CN103842527A

CN103842527A - Preparation method of steel product having different strengths using laser heat treatment, and heat hardened steel used therein

Info

Publication number: CN103842527A
Application number: CN201180073901.8A
Authority: CN
Inventors: 林熙重; 南承万; 李辅龙; 金庚保; 郑然日
Original assignee: Hyundai Hysco Co Ltd
Current assignee: Hyundai Steel Co
Priority date: 2011-09-30
Filing date: 2011-10-17
Publication date: 2014-06-04
Also published as: US20140227553A1; US20150211086A1; WO2013047939A1; KR101119173B1; JP5898772B2; EP2762577A4; JP2014534334A; EP2762577B1; EP2762577A1

Abstract

Disclosed are a preparation method of a steel product capable of local reinforcement using laser heat treatment, and a heat hardened steel used in the method. According to the present invention, the preparation method of a steel part comprises the following steps: (a) preparing a material comprising 0.1-0.5 wt% of C, 0.1-0.5 wt% of Si, 0.5-3.0 wt% of Mn, 0.1 wt% or less of P, 0.05 wt% or less of S, 0.01-1.0 wt% of Cr, 0.1 wt% or less of Al, 0.2 wt% or less of Ti, 0.0005-0.08 wt% of B, and the balance of Fe and inevitable impurities; (b) preparing a formed product by forming the material into a predetermined shape; and (c) locally reinforcing the high strength portion by carrying out laser heat treatment on a portion requiring high strength at the formed product.

Description

Use LASER HEAT TREATMENT preparation to there is the method for varying strength product made from steel and the steel of hot quenching used wherein

Technical field

The present invention relates to manufacture the mounting of for example automobile of product made from steel and the method for bumper back beam, and more specifically use LASER HEAT TREATMENT manufacture to there is the method for varying strength product made from steel and use its heat treated hardened steel.

Background technology

Recently, motor vehicle assembly is just becoming gentlier and is stronger, to improve fuel efficiency.Gentlier and stronger assembly be for example component alloying, the thermal treatment etc. of material to be realized by technique.

Recently, along with the growth of the production technology for motor vehicle assembly has developed hot stamping technology.Hot stamping technology be can there is about 500MPa by heating the material of tensile strength to approximately 900 DEG C and be configured as desired shape and the rapid cooling technology to form the production of martensite microstructure with the high strength assembly of the tensile strength that exceedes 1000MPa at one time.

No. 10-2009-0086970th, Korean Patent JP (being disclosed on August 14th, 2009), Korean Patent No. 10-0765723 (being disclosed on October 11st, 2007) has been applied hot stamping technology.

But described in above disclosing, hot stamping technology is only used to strengthen integral material and it is difficult to be applied to partially hardened.

Meanwhile, Korean Patent JP No. 10-2011-0062428 (being disclosed on June 10th, 2011) is mentioned partial reinforment hot stamping.But existing problems for using the partial reinforment of hot stamping method, for example, experienced pre-treatment such as to the certain applications isolator that does not carry out partial reinforment etc. before hot stamping.

Summary of the invention

technical problem

One aspect of the present invention provides the product made from steel that uses single-material manufacture to have varying strength and without independent pretreated method.

Another aspect of the present invention provides the heat-treatment quenching steel that can be applicable to steel production method.

technical scheme

According to the embodiment that realizes a technical scheme of the present invention, the method for manufacturing product made from steel comprises: (a) preparation comprises following material: weighing scale %, 0.1～0.5% carbon (C); 0.1～0.5% silicon (Si); 0.5～3.0% manganese (Mn); 0.1% or phosphorus (P) still less; 0.05% or sulphur (S) still less; 0.01～1.0% chromium (Cr); 0.1% or aluminium (Al) still less; 0.2% or titanium (Ti) still less; 0.0005～0.08% boron (B); And surplus is Fe and inevitable impurity; (b) by being formed to predetermined shape, described material produces molding (formed body); (c) to needing high-intensity part (high strength part) to carry out LASER HEAT TREATMENT and by described high strength part local strengthening in described molding.

According to the embodiment that realizes another technical scheme of the present invention, the ladle of heat-treatment quenching contains: weighing scale %, 0.1～0.5% carbon (C); 0.1～0.5% silicon (Si); 0.5～3.0% manganese (Mn); 0.1% or phosphorus (P) still less; 0.05% or sulphur (S) still less; 0.01～1.0% chromium (Cr); 0.1% or aluminium (Al) still less; 0.2% or titanium (Ti) still less; 0.0005～0.08% boron (B); And surplus is Fe and inevitable impurity; After thering is the tensile strength of 400～990MPa and 10～40% elongation and thermal treatment before thermal treatment, there is the tensile strength of 1200～1900MPa and 1～13% elongation.

