CN105002438A - SY17MnNiVNbTi steel and preparation method of SY17MnNiVNbTi steel structural member - Google Patents

Abstract

The invention discloses SY17MnNiVNbTi steel and further discloses a preparation method of a SY17MnNiVNbTi steel structural member. The SY17MnNiVNbTi steel consists of the following ingredients by mass percent: 0.16-0.2% of C, 0.2-0.45% of Si, 1.4-1.6% of Mn, 0.3-0.5% of Ni, 0.02-0.2% of Ti, 0.03-0.06% of Nb, 0.1-0.2% of V, 0.2-0.3% of Cr, 0.03-0.06% of Mo, 0.09-0.13% of Cu, less than or equal to 0.035% of P, less than or equal to 0.035% of S, greater than or equal to 0.015% of Al, and the balance Fe, in a total of 100%. The SY17MnNiVNbTi steel and the SY17MnNiVNbTi steel structural member reaches the performances of the design requirements through a reasonable heat treatment technology; the requirements of a working environment where the steel structural member of the type is located are met; performance indexes such as the strength, the rigidity, the stability, the cold and hot processing formability and the weldability of the steel structural member are improved; and the service life of the steel structural member is prolonged.

Description

A kind of SY17MnNiVNbTi steel and steel construction piece preparation method thereof

Technical field

The invention belongs to metallurgical technology field, relate to a kind of SY17MnNiVNbTi steel, the invention still further relates to the preparation method of this kind of SY17MnNiVNbTi steel construction piece.

Background technology

At present in metallurgy industry, along with the development of metallurgical technology, progressively there is the welding low-carbon (LC) Kind of Steels Used in Engineering Structures of a class.Carbon structural steel compared by this type of steel, has lower carbon content, higher yield-point or yield strength, preferably cold and hot working formability and good weldability.This type of steel is mainly used in oil gas pipeline, TUBE IN DEEP WELL, autobody sheet and the field such as coal mine machinery, war industry equipment (steel grade of the present invention is for the preparation of war products), simultaneously due to this type of steel construction piece compare the intensity of carbon structural steel, rigidity, stability three major control indexs have larger advantage, especially in large span or heavy loading structure, advantage is more outstanding, general comparable structural carbon steel saves the steel using amount of about 20%, and therefore this kind of steel is being produced in a large number and widely used.

In view of the extensive degree of this type of low-carbon (LC) engineering steel application, for improving the mechanical propertys such as its yield strength, weldability and processing forming further, be badly in need of a kind of new SY17MnNiVNbTi steel of development.

Summary of the invention

The object of this invention is to provide a kind of SY17MnNiVNbTi steel, solve the C element existed in prior art on the low side, make the problem that its intensity, rigidity are on the low side.

Another object of the present invention is to provide the preparation method of this kind of SY17MnNiVNbTi steel construction piece.

The technical solution adopted in the present invention is, a kind of SY17MnNiVNbTi steel, according to mass percent, be made up of following component and content: C is 0.16-0.2, Si be 0.2-0.45, Mn is 1.4-1.6, Ni is 0.3-0.5, Ti be 0.02-0.2, Nb is 0.03-0.06, V is 0.1-0.2, Cr be 0.2-0.3, Mo is 0.03-0.06, Cu is 0.09-0.13, P≤0.035, S≤0.035, Al >=0.015, all the other are Fe, add up to 100%.

Another technical scheme of the present invention is, a kind of preparation method of SY17MnNiVNbTi steel construction piece implements according to following steps:

Step 1, just to refine

1.1) in EBT electric furnace, initial feed is put into

Furnace charge batching selects ordinary scrap steel to account for 97.2% of total component, and electric furnace steel tapping requires: C≤0.1%, P≤0.01%;

1.2) select high-quality steel scrap, stub bar, the melting down remnants of guaranteeing meet processing requirement, allocate with a defective material 4%-5% that lime is Metal Weight into; In time a large amount of slagging oxidation period and add slag charge, P≤0.01% when guaranteeing to tap;

