Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
  • C22B9/16—Remelting metals
  • C22B9/20—Arc remelting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
  • B22D27/02—Use of electric or magnetic effects
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
  • B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
  • C22B9/04—Refining by applying a vacuum
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
  • F27B3/10—Details, accessories, or equipment peculiar to hearth-type furnaces
  • F27B3/28—Arrangement of controlling, monitoring, alarm or the like devices
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
  • F27D19/00—Arrangements of controlling devices

Definitions

• the invention relates to methods for manufacturing low alloy steel ingots and to steel parts obtainable by such methods.
• the minimum design curves depend not only on the average value but also on the dispersion of results. This is particularly true for parts used in the aeronautical field with which a statistical analysis is generally taken into account. Reducing the dispersion of the results therefore makes it possible to trace the minimum dimensioning curves and, consequently, to improve the performances of the parts, for example by making it possible to lighten the parts, to extend their service life or to to increase the constraints to which they may be exposed. The reduction of the dispersion of the results advantageously makes it possible to confer a competitive technical differentiation as well as an economic gain in the material used.
• the service life during oligo-cyclic fatigue stresses may depend, on the one hand, on the energy consumed at the moment of initiation on one of the particles present in the metallic material leading to a microcracking and, on the other hand, the propagation of the crack.
• a dispersion in the types of primers can induce a large dispersion of the priming energy reductions and can, therefore, further reduce the curve enveloping the minimum points (lowering of the mean and increase of the standard deviation).
• each reflow oven has a certain dispersion, inducing a dispersion of the sizes of these primers and, consequently, disparities in the lifetimes of the products obtained.
• the invention proposes, in a first aspect, a method for manufacturing a low alloy steel ingot comprising the following steps:
• the electrode comprising, before melting, iron and carbon, the molten portion of the electrode being collected in a crucible and thus forming in the crucible a molten bath, and
• step b) solidification of the molten bath by heat exchange between the melt and a cooling fluid, the heat exchange achieved to impose a mean solidification rate during step b) less than or equal to 45 pm / s and obtain a low alloy steel ingot.
• Low-alloy steel means a steel for which no alloying element is present in a mass content greater than 5.00%. In other words, in a low-alloy steel, each of the chemical elements, other than iron, is present in a mass content less than or equal to 5.00%.
• the "molten bath” comprises the liquid part obtained after melting the electrode and the pasty part situated between the liquid part and the ingot obtained.
• average speed of solidification during step b) is meant the ratio (distance traveled by the solidification front during step b)) / (duration of step b)).
• the solidification front corresponds to the boundary between the ingot obtained and the pasty zone of the molten bath.
• the distance traveled by the solidification front is equal to the distance, measured along the longitudinal axis of the crucible, which is traversed by the bottom of the molten bath (ie by the point of the molten bath closest to the bottom of the crucible and situated at the contact of the solidification front).
• the duration of step b) is the time during which solidification of the melt is performed.
• the invention advantageously makes it possible to obtain low alloy steel ingots with reduced inclusions of size and alignment.
• the invention advantageously makes it possible to obtain low alloy steel ingots having a dispersion of the inclusion population obtained during the reduced production compared to the ingots manufactured by the methods of the state of the art.
• the ingots obtained by the process according to the invention advantageously have mechanical properties as well as improved lifetimes compared to ingots made by known processes.
• a solidification rate of the melt sufficiently low is imposed so that all or part of the inclusions present in the melt "up" faster to the surface of the melt than the solidification front.
• the average solidification rate is chosen to be less than the flotation rate (i.e. the rate of rise to the surface of the melt) of all or part of the inclusions present in the melt.
• Equation 1 K. r 2 . ⁇ ( ⁇ ) (Equation 1) where K is a physical constant describing the constant of gravitational acceleration and dynamic viscosity at a given temperature, r is the radius of inclusion and ⁇ (MV) is the difference of density between the inclusion and the melt.
• Equation 1 shows that small inclusions take longer to rise to the surface than larger inclusions in a radius-to-square ratio. Equation 1, on the other hand, shows that an increase in the density difference increases the flotation rate.
• the flotation duration of an inclusion corresponding to the time required for an inclusion to rise to the surface of the melt, can be estimated by the following equation:
