CN103266269B - HB500 grade hot continuous rolling high strength wear-resisting steel and production method thereof - Google Patents

Abstract

The invention relates to HB500 grade hot continuous rolling high strength wear-resisting steel which comprises the components in percentage: 0.21-0.30% of C, less than or equal to 0.20% of Si, 0.8-1.60% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.10-0.40% of Mo, 0.050-0.20% of Ti, 0.0005-0.0030% of B and less than or equal to 0.0050% of N, wherein the condition is met that Ti/N is greater than or equal to 10, and Mo/Ti is greater than or equal to 2. The preparation method comprises the following steps: smelting and continuously casting to blanks; directly heating the blanks; continuously rolling; batching; finishing and cutting; heating and insulating by a thermal treatment furnace; quenching by a roller type quenching machine; performing water cooling to reach room temperature; and annealing at low temperature and air-cooling to room temperature. According to the invention, the production cost is lower, and the Brinell Hardness of the steel plate after thermal treatment reaches 480-520 and KV2 at minus 40 DEG C is greater than or equal to 30J. The steel plate is excellent in shape, and the inequality in the length direction is less than or equal to 13mm/1000mm. The steel plate is good in cold roll forming performance.

Description

A kind of HB500 level hot continuous rolling high-strength wearable steel and production method thereof

Technical field

The present invention relates to wear resisting steel and production method thereof, belong to HB500 level hot continuous rolling high-strength wearable steel and production method thereof particularly.

Background technology

Wear resisting steel is the class high-abrasive material being widely used in the various wear working conditions such as metallurgy, mine, building materials, electric power, railway and military affairs, is one of most important steel grade of current China construction machinery industry.In recent years, along with manufacturing development, Thin Specs high-strength wearable steel becomes new demand direction.Because wear resisting steel Working environment is comparatively severe, require that it must possess enough hardness and resist wearing and tearing, possess certain toughness simultaneously and prevent impact fracture, after Thin Specs high-strength wearable steel heat treatment, also must ensure that good plate shape and excellent cold roll forming performance are to meet process requirements in addition.

The production technology development of wear resisting steel is very fast both at home and abroad at present, has formed the standards system of system and perfect product line.But in these steel grades, for ensureing good mechanical property, usually by adding the precious alloys such as Ni, Cr, Nb, V to realize, as through retrieval:

The CN201010185080 patent documentation that Chinese Patent Application No. is, it discloses a kind of 500HB grade wear-resisting steel plate, and its chemical element percent mass proportioning is: C:0.23 ~ 0.33%; Si:0.10 ~ 0.50%, Mn:0.50 ~ 1.50%, Cr≤1.50%; Mo≤0.80%, Al:0.01 ~ 0.10%, Ti:0.01 ~ 0.10%, B:0.0005 ~ 0.0040%, RE:0.01 ~ 0.08%, Ca:0.002 ~ 0.010%, Ni≤2.50%, P≤0.050%, S≤0.030%, surplus are Fe and other inevitable impurity; And the mass percentage of above-mentioned each chemical element meets: 1.50% >=(Si+Mn) >=0.50%; 0.15% >=(Al+Ti) >=0.03%.Procedure of processing is: smelting, casting, heating, rolling, cooling, quenching, tempering.The steel plate obtained by the method has good machining property, and hardness can reach more than 508-523HB, and-20 DEG C of summers are than impact of collision merit 48-73J.

Chinese Patent Application No. is the patent documentation of CN200910090637, it discloses a kind of production technology method of low content alloy ultrahigh hardness wear-resistant steel plate, specifically, steel plate after rolling is carried out intensive control cooling, opening cold temperature is 850 ~ 780 DEG C, speed of cooling controls at 15 ~ 30 DEG C/s, final cooling temperature 350 ~ 550 DEG C; Air cooling is to room temperature afterwards, reheats 10min ~ 120min and is quenched to room temperature, and quenching temperature is 950 ~ 900 DEG C; Carry out 100 ~ 400 DEG C of tempering to the steel plate after quenching, tempering time is at 20min ~ 180min.Composition is by weight percentage for C:0.2 ~ 0.25%, Si:0.3 ~ 2.0%, Mn:1.5 ~ 1.9%, Cr:0.7 ~ 1.4%, B:0.002 ~ 0.005%, Ni≤0.5%, Mo≤0.4%, Nb≤0.1%, V≤0.07%, Ti≤0.04%, alloy total amount are less than 6%, all the other are Fe and inevitable impurity, steel plate thickness is 10-50mm, and hardness is greater than 500HB.