1.3) steel remaining slag operation is stayed in employing, forbids oxidation sludge to enter refining bag;

1.4) electric furnace steel tapping temperature>=1650 DEG C, pre-deoxidation is carried out in tapping, and in ladle, add silicon Al-Mn and Al, silicon Al-Mn span of control is 2kg/t simultaneously _steel, Al span of control is for for 0.5Kg/t _steel;

Step 2, refining

2.1) refining bag is hung after on buggy ladle carry out argon replaces as early as possible;

2.2), after refining bag to refining station, thermometric, slag charge is added,

Slag charge composition is that lime and fluorite are prepared according to the mass ratio of 4-5:1, and refinery scum gauge control is at 200mm ± 10mm;

2.3) carry out diffusive deoxidation with carbon dust and aluminium powder, diffusion deoxidizer will add in batches; Bleach until slag, viscosity suitable after thermometric sampling, according to analytical results, liquid steel temperature is raised to >=1620 DEG C after adjust alloy compositions, add Mn, Si, Nb, Ni in batches, after alloying, temperature be raised to 1590 DEG C ± 10 DEG C;

2.4) refining operation is complete, temperature is risen to 1670 DEG C ± 10 DEG C, adds carburelant and vacuumize, and vacuum is evacuated to after below 67Pa keeps 20min and breaks sky,

Add V, Ti after broken sky, adjustment component is to pre-determined range;

2.5) refining furnace tapping temperature is 1600 DEG C-1610 DEG C;

Step 3, cast;

Casting process requires cryogenic fast injection, and teeming temperature is 1545-1550 DEG C; Rising head after-teeming operation strengthened by molten steel during rising head, riser gating time 6min, the ingot body 4min duration of pouring;

Step 4, front heat treated is forged to steel ingot;

Step 5, forging carried out to forging after positive temper.

The invention has the beneficial effects as follows, the performance of design requirements is reached by rational thermal treatment process, meet the operating environment requirements residing for this type of steel construction piece, improve the performance index such as the intensity of steel construction piece, rigidity, stability, cold and hot working formability, weldability, extend the work-ing life of steel construction piece, greatly improve production and economic benefit.

Embodiment

Below in conjunction with embodiment, the present invention is described in detail.

At the initial stage of Hi-Stren steel development, obtain the steel grade material of higher-strength, Main Means still depends on higher carbon content, by analyzing each alloying element in steel grade role, reduce and increase certain alloying element, obtaining the steel grade material meeting mechanical property requirements.But along with steel construction is by the development of riveting to welding technique, in order to improve the brittle fracture resistance of steel construction, progressively require that steel construction material meets the performance requriements of higher-strength again while of containing lower carbon content, in order to meet steel construction material, there is lower carbon content and higher intensity, steel construction material must to the future development of composite alloying, take suitable heat treatment mode, obtaining intensity and toughness when saving alloying element can the steel construction piece of good combination simultaneously.

The performance index design requirements of SY17MnNiVNbTi steel of the present invention, as shown in table 1.

The requirement of table 1 SY17MnNiVNbTi performance index

SY17MnNiVNbTi	Rm(Mpa)	Rp(Mpa)	A％	Z％	AKv(J)
						Design requirements value	520-680	≥360	≥19	≥55	≥34

Analyze and contrast component and the performance of existing Hi-Stren steel structure material, simultaneously according to the design requirements performance index of SY17MnNiVNbTi steel of the present invention, according to mass percent, be made up of following component and content:

C is 0.16-0.2, Si be 0.2-0.45, Mn be 1.4-1.6, Ni be 0.3-0.5, Ti is 0.02-0.2, Nb is 0.03-0.06, V be 0.1-0.2, Cr be 0.2-0.3, Mo be 0.03-0.06, Cu is 0.09-0.13, P≤0.035, S≤0.035, Al >=0.015, all the other are Fe, add up to 100%.

C≤0.2 in traditional Q 420C steel constituent, Mn are 1-1.7, V be 0.02-0.2, Nb is 0.015-0.06, Ni≤0.7, its C, Mn, V, Nb are controlled to the middle upper limit, residual element Ni is controlled to 0.3-0.5 simultaneously, obtain SY17MnNiVNbTi steel of the present invention.