• tfiottation AD / vf (Equation 2) where ⁇ is the distance increase from the bottom of the crucible, measured along the longitudinal axis of the crucible, between the initial position of the inclusion and the position where the inclusion is located on the surface of the melt.
• the flotation time of all or part of the inclusions present in the melt is less than the duration of step b).
• the average rate of solidification imposed during step b) may advantageously be less than the flotation rate of all or part of the nonmetallic inclusions present in the melt.
• the average rate of solidification imposed during step b) may advantageously be less than the flotation rate of inclusions present in the melt and able to crystallize in the melt but not in the ingot obtained.
• the average rate of solidification imposed during step b) may advantageously be less than the flotation rate of Al 2 O 3 aluminas and / or the flotation rate of lime aluminates of formula [(AI 2 O 3 ) x (CaO) y ] present in the melt.
• the flotation rates and, therefore, the flotation times can be similar.
• the flotation times may, for example, be less than 60 minutes.
• the duration of step b) may, for example, be greater than or equal to 60 minutes, for example 100 minutes.
• the method according to the invention may further comprise after step b) a step c) of homogenizing the alloying elements present in the ingot obtained.
• Step c) may, for example, comprise a heat treatment of the ingot obtained by submitting the ingot at a temperature below its melting temperature.
• Such a step is advantageous insofar as it makes it possible to diffuse the alloying elements from a zone heavily loaded with alloying elements to a zone weakly loaded with alloying elements.
• the method according to the invention may, furthermore, comprise, after step c), a step d) of shaping to hot ingot.
• Step d) may make it possible to obtain from the ingot a semi-finished product, for example in the form of a bar or a sheet.
• the average speed of solidification imposed during step b) may preferably be less than or equal to 40 ⁇ / s, preferably 35 Mm / s, preferably 30 ⁇ / s, particularly preferably 25 ⁇ / s.
• the reflow oven can have instabilities which can lead to the return to the bottom of the molten bath of rafts of inclusions.
• the presence of such instabilities may lead to an increase in the time required for the inclusions to rise to the surface of the melt and remain there.
• Operating at such average rates of solidification advantageously makes it possible to further increase the difference between the time required to solidify the melt and the time required for an inclusion to rise to the surface. Consequently, the negative impact of the instabilities of the reflow oven is advantageously reduced because the solidification is slower, thus leaving time for the inclusions possibly returned to the bottom of the molten bath to rise to the surface.
• the flotation time of all or part of the inclusions present in the melt may advantageously be less than or equal to two-thirds, or even half, of the duration of step b).
• the diameter of the electrode before fusion can, for example, be between 650 mm and 1200 mm.
• electrode diameter is meant the largest dimension of the electrode measured perpendicular to the longitudinal axis of the electrode.
• the electrode may, before melting, be of cylindrical shape.
• a cylindrical electrode advantageously makes it possible, after merging, to obtain an upward movement of the inclusions within the molten bath essentially directed along the longitudinal axis of the crucible. This advantageously allows to further limit the amount of inclusions trapped in the ingot obtained after solidification due to a rise of inclusions more direct to the surface of the molten bath.
• the invention is not limited to the implementation of a cylindrical electrode before melting. Indeed, the electrode may, alternatively, be of conical or parallelepipedal shape before melting.
• the diameter of the molten bath may, for example, be between 650 mm and 1200 mm.
• the diameter of the molten bath can be between 700 mm and 950 mm.
• the diameter of the molten bath can be between 650 mm and 950 mm.
• the diameter of the molten bath can be between 700 mm and 1200 mm.
• the diameter of the molten bath corresponds to its largest dimension measured perpendicularly to the longitudinal axis of the crucible.
• the diameter of the molten bath is measured perpendicular to the height of the cylinder.
• the diameter of the melt is measured without taking into account the thickness of the side wall of the crucible.
• the average speed of solidification imposed during step b) may be greater than or equal to 9 pm / s and more preferably greater than or equal to 14 pm / s.
• the cooling fluid may, for example, be a coolant.
• the combination of a cooling liquid and a cooling gas can be used during step b) to achieve the heat exchange.
• the cooling gas may be chosen from: helium, argon or nitrogen.
• the cooling liquid may, for example, be selected from: water, a polymer fluid or molten sodium.
• the water used as coolant may optionally include additives such as anti-scale and / or anti-bacterial additives.
• the cooling fluid may, for example, be in motion relative to the crucible during all or part of step b).
• the circulation velocity of the cooling fluid performing the heat exchange may, for example, be greater than or equal to 1000 l / min, preferably between 2000 and 6000 l / min, during all or part of step b).
• the cooling fluid may, before the start of the heat exchange, be at a temperature of less than or equal to 80 ° C.
