Method of making flat sections from zirconium-niobium alloys

FIELD: plastic metal working.

SUBSTANCE: invention is designed for manufacturing of flat sections from zirconium-niobium alloys for use as structural materials of active zone in nuclear reactors. Proposed method includes forging of ingot of zirconium-niobium alloys, hot rolling with heating in α+β-area, cold rolling with intermediate and vacuum thermal treatments. Hot rolling is carried out at one stage of heating with integral value of deformation 1nμ.2.5 and partial reductions per pass of 1nμ≤0.32 or at two heating stages at summary deformation of 1nμ≤2.8. In some cases, prior to one of hot rolling stages, hardening of semifinished products is carried out from area of existence of β-zirconium. Invention guarantees mechanical properties of structural members for active of nuclear reactors at height technical and economical characteristics of production of flat sections from zirconium-niobium alloys featuring form-changing capabilities.

EFFECT: improved economy and homogeneity of mechanical properties of rolled product.

2 cl, 2 ex, 1 tbl

 

The invention relates to the field of metal forming and heat treatment, in particular to a method for the flat profile of zirconium-niobium alloys are used as structural elements of the active zones of nuclear reactors.

To the flat profile of zirconium-niobium alloys high demands on the mechanical properties.

For reliable operation of the structural elements of zirconium alloys under operational conditions in the presence of brine formation must be uniformity of properties and provision of strength and plastic characteristics, regulated specifications. In addition, for the formation of structural elements necessary to ensure the ability of the alloy to the forming without failure.

The ability of a flat profile to the forming without fracture is characterized by mechanical properties of the alloy formed by the process.

It is known [P.D.Kaufmann and E.F.Baroch. Potential for Improvement of Mechanical Properties in Zircaloy Cold Rolled Strip and Sheet. Zirconium in Nuclear Applications. ASTM stp 551. American Society for Testing and Materials, 1974, p 129]that the most important parameters determining the mechanical properties of the end products of zirconium alloys are the temperature and deformation parameters of hot rolling. The presented method applies to the alloy is zircaloy-4 and because of differences in the chemical composition of zirconium-niobium alloys determines various conditions optimization of temperature and deformation parameters of the process.

A method of obtaining sheets of an alloy of zirconium-2.5 wt.% niobium, which includes forging ingot, hot rolling with heat in the interval boundary values which are below the temperatureturning 70÷150°C, cold rolling with intermediate and final vacuum heat treatments [EN 2021043 1]. This method adopted by the authors for the prototype. The disadvantages of this method include the lack of regulation of deformation parameters of hot rolling.

The proposed method solves the problem of obtaining a flat profile with a higher technical and economic parameters and homogeneous mechanical properties which meet the technical requirements.

This is achieved by the fact that in contrast to the known methods of producing sheets, comprising heating the forged blanks in the interval boundary values which are below the temperatureturning 70÷150°C, hot and cold rolling with intermediate and final vacuum heat treatment, the integral value of the strain hot rolling stand more lnμ=2.5, private compression for the passage of no more than lnμ=0,32.

To increase the efficiency of the process of obtaining a flat profile of zirconium-niobium alloys hot rolling is avodat with an integral value of total strain lnμ >2,8 two stage heating.

Texturing flat profile in the rolling process is important for the formation of mechanical properties. Typically, in the manufacture of flat profile share hot working prevails over share of cold-working and the most economically viable. It takes decisive importance to the hot rolling process in the formation of the mechanical characteristics of the flat profile of zirconium-niobium alloys. The most important indicator in determining the mechanical properties is the direction normal to the plane of the basis of the crystallographic lattice, which is characterized by the coefficients of the texture, or the angle to the normal direction of the flat profile.

