EP1461470A2 - Alliages de plomb traites de maniere thermo-mecanique - Google Patents

Alliages de plomb traites de maniere thermo-mecanique

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Publication number
EP1461470A2
EP1461470A2 EP01989121A EP01989121A EP1461470A2 EP 1461470 A2 EP1461470 A2 EP 1461470A2 EP 01989121 A EP01989121 A EP 01989121A EP 01989121 A EP01989121 A EP 01989121A EP 1461470 A2 EP1461470 A2 EP 1461470A2
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EP
European Patent Office
Prior art keywords
lead
alloy
lead alloy
temperature
strip
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Application number
EP01989121A
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German (de)
English (en)
Other versions
EP1461470A4 (fr
Inventor
Gino Palumbo
Karl T Aust
David L. Limoges
Francisco Gonzalez
Klaus Tomantschger
Peter K. Lin
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Integran Technologies Inc
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Integran Technologies Inc
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Application filed by Integran Technologies Inc filed Critical Integran Technologies Inc
Priority claimed from PCT/US2001/044061 external-priority patent/WO2003046243A1/fr
Publication of EP1461470A2 publication Critical patent/EP1461470A2/fr
Publication of EP1461470A4 publication Critical patent/EP1461470A4/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/12—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of lead or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C11/00—Alloys based on lead
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • This invention relates to wrought and recrystallized lead and lead alloys, with increased resistance to creep and intergranular cracking and corrosion.
  • This invention is more particularly concerned with positive lead and lead alloy current collectors and connectors used in lead-acid batteries which, via recrystallization treatment to generate new grain boundaries in the microstructure, have improved resistance to corrosion and growth, so as to provide enhanced battery reliability, extended service life and greater energy density.
  • Intergranular degradation i.e., creep deformation, cracking and corrosion
  • lead-based positive current collector grids, tubular spines, foils and connectors are the principal cause of premature failure of lead-acid batteries.
  • Intergranular corrosion occurs when Pb current collector and its components are transformed to Pb0 2 . itergranular corrosion limits the life of automotive batteries and affects the life of industrial batteries.
  • Creep deformation which arises primarily from grain boundary sliding processes, results in dimensional expansion of the positive current collector.
  • the so-called “growth” causes a loss of contact between the electrode surface and the Pb0 2 paste and leads to shorting between adjacent electrodes.
  • the growth of the positive current collector also contributes to intergranular "cracking". Growth of the positive current collector in lead-acid batteries is the predominant failure mode of automotive batteries as under-the-hood temperatures in modern automobiles increase. As a result of these intergranular degradation processes, and in order to maintain sufficient operating- and cycle- life performance, considerable weight allowances are required on the minimum dimension of the positive current collectors, which commensurately increase the overall size and weight of the batteries.
  • Hardening is typically achieved by straining and then heat treating the lead alloy above the solvus temperature, to solutionize the second phase, and then quenching the metal to form a supersaturated solution of the alloyed element in the lead. Over time, the alloyed element precipitates out of solution to form a second phase, preferably in the form of small precipitates, in the metal. These second phase precipitates impede dislocation motion in the metal, inhibit grain boundary sliding, and consequently strengthen and harden the material. Quenching following the heat treatment is necessary to keep the precipitate size small and effective in terms of strengthening and growth resistance.
  • the deformation prior to heat treatment typically achieved through cold or hot working, forms dislocations in the crystallographic structure of the metal which act as the nucleation sites for the precipitation of the second phase, and result in a more uniform precipitate distribution.
  • Precipitation hardening processes involving the proper choice of alloying constituents, and prior deformation to enhance the uniformity of precipitate distribution from aging at ambient or elevated temperature, undoubtedly have a beneficial impact on minimizing grid growth from grain boundary sliding (i.e., grain boundary "pinning by precipitates").
  • grain boundary sliding i.e., grain boundary "pinning by precipitates”
  • Unlike precipitation-based processes such a new approach, according to the present invention, is also applicable to pure lead and lead alloys not containing precipitate-formers. This opens the way to the advantageous use of less expensive alloys.