Can on steel surface, form and be selected from the resin-coated layer of Al coating, Al-Si coating, Zn-Ni coating, Zn coating, Zn-Al coating and high-temperature oxidation resistant.

beneficial effect

According to the method for manufacture product made from steel according to the present invention, be possible by using LASER HEAT TREATMENT without the local hardening of independent pretreated single-material.Therefore, can be used to vehicle seat frame, the bumper back beam etc. of need of production tensile strength according to the method for production product made from steel of the present invention.

Intensity equally, can continue to reduce weight according to the method for manufacture product made from steel of the present invention, because may obtain and can omit stiffener via thermal treatment.

Brief description of the drawings

Fig. 1 is schema, and it shows according to the summary of the method for the manufacture product made from steel of embodiment of the present invention.

Fig. 2 is that display application is in the diagram of the example of LASER HEAT TREATMENT of the present invention.

best mode

Realizing their advantage, feature and method comes with reference to below exemplary and accompanying drawing are apparent.But should be understood that the present invention is not limited to following embodiment and can implements in a different manner, and provide described embodiment to provide of the present invention complete open and provide thorough understanding of the present invention to those those skilled in the art.Scope of the present invention only limits by appended claims and its equivalent.

Hereinafter, will specifically describe according to use LASER HEAT TREATMENT of the present invention manufacture and have method and the heat treated hardened steel used wherein of the product made from steel of varying strength.

With reference to Fig. 1, the method for manufacturing product made from steel comprises prepares material (S110), produces organizer (S120) and LASER HEAT TREATMENT (S130).

Prepare material

Prepare material preparing in material step, it comprises weighing scale %, 0.1～0.5% carbon (C); 0.1～0.5% silicon (Si); 0.5～3.0% manganese (Mn); 0.1% or phosphorus (P) still less; 0.05% or sulphur (S) still less; 0.01～1.0% chromium (Cr); 0.1% or aluminium (Al) still less; 0.2% or titanium (Ti) still less; 0.0005～0.08% boron (B); And surplus is Fe and inevitable impurity.

Equally, material can be blank shape and can use hot-rolled steel or cold-rolled steel.

Equally, can on steel surface, form and be selected from the resin-coated layer of Al coating, Al-Si coating, Zn-Ni coating, Zn coating, Zn-Al coating and high-temperature oxidation resistant to avoid surface oxidation or the decarburization in laser heat treatment process process.

Meanwhile, it is preferred preparing the heat treated steel that has certain level intensity, has excellent formability and have a superstrength by thermal treatment.

For the heat treated hardened steel with advised component,

tensile strength and

elongation be to reheat by strand, approximately more applied than the higher hot rolling of Ar3 and application

coiling temperature ordinary hot roll process or application approximately

the common cold-rolling process of annealing temperature obtain.

Equally, the heat treated hardened steel that has a described composition has added boron (B).Therefore the heat treated hardened steel that, has a described composition can have by thermal treatment tensile strength and

elongation.

Hereinafter, describe for according to every kind of component of adding of heat treated hardened steel of the present invention and the content of reason.

carbon (C)

Add carbon (C) to obtain the intensity of steel.In addition, carbon plays according to the effect of the amount stable austenite of austenite concentration.Gross weight based on steel is added

the carbon of % by weight is preferred.In the time that the amount of carbon is less than 0.1 % by weight, be difficult to obtain enough intensity.In contrast, in the time that the amount of carbon is greater than 0.5 % by weight, strength increase but weldability can decline greatly.

silicon (Si)

Silicon plays the effect of reductor and contributes to improve by solution strengthening the intensity of steel.Gross weight based on steel is added the silicon of % by weight is preferred.In the time that the amount of silicon is less than 0.1 % by weight, additive effect is insufficient.In contrast, in the time that the amount of silicon is greater than 0.5 % by weight, weldability and electroplating characteristic can decline greatly.

manganese (Mn)

Manganese (Mn) contributes to improve intensity by stabilization of austenite.

The manganese that gross weight based on steel is added 0.5～3.0 % by weight is preferred.In the time that the amount of manganese is less than 0.5 % by weight, additive effect is insufficient.In contrast, when the amount of manganese is when being greater than 3.0 % by weight, can occur that weldability declines and the problem of toughness drop.

phosphorus (P), sulphur (S)

Phosphorus (P) contributes to improve intensity, but in the time that interpolation is too much, quality of materials is because liquate reduces and weldability decline.Therefore,, based on the gross weight of steel, phosphorus content is limited to 0.1 % by weight or still less.