Experimentally established that the most stable is the texture with small angles (30÷45°) the direction normal to the plane of the base to the normal direction of the flat profile. When interalloy the deflection lnμ≤2,5 hot rolling semi-finished products of zirconium-niobium alloys angle direction normal to the plane of the base to the normal direction of the flat profile is >45°. This reduces the resistance to cracking of a flat profile when tested in bending in the transverse direction of the roll axis below the values regulated by the requirements of the technical the ski conditions.

The increasing strain hot rolling heating for 1 lnμ>2,5 provides the angle of the direction of the normal to the plane of the base to the normal direction of <45°that increases the resistance to cracking of zirconium-niobium alloys in the direction transverse to the axis of rolling.

With increasing strain for 1 heating to provide hot rolling process in the optimum temperature range, there arises a need to increase private reductions per pass. With the increase in private reductions per pass more lnμ=0,32 increases the heterogeneity of the deformation and blur the texture parameters of the crystallographic lattice. As a consequence, increases the heterogeneity of the mechanical properties after tensile tests at 320÷350°and the deviations of the actual values do not provide a limit value, regulated by the requirements of technical conditions, which leads to the rejection of the final product.

The decrease in private reductions per pass during hot rolling for 1 heating results or increase the number of passes, or to the need to reduce the thickness of the forged workpiece and, accordingly, the magnitude of the deformation at the stage of rolling. Increasing the number of passes increases the temperature range of hot rolling and with a significant reduction of the temperature to uproc the structure of the alloy and the cracks in later passes.

With the goal of significantly reducing the cross-sectional area and achieve high efficiency of the process of forging ingots in industrial conditions is carried out in a high temperature region of existence β- and α+β-Zirconia phases. With decreasing thickness of the workpiece increases the deformation of the forging ingots in the high temperature area and the high activity of zirconium alloys for gas components of the atmosphere leads to an increase in the thickness of the surface oxidized layer. In addition, by reducing the thickness of the workpiece increases the percentage of the perimeter to the cross-sectional area of the workpiece that is economically feasible, as it entails an increase in the share of losses attributable to the removal of substandard oxidized layer.

The proposed method of hot rolling a 2 stage heating helps to ensure uniformity of mechanical properties and high resistance to cracking when bending tests in the transverse direction of the roll axis. Hot rolling a 2 stage allows to increase the total deformation over lnμ=2,8 for small values of private reductions per pass (lnμ≤0,32) in the optimal temperature range.

In addition, this method allows to reduce the share of losses attributable to the removal of substandard about ikenaga layer, and to increase the economic efficiency of the process.

As you know, quenching and tempering workpieces leads to phase recrystallization, improves the uniformity and dispersion of the structural-phase components of the zirconium-niobium alloys.

To achieve a higher degree of dissolution and intermetallic impurity phases for the multi-zirconium-niobium alloys by the present method are hardening of semi-finished products by heating in β-region. Tempering by heating in β-the area most effective for maximum dissolution and dispersion of intermetallic and impurity phases. The greatest efficiency of quenching is achieved if the thickness is smaller semis, but with the increase in the share of the perimeter to the cross-sectional area of the billet increases the share of losses attributable to the removal of substandard oxidized layer formed after quenching. In the case hardening of semi greater thickness decreases hardenability and efficiency of quenching, but at the same time decreases and the share of losses attributable to the removal of non-conforming layer.

A method of obtaining a flat profile zirconium-based alloys, including hardening of the β-area and leave blanks prior to hot rolling in α+β-field [EN 2184795 C2].

The disadvantages of this with the person is increasing the production cycle by conducting additional operations leave blanks. The effectiveness of vacation before heating for hot rolling in the temperature range of α+β-Zirconia low. In addition, leave blanks in an oxidizing atmosphere leads to additional saturation of zirconium alloys gas components of the atmosphere (N, H, O).

The proposed method solves the problem of obtaining a flat profile of zirconium-niobium alloys with similar mechanical properties as a result of what is in front of one of the stages of heating and rolling, defined requirements for products of zirconium-niobium alloys and economic feasibility, conduct training of semi-finished products from the field of existence β-Zirconia.