  • Lehockey in US Patent No. 6,086,691 (2000) discloses a thermo-mechanical process for increasing the population of such special grain boundaries in commercial Pb-alloy electrowinning electrode materials to levels in excess of 50% by cold deforming a Pb-alloy sheet to achieve a thickness reduction of 30% to 80% and annealing the material at temperatures ranging from 180 °C to 300 °C for 15 to 30 minutes and repeating the deformation/annealing treatment for a second cycle
  • Rao in WO/00/60677 (2000) describes a method for making Pb-Ca-Sn-Ag grids by casting an alloy strip and then "hot rolling" the strip at a temperature between the solvus temperature and the peritectic temperature of the alloy, quenching the hot rolled strip and preferably heat aging the strip at a temperature of 200°F (93°C) to 500°F (260°C) to enhance mechanical and high temperature corrosion characteristics prior to perforating the strip, e.g. by an expansion process to fabricate suitable battery grids.
  • Palumbo in WO 01/26171 describes recrystallized lead and lead alloy positive electrodes for lead-acid batteries having an increased percentage of special grain boundaries in the microstructure, preferably at least 50%, which have been provided by a process comprising steps of working or straining the lead alloy, and subsequently annealing the lead or lead alloy. Either a single cycle of working and annealing can be provided, and a number of repetitions of such steps are selected to ensure that a substantial increase in the population of special grain boundaries is provided in the microstructure, to improve resistance to creep, intergranular corrosion and intergranular cracking of the electrodes during battery service, and result in extended battery life and the opportunity to reduce the size and weight of the battery
  • Peening is a non-conventional method of deformation in which compressive stresses are induced in the exposed surface layers of metallic parts by the impingement of a stream of shot, directed at the surface at high velocities under controlled conditions. Peening cleans the surface of the test article, increases the fatigue strength and relieves tensile stresses that contribute to stress-corrosion cracking.
  • YamadainU.S. 5,816,088 (1998) describes a surface treatment method for a steel work piece using high speed shot peening.
  • Mannava in U.S. 5,932,120 (1999) describes a laser shock peening apparatus using a low energy laser.
  • the current collector can be a bookmold grid, a tubular grid, a foil or sheet, a perforated strip, i.e. suitably punched or expanded, a continuous cast grid or a continuous cast grid which is subsequently rolled to its final dimension. It is an object of this invention to provide a method for making current collectors for flooded, gelled or valve regulated lead-acid batteries by implementing the novel thermo- mechanical process into the continuous "conventional" manufacturing process.
  • thermo-mechanical treatment employed to treat the lead or lead alloy current collectors or their precursors substantially increases the percentage of special grain boundaries to increase at least one of the resistance of the lead or lead alloy to creep and resistance to intergranular corrosion and intergranular cracking, wherein the lead or lead alloy has been subjected to at least one processing cycle comprising: suitably deforming the lead alloy below the solvus temperature, and subsequently annealing the lead alloy for a time and temperature sufficient to effect recrystallization to substantially increase the concentration of special grain boundaries.
  • deformation involves mechanical deformation on an article at a low enough temperature that dislocations are retained, leading to a structure of non-recrystallized, deformed grains.
  • This invention relies on deforming at least part of the surface layer of the article or the entire article below the solvus temperature, preferably between about 40 °C and the solvus temperature, followed by an annealing treatment. Suitable deformation treatments comprise rolling, extruding, punching, expanding, repeated bending or peening.
  • the deformation treatment temperature e.g. as determined by the temperature of the strip exiting the rolling mills or extrusion chamber, can be between 25°C and 250°C, more preferably between 35°C and 200°C, 40°C to 150°C and 60°C to 125°C.
  • the maximum deformation temperature needs to be below the solvus temperature of the alloy being treated.
  • the billet or thick strip generally ranges from about 0.030" (0.76mm) to 1" (25.4mm).
  • the rolling process can be carried out by any of the conventionally known techniques, e.g. using equipment provided by Continuus S.p.A. of Milan, Italy.
  • the thickness of the strip can be adjusted to meet the particular battery application, typically the thickness ranges from 0.002" (0.05mm) to 0.125" (3.2mm) inches. Small, e.g.
