CN107574280A - A kind of preparation method of hot rolled ribbed bars - Google Patents

Abstract

The invention discloses a kind of preparation method of hot rolled ribbed bars, belong to the production technical field of low-alloy steel.A kind of preparation method of hot rolled ribbed bars, step include:Desulfurizing iron, converter smelting, nitrogen flushing, continuous casting, square billet are heated, rolled, controlling cold, cold bed air cooling；High ferrochrome mineral aggregate is added during desulfurizing iron, in sintering feed, controls outbound molten iron S≤0.045%；During converter smelting, 1,620 1670 DEG C of tapping temperature is controlled, the 6min of time 3, alloy raw material is added during tapping and carries out deoxidation, control chromium amount of oxidation 35 47%, C：0.21‑0.25%、Si：0.40‑0.60%、P≤0.045%、S≤0.045%、Ceq≥0.38%、Mn：0.90‑1.00%、Cr：0.06 0.19%, surplus is Fe and impurity.The present invention utilizes molten iron residual elements, compensator alloy manganese element, drops low alloy-consumption.

Description

A kind of preparation method of hot rolled ribbed bars

Technical field

The invention belongs to the production technical field of low-alloy steel, in particular to a kind of preparation method of hot rolled ribbed bars.

Background technology

As the labyrinth such as rapid development, large public building, skyscraper of building industry is to the demand of reinforcing bar Measure increasing, the requirement more and more higher to reinforcing bar bearing capacity.

The traditional processing technology of the reinforcing bar of HRB400MPa ranks is the carbon manganese steel system of the mainly composition based on 20MnSi Composition designs, manganese and alloying with silicon are carried out using manganese systems and silicon series ferroalloys, vanadium micro-alloying is carried out with vanadium iron or VN alloy, Or Nb-microalloying is carried out using ferrocolumbium, its main component controls Mn constituent contents, and Si elements exist between 1.2-1.6% Between 0.40-0.60%, C element is between 0.17-0.25%, yield strength (Rel) >=400MPa, and tensile strength >= 550MPa, the contraction percentage of area (A) >=16%, but there are the following problems for this method：Silicomanganese and carbon content are higher, cost of alloy liter It is high；The higher welding performance of carbon equivalent is poor；Easily there is surrender unobvious and mixed crystal phenomenon.

Because reinforcing bar requires higher to alloy manganese content（More than 1.05%）Between 1.2-1.6%, steel grade manganese element mainly according to Completed by steelmaking alloy process, increase manganese using silicomangan, silicomangan cost is higher, and silicon need to be consumed by averagely increasing manganese 0.01% Manganese alloy 0.17kg/ ton steel, manganese content can reduce STEELMAKING PRODUCTION cost in reducing steel under the premise of steel performance after ensureing to roll, Therefore, it is the effective way for reducing cost to seek cheap element instead of common metal element.

The content of the invention

It is an object of the invention to provide a kind of preparation method of hot rolled ribbed bars.

The present invention is achieved by the following technical solutions：

A kind of preparation method of hot rolled ribbed bars, step include:Desulfurizing iron, converter smelting, nitrogen flushing, continuous casting, square billet heating, Roll, control cold, cold bed air cooling；

During wherein described desulfurizing iron, high ferrochrome mineral aggregate is added in sintering feed and carries out ironmaking production, Chromium in Ores element is in height Furnace reduction is that simple substance chromium enters molten iron, controls outbound molten steel sulfur content S≤0.045%；

During described converter smelting, it is 1620-1670 DEG C to control tapping temperature, and tap time 3-6min, adds alloy during tapping Raw material carries out deoxidation, and control chromium amount of oxidation is in 35-47%, C：0.21-0.25%、Si：0.40-0.60%、P≤0.045%、S ≤0.045%、Ceq≥0.38%、Mn：0.90-1.00%、Cr：0.06-0.19%, surplus are Fe and inevitable impurity.