The proposed method solves the problem of obtaining a flat profile with characteristics applicable to structural elements of the active zones of nuclear reactors, more cost-effective way compared with the method of the prototype.

In the analysis of scientific and technical information ways to get flat profile of zirconium-niobium alloys having a set of essential features of the claimed technical solution is not found.

Examples of the method.

Example 1.

The process of obtaining the flat profile of the multi-zirconium-niobium alloy consisted of the following operations.

Forging ingots of the alloy is Zr - 2,2÷3.2 wt.% (x), where x is the alloying elements Nb, Sn, Fe, O, in a strip thickness of 98 mm, cutting and machining with the removal of at least 1.5 mm on the side.

Hot rolling of workpieces with up to 770°With route-strain diagram: 90→58 mm lnμ1=0,45, lnμi≤0,18, where lnμ1- integral value of the total strain, lnμi- the amount of deformation per pass.

β-hardening workpieces up to 1070°, machining with the removal of up to 3 mm on the side.

Hot rolling up to 770°With route-strain diagram: 50→4.5 mm when lnμ2=2,41, lnμ1,2=2,9, lnμi≤0,32, where lnμ1- integral deflection at the first stage of rolling, lnμ2- in the second stage, lnμ1,2- two stage rolling, lnμi- the amount of deformation per pass. Cold rolling route-strain diagram: 4,5→3,0→1,9→0,72 mm with intermediate and final vacuum heat treatments in the temperature range 530÷650°C.

Mechanical properties provided by the present method (a) and method prototype (b):

The angle at the bending tests in a direction transverse to the axis of the rolling mandrel with a radius equal to the thickness of the profile prior to the first crack (GOST 14019): (a) more than 83°b) less than 8° the depth of the hole after testing for deep drawing according to Eriksen (GOST 10510): (a) more than 8.0 mm, b) less than 7.0 mm

Example 2.

The process of obtaining a flat profile of binary zirconium-niobium alloy consisted of the following operations.

Forging ingots of alloy Zr - 2.5 wt.% Nb in strip thickness of 107 mm, cutting, machining with the removal of at least 1.5 mm on the side.

Hot rolling of the billet (the first stage) up to 760°With blanks on the route-strain diagram: 100→50 mm, lnμ1=0,7, lnμi≤0.25 in.

Hot rolling of the billet (second stage) up to 740°With route-strain diagram: 50→5.0 mm, lnμ2=2,3, lnμ1,2=3,0, lnμi≤0.25 in.

Cold rolling along the route: 5,0→2,15 mm with intermediate and final vacuum heat treatments in the temperature range 630÷740°C.

Mechanical properties after tensile tests at 320°s in the direction transverse to the axis of rolling of the flat profile of the alloy Zr-2.5 wt.% Nb shown in the table.

The inventive method of getting flat profile of zirconium-niobium alloys has been successfully tested in production JSC CHMP for release sheets with a thickness of 0.65, 1.5, and 2.0 mm

1. A method of obtaining a flat profile of zirconium-niobium alloys containing processing merged the s forging by heating in the temperature range of existence β and α+β-Zirconia, hot rolling with heat α+β-region and below not less than 70°temperature α+β⇄β turning, cold rolling with intermediate and final vacuum heat treatment, characterized in that the hot rolling is carried out with the integrated values of total strain lnμ>2,5, private reductions per pass lnμ≤0,32 or two stage heating when the total deformation lnμ>2,8, where μ - the ratio of the cross-sectional area of the flat profile before and after deformation.

2. The method according to claim 1, characterized in that the front of one of the stages of hot rolling carry out the quenching of semi-finished products from the field of existence β-Zirconia.



 

Same patents:

FIELD: rolling.