Chinese Patent Application No. is the patent documentation of CN201210002787, it discloses a kind of high-strength abrasion-proof steel plate and preparation method thereof, this steel plate comprises following component (wt%): C 0.28 ~ 0.35%, Si 0.10 ~ 0.60%, Mn 0.7 ~ 1.0%, P≤0.025%, S≤0.010%, Cr 0.4 ~ 0.8%, Mo 0.10 ~ 0.60%, Nb 0.01 ~ 0.05%, V 0.01 ~ 0.08%, Ti 0.005 ~ 0.05%, B 0.001 ~ 0.003%, all the other are Fe and impurity; This preparation method comprises the operations such as smelting, continuous casting, controlled rolling, press quenching and low-temperaturetempering.The present invention carries out appropriate design by alloy composition and production technique, obtained product Brinell hardness number > 500HB, Hardness Distribution is even,-20 DEG C of impelling strength >=24J, microtexture is tempered martensite, and welding, cold-bending property and steel plate template are all good, and production technique is simple, cycle is short, and cost is low, can be widely used in construction machinery production.

Chinese Patent Application No. is the patent documentation of CN201110326202.1 ,it discloses " a kind of Brinell hardness is shovel loader and digger shovel blade steel and the production method of 470 ~ 520 ".Its chemical composition and weight percent are: C 0.26 ~ 0.35%, Si≤0.20 ~ 0.50%, Mn 1.0 ~ 1.50%, P≤0.020%, S≤0.015%, Cr 0.20 ~ 0.70%, Ti 0.020 ~ 0.06%, Mo≤0.35%, B 0.0005 ~ 0.0050%, Cu≤0.3%, As≤0.018%, all the other are Fe and inevitable impurity.Production stage: carry out desulfurizing iron, converter top bottom blowing, RH vacuum-treat, whole process molding casting becomes continuously cast bloom; Continuously cast bloom heats; Breaking down; Finish rolling; Stand-by (quenching; Tempering).Present component is simple, and process stabilizing, excellent in mechanical performance, cost performance is high, good welding performance, and hardened and tempered steel plate directly can weld when not preheating, and cold-bending property is good ,-40 DEG C of KV ₂>=18-36J.

Above-mentioned prior art, with the addition of Ni, Cr, Nb, V precious alloy all to some extent, result in the increase of production cost and the waste of resource; And the product specification of above-mentioned steel grade concentrates on uni-tension rolling plate of moderate thickness product (i.e. thickness specification >=15mm), and the hot continuous rolling thin panel products being less than 15mm thick did not relate to.

The technical characteristics of this patent is using C, Mn as fundamental element, utilize the Ti of relative low price as main strengthening element, add a small amount of Mo control Ti precipitation size, the B of trace is coordinated to improve steel plate hardening capacity again, by the compound action of Mo, Ti, what in rolling, heat treatment process, obtain the nano-scale (5-10nm) of a large amount of Dispersed precipitate contains Ti precipitate, and improve the obdurability of steel plate, steel plate cost of alloy is lower.

Summary of the invention

The object of the invention is to for prior art metallic element many, add noble element many, the deficiency that production cost is high, there is provided a kind of can ensure steel plate the mechanical property such as hardness, intensity prerequisite under, not only use metallic element few, noble element is common element except Mo, is produced into HB500 level hot continuous rolling high-strength wearable steel and production method thereof that instinct reduces by 20%.

Realize the measure of above-mentioned purpose:

A kind of HB500 level hot continuous rolling high-strength wearable steel, its component and weight percent content are: C:0.21 ~ 0.30%, Si :≤0.20%, Mn:0.8 ~ 1.60%, P :≤0.015%, S :≤0.005%, Mo:0.10 ~ 0.40%, Ti:0.050 ~ 0.20%, B:0.0005 ~ 0.0030%, N≤0.0050%, all the other are Fe and inevitable impurity, and meet: Ti/N >=10, Mo/Ti >=2.