Further, during described converter ironmaking, Cr is worked as：During 0.06-0.10%, Mn is controlled：0.97-1.00%；Work as Cr： During 0.10-0.14%, Mn is controlled：0.93-0.97%；Work as Cr：During 0.14-0.19%, Mn is controlled：0.90-0.93%.

Described reinforcing bar is HRB400E reinforcing bars, high line φ 10.

The present invention utilizes molten iron remnants chromiums, compensator alloy manganese element, drops low alloy-consumption.Manganese main function in steel Have：Improve the quenching degree of steel；Improve the intensity of low-carbon and middle carbon pearlitic steel；Improve the high-temperature instantaneous intensity of steel.Chromium is in steel Effect be：Improve the intensity and hardness of steel；Improve the high-temperature mechanical property of steel；Make steel that there is good corrosion resistance and antioxygen The property changed；Prevent graphitization；Improve quenching degree.For hot rolled ribbed bars, manganese and the element of chromium two are acted in steel with weight Part is closed, steel performance is influenceed in steel according to manganese, chromium, inventor, which sums up two kinds of elements, can improve the intensity of steel and hard Degree, improve the quenching degree of steel.Learnt according to carbon equivalent calculation formula Ceq=C+Mn/6+ (Cr+V+Mo)/5+ (Cu+Ni)/15 in steel Each element contributes carbon equivalent relation, and wherein Mn and Cr relation can be approximately Mn/6=Cr/5, that is, ensure certain carbon equivalent premise Under, Cr, which improves 0.05%, can reduce Mn0.06%.

In converter smelting process, chromium highest oxidation amount 47%, average 39%, average remnants 61%, Blowing Nitrogen Process after tapping Ensure that alloying component is full and uniform.Because manganese and iron form solid solution, the hardness and intensity of ferrite and austenite in steel are improved； It is again simultaneously carbide former, a part of iron atom is substituted into cementite；In addition, manganese is critical due to reducing in steel Transition temperature, play a part of refining pearlite, also play a part of improving pearlitic steel intensity indirectly；Manganese stable austenite The ability of tissue is only second to nickel, also strongly increases the quenching degree of steel.And chromium is solid-solution in matrix in steel, crystal grain thinning can The intensity of steel is dramatically increased, reduces critical cooling rate, improves quenching degree；And Cr forms carbide with C, Fe, steel can be improved Hardness and wearability.Analyzed according to Cr, Mn element effect contrast played in steel, inventor proposes to replace with residual chromium in steel Alloy manganese, steel-smelting alloy consumption on the one hand can be reduced, residual elements in molten iron is utilized effectively.

In order to verify the effect according to reinforcing bar made from the inventive method, tension test has been carried out respectively, test Rel, R_{M values}Contrast test, performance test result is as shown in table 1,

Composition corresponds to mechanical property after the corresponding mechanical property of table 1

Learnt by upper table comparative analysis, in steel after the rise of Cr contents, in the case of carbon equivalent is ensured, steel rolling process is not adjusted Whole, the appropriate alloy Mn contents that reduce do not make significant difference influence on mechanical property, can meet finished product mechanical property requirements.

The present invention utilizes molten iron residual elements, compensator alloy manganese element, drops low alloy-consumption.

Embodiment

In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to embodiments, to the present invention It is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to Limit the present invention.

Embodiment 1

A kind of preparation method of hot rolled ribbed bars, wherein reinforcing bar are HRB400E reinforcing bars, and high line φ 10, step includes:

（1）Desulfurizing iron：High ferrochrome mineral aggregate is added in sintering feed and carries out ironmaking production, Chromium in Ores element is reduced in blast furnace Simple substance chromium enters molten iron, controls outbound molten steel sulfur content S≤0.045%；

（2）Converter smelting：It is 1620-1670 DEG C to control tapping temperature, and tap time 3-6min, and addition alloy raw material enters during tapping Row deoxidation, control chromium amount of oxidation is in 35-47%, C：0.21-0.25%、Si：0.40-0.60%、P≤0.045%、S≤ 0.045%th, Ceq >=0.38%, work as Cr：During 0.06-0.10%, Mn is controlled：0.97-1.00%；Surplus be Fe and inevitably it is miscellaneous Matter；

（3）Then conventionally progress nitrogen flushing, continuous casting, square billet are heated, rolled, controlling cold, cold bed air cooling.