SUBSTANCE: proposed hot-rolling mill is provided with roller for measuring flatness which is installed on at least one roll table mounted before and/of after rolling stand and which acts onto at least one stand. Flatness check roller can be shifted from its working position in preset place. Roll table is furnished additionally with one roll table roller installed for turning, flatness check roller and roll table roller or rollers are arranged in compartment which can be turned by drive so that flatness check roller and roll table rollers can be set in working position by turning in same direction.

EFFECT: protection of flatness check roller from influence of ambient medium, increased quality of rolled product owing to prevention of damage to thin hot rolled strip.

20 cl, 5 dwg

Pressure roll unit // 2260491

FIELD: sets of pressure rolls of hot rolling mills for making strip and wire products.

SUBSTANCE: pressure roll unit for driving article to motion or to braking its motion along rolling line includes pair of levers mounted with possibility of rotation around mutually parallel first axles. Shafts of rolls are rested upon levers; each roll shaft is provided with journals for rotation around second axis parallel to first axis of respective lever. Pressure rolls are mounted in shafts, they are mutually spaced one form other by gap for receiving article. First electric motor is mounted with possibility of rotation through intermediate joint of levers around their first axes and with possibility of moving pressure rolls between open position when article is spaced from rolls and closed positions when article is engaged with rolls. Second electric motor drives pressure rolls to rotation. In description of invention method for controlling pressure rolls of rolling mill for moving or braking article in different zones of rolling line is also offered.

EFFECT: enhanced quality of products, improved operational reliability of apparatus.

10 cl, 5 dwg

FIELD: rolling mill stands with rolls mounted by cantilever fashion.

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EFFECT: increased total rigidity of roll set in roll stand.

5 cl, 4 dwg

FIELD: rolling processes and equipment, namely four-high rolling stands of continuous sheet rolling mills.

SUBSTANCE: four-high rolling stand includes housings, rolling and backup rolls with chocks. Protrusions are provided in chocks of upper rolling roll; said protrusions are placed with gaps in grooves of chocks of lower rolling roll. At side of changing roll, chocks of rolling rolls have shoulders arranged with gaps between struts of housing and latches. Hydraulic cylinders for balancing upper rolls are mounted in chocks of lower rolling roll. On end portions of end vertical surfaces of protrusions, in chocks of upper roll and in upper portions of reciprocal surfaces of grooves of chocks of lower roll normal relative to roll axes and similarly inclined relative to horizon there are tapers. Edges of tapers in grooves formed at crossing tapers with upper horizontal surface of chocks of lower rolling roll are spaced by distance δc from vertical surfaces of grooves determined according to relation δc = δg - δp /2 where δg - gaps between shoulders of chocks and latches or struts of housing; δp - gaps between protrusions of chocks of upper rolling roll and grooves of chocks of lower rolling roll.

EFFECT: enhanced efficiency of rolling mill, lowered labor consumption and reduced time period of roll changing procedure, increased useful life period of rolls and their bearing assemblies.

2 dwg

FIELD: rolling processes and equipment, namely manufacture of armor sheets and plates of aluminum base alloys used in aircraft- and ship manufacture, for making armored transport vehicles and so on.

SUBSTANCE: method for making armor sheets and plates of aluminum base Al-Mg-Mn alloys with Mg content no less than 4 mass % comprises steps of hot rolling of ingot to plate and finish rolling of it; performing as finish rolling warm rolling at temperature 80 - 300°C with total deformation degree no less than 60%; preferably realizing warm rolling at temperature 250 - 290°C with total deformation degree 65 - 80%. Invention provides ballistic protection degree 738 - 742 m/s for plates with thickness 38.0 -38.2 mm at firing on with armor-piercing shells 7.62.

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4 cl, 3 dwg, 2 tbl, 2 ex

FIELD: non-ferrous metallurgy; methods of titanium alloy bricks production.

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EFFECT: the invention ensures production of a brick out of the high-strength titanium alloy having a super pliability, excellent fatigue characteristics and moldability.