Preferred: C:0.24 ~ 0.30%, Si :≤0.08%, Mn:0.9 ~ 1.40%, Mo:0.15 ~ 0.40%, Ti:0.06 ~ 0.15%, B:0.0005 ~ 0.0020%.

Produce a kind of method of HB500 level hot continuous rolling high-strength wearable steel, its step:

1) smelt also continuous casting and become base;

2) heat strand: the strand that rolls off the production line directly enters process furnace, control charging temperature and be not less than 700 DEG C, Heating temperature is 1280 ~ 1350 DEG C, and heat-up time was at 150 ~ 180 minutes;

3) carry out continuous rolling, control roughing temperature out at 1030 ~ 1070 DEG C, finish rolling finishing temperature is at 800 ~ 840 DEG C;

4) batch, control coiling temperature at 480 ~ 520 DEG C;

5) finishing cutting is carried out;

6) carry out heating and thermal insulation at heat treatment furnace, Heating temperature 870 ~ 890 DEG C, soaking time is: the data of the thickness of slab H+20 millimeter sum in units of millimeter, and time unit is minute;

7) adopt rolled quenching machine to quench, quenching temperature controls at 870 ~ 890 DEG C;

8) water-cooled is to room temperature, and water-jet Angle ambiguity is at 20 ~ 30 °, and the water yield controlling steel plate upper and lower surface compares 0.6 ~ 0.9;

9) carry out low-temperaturetempering, tempering temperature controls at 180 DEG C ~ 220 DEG C, and tempering insulation time is: the data of the thickness of slab H+70 millimeter sum in units of millimeter, and time unit is minute; After tempering insulation terminates, air cooling is to room temperature.

The mechanism of action of interalloy element of the present invention and main technique point

C: in steel of the present invention, the content of C is 0.21-0.30%, C is one of element of indispensable raising steel strength in steel, in order to ensure high tenacity, excellent weldability and cold-forming etc., C content being limited between 0.21-0.30%, not only can ensureing the intensity of steel but also be applicable to production operation.

Mn: be improve the tensile strength of steel and the element of yield strength, it does not significantly worsen the deformability of steel.In general, Mn content is favourable to improving the toughness of weld metal below 2%.In order to ensure intensity and the hardening capacity of steel, Mn content is selected 0.8 ~ 1.6%.。

The intensity of Si:Si to steel has certain strengthening effect, but Si is harmful to the plasticity of steel and toughness, must control its content in steel.

P, S:P have the disadvantageous effect such as low-temperature impact toughness, raising ductile-brittle transition temperature easily causing segregation, deterioration welding property, restriction reduction steel in steel.But be then combined with the Mn easily in steel and form MnS and be mingled with, thus affect the low-temperature impact toughness of steel.Therefore, in the present invention, the disadvantageous effect of P, S element to Steel Properties should be reduced as far as possible, thus controlled at P≤0.015%, S < 0.005%.

Mo:Mo effectively can extend the incubation period of perlitic transformation, and ferrite and pearlite region is moved to right, but very little on the impact of bainitic transformation.Mo can reduce the diffusibility of carbide forming element as Ti etc., thus hinders the formation of carbide, postpones the precipitation process of carbide, the effective TiC precipitate quantity increasing steel grade nano-scale.

Ti:Ti is main alloy element of the present invention, add the effect that Ti element can play dispersion-strengthened and crystal grain thinning, the precipitation situation of Ti in continuous casting and rolling steel flow process is as follows: 1) at continuous casting and cooling stages, with TiN and liquation (accounting for 15% of total Ti content); 2) in the soaking stage; TiN particle coarsening; 3) the tandem rolling stage, TiC deformation inductdion in austenite is separated out; 4) there is the alternate precipitation of TiC in the layer cold stage; 5) coil ing one TiC separates out in ferrite.Experiment proves, the size of particles that Ti separates out in ferrite is significantly less than the size of precipitation particles in austenite, strengthening effect is more obvious, so more wish the tiny TiC obtaining separating out in coiling process, therefore the precipitation phase of control Ti and size of particles are the keys of Appropriate application Ti.

B:B can significantly improve the hardening capacity of steel, but add excessive B can be unfavorable in the toughness of crystal boundary enrichment to steel, therefore its content controls 0.0005 ~ 0.0020%.

