阅读说明：本技术 一种消除过共析工具钢盘条渗碳体魏氏组织的控轧控冷工艺 (A kind of cooling controlling and rolling controlling process for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure ) 是由 苏振伟 周淼 屠兴圹 张盛华 沈艳 沙梦雨 左锦中 林俊 万文华 于 2019-08-16 设计创作，主要内容包括：本发明属于轧制技术领域,涉及一种钢材控轧控冷工艺,具体的说是一种消除过共析工具钢盘条渗碳体魏氏组织的控轧控冷工艺。钢坯在不低于1210℃温度经过1.5～2小时加热,使钢中碳化物充分溶解和扩散；精轧机组、减定径机组采用不高于750℃的超低温度轧制,将轧制过程中沿奥氏体晶界析出的碳化物轧碎,并控制终轧温度不超过800℃；吐丝温度采用不高于730℃的超低温度,为轧后控冷提供低温保障；控冷前期采用3台以上水雾风机强冷,随后关闭保温罩缓冷以减少组织转变应力,同时防止出现贝氏体、马氏体。该工艺有效消除了过共析工具钢盘条显微组织中存在的渗碳体魏氏组织。(The invention belongs to rolling technical fields, are related to a kind of steel cooling controlling and rolling controlling process, specifically a kind of cooling controlling and rolling controlling process for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure.Steel billet was heated in not less than 1210 DEG C temperature by 1.5~2 hours, and carbide in steel is made sufficiently to dissolve and spread；Mm finishing mill unit, reducing-sizing mill use the ultra low temperature not higher than 750 DEG C to roll, the carbide grating that will be precipitated in the operation of rolling along austenite grain boundary, and control finishing temperature no more than 800 DEG C；Laying temperature uses the ultra low temperature not higher than 730 DEG C, provides low temperature guarantee for cooling control after rolling；It controls and uses 3 or more water mist blowers cold by force cold early period, be then turned off insulation cover slow cooling to reduce structural transformation stress, while preventing bainite, martensite.The technique effectively eliminates cementite Widmannstatten structure present in hypereutectoid tool steel wire rod microscopic structure.)

1. a kind of cooling controlling and rolling controlling process for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure, which is characterized in that technique packet Include: heating stove heating, mm finishing mill unit rolling, reducing-sizing mill rolling, spinning, water mist blower and insulation cover are cooling, and steps are as follows:

(1) steel billet is heated 1.5~2 hours by heating stove heating in not less than 1210 DEG C temperature；

(2) enter mm finishing mill unit to roll, mm finishing mill unit rolling temperature is not higher than 750 DEG C；

(3) rolled piece after mm finishing mill unit rolls enters reducing-sizing mill and is rolled into wire rod trimmed size, reducing-sizing mill rolling temperature Degree is not higher than 750 DEG C, and finishing temperature is not higher than 800 DEG C；

(4) wire rod is by Laying head lopping after finish to gauge, and laying temperature is not higher than 730 DEG C；

(5) control and open cold early period 3 or more water mist blowers and be cooled to predetermined temperature, water mist blower cooling rate not less than 12 DEG C/ s；Cold later period capping insulation cover slow cooling is controlled, slow cooling rate is not higher than 0.8 DEG C/s.

2. the cooling controlling and rolling controlling process according to claim 1 for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure, Be characterized in that: the wire rod chemical component is calculated as C:1.20~1.30%, Si≤0.20%, Mn according to mass percent :≤ 0.35%, P≤0.035%, S≤0.030%, Cr:0.50~0.70%, Ni≤0.20%, Cu≤0.25%, remaining is iron.

3. the cooling controlling and rolling controlling process according to claim 1 for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure, Be characterized in that: heating temperature described in step (1) is at 1210~1250 DEG C.

4. the cooling controlling and rolling controlling process according to claim 1 for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure, Be characterized in that: mm finishing mill unit rolling temperature described in step (2) is at 720~750 DEG C.

5. the cooling controlling and rolling controlling process according to claim 1 for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure, Be characterized in that: reducing-sizing mill rolling temperature described in step (3) is at 720~750 DEG C, 760~800 DEG C of finishing temperature.

6. the cooling controlling and rolling controlling process according to claim 1 for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure, Be characterized in that: laying temperature described in step (4) is at 700~730 DEG C.

7. the cooling controlling and rolling controlling process according to claim 1 for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure, Be characterized in that: the cooling of blower described in step (5) is 3~6 water mist blowers of unlatching, and fan delivery 85~95% controls cold early period 12~15 DEG C/s of cooling velocity, is cooled to 580~600 DEG C, controls cold 0.2~0.8 DEG C/s of later period cooling velocity.

Technical field

The invention belongs to rolling technical fields, are related to the rolling and cooling means of a kind of tool steel wire rod, specifically A kind of cooling controlling and rolling controlling process for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure.