7 cl, 7 dwg, 21 tbl, 2 ex

FIELD: rolling; sheet rolling processes.

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EFFECT: improved planeness of rolled strips owing to increased accuracy of measurement of nonuniformity of metal flow in process of rolling.

FIELD: rolling.

SUBSTANCE: invention can be used in automation of hot and cold rolling mills. Method provides determination of parameters of elastic deformation of stand: modulus of rigidity of stand, correction factor for transfer from absolute roll-to-roll clearance of stand to relative position in respect to roll pass design point, efforts on stand elastic deformation line corresponding to beginning of linear section and use of obtained parameters for refined determination of parameters of adjustment (rearrangement) of stand. Method of determination of parameters of stand elastic deformation line is combined with process of stand designing and it is implemented at step or continuous loading of stand rolls by roll compression force created by hydraulic pressure devices from minimum stand off-loading force to designing force. Proposed method improves accuracy of adjustment (rearrangement) of rolling stand by roll-to-roll clearance, decreases breaking of strips and increases yield of good strips by decreasing rejection of metal caused grow-back defect, reduces consumption of metal and work and support rolls owing to exclusion of additionally changing and re-grinding of rolls in case of strip break in stand.

EFFECT: increased yield of strips.

3 cl, 4 tbl, 2 ex, 4 dwg

FIELD: rolling.

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3 cl, 4 tbl, 2 ex, 4 dwg

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4 dwg

FIELD: plastic working of metals, possibly manufacture of thin high-strength foil of titanium.

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2 cl, 2 tbl

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EFFECT: automatic prevention of roll skewing, enhanced quality of rolled products, improved operational properties of roll.

6 cl, 2 dwg

FIELD: rolled stock production, namely equipment of shape bending mills, mainly for making tinned corrugated sheets.

SUBSTANCE: drive unit of shape bending mill with first guiding stand and pulling roller devices includes motor, reduction gear, sprockets, forcing and tensioning gear wheels, roller chain embracing sprockets along S-shaped curve and sine curve. Torque of motor is transmitted only to lower shaping rolls of even stands and of last stand of mill and also to both rolls of guiding stand and to horizontal rollers of pulling devices through sprockets mounted on their axles. Chain embraces sprockets of rolls of guiding stand and of rollers of pulling devices along S-shaped curve and it embraces sprockets of drive rolls and sprockets that are not joined with shaping rolls along sine curve. Axles of sprockets that are not joined with shaping rolls may be arranged higher than axles of lower drive rolls by value determined according to relation given in claims of invention.

EFFECT: lowered cost of shape bending mill, reduced power consumption for profiling, enhanced quality of ready shapes.

2 cl, 1 dwg, 1 ex

FIELD: automation of rolling processes.

SUBSTANCE: method comprises steps of measuring disturbance-stimulated strip thickness in front of rolling stand; controlling measurement result until inlet of stand; compensating it in stand by moving screws of screw-down mechanism at predetermined rate for preset time interval; measuring fluctuation of strip thickness relative to predetermined value when strip leaves stand; acting upon movement rate of screws according to disturbance and to fluctuation of strip thickness after multiplying said values and differentiating received product.

EFFECT: enhanced accuracy and reliability of controlling strip thickness.

2 dwg

FIELD: continuous rolling of strip, namely rolling strip having different thickness portions joined through transition wedge-shaped portion.

SUBSTANCE: method is used for rolling metallic strip 1 in rolling mill having at least two rolling stands. Metallic strip 1 has at least two zones 3,4 of different thickness mutually joined through wedge-shaped or approximately wedge-shaped transition portion 2. Rolling rate in rolling stand at rolling wedge-shaped portion 2 is tuned depending upon forward slip of rolling stand and also depending upon temperature of metallic strip 1. Apparatus for rolling includes rolling mill having at least two rolling stands providing tuning of rolling rate at rolling wedge -like or approximately wedge-like transition portion 2 of strip depending upon forward slip of rolling stand and upon temperature of metallic strip 1.