N: the N in steel can be combined with Ti; oarse-grained TiN is formed in casting process; in 2 Mo Steel Slab during Heating Process subsequently; this TiN particle does not dissolve substantially; disadvantageous effect is caused to performance; decrease the amount of precipitation to the favourable nano level TiC of performance, therefore must control by low N in smelting process, N content controls below 0.0050% simultaneously.

First Ti/N: steel grade Ti be combined with N and form TiN, is to ensure that residue Ti and C combines the enough disperse educt TiC particles of acquisition, gives full play to the precipitation strength effect of Ti, stoicheiometry Ti/N >=10 of Ti and N in steel.

The interpolation of Mo/Ti >=2:Mo element can containing the size of Ti precipitated phase in refinement steel, what is more important Mo has participated in the precipitation of precipitated phase directly thus has added the quantity of precipitated phase, also can suppress or precipitated phase growing up under austenitic temperature of significantly slowing down simultaneously., the precipitated phase that the compound of Mo, Ti adds the tiny nano-scale (5-10nm) obtained obtains content apparently higher than the single steel adding Ti.For ensureing that enough Mo element participates in separating out containing Ti precipitate, obtaining the favourable tiny nano-scale precipitated phase of obdurability and suppressing it to grow up in heat-processed subsequently, in steel the chemical composition proportioning of Mo/Ti necessary >=2.

In process: rolled off the production line by continuously cast bloom and directly fill technique (continuous casting billet skin temperature >=700 DEG C), can significantly save energy, during high temperature, strand plasticity is better simultaneously, effectively can prevent the insufficient disconnected base accident caused of thermal stresses release in slab cooling process; Lower finish rolling finishing temperature (finish rolling finishing temperature 800-840 DEG C) can ensure that steel plate of the present invention obtains the austenite crystal of flattening when Unhydrated cement rolling, obtains larger deformation energy storage; Lower coiling temperature (480 ~ 520 DEG C) can reduce the size of Ti-Mo complex precipitates in coiling process by crystal grain thinning simultaneously; Suitable quenching temperature (870-890 DEG C) and soaking time can ensure steel plate complete austenitizing, and austenite crystal is not grown up simultaneously, can obtain tiny lath martensite in quenching process; Quenching process water-jet Angle ambiguity between 20 ~ 30 ° and the water yield controlling steel plate upper and lower surface than 0.6 ~ 0.9, effectively can control the distortion of steel plate upper and lower surface, ensure steel plate roughness after quenching; Suitable tempering temperature (tempering temperature controls at 180-220 DEG C) and soaking time can reduce quenching stress, improve steel plate toughness, the final steel plate obtaining obdurability coupling.

The present invention has the following advantages compared with traditional high-strength wearable steel:

(1) cost performance is high, with traditional high-strength wearable steel Ni, V, Nb as compared with main alloy element, the Ti that have employed relative inexpensiveness coordinates a small amount of Mo element as main alloy element, makes production cost lower, has good economic benefit and social benefit;

(2) after heat treatment, steel plate Brinell hardness reaches 480 ~ 520 ,-40 DEG C of KV ₂>=30J, meets user's service requirements completely;

(3) after heat treatment steel-plate shape is excellent, length direction roughness≤13mm/1000mm;

(4) steel plate cold bending good forming ability, adopts B=30mm clod wash sample, transverse cold bending D=4a bending 180 ° qualified.

Embodiment

Below the present invention is described in detail:

Table 1 is the chemical composition value list of various embodiments of the present invention and comparative example;

Table 2 is the main rolling technological parameter list of various embodiments of the present invention and comparative example;

Table 3 is various embodiments of the present invention and the list of comparative example thermal treatment process;

Table 4 is various embodiments of the present invention and comparative example mechanical properties test result.