SY17MnNiVNbTi steel constituent scope of the present invention is according to product mechanical property requirements, is controlled, meet the steel ingot requirement of this series products to Elements C, Mn, V, Nb and residual element Ni in traditional low-carbon (LC) engineering steel Q420C.

Wherein C, Mn are controlled when the middle upper limit be ensure its Mn/C than improve weldability and the toughness of steel construction as far as possible.Yield strength and the impelling strength of Mn/C comparison raising steel construction piece higher in steel construction are beneficial to, Mn can reduce γ-a transition temperature, be conducive to the forming core of acicular ferrite, the disperse educt amount of carbide in ferrite can be increased in heat-processed, in addition because high mangaenese steel causes the change of steel stress/strain characteristic, the loss of strength of Bao Xinge effect can be offset.Ni can fining ferrite grains in steel, improves the corrosion resisting property of steel, improves heat resistance and the solidity to corrosion of steel construction.Nb, V, in steel, there is the effect of obvious grain refining and precipitation hardening.By can give full play to the effect in each comfortable steel to the control of this several alloying element.

The preparation method of SY17MnNiVNbTi steel construction piece of the present invention, implements according to following steps:

Step 1, just to refine

1.1) in EBT electric furnace, initial feed is put into:

Furnace charge batching selects ordinary scrap steel to account for 97.2% of total component, and electric furnace steel tapping requires: C≤0.1%, P≤0.01%;

1.2) select high-quality steel scrap, stub bar, the melting down remnants of guaranteeing meet processing requirement, allocate with a defective material 4%-5% that lime is Metal Weight into; In time a large amount of slagging oxidation period and add slag charge, P≤0.01% when guaranteeing to tap;

1.3) steel remaining slag operation is stayed in employing, forbids oxidation sludge to enter refining bag;

1.4) electric furnace steel tapping temperature >=1650 DEG C, actual tapping temperature 1670 DEG C, pre-deoxidation is carried out in tapping, in ladle, add silicon Al-Mn and Al simultaneously,

Silicon Al-Mn span of control is 2kg/t _steel, Al span of control is for for 0.5Kg/t _steel;

Step 2, refining

2.1) refining bag is hung after on buggy ladle carry out argon replaces as early as possible;

2.2), after refining bag to refining station, thermometric, slag charge is added,

Slag charge composition is that lime and fluorite are prepared according to the mass ratio of 4-5:1, and refinery scum gauge control is at 200mm ± 10mm;

2.3) carry out diffusive deoxidation with carbon dust and aluminium powder, diffusion deoxidizer will add in batches, treat that slag bleaches, the suitable rear thermometric sampling of viscosity, according to analytical results, liquid steel temperature is raised to >=1620 DEG C after adjust alloy compositions, add alloy: (the Mn content in Mn iron is 78.12% to add middle Mn iron by 1.5% of component in batches, recovery rate about 95%), (the Si content in Si iron is 72.69% to add Si iron by 0.3% of component, recovery rate about 95%), Nb iron (the Nb content 60% in Nb iron is added by 0.035% of component, recovery rate about 90%), Ni plate (the Ni content 99% in Ni plate is added by 0.35% of component, recovery rate 95%), temperature is raised to 1590 DEG C ± 10 DEG C after alloying,

Will keep pressure-fired in refining later stage stove, constantly add diffusion deoxidizer (carbon dust and aluminium powder), keep reducing atmosphere, in refining process, will observe argon gas situation the moment, adjustment argon pressure and flow, be advisable with not exposed molten steel face in good time;

2.4) refining operation is complete, after composition is all qualified except C, V, Ti, temperature is risen to 1670 DEG C ± 10 DEG C, add carburelant (Henan Xixia Mine carburelant selected by carburelant) and vacuumize, vacuum is evacuated to after below 67Pa keeps 20min and breaks sky