  • cylindrical thin film type batteries may utilize the foil treated according to this invention in a thickness range of about 0.002" (0.05mm) to 0.010" (0.25mm); automotive 12 to 42V batteries typically use strip thickness ranges of 0.010" (0.25mm) to 0.045" (1.14mm) and industrial battery the strip thickness can reach 0.150" (3.8mm). It is obvious from comparing the strip thickness before and after rolling that significant mechanical work is induced into the strip during the deformation treatment.
  • the deformation treatment required prior to the recrystallization step is performed at temperatures ranging from above room temperature (15°C to 25°C) up to the solvus temperature of the material. More typically, the deformation treatment is carried out between 30°C and 125°C, and even more typically between 40°C and 95°C.
  • the thickness reduction ratios can be suitably chosen to deform e.g. a billet to the desired strip thickness and the deformation temperature is adjusted to optimize the creation of special grain boundaries in the subsequent recrystallization heat-treatment.
  • a reference to lead means either pure lead or a lead alloy
  • a reference to deformation means any forming operation such as rolling, extruding, punching, expanding, bending and peening etc. conducted at between ambient temperature and the solvus temperature of the lead or lead alloy
  • a reference to lead alloy denotes lead that includes one or more specific alloying elements alloyed with the lead.
  • the steps of deforming the lead alloy and annealing to recrystallize the lead alloy are repeated a plurality of times. Excessive strain between recrystallization steps can have a negative effect on the present process.
  • the inventors have found that, at least for some alloys, an improved concentration of special grain boundaries can be obtained with a single step of deforming or straining and annealing.
  • the lead alloys may be comprised of at least one alloying element selected from the group comprising, of Ag, Al, As, Ba, Bi, Ca, Cd, Cu, Fe, Li, Mg, Na, Se, Sb, Sn, Sr, and Zn, but the alloy can also include two or more alloying elements.
  • the alloying element(s) need not be soluble in lead, i the case of substantial alloys, the lead alloy is preferably reduced in thickness or strained by approximately 1 %-99% in each deformation step, and the lead alloy is then recrystallized, in the annealing step, at a temperature and time sufficient to allow recrystallization to occur, generally in the range of approximately 100° to 325°C (which is below the melting point of the lead or lead-alloys) for 1 second to 360 minutes (preferably from 5 seconds to 360 minutes) and subsequently air-cooled or quenched to ambient temperature. It is to be appreciated that the exact deformation and annealing temperature and time required for recrystallization and the formation of special grain boundaries will vary depending on the alloying additions and the percentages added.
  • the percentage of special grain boundaries is at least 50% of the total grain boundaries; however, it was found that at least 20%>, 30%) or 40% of special grain boundaries already improve the corrosion performance.
  • the lead or lead alloy is subsequently processed into components for lead-acid batteries, for example positive grids or foils and cell interconnects. It is preferred for the lead or lead alloy to be subject, first, to processing according to the present invention, and that this processing be applied to at least a portion of the lead article.
  • the degree of uniformity may depend on the method of deforming the lead alloy, e.g. stamping, extrusion, rolling, expanding, forging, peening, etc., and component geometry.
  • thermomechanical treatment process according to this invention is different from the prior art approaches which require precipitation or age hardening. Therefore, unlike prior- art precipitation processes, the process described herein is applicable to pure lead and lead- alloys which do not contain the required precipitate formers of the prior art.
  • the process described in this invention enhances the corrosion resistance of lead or lead-alloys regardless of whether the lead alloy contains an alloying material which is precipitated during the deformation step or steps of a precipitation hardening procedure.
  • the process of this invention elevates the contents of special grain boundaries without hardening of the starting lead or lead alloy material. The avoidance of hardening is completely different from the alloys subjected to prior art processes since the prior art processes are specifically directed toward increasing the hardness of the alloy to improve various physical characteristics.
  • Figure 1 is a sectional view through a conventional lead acid battery.
  • Figure 2 is a graph showing variation of cycle life with a critical electrode dimension
  • Figure 3 is a graph showing a comparison of the creep rate for pure as cast lead and the creep rate of pure lead processed by the method of the present invention
  • Figure 4 is a map of special grain boundary character distribution in (a) cast pure lead and (b) processed method of the present invention.