• the crucible may, for example, comprise, in particular consist of, a heat-transfer metal.
• the crucible may, for example, comprise, in particular consist of, copper or brass.
• the carbon may be present in the electrode before melting in a mass content of between 0.09% and 1.00%.
• the electrode may further comprise before chromium melting in a mass content of between 0.10% and 5.50%.
• the electrode may further comprise before molybdenum melting at a mass content less than or equal to 5.00%, for example between 0.05% and 5.00%.
• the electrode may comprise, before melting, iron as well as: ⁇ carbon in a weight content of between 0.09% and 1.00%,
• ⁇ vanadium in a lower weight than or equal to 5.00% for example between 0.005% and 5.00%
• ⁇ optionally one or more other alloying elements, all the other alloying elements being present in a mass content of less than or equal to 3.00%, for example between 0.010% and 3.00%.
• the electrode may have, before melting, the following composition:
• ⁇ manganese less than or equal to 6.00% mass content for example between 0.010% and 6.00%
• ⁇ molybdenum less than or equal to 5.00% mass content for example between 0.05% and 5.00%
• ⁇ optionally one or more other alloying elements, all other alloying elements being present in an mass content less than or equal to 3.00%, for example between 0.010% and 3.00%, and
• the present invention also relates to a low-alloy steel part comprising iron and carbon, the part extending along a longitudinal axis, the part being such that, when it is evaluated according to method D of the ASTME standard 45-10, the following results are obtained in analysis along the longitudinal axis:
• Such a part according to the invention advantageously has improved fatigue strength compared to the parts of the state of the art.
• the part can be obtained by implementing a method as described above.
• the part may include non-metallic inclusions.
• the part may correspond to the ingot obtained at the end of step b) or possibly of step c) described above.
• the part may also correspond to the half-product obtained after implementation of step d) described above.
• the following result can be obtained by adding the three measurement results obtained along the longitudinal axis of the part and along two axes perpendicular to this longitudinal axis:
• the total number of fields comprising type D inclusions with a severity level equal to 0.5 is less than or equal to 15, preferably greater than 10.
• the carbon may be present in the part in a mass content of between 0.09% and 1.00%.
• the part may further comprise chromium in a mass content of between 0.05% and 5.00%.
• the part may further comprise molybdenum in a mass content less than or equal to 5.00%, for example between 0.05% and 5.00%.
• the part may comprise iron as well as:
• manganese in a mass content of less than or equal to 5.00% for example between 0.005% and 5.00%, nickel in a mass content of less than or equal to 5.00%, for example between 0.010% and 5%; , 00%, silicon in a mass content less than or equal to 3.00%, for example between 0.010% and 3.00%, of chromium in a mass content of between 0.05% and 5.00%,
• the part may have the following composition:
• Nickel in a mass content of less than or equal to 5.00%, for example between 0.010% and 5.00%
• one or more other alloying elements all the other alloying elements being present in a mass content of less than or equal to 3.00%, for example between 0.010% and 3.00%, and
• the part according to the invention may, for example, comprise different alloying elements in the proportions indicated in Table 1 given below.
• the part may have a cylindrical shape.
• the part may, for example, have a conical or parallelepiped shape.
• the present invention relates to a low-alloy steel part comprising iron and carbon and obtainable by implementing a method as described above.
• a low-alloy steel part comprising iron and carbon and obtainable by implementing a method as described above.
• Such a piece may, for example, have the same constituents present at the same mass contents as for the piece described above.
• FIG. 1 and 2 show schematically and partially the implementation of a method according to the invention.
• the electrode 1 intended to be melted is present in the interior volume delimited by the crucible 10.
• the electrode 1 may, beforehand, have been produced by any means known as elaboration at the air or vacuum induction processing.
• the electrode 1 may, as shown, have a cylindrical shape before melting. As explained above, it is not beyond the scope of the present invention if an electrode having another form before fusion is implemented.
• the crucible 10 is, for example, copper.
• the crucible 10 extends along a longitudinal axis X.
• a generator G imposes a potential difference between the crucible 10 and the electrode 1.
• a first terminal of the generator G can, as shown, be connected to the electrode 1 and a second terminal of the generator G may, as shown, be connected to the bottom 11 of the crucible 10.
• the potential difference imposed between the crucible 10 and the electrode 1 by the generator G makes it possible to create electric arcs 3 in the space 2 in which there is a void. These electric arcs 3 make it possible to melt the electrode 1 and to carry out step a).
• the molten portion of the electrode 1 is collected in the crucible 10 and thus forms a melt 20.