Background technique

Tool steel be for manufacturing cutting tool, measurer, mold and the steel of wear resistant tools, hardness with higher and High rigidity and red hardness and high wearability and toughness appropriate are able to maintain under high temperature.Tool steel is generally divided into carbon, C Steel, alloy tool steel and high-speed tool steel three categories.Hypereutectoid tool steel majority is all carbon tool steel, common hypereutectoid work Has steel carbon content 0.85%~1.35%.Hypereutectoid tool steel is not easy to overheat, be remained to due to carbon content height in Quench heating Fine grain structure is kept, and has not molten superfluous carbide in steel after quenching, so wearability is high.Therefore it is widely used in manufacturing Lathe tool, milling cutter, drill bit, screw tap, screw die, scraper with sharp edge and the tool for having a little toughness, such as lathe.

Since hypereutectoid steel carbon content is high, using conventional rolling and the hypereutectoid tool steel steel hot rolling of cooling means production There is flourishing cementite Widmannstatten structure in wire rod microscopic structure.Cementite is precipitated along the certain crystal face of austenite, and in crystal grain Many parallel cementite faller gills are formed, cementite Widmannstatten structure is formed.

And due to the fragile face that a large amount of cementite faller gills are formed, make the mechanical property and flexibility dramatic decrease of steel, especially It is fallen to very with impact property.It is very big in the presence of the hypereutectoid steel tool steel wire rod brittleness of flourishing cementite Widmannstatten structure, it is unfavorable Production and processing in downstream, and reduce the mechanical performance and service life of finished tool.

Currently, the means of most steel mill's control hypereutectoid tool steel cementite Widmannstatten structure ranks mainly pass through control continuous casting It is segregated, improves billet heating temperature and extend heating time, using means such as two fiery material techniques, but do not have also in controlled rolling control at present Cold aspect controls the relevant report of hypereutectoid tool steel wire rod cementite Widmannstatten structure.

Summary of the invention

The purpose of the present invention is to provide a kind of controlled rolling and controlled coolings for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure Process can effectively eliminate cementite Wei Shi group present in hypereutectoid tool steel wire rod microscopic structure using the process It knits, solves wire rod brittleness caused by flourishing cementite Widmannstatten structure net greatly and finished tool mechanical performance, service life Reduction problem.

A kind of cooling controlling and rolling controlling process for eliminating hypereutectoid tool steel wire rod cementite Widmannstatten structure, technique includes: heating furnace Heating, mm finishing mill unit rolling, reducing-sizing mill rolling, spinning, water mist blower and insulation cover are cooling, and steps are as follows:

(1) steel billet is heated 1.5~2 hours by heating stove heating in not less than 1210 DEG C temperature；

Further, preferred heating temperature is at 1210~1250 DEG C；

(2) rolled piece enters mm finishing mill unit rolling, and mm finishing mill unit rolling temperature is not higher than 750 DEG C；

Further, preferred rolling temperature is at 720~750 DEG C；

(3) rolled piece after mm finishing mill unit rolls enters reducing-sizing mill and is rolled into wire rod trimmed size, and reducing-sizing mill rolls Temperature processed is not higher than 750 DEG C, and finishing temperature is not higher than 800 DEG C；

Further, preferred rolling temperature is at 720~750 DEG C, 760~800 DEG C of finishing temperature；

(4) wire rod is by Laying head lopping after finish to gauge, and laying temperature is not higher than 730 DEG C；

Further, preferred laying temperature is at 700~730 DEG C；

(5) cold unlatching early period 3 or more water mist blowers are controlled and are cooled to set temperature, water mist blower cooling rate is not less than 12 ℃/s；Cold later period capping insulation cover slow cooling is controlled, slow cooling rate is not higher than 0.8 DEG C/s；

Further, the preferred type of cooling are as follows: open 3~6 water mist blowers, fan delivery 85~95%, before control is cold 12~15 DEG C/s of phase cooling velocity, is cooled to 580~600 DEG C, controls cold 0.2~0.8 DEG C/s of later period cooling velocity.

The wire rod composition range is C:1.20~1.30%, Si≤0.20%, Mn :≤0.35%, P≤0.035%, S ≤ 0.030%, Cr:0.50~0.70%, Ni≤0.20%, Cu≤0.25%, remaining is iron.

Below to main technique control process of the invention to elimination hypereutectoid tool steel wire rod cementite Widmannstatten structure grade Other influence is described in detail.

Heating steel billet: section 160mm*160mm continuous casting square billet is used, is heated by recuperative heater, wherein guaranteeing base Expect that heating time under the conditions of 1210~1250 DEG C of temperature is 1.5~2 hours, Aliquation carbide is made sufficiently to dissolve and spread. Air-fuel ratio control prevents air excess from aggravating decarburization 0.45~0.65 in furnace.

If heating temperature is more than 2 hours, it will cause decarburized layer deepness to obviously increase, so that product quality is reduced, into And improve the difficulty for eliminating cementite Widmannstatten structure.

Roll in thick and roll with pre-finishing mill group: the steel billet after heating enters thick intermediate mill tandem rolling, to guarantee milling train in thick Operation of rolling rolled piece is organized all in the state of abundant austenitizing, to guarantee that the operation of rolling is gone on smoothly.Become based on being rolled in thick The shape stage, on control cementite Widmannstatten structure without influence.