  • Figure 5 is a bar graph summarizing the increases in special grain boundary content for a range of lead-alloy compositions achieved using the method of the present invention
  • Figures 6A and 6B are bar graphs summarizing the improvements in corrosion and electrode growth for a range of lead-alloy compositions achieved using the method of the present invention
  • Figures 7A and 7B are bar graphs summarizing the relative corrosion and electrode growth performance for a Pb-0.03Ca-0.7Sn-0.06Ag alloy in the cast, wrought, and wrought and recrystallized condition; the latter achieved using the method of the present invention.
  • the present invention relates to the processing of lead and lead alloys for application as positive current collectors and connectors in lead-acid batteries in order to provide superior resistance to creep deformation (growth) and intergranular corrosion and cracking in the batteries acidic environment.
  • a traditional lead-acid battery shown generally at 10, comprises a housing 12, an internal compartment 14, electrodes 16, a busbar 18 and electrolyte solution 20. Compartment 14 serves to contain the electrolyte solution 20. Electrodes 16 and busbar 18 have traditionally been made of either a cast or wrought lead alloy. Alloys have traditionally been used, as opposed to pure lead, since appropriate alloying elements are required to provide improved strength, creep resistance and improved gassing characteristics, for example. While traditional lead-acid batteries have proven to be dependable, they have a limited life span and energy density. The life span is due to the creep (growth), corrosion and cracking of the electrodes resulting from successive charge-discharge cycles.
  • lead-acid battery components are generally formed initially from cast lead or lead alloys. Although deformation is also frequently applied in the rolling of cast ingots or strip to sheet, and then subsequently by slitting and straining the lead alloy sheets to form grids, treatments that result in complete recrystalization of the microstructure have not been used in prior lead-acid battery components.
  • the percentage of special or coincident site lattice (CSL) grain boundaries in as-cast or wrought lead-based lead-acid battery components is always less than 20% and usually in the range of between 14% and 17%.
  • Traditional as- cast and wrought lead-based positive current collectors are susceptible to intergranular corrosion, cracking and creep deformation (growth).
  • the lead alloy positive current collector components of the battery are provided with a metallurgical microstructure having a high percentage, that is over 20%, 30%, 40% or 50%, of special grain boundaries.
  • Special grain boundaries can be defined crystallographically as lying within
  • the method of the present invention comprises processing the lead-based positive current collector components to improve the concentration of special grain boundaries. More particularly, this is achieved without invoking conventional strengthening mechanisms, such as precipitation hardening, and without substantially altering the tensile strength or hardness of the material.
  • the process is referred to as Grain Boundary Engineering (GBE).
  • GEB Grain Boundary Engineering
  • f 0 is the fraction of interfaces in the material which are unfavourably oriented to the applied stress axis (note that f 0 is strongly dependent on the grain shape and has a value of 1/3 for conventional equiaxed materials) and f sp is the fraction of special interfaces which are intrinsically resistant to cracking.
  • the probability ⁇ of arresting a crack within a length L from the initiating surface is given by,
  • Intergranular corrosion can also compromise the integrity of a positive lead acid electrode by general loss of cross-sectional thickness arising from "grain dropping'.
  • grain dropping' For any grain to be ejected from the matrix, all of its bounding grain boundaries must be fully compromised by corrosion. Assuming that 'special' grain boundaries are immune to corrosion, and considering a material comprised of hexagonal prism grains, it can be shown that the probability of arresting such a grain dropping process at any junction is given by,
  • the probability (P) derived in eqn (4) can be applied with eqn (3), where it can be shown that, in a manner similar to intergranular cracking, decreasing grain size (d) and increasing special boundary frequency (f sp ) are expected to significantly increase resistance to section loss by intergranular corrosion.
  • X is the statistical certainty
  • P is the probability of arresting the degradation process, which is obtained from eqn. (3) or eqn. (4) for intergranular -cracking and -corrosion processes, respectively.