• the melt 20 comprises a liquid portion 21 located on the electrode side 1 and a pasty portion 22 located between the liquid portion 21 and the ingot 30.
• the ingot 30 is obtained by cooling the molten portion of the electrode.
• the solidification front 34 separates the resulting ingot from the melt 20 and propagates during step b) to the free surface of the melt bath 20. Water circulates around the crucible 10 to continuously cool the crucible 10 as well as the melt 20 and to ensure the solidification of the latter.
• a cooling channel 13 is present within the side wall 12 and the bottom wall 14 of the crucible 10.
• a coolant can circulate within the cooling channel 13 in order to also participate in the solidification of the molten bath 20.
• the ingot 30 is present, during step b), between the melt 20 and the bottom 11 of the crucible 10 as well as between the melt 20 and the side wall 12 of the crucible 10.
• at least a portion of the peripheral surface 31 of the ingot 30 may not be in contact with the side wall 12 of the crucible 10 and be separated from the latter by a space 33.
• a gas for example He , Ar, N 2
• He , Ar, N 2 can be injected to improve cooling.
• the resulting ingot 30 may have a cylindrical shape.
• FIG 2 provides a simplified representation of certain details of the method according to the invention.
• the electrode 1 comprises before fusion inclusions 40. These inclusions 40 may be non-metallic inclusions.
• the end 1a of the electrode 1 is, during melting, melted by the energy of the electric arcs 3. Molten electrode drops are produced which will be collected by the crucible 10.
• the crucible 10 is , as explained above, cooled with water.
• the melt 20 has a diameter d equal to the internal diameter of the crucible 10.
• the melt 20 may, as shown, have during all or part of step b) a hemispherical shape. Such a shape can for example be obtained when using a crucible 10 of cylindrical shape.
• the melt 20 may take other forms, for example a semi-quasi-ovoid shape. Such a shape can for example be obtained when using a parallelepiped shaped crucible.
• the distance e between the free surface of the melt 20 and the electrode 1 is advantageously kept constant during step b).
• This distance e can be driven either in voltage (V) or in pulses 5.
• the electrode 1 is during step b) moved along the longitudinal axis X of the crucible 10 in order to maintain the distance e constant.
• the drops 5 fall and are collected by the crucible 10.
• the drops 5 may include inclusions 40 which were initially present in the electrode 1.
• the Inclusions 40 may be entrained to the bottom 26 of the melt 20 (ie the point of the melt 20 closest to the bottom 11 of the crucible and in contact with the solidification front 34).
• the melt 20 has an axial portion having a temperature greater than that of its peripheral portion. This leads to a natural convection, corresponding to the engaged forces of buoyancy, which starts from the bottom 26 of the melt 20, joins the free surface 25 of the melt 20 and goes to the edge 27 of the molten bath 20. This convection is shown schematically in FIG. Figure 2 by the arrows 28a and 28b.
• the inclusions 40 either solid or liquids of lower density than that of the melt 20 will tend to rise to the surface 25 with some velocity by flotation mechanisms as explained above.
• aggregates 41 formed of agglomerated inclusions 40. These aggregates 41 are driven towards the periphery of the ingot 30 where they will be fixed.
• the solidification front 34 propagates from the bottom 11 of the crucible 10 to the free surface 25 of the melt.
• the solidification front 34 propagates during step b) along the longitudinal axis X of the crucible 10 as shown by the arrow 35.
• the solidification front 34 may retain its shape during all or part of the step b).
• the average rate of rise of the solidification front 34 is controlled so as to be less than the rate of rise to the surface of all or part of the inclusions 40 as explained above.
• FIG. 2 shows the successive positions P 1 and P 2 occupied by the bottom 26 of the melt 20. The distance d 1 through the bottom 26 of the melt is measured along the longitudinal axis X of the crucible 10. Examples
• the diameter of the electrode before fusion was 920mm.
• Pulse 250 melted electrode cut-off drops produced per minute.
• the molten electrode drops are collected in a crucible with a diameter of 975 mm and form a molten bath in the copper crucible.
• the melted bath is then solidified by heat exchange between the molten bath and water circulating at 3000 l / minute with a temperature thermostated at 38 ° C. at the inlet and a continuous injection of He at 20mbar.
• the heat exchange achieved makes it possible to impose a mean solidification rate during step b) equal to 24 pm / s.
• the diameter of the electrode before fusion was 550mm.
• the molten electrode drops are collected in a crucible with a diameter of 600 mm and form a molten bath in the copper crucible.
• the melted bath is then solidified by heat exchange between the molten bath and water circulating at 1500 l / min with a temperature thermostated at 38 ° C. at the inlet and without gas injection.
• the heat exchange achieved makes it possible to impose a mean solidification rate during step b) equal to 49 ⁇ / 5.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Analysing Materials By The Use Of Radiation (AREA)
• Investigating And Analyzing Materials By Characteristic Methods (AREA)
• Treatment Of Steel In Its Molten State (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Related Child Applications (2)