Various embodiments of the present invention are produced according to following steps:

Its step:

1) smelt also continuous casting and become base;

2) to strand heating, the continuous caster strand that rolls off the production line directly enters stove, and control charging temperature and be not less than 700 DEG C, Heating temperature is 1280 ~ 1350 DEG C, and heat-up time was at 150 ~ 180 minutes;

3) carry out continuous rolling, control roughing temperature out at 1030 ~ 1070 DEG C, finish rolling finishing temperature is at 800 ~ 840 DEG C;

4) batch, control coiling temperature at 480 ~ 520 DEG C;

5) finishing cutting is carried out;

6) steel plate enters heat treatment furnace and carries out heating and thermal insulation, Heating temperature 870 ~ 890 DEG C, and soaking time is: the data of the thickness of slab H+20 millimeter sum in units of millimeter, and time unit is minute;

7) adopt rolled quenching machine to quench, quenching temperature controls at 870 ~ 890 DEG C;

8) water-cooled is to room temperature, water-jet Angle ambiguity between 20 ~ 30 ° and the water yield controlling steel plate upper and lower surface than 0.6 ~ 0.9;

9) carry out low-temperaturetempering, tempering temperature controls at 180 DEG C ~ 220 DEG C, and tempering insulation time is: the data of the thickness of slab H+70 millimeter sum in units of millimeter, and time unit is minute; After tempering insulation terminates, air cooling is to room temperature.

Table 1 various embodiments of the present invention and comparative example chemical composition (Wt%)

Sequence number	C	Si	Mn	P	S	Mo	Ti	B	N	Ti/N	Mo/Ti
												1	0.30	0.02	0.90	0.015	0.004	0.24	0.12	0.0009	0.0031	38	2.0
2	0.28	0.02	1.05	0.011	0.001	0.32	0.15	0.0030	0.0042	36	2.1
												3	0.25	0.08	1.40	0.013	0.002	0.15	0.06	0.0027	0.0028	28.5	2.5
4	0.24	0.05	1.21	0.006	0.002	0.28	0.12	0.0012	0.0036	33	2.3
												5	0.24	0.05	1.37	0.011	0.005	0.40	0.08	0.0018	0.0050	16	5.0
6	0.27	0.07	1.13	0.008	0.001	0.36	0.13	0.0005	0.0043	30	2.76
												Contrast 1	0.25	0.06	1.20	0.012	0.003	—	0.10	0.0020	0.0035	29	—
Contrast 2	0.23	0.03	1.18	0.014	0.004	0.30	0.02	0.0022	0.0040	5	15

Table 2 various embodiments of the present invention and comparative example hot continuous rolling process

Table 3 various embodiments of the present invention and comparative example thermal treatment process

Table 4 various embodiments of the present invention and comparative example performance test results

Note: 8mm, 10mm steel plate impacts toughness test and adopts the non-standard sample of 7.5*10*55mm.

Above-described embodiment is only the best and exemplifies, and is not the restriction to embodiments of the present invention.

Claims (2)

1. a HB500 level hot continuous rolling high-strength wearable steel, its component and weight percent content are: C:0.21 ~ 0.30%, Si :≤0.08%, Mn:0.8 ~ 1.60%, P :≤0.015%, S :≤0.005%, Mo:0.10 ~ 0.40%, Ti:0.12 ~ 0.20%, B:0.0005 ~ 0.0030%, N≤0.0050%, all the other are Fe and inevitable impurity, and meet: Ti/N >=10, Mo/Ti >=2.

2. the method for a kind of HB500 level hot continuous rolling high-strength wearable steel described in production claim 1, its step:

1) smelt also continuous casting and become base;

2) heat strand: the strand that rolls off the production line directly enters process furnace, control charging temperature and be not less than 700 DEG C, Heating temperature is 1305 ~ 1350 DEG C, and heat-up time was at 150 ~ 180 minutes;

3) carry out continuous rolling, control roughing temperature out at 1030 ~ 1070 DEG C, finish rolling finishing temperature is at 800 ~ 840 DEG C;

4) batch, control coiling temperature at 480 ~ 520 DEG C;

5) finishing cutting is carried out;

6) carry out heating and thermal insulation at heat treatment furnace, Heating temperature 870 ~ 890 DEG C, soaking time is: the data of the thickness of slab H+20 millimeter sum in units of millimeter, and time unit is minute;

7) adopt rolled quenching machine to quench, quenching temperature controls at 870 ~ 890 DEG C;

8) water-cooled is to room temperature, and water-jet Angle ambiguity is at 20 ~ 30 °, and the water yield controlling steel plate upper and lower surface compares 0.6 ~ 0.9;

9) carry out low-temperaturetempering, tempering temperature controls at 180 DEG C ~ 220 DEG C, and tempering insulation time is: the data of the thickness of slab H+70 millimeter sum in units of millimeter, and time unit is minute; After tempering insulation terminates, air cooling is to room temperature.