  • K is a constant which can be estimated from the typical performance of conventional lead-acid batteries. For example, in severe laboratory testing of typical SLI batteries, a charge- discharge cycle life, C, of approximately 200 is observed with grids having a minimum cross-section of approximately 1mm, average grain size, d, of 50 ⁇ m, and a microstructure consisting of approximately 15% special grain boundaries (f sp ). Assuming a statistical certainty (X) of 99%, these conditions lead to K values of 408 cycles, and 48 cycles for intergranular cracking and corrosion processes, respectively.
  • Figure 2 summarizes the estimated improvements in lead-acid battery performance from increases in special grain boundary content as calculated from eqn (5) for material having a conventional grain size of 50 ⁇ m.
  • significant improvements in cycle life are expected for both intergranular-cracking and corrosion dominated degradation processes, by increasing the population of special grain boundaries, f sp .
  • increasing the special grain boundary population from that typically observed (i.e., 15%) to 50%> is expected to result in approximately a 4 - fold improvement in cycle life.
  • this improvement in performance would allow the use of grids having a minimum dimension of as low as 0.2mm, while still retaining the current performance of SLI batteries.
  • Such a reduction in positive grid thickness would be expected to significantly reduce the size and weight of lead-acid batteries (1mm positive grid accounts for 25% of total battery weight), or result in commensurate increases in energy density.
  • grain boundary engineering increases the resistance of the metal to crack propagation and strain deformation (creep) by altering the crystallographic structure of the grain boundaries. This is in contrast to previous efforts at providing improved components for lead-acid batteries, such as precipitation or age hardening, which were directed at changing the composition, size and distribution of the microconstituents within the grains.
  • the special grain boundary fraction can be beneficially increased.
  • the method of the present invention is based on the discovery that the special grain boundary fraction can be increased through careful selection of process parameters for deforming and then recrystallizing the lead or lead alloy.
  • the specified steps maybe repeated until the desired concentration of special grain boundaries is achieved.
  • the deformation can take the form of drawing, stamping, rolling, pressing, extruding, expanding, forging, bending or any other physical deformation.
  • special grain boundary concentrations or fractions of greater than 40% to 50% can be achieved with only one deformation and recrystallization step; however, additional deformation and recrystallization steps may yield a more uniform product having a smaller overall average grain size.
  • a smaller grain size increases the amount of special grain boundaries and thereby improves crack resistance.
  • the recrystallization temperature there is a relationship between the recrystallization temperature, the amount of deformation per step, the temperature at which such deformation occurs, the amount of time at which the lead or lead alloy is held at the recrystallization temperature, the composition of the lead or lead alloy used and the resulting special grain boundary fraction in the lead or lead alloy.
  • the temperature at which the lead is recrystallized is critical to the present invention. Typically, recrystallization will occur in a metal at temperatures over 0.5 Tm, where Tm is the absolute melting temperature in degrees Kelvin. For pure lead, ambient temperature is approximately 0.5 Tm . In the present invention, the temperature at which recrystallization occurs must be chosen so that the special grain boundary fraction is maximized. The temperature must not be so high, however, that excessive grain growth occurs.
  • the desired recrystallization temperature must be achieved within a relatively short period of time in order to prevent premature recovery, and in certain alloys, precipitation of secondary phases during prolonged heat-up, which can excessively harden the alloy and hinder the nucleation of new grains and grain boundaries.
  • grain boundary concentrations of greater than 50% can be produced in one or more cycles comprised of induced deformations or strains in the range between 1% to 70% per step, and recrystallization at temperatures within the range of 150°C to 325°C for annealing times in the range of 5 seconds to 360 minutes.
  • X elements are comprised of the strong precipitate formers and Y elements are the weak or non-precipitating elements.
  • the X elements are comprised of the Group I and Group TJ elements of the periodic table, which in terms of common and potential battery alloying constituents include: Li, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, and Sb.
  • the Y elements are comprised of other common lead alloying constituents which include: Ag, Sn, Cu, Zn, As, and Bi. Certain combinations of alloying elements result in the formation of better strengthening precipitates then when present alone.
