging, Slow cooling is annealed to room temperature again, annealing temperature 650-700 ℃, soaking time 1-1.5h; Then carry out quench treatment, quenching temperature 820-870 ℃, tempering temperature 400-480 ℃, tempering time 40-50min.

Beneficial effect of the present invention:

The present invention first makes alloy block again by melting and adding alloying element to make foundry goods, to reach the toughness that improves ultra high strength alloy steel forging, reduce the decline degree of ultra high strength alloy steel forging fatigue strength/tensile strength ratio, in steel of the present invention by adding the rare earth metals such as bismuth, niobium, tantalum, greatly increased the wear resisting property of alloy, cold-forming property.

Embodiment

Embodiment 1: high-strength vehicle hood steel, chemical element composition and mass percent thereof that it contains are: carbon 0.4%, silicon 0.05%, manganese 0.22%, cobalt 0.68%, copper 0.04%, boron 0.035%, nickel 0.025%, bismuth 0.002%, niobium 0.065%, tantalum 0.035%, titanium 0.04%, sulphur 0.062%, phosphorus 0.03%, surplus are iron.

The manufacturing process of high-strength vehicle hood steel, comprises the following steps:

(1) making of alloy block: ferrochrome and scrap iron are dropped in vacuum induction furnace and melted in 3:1 ratio, then add steel scrap, originate as ferrous substrate; Carry out desulfurization, deoxidation; Then add successively carbon, silicon, manganese, copper, boron, tantalum, titanium alloy element alloyed, described silicon, tantalum, titanium alloy element add-on are in its formula separately 3/5 of mass percent, in melting process, adopt refining agent refining, casting, casting postheat treatment etc., make steel billet after cooling;

(2) casting: the steel billet of step (1) is put into electric arc furnace and be melted to molten state, then add wherein silicon, tantalum, the titanium alloy element of residual content, stir, be incubated 25 minutes, add wherein again other remaining set alloying element, stir, at 1550 ℃ of refining 55min, after insulation 15-20min, sample, after analysis ingredient, adjusting component, fusing 15-20min, casting, tapping temperature is 1510 ℃;

(3) forging and thermal treatment: the profiled member in step (2) is forged, open forging temperature >=1050 ℃, final forging temperature >=880 ℃, forging deformation amount >=28%, after forging, Slow cooling is annealed to room temperature again, 680 ℃ of annealing temperatures, soaking time 1-1.5h; Then carry out quench treatment, 850 ℃ of quenching temperatures, 450 ℃ of tempering temperatures, tempering time 45min.

The present invention manufacture car engine cover testing data: tensile strength sigma b>=1150MPa; Yield strength σ 0.2>=1092MPa; Unit elongation δ 5 (‰)>=9; Relative reduction in area ψ (‰)>=24; Room temperature impelling strength α ku (42 ℃)>=72J/cm ²; Low-temperature impact toughness σ ku (40 ℃)>=38J/cm ²; Hardness HRC42-45; The performances such as the tensile strength of the car engine cover that steel alloy is made thus and low-temperature impact are much better than high mangaenese steel, and can greatly improve the work-ing life of car engine cover.

Claims (2)

1. a high-strength vehicle hood steel, is characterized in that: chemical element composition and mass percent thereof that it contains are: carbon 0.2-0.5%, silicon 0.045-0.06%, manganese 0.2-0.25%, cobalt 0.65-0.7%, copper 0.03-0.05%, boron 0.03-0.04%, nickel 0.02-0.03%, bismuth 0.001-0.003%, niobium 0.06-0.07%, tantalum 0.03-0.04%, titanium 0.02-0.05%, sulphur 0.06-0.065%, phosphorus 0.028-0.032%, surplus are iron.

2. a manufacturing process for high-strength vehicle hood steel as claimed in claim 1, is characterized in that comprising the following steps:

(1) making of alloy block: ferrochrome and scrap iron are dropped in vacuum induction furnace and melted in 2.5-3.5:1 ratio, then add steel scrap, originate as ferrous substrate; Carry out desulfurization, deoxidation; Then add successively carbon, silicon, manganese, copper, boron, tantalum, titanium alloy element alloyed, described silicon, tantalum, titanium alloy element add-on are in its formula separately 3/5 of mass percent, in melting process, adopt refining agent refining, casting, casting postheat treatment etc., make steel billet after cooling;

(2) casting: the steel billet of step (1) is put into electric arc furnace and be melted to molten state, then add wherein silicon, tantalum, the titanium alloy element of residual content, stir, insulation 20-30 minute, add wherein again other remaining set alloying element, stir, at 1340-1550 ℃ of refining 50-55min, after insulation 15-20min, sample, after analysis ingredient, adjusting component, fusing 15-20min, casting, tapping temperature is 1150-1520 ℃;

(3) forging and thermal treatment: the profiled member in step (2) is forged, open forging temperature >=1050 ℃, final forging temperature >=880 ℃, forging deformation amount >=28%, after forging, Slow cooling is annealed to room temperature again, annealing temperature 650-700 ℃, soaking time 1-1.5h; Then carry out quench treatment, quenching temperature 820-870 ℃, tempering temperature 400-480 ℃, tempering time 40-50min.