Equally, sulphur (S) contributes to partly to improve machining property, but in the time that interpolation is too much, can form the problem of too much MnS inclusion.Therefore,, based on the gross weight of steel, sulphur content is limited to 0.05 % by weight or still less.

chromium (Cr)

Chromium (Cr) thus improve elongation and contribute to improve intensity by improving carbon stabilization austenite in austenite concentration by stabilization ferrite.

The chromium that gross weight based on steel is added 0.01～1.0 % by weight is preferred.In the time that the amount of chromium is less than 0.01 % by weight, additive effect is insufficient.In contrast, when the amount of chromium is when being greater than 1.0 % by weight, can there is the problem that plating characteristic declines.

aluminium (Al)

Aluminium (Al) plays and prevents the effect of hydrogen embrittlement and can effectively improve ductility and coating property.But, in the time that the aluminium adding is greater than 0.1 % by weight, the ductility and the toughness that form too much inclusion and can hinder steel.

Therefore, the gross weight based on steel is added 0.1 % by weight or following aluminium is preferred.

titanium (Ti)

Titanium (Ti) is a kind of carbonitride forming element, contributes to improve intensity.At that time, in the time adding the titanium that is greater than 0.2 % by weight, can hinder toughness.

Therefore, the gross weight based on steel is added 0.2 % by weight or following titanium is preferred.

boron (B)

Boron (B) is a kind of element of strong sclerosis character, and can contribute to superhardization of the steel after thermal treatment by only adding 0.0005 % by weight.

The boron that gross weight based on steel is added 0.0005～0.08 % by weight is preferred.In the time that the addition of boron is less than 0.0005 % by weight, additive effect is insufficient.In contrast, when the amount of boron is when being greater than 0.08 % by weight, because sclerosis character too much increases, can there is greatly to hinder the problem of toughness.

Produce organizer

Next, producing in organizer shape (S120), by forming material produce organizer with predetermined shape.

Cold shapings etc. can be used for being shaped.

Meanwhile, all shapings do not need all in this step (S120), to complete, and a part is shaped and can after LASER HEAT TREATMENT, completes as deburring, fusion piercing etc.

LASER HEAT TREATMENT (local strengthening)

Next,, to needing high-intensity part (high strength part) to carry out LASER HEAT TREATMENT in organizer, high strength part is by local strengthening.

Herein, high strength part can be the part of stress concentration as the middle portion of the bumper back rest, and the part of stress concentration is as being applied to track, base, recliner or the arm etc. of mounting.

LASER HEAT TREATMENT can, by irradiating laser in high strength part if semiconductor laser local heating high strength part are to higher than Ac3, approximately be carried out for Ac3+200 DEG C, is then cooled to the temperature lower than Ms, approximately Ms～Ms-200 DEG C.

Preferably cooling with the rate of cooling of 5～300 DEG C/sec.When rate of cooling is during lower than 5 DEG C/sec, be difficult to obtain enough intensity.In contrast, when rate of cooling is during higher than 30 DEG C/sec, be difficult to obtain enough toughness and ductility.

In LASER HEAT TREATMENT, adjust laser irradiation time and laser intensity so that the tensile strength of high strength part is 1200～1900MPa.For example, can increase that laser irradiation time maybe can increase laser intensity so that the tensile strength of high strength part is about 1900MPa.In contrast, can corresponding minimizing laser irradiation time or can corresponding minimizing laser intensity so that the tensile strength of high strength part is about 1200MPa.

Also, the laser irradiation time in LASER HEAT TREATMENT and laser intensity can be different according to the target strength of high strength part.Equally, laser irradiation time and laser intensity can be different according to LASER HEAT TREATMENT laser irradiation device used.

Fig. 2 is that display application is in the diagram of the enforcement of LASER HEAT TREATMENT of the present invention.

Referring to Fig. 2, the laser radiation in LASER HEAT TREATMENT is undertaken by the high strength part that laser beam 210 is exposed to the organizer 201 being fixed on stationary fixture 220.Heat conducts to contiguous sections and certain part from the part of laser direct irradiation and is heated to and increases temperature.

Embodiment

Hereinafter, explain in further detail composition of the present invention and effect by the description of the embodiment possible according to the present invention.Be to be understood that cited embodiment is preferred embodiment and the invention is not restricted to following embodiment.

Omit the description of apparent technology for a person skilled in the art for clear.

1. production sample

Preparation rolled samples, it has the component shown in table 1 and anneal at the temperature shown in table 2.Then, sample 1～10 is carried out to LASER HEAT TREATMENT.For LASER HEAT TREATMENT, use semiconductor laser (being produced by Eurovision) so that the temperature of each sample central authorities reaches 950 DEG C and be cooled to 100 DEG C with the rate of cooling of 50 DEG C/sec afterwards.