  • the treatment time varies, depending on the material, but typically ranges from 1 seconds to three days, more typically from 5 seconds to 12 hours, and preferably from 10 seconds to 3 hours.
  • the deformations were performed on a rolling mill at room temperature and were limited to 20% reduction in thickness per step .
  • Each recrystallization treatment was carried out at 160°C for 15 minutes.
  • a Pb-0.073wt% Ca-0.07wt% Sn alloy (Class JJL) was processed by three cycles each comprised of cold rolling at room temperature to achieve a 40% reduction in thickness, annealing at 270 °C for 10 minutes in air followed by air cooling.
  • the resulting microstructural improvement in terms of special grain boundary content is summarized in Figure 5 (identified as PbCaSn in Figure 5).
  • the special grain boundary content was increased from 11% in the as-cast starting material, to 51% in the material processed by the method described.
  • a Pb-0.065wt% Ca-0.07wt% Sn 0.03wt% Ag alloy (Class II) was processed by two cycles each comprised of cold rolling at room temperature to achieve a 40% reduction in thickness, annealing at 250 °C for 10 minutes in air followed by air cooling.
  • the resulting microstructural improvement in terms of special grain boundary content is summarized in Figure 5 (identified as PbCaSnAg in Figure 5).
  • the special grain boundary content was increased from 12% in the as-cast starting material, to 70% in the material processed by the method described.
  • a Pb-0.073wt% Ca-1.4wt% Sn alloy (Class H) was processed by two cycles each comprised of cold rolling at room temperature to achieve a 40% reduction in thickness, annealing at 250 °C for 10 minutes in air followed by air cooling.
  • the resulting microstructural improvement in terms of special grain boundary content is summarized in Figure 5 (identified as PbCa"Hi"Sn in Figure 5).
  • the special grain boundary content was increased from 17% in the as-cast starting material, to 70%> in the material processed by the method described.
  • Positive grids were cycled between 0.8 V and 1.4V at a rate of two cycles per day for 35 days in a solution of 1.27 specific gravity sulfuric acid at 70 °C.
  • grids were cleaned of residual paste, and reweighed to the nearest milligram. Also, grid growth susceptibility was established by digitally scanning the area of the grids both prior to and following the test exposure.
  • a Pb-0.03 wt %Ca-0.7 wt.% Sn 0.06wt%Ag alloy, representative of a Class I alloy was produced using a commercial rotary net shape casting process.
  • the cast strip of 0.86-0.89 mm thickness was subsequently subjected to a single processing cycle comprised of approximately 20% cold tensile strain (room temperature), and heat treatment in an air convection oven at a temperature of 250 °C for 5 minutes followed by cooling to ambient temperature.
  • the strain was introduced at room temperature solely through the grid expansion process and was controlled by the tool die geometry (i.e., diamond height of expanded mesh).
  • a wrought strip was produced without subsequent recrystallization heat treatment, hi this case, cast strip of 1.72mm thickness was cold rolled by 50% and similarly expanded to mesh.
  • the proportion of special grain boundaries present in the as-cast, wrought, and single step GBE processed materials were found to be 16.0%, 15.4% and 64.4%, respectively.
  • the f sp increased from 10% (as cast) to 59% (after subjecting the sample to the GBE processing).
  • one set of samples was processed according to Meyers (US 4,753,688), more particularly, to nine sequential cold rolling cycles of 25% (without intermittent annealing) followed by a final heat treatment at 230 °C for one minute.
  • the hardness of the age hardenable lead alloy was measured immediately after completion of the respective treatments and at various times of aging at room temperature. The same hardness measurement technique described in example 4 above but using a 50 gram load was used. The hardness numbers are depicted in Table 3. The results clearly indicate that the Meyers process results in an as-processed hardness (VHN: 12) which is greater than that of the as-cast material (VHN: 11), and significantly higher than that of the GBE-processed material (VHN: 8) It also shows significantly enhanced short term hardenability whereby its hardness increases to VHN:21 within the first 24 hours of aging, hi comparison, the GBE material shows no increase from its initial value during the same time frame.
  • the Meyers-processed material shows a further hardness increase to 27 VHN. It is also noted that the GBE processed material even after 240 hours has a hardness which is not as great as the as-cast hardness.