Add after broken sky and add V-Fe (the V content 52.49% in V-Fe by 0.1% of component, recovery rate about 90%), add Ti-Fe (the Ti content 33.02% in Ti-Fe by 0.05% of component, recovery rate about 50%), adjustment component is to pre-determined range;

2.5) refining furnace tapping temperature is 1600 DEG C-1610 DEG C, actual tapping temperature 1605 DEG C;

Step 3, cast

Casting process requires cryogenic fast injection, and teeming temperature is 1545-1550 DEG C, and actual teeming temperature is 1550 DEG C; Rising head after-teeming operation strengthened by molten steel during rising head, riser gating time 6min, the ingot body 4min duration of pouring.

Step 4, front heat treated is forged to steel ingot

1 hour is incubated after steel ingot enters stove at 650 DEG C ± 10 DEG C, then heat-up rate is controlled at 100 DEG C/h, be warmed up to 900 DEG C ± 10 DEG C insulations 3 hours, then heat-up rate controlled at 100 DEG C/h, be warmed up to 1240 DEG C ± 10 DEG C insulations 5 hours, afterwards steel ingot pulled out heat treatment furnace and forge;

Step 5, forging carried out to forging after positive temper

Forging is incubated 4 hours at 650 DEG C ± 10 DEG C heat treatment furnaces, then heat-up rate is controlled at 100 DEG C/h, be warmed up to 920 DEG C ± 10 DEG C insulations 3 hours; After forging pulled out heat treatment furnace carry out air cooling, be cooled to be incubated 3 hours when 300 DEG C-450 DEG C until forging temperature; Heat-up rate is controlled at 100 DEG C/h again, be warmed up to 580 DEG C ± 10 DEG C insulations 6 hours, last air cooling.

The structural part of SY17MnNiVNbTi steel of the present invention is through the experimental production of too much heat, and each heat structural part performance all meets design requirements, and wherein four final components of heat (four stove steel) structural part are with reference to showing 2-1 to showing 2-4;

Table 2-1, the final component (constituent content is quality %) of steel construction piece embodiment 1 of the present invention

C	Si	Mn	P	S	Ni	Ti
							0.18	0.3	1.47	0.02	0.011	0.34	0.05
Nb	V	Al	Cr	Mo	Cu
							0.035	0.11	0.04	0.28	0.06	0.13

Table 2-2, the final component (constituent content is quality %) of steel construction piece embodiment 2 of the present invention

C	Si	Mn	P	S	Ni	Ti
							0.19	0.35	1.48	0.008	0.014	0.35	0.04
Nb	V	Al	Cr	Mo	Cu
							0.038	0.11	0.05	0.27	0.06	0.12

Table 2-3, the final component (constituent content is quality %) of steel construction piece embodiment 3 of the present invention

C	Si	Mn	P	S	Ni	Ti
							0.16	0.38	1.45	0.015	0.012	0.39	0.06
Nb	V	Al	Cr	Mo	Cu
							0.036	0.13	0.03	0.25	0.05	0.13

Table 2-4, the final component (constituent content is quality %) of steel construction piece embodiment 4 of the present invention

C

Si

Mn

P

S

Ni

Ti

0.18	0.37	1.52	0.016	0.01	0.32	0.06
							Nb	V	Al	Cr	Mo	Cu
0.034	0.12	0.04	0.2	0.03	0.09

4 steel construction piece embodiment final performance measured values of the present invention are as shown in table 3,

The final performance measured value of table 3 four embodiments

SY17MnNiVNbTi	Rm(Mpa)	Re(Mpa)	A％	Z％	AKv(J)
						Embodiment 1	618	437	27.5	67	122
Embodiment 2	618	415	25.0	66	123
						Embodiment 3	616	442	26.0	69	122
Embodiment 4	617	440	27.0	68	124

In sum, SY17MnNiVNbTi steel of the present invention and steel construction piece thereof meet design requirements, have good mechanical property, have a good application prospect.