Embodiment 2

A kind of preparation method of hot rolled ribbed bars, wherein reinforcing bar are HRB400E reinforcing bars, and high line φ 10, step includes:

（1）Desulfurizing iron：High ferrochrome mineral aggregate is added in sintering feed and carries out ironmaking production, Chromium in Ores element is reduced in blast furnace Simple substance chromium enters molten iron, controls outbound molten steel sulfur content S≤0.045%；

（2）Converter smelting：It is 1620-1670 DEG C to control tapping temperature, and tap time 3-6min, and addition alloy raw material enters during tapping Row deoxidation, control chromium amount of oxidation is in 35-47%, C：0.21-0.25%、Si：0.40-0.60%、P≤0.045%、S≤ 0.045%th, Ceq >=0.38%, work as Cr：During 0.10-0.14%, Mn is controlled：0.93-0.97%；Surplus be Fe and inevitably it is miscellaneous Matter；

（3）Then conventionally progress nitrogen flushing, continuous casting, square billet are heated, rolled, controlling cold, cold bed air cooling.

Embodiment 3

A kind of preparation method of hot rolled ribbed bars, wherein reinforcing bar are HRB400E reinforcing bars, and high line φ 10, step includes:

（1）Desulfurizing iron：High ferrochrome mineral aggregate is added in sintering feed and carries out ironmaking production, Chromium in Ores element is reduced in blast furnace Simple substance chromium enters molten iron, controls outbound molten steel sulfur content S≤0.045%；

（2）Converter smelting：It is 1620-1670 DEG C to control tapping temperature, and tap time 3-6min, and addition alloy raw material enters during tapping Row deoxidation, control chromium amount of oxidation is in 35-47%, C：0.21-0.25%、Si：0.40-0.60%、P≤0.045%、S≤ 0.045%th, Ceq >=0.38%, work as Cr：During 0.14-0.19%, Mn is controlled：0.90-0.93%；Surplus be Fe and inevitably it is miscellaneous Matter；

（3）Then conventionally progress nitrogen flushing, continuous casting, square billet are heated, rolled, controlling cold, cold bed air cooling.

Claims (3)

1. a kind of preparation method of hot rolled ribbed bars, step include:Desulfurizing iron, converter smelting, nitrogen flushing, continuous casting, square billet add Heat, roll, control cold, cold bed air cooling, it is characterised in that：

During described desulfurizing iron, high ferrochrome mineral aggregate is added in sintering feed and carries out ironmaking production, Chromium in Ores element is in blast furnace It is reduced to simple substance chromium and enters molten iron, controls outbound molten steel sulfur content S≤0.045%；

During described converter smelting, it is 1620-1670 DEG C to control tapping temperature, and tap time 3-6min, adds alloy during tapping Raw material carries out deoxidation, and control chromium amount of oxidation is in 35-47%, C：0.21-0.25%、Si：0.40-0.60%、P≤0.045%、S ≤0.045%、Ceq≥0.38%、Mn：0.90-1.00%、Cr：0.06-0.19%, surplus are Fe and inevitable impurity.

A kind of 2. preparation method of hot rolled ribbed bars according to claim 1, it is characterised in that described converter ironmaking When, work as Cr：During 0.06-0.10%, Mn is controlled：0.97-1.00%；Work as Cr：During 0.10-0.14%, Mn is controlled：0.93-0.97%；When Cr：During 0.14-0.19%, Mn is controlled：0.90-0.93%.

A kind of 3. preparation method of hot rolled ribbed bars according to claim 1 or 2, it is characterised in that described reinforcing bar For HRB400E reinforcing bars.