Publications (2)

Family

ID=51688171

Family Applications (2)

Family Applications After (1)

Country Status (9)

Families Citing this family (1)

Family Cites Families (18)

• 2014
  • 2014-06-10 FR FR1455202A patent/FR3021977B1/fr active Active
• 2015
  • 2015-06-03 WO PCT/EP2015/062406 patent/WO2015189083A1/fr active Application Filing
  • 2015-06-03 US US15/317,508 patent/US10364479B2/en active Active
  • 2015-06-03 JP JP2017517188A patent/JP2017524828A/ja active Pending
  • 2015-06-03 EP EP15727949.8A patent/EP3155137B1/de active Active
  • 2015-06-03 BR BR112016028856A patent/BR112016028856A2/pt not_active Application Discontinuation
  • 2015-06-03 EP EP19169956.0A patent/EP3536815A1/de not_active Withdrawn
  • 2015-06-03 RU RU2017100062A patent/RU2695682C2/ru active
  • 2015-06-03 CN CN201580031242.XA patent/CN106574321B/zh active Active
  • 2015-06-03 CA CA2951574A patent/CA2951574C/fr active Active
• 2017
  • 2017-08-23 FR FR1757823A patent/FR3055340B1/fr active Active
• 2019
  • 2019-06-24 US US16/450,219 patent/US11560612B2/en active Active

Also Published As

Similar Documents

Legal Events