Claims (4)

1. a SY17MnNiVNbTi steel, is characterized in that, according to mass percent, be made up of following component and content: C is 0.16-0.2, Si be 0.2-0.45, Mn is 1.4-1.6, Ni is 0.3-0.5, Ti be 0.02-0.2, Nb is 0.03-0.06, V is 0.1-0.2, Cr be 0.2-0.3, Mo is 0.03-0.06, Cu is 0.09-0.13, P≤0.035, S≤0.035, Al >=0.015, all the other are Fe, add up to 100%.

2. a preparation method for SY17MnNiVNbTi steel construction piece, is characterized in that, implements according to following steps:

Step 1, just to refine

1.1) in EBT electric furnace, initial feed is put into

Furnace charge batching selects ordinary scrap steel to account for 97.2% of total component, and electric furnace steel tapping requires: C≤0.1%, P≤0.01%;

1.2) select high-quality steel scrap, stub bar, the melting down remnants of guaranteeing meet processing requirement, allocate with a defective material 4%-5% that lime is Metal Weight into; In time a large amount of slagging oxidation period and add slag charge, P≤0.01% when guaranteeing to tap;

1.3) steel remaining slag operation is stayed in employing, forbids oxidation sludge to enter refining bag;

1.4) electric furnace steel tapping temperature>=1650 DEG C, pre-deoxidation is carried out in tapping, and in ladle, add silicon Al-Mn and Al, silicon Al-Mn span of control is 2kg/t simultaneously _steel, Al span of control is for for 0.5Kg/t _steel;

Step 2, refining

2.1) refining bag is hung after on buggy ladle carry out argon replaces as early as possible;

2.2), after refining bag to refining station, thermometric, slag charge is added,

Slag charge composition is that lime and fluorite are prepared according to the mass ratio of 4-5:1, and refinery scum gauge control is at 200mm ± 10mm;

2.3) carry out diffusive deoxidation with carbon dust and aluminium powder, diffusion deoxidizer will add in batches; Bleach until slag, viscosity suitable after thermometric sampling, according to analytical results, liquid steel temperature is raised to >=1620 DEG C after adjust alloy compositions, add Mn, Si, Nb, Ni in batches, after alloying, temperature be raised to 1590 DEG C ± 10 DEG C;

2.4) refining operation is complete, temperature is risen to 1670 DEG C ± 10 DEG C, adds carburelant and vacuumize, and vacuum is evacuated to after below 67Pa keeps 20min and breaks sky,

Add V, Ti after broken sky, adjustment component is to pre-determined range;

2.5) refining furnace tapping temperature is 1600 DEG C-1610 DEG C;

Step 3, cast;

Casting process requires cryogenic fast injection, and teeming temperature is 1545-1550 DEG C; Rising head after-teeming operation strengthened by molten steel during rising head, riser gating time 6min, the ingot body 4min duration of pouring;

Step 4, front heat treated is forged to steel ingot;

Step 5, forging carried out to forging after positive temper.

3. the preparation method of SY17MnNiVNbTi steel construction piece according to claim 2, is characterized in that: in described step 4, and detailed process is,

1 hour is incubated after steel ingot enters stove at 650 DEG C ± 10 DEG C, then heat-up rate is controlled at 100 DEG C/h, be warmed up to 900 DEG C ± 10 DEG C insulations 3 hours, then heat-up rate controlled at 100 DEG C/h, be warmed up to 1240 DEG C ± 10 DEG C insulations 5 hours, afterwards steel ingot pulled out heat treatment furnace and forge.

4. the preparation method of SY17MnNiVNbTi steel construction piece according to claim 2, is characterized in that: in described step 5, and detailed process is,

Forging is incubated 4 hours at 650 DEG C ± 10 DEG C heat treatment furnaces, then heat-up rate is controlled at 100 DEG C/h, be warmed up to 920 DEG C ± 10 DEG C insulations 3 hours; After forging pulled out heat treatment furnace carry out air cooling, be cooled to be incubated 3 hours when 300 DEG C-450 DEG C until forging temperature; Heat-up rate is controlled at 100 DEG C/h again, be warmed up to 580 DEG C ± 10 DEG C insulations 6 hours, last air cooling.