EFFECT: enhanced quality of rolled products.

2 cl, 5 dwg

FIELD: rolling equipment, namely transporting apparatuses, particularly roller table of rolling mill.

SUBSTANCE: roller table includes driven transporting rollers and lifting mechanism; lifting framework jointly mounted on struts and supporting transporting rollers; additional mechanism for lifting framework. Each mechanism for lifting framework is arranged in strut and it is in the form of sleeve, nut mounted inside said sleeve with possibility of motion and jointly connected through lug with framework; worm reduction gear joined with sleeve. In reduction gear and in sleeve there is opening in which screw is arranged. Said screw has cut splines in one end and in other end it has thread engaged with nut of sleeve. At least in one strut rotary crosspiece is jointly mounted. Lifting mechanism is mounted on said crosspiece.

EFFECT: enhanced operational efficiency of mill due to elimination of jamming movable links.

2 dwg

FIELD: automation of rolled stock production.

SUBSTANCE: at controlling thickness of tube wall in multi-stand continuous stretch-reducing mill, thickness of tube wall is measured behind mill by means of wall thickness measuring devices. Measured values are processed in computing unit. Revolution numbers of drive engines of rolls are controlled by means of units for controlling revolution number. In order to minimize formation of inner multi-arc profile at passing tube, total elongation value is kept constant due to changing revolution number of drive engines of rolls under control of computing unit.

EFFECT: enhanced quality of products.

5 cl, 4 dwg

FIELD: making of embossing on the commercial packing materials.

SUBSTANCE: the offered technology is dealt with making embossment on the flat materials and is used for packing of tobacco products. Rollers of the devices for making embossment, which are used for machining of the flat materials, including the firs driven roller and the conjugate roller are located in parallel to each other in a holder and may be placed so, that to enter into a definite mutual contact. At least one of the rollers for making embossment is located in a replaceable unit. At that the replaceable unit is supplied with retention tools. The holder contains pockets, the form of which is in essence complimentary for the retention tools so, that the replaceable unit may be entered in a predominantly defined position into the holder by insertion of the retention tools into corresponding pockets. The given technology provides more mild replacement of the rollers.

EFFECT: the invention ensures more mild replacement of the rollers.

20 cl, 16 dwg

FIELD: rolled stock production, namely apparatuses for mounting -dismounting bearing unit of backup roll of rolling stand.

SUBSTANCE: apparatus includes chock in which bearing assembly for roll journal is arranged. Apparatus that may be temporarily joined with bearing unit and may be axially moved in direction of backup roll and from it includes lever type inner and outer cams. Inner cams are introduced to end part of backup roll journal; outer cams are introduced to bearing unit. Inner and outer cams are mounted with possibility of rotation and locking by means of bayonet type lock in end part of journal and in bearing unit. End part of journal and intermediate ring screwed-on to bearing unit at its outer side are in the form of clover leaf having through grooves for inner and outer cams. Said cams after their rotation to clamp position may engage with respective locking protrusions of journal end part and of intermediate ring. In front of outer cams, pressure ring arranged before bearing assembly of journal is mounted.

EFFECT: lowered costs of changing bearing assemblies, increased useful life period and enlarged using range of apparatus.

5 cl, 3 dwg

FIELD: metallurgy, processes for making hot rolled band of magnesium alloy.

SUBSTANCE: method comprises steps of producing strip blank by continuous casting of melt of magnesium alloy; hot rolling of strip blank directly after casting at several passes for producing hot rolled band with thickness no more than 50 mm. Hot rolling is performed at initial temperature values 250°C - 500°C for providing final thickness of band no more than 4 mm. At first pass of hot rolling reduction degree is equal at least to 15%.

EFFECT: possibility for making magnesium sheets with improved deformation capability at less costs of manufacturing process.

11 cl, 1 dwg, 2 tbl, 1 ex

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