Mm finishing mill unit rolling: the rolled piece after thick intermediate mill rolling carries out Water cooling, and rolled piece subsequently enters mm finishing mill unit Rolling, control enter the temperature of mm finishing mill unit at 720~750 DEG C.

Under the conditions of 720~750 DEG C of temperature, partially carbonized object and agglomeration can be precipitated in crystal boundary in rolled piece microscopic structure, But by the rolling of mm finishing mill unit, the crystal grain of rolled piece is constantly rolled broken, and the carbide of precipitation can not be distributed along crystal boundary, but Dispersed precipitate is in matrix.If rolling is higher than 750 DEG C of temperature, cementite precipitation can be dramatically increased, and be lower than 720 DEG C of temperature, deformation Drag is just too big, can not roll.

Reducing-sizing mill rolling: it is wire rod trimmed size, reducing sizing mill that the rolled piece after finish rolling, which enters reducing-sizing mill rolling, Group rolling temperature control is higher than 750 DEG C of temperature at 720~750 DEG C, and cementite precipitation can dramatically increase, and is lower than this temperature, industry Interior reducing-sizing mill can not be rolled normally.And reducing-sizing mill temperature selection be it is consistent with mm finishing mill unit, because of finish rolling Unit and reducing-sizing mill have cooling water tank, although therefore by mm finishing mill unit roll after rolled piece can heat up, can be cooled Get off, to guarantee that the temperature for entering reducing-sizing mill is consistent with the temperature of mm finishing mill unit.

In the reducing-sizing mill operation of rolling, crystal boundary can further be precipitated partially carbonized object and assemble length in rolled piece microscopic structure Greatly, but since reducing-sizing mill is still rolling, the carbide being newly precipitated is caused still to be distributed along crystal boundary, and before this in finish rolling The carbide that is precipitated can be also rolled broken when unit rolls, and Dispersed precipitate is in matrix.The ultralow temperature of reducing-sizing mill rolls real The reduction of finishing temperature is showed, finishing temperature guarantees at 760~800 DEG C, not only inhibits and rolls rear crystal grain and grow up, keeps crystal boundary thin It is small.

Spinning: wire rod is controlled laying temperature at 700~730 DEG C by water tank water cooling by Laying head lopping after finish to gauge, Advantage is provided for control cooling later.

Control cold: roll rear wire rod control it is cold realized on Stelmor controlled cooling line, it is cooling using water mist blower.Control cold beginning first 3~6 water mist blowers are opened, fan delivery 85~95% controls cold 12~15 DEG C/s of cooling velocity early period, it is cooled to 580~ 600 DEG C of laggard insulation cover slow cooling processing, make wire rod with the cooling velocity Slow cooling of 0.2~0.8 DEG C/s, until being cooled to 500 DEG C Hereinafter, the brittle failure tendency to reduce the stress of structural transformation, after reduction wire rod is offline.

If cooling velocity early period can not effectively eliminate cementite Widmannstatten structure lower than 12 DEG C/s, can make if being higher than 15 DEG C/s Wire rod structural transformation stress, which increases, even generates martensite, and then causes brittle failure.If entering slow temperature > 600 DEG C, cementite still exists It is precipitated, therefore is difficult to ensure and eliminates cementite Widmannstatten structure.

Advantages of the present invention: it does not need to carry out prolonged High temperature diffusion to blank, it is only necessary to heat 1.5~2 in high temperature section Hour, improve production efficiency；Using a fiery material small billet rolling, do not need to considerably reduce life using two fiery material techniques Produce cost；Mm finishing mill unit, reducing-sizing mill use low temperature controlled rolling, and spinning uses low temperature；It is cooling using water mist blower after rolling, then The assembled scheme of slow cooling immediately effectively inhibits the formation of cementite Widmannstatten structure, eliminates disk by rolling and cooling technique Cementite Widmannstatten structure in microscopic structure.

Detailed description of the invention

Fig. 1 be Φ 10.0mm specification T12 wire rod using cooling controlling and rolling controlling process of the invention obtain without cementite Wei Shi group Knit photo (0 grade)；

Fig. 2 is the Typical carburization body Widmannstatten structure photo that Φ 10.0mm specification T12 wire rod uses 1 technique of comparative example to obtain (2.0 grades)；

Fig. 3 is the Typical carburization body Widmannstatten structure photo that Φ 10.0mm specification T12 wire rod uses 2 technique of comparative example to obtain (3.0 grades).

Specific embodiment

Illustrate by taking the production of hypereutectoid tool steel T12 wire rod (Φ 10.0mm) as an example:

The specific ingredient of T12 (Wt.%) is as follows:

The trade mark

C

Si

Mn

P

S

Cr

Ni

Cu

T12

1.23-1.29

≤0.20

≤0.35

≤0.035

≤0.03

0.50-0.70

≤0.20

≤0.25

Steel rolling process process: it is rolled and pre-finishing mill group-mm finishing mill unit-reducing-sizing mill-during recuperative heater-is thick Laying head-water mist blower cooling-closing insulation cover slow cooling-bundling.The condition for not making wherein to limit is normal condition, to infiltration Carbon body Widmannstatten structure is without influence.