[table 1] (unit: % by weight)

Sequence number	C	Si	Mn	P	S	Cr	Al	Ti	B
										1	0.22	0.23	1.23	0.0015	0.0001	0.17	0.04	0.018	0.003

2	0.21	0.26	1.33	0.0020	0.0008	0.20	0.05	0.022	0.003
										3	0.20	0.19	1.13	0.0115	0.0021	0.22	0.07	0.024	0.003
4	0.23	0.26	1.51	0.0098	0.0001	0.09	0.04	0.011	0.003
										5	0.19	0.22	1.61	0.0110	0.0021	0.03	0.08	0.084	0.003
6	0.23	0.26	1.51	0.0098	0.0001	0.09	0.04	0.011	0.003
										7	0.17	0.13	1.12	0.0021	0.0001	0.32	0.08	0.008	0.021
8	0.35	0.11	1.81	0.0032	0.003	0.18	0.003	0.121	0.007
										9	0.38	0.41	2.21	0.08	0.020	0.82	0.012	0.17	0.062
10	0.43	0.44	0.71	0.001	0.0002	0.92	0.09	0.18	0.001

For sample 1～10, the mechanical property (B) of the sample central authorities before mechanical property (A) LASER HEAT TREATMENT of the sample central authorities after Laser Measurement thermal treatment, and do not carry out the mechanical property (C) at the edge of the sample of LASER HEAT TREATMENT.

Measure tensile strength (TS) and elongation (El), result is as shown in table 2.

[table 2]

Referring to table 2, for the sample 1～10 after LASER HEAT TREATMENT, the tensile strength of carrying out LASER HEAT TREATMENT part becomes the superstrength of 1200～1900MPa, and the tensile strength of not carrying out LASER HEAT TREATMENT part is that 400～990MPa and elongation are 10～40%, identical with the character before thermal treatment.

Therefore, according to the present invention, the production method of steel assembly can be applicable to need the steel assembly of varying strength as the nerf bar back rest.Therefore, can omit and use independent stiffener, and can contribute to weight reduction.In addition, due to by only using LASER HEAT TREATMENT to make partial reinforment become possibility, thereby do not need to carry out providing for same material the independent pre-treatment of varying strength.

Although described some typical embodiment herein, it will be appreciated by those skilled in the art that these embodiment provide with the form of illustration, can carry out various distortion, variation and change not departing from spirit and scope of the invention.Scope of the present invention should be defined by the following claims.

Claims

1. a method of manufacturing product made from steel, it comprises:

(a) preparation comprises following material: weighing scale %, 0.1～0.5% carbon (C); 0.1～0.5% silicon (Si); 0.5～3.0% manganese (Mn); 0.1% or phosphorus (P) still less; 0.05% or sulphur (S) still less; 0.01～1.0% chromium (Cr); 0.1% or aluminium (Al) still less; 0.2% or titanium (Ti) still less; 0.0005～0.08% boron (B); And surplus is Fe and inevitable impurity;

(b) by being formed to predetermined shape, described material produces molding; With

(c) to needing high-intensity part (high strength part) to carry out LASER HEAT TREATMENT and by described high strength part local strengthening in described molding.

2. method according to claim 1 wherein, in step (a), forms and is selected from the resin-coated layer of Al coating, Al-Si coating, Zn-Ni coating, Zn coating, Zn-Al coating and high-temperature oxidation resistant on the surface of described material.

3. method according to claim 1, wherein, in step (c), described LASER HEAT TREATMENT irradiating laser and heat described high strength part to higher than the temperature of Ac3 and be cooled to the temperature lower than Ms with the speed of cooling of 5～300 DEG C/sec afterwards in described high strength part.

4. method according to claim 1, wherein, in step (a), described material has the tensile strength of 400～990Mpa and 10～40% elongation.

5. method according to claim 1, wherein, in step (c), adjusts laser irradiation time and laser intensity so that the tensile strength of described high strength part is 1200～1900Mpa in LASER HEAT TREATMENT.

6. a heat-treatment quenching steel, it comprises:

Weighing scale %, 0.1～0.5% carbon (C); 0.1～0.5% silicon (Si); 0.5～3.0% manganese (Mn); 0.1% or phosphorus (P) still less; 0.05% or sulphur (S) still less; 0.01～1.0% chromium (Cr); 0.1% or aluminium (Al) still less; 0.2% or titanium (Ti) still less; 0.0005～0.08% boron (B); And surplus is Fe and inevitable impurity;

Before thermal treatment, there is the tensile strength of 400～990MPa and 10～40% elongation; And

After thermal treatment, there is the tensile strength of 1200～1900MPa and 1～13% elongation.

7. heat-treatment quenching steel according to claim 6, wherein said steel have on the surface of described steel, form be selected from the resin-coated layer of Al coating, Al-Si coating, Zn-Ni coating, Zn coating, Zn-Al coating and high-temperature oxidation resistant.