  • Table 3 Hardness as a function of aging time at room temperature for Pb-2Sb-0.15As processed according to Meyers and according to this invention.
  • the treatment represented a 60% thickness reduction at room temperature followed by an annealing treatment of 3 minutes at 250 °C.
  • the treatment represented three successive cycles of a 50% thickness reduction at room temperature followed by an annealing treatment of 10 minutes at 270 °C.
  • the ultimate hardness of each of the metals was measured after four weeks of age hardening.
  • the hardness values were obtained using the measurement described above with a 50 gram load.
  • the hardness of each alloy prior to GBE processing i.e., the as cast hardness
  • the obtained hardness values for each of the alloys processed according to this invention and as cast are shown in Table 4, as is the f sp count and grain size for the GBE processed samples.
  • the as-cast samples ranged in f sp count from 10 to 15%. Table 4 established that the ultimate hardness achievable by age hardening of the GBE processed materials is not as great as the as-cast hardness demonstrating that GBE-processed materials permanently possess hardness values equivalent to or less than that of the as-cast counterparts.
  • a Pb-0.06Ca- 1.2Sn alloy was cast and processed using rolling deformation at various temperatures as indicated in the table 5. As is evident from the data, working the strip at temperatures of 20, 40 and 80 °C, followed by an annealing treatment, raised the f sp count of the samples to over 60% in all cases and lowered the UTS to a value below the one of the as cast or room temperature rolled sample.
  • Table 5 Rolling temperature vs f sp and UTS for various processing parameters.
  • a Pb-0.06Ca-l.2Sn alloy was processed using hot deformation with and without a subsequent annealing treatment as indicated in Table 6.
  • the fsp count of hot deformed Pb- alloys using rolling or extrusion elevated the fsp count to over 40% even without a subsequent annealing step.
  • Table 6 Rolling temperature versus fsp and UTS for various processing parameters.
  • a set of Pb-Ca-Sn-alloy bookmould cast grids was surface peened at room temperature for 10 seconds, followed by heat treatment (275 °C, 10 minutes). Careful analysis of grid cross sections revealed that the penetration depth achieved extended up to 350 micron below the peened surface and that the grain size in the near surface layer was 10 micron, while it remained at about 260 micron in the bulk material.
  • the surface layer of the peened and annealed sample had a of 40%, whereas the untreated sample f sp and the f sp of the treated material more than 350 microns below the surface remained at 15% (table 8).
  • Two Pb-Ca-Sn alloys were cast into sheets.
  • An as received set representing prior art and a set processed according to the invention were corrosion tested in an environment representative of a zinc-electro winning operation.
  • the peening was performed using 28 mil steel shot at 80 psi at room temperature.
  • Three passes per substrate were performed within three minutes and the peened samples were subsequently annealed at 250 °C for 10 minutes.
  • a prefreatment comprising a 30 minute soak at 300 °C was used to modify existing precipitates to facilitate the GBE process.
  • the following table illustrates the sample characteristics and the corrosion performance.
  • the corrosion test was performed by submersing test samples in a typical zinc electrowinning electrolyte (160 g/1 sulfuric acid, 60 g/1 Zh 1""1" at 60 °C) and anodizing them at 40 mA/cm2 against steel cathodes. The results are depicted in tables 9 and 10.
  • Table 10 f sp count and corrosion rates for a cast and peened Pb strip (0.40% Ca, 0.31%Ag, balance commercial purity Pb).

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Abstract

Collecteurs et connecteurs de courant positif en plomb et en alliage de plomb recristallisé, tels que des cavaliers et des languettes de contact, destinés à être utilisés par ex. dans des accumulateurs au plomb-acide et des anodes d'extraction électrolytique, qui possèdent un pourcentage accru de joints de grains spéciaux dans au moins une partie de la microstructure. Lesdits collecteurs et connecteurs sont fabriqués selon un processus qui comporte (i) le laminage à froid ou à chaud ou l'extrusion à chaud ou (ii) des étapes de déformation du plomb ou de l'alliage de plomb, et de recuit ultérieur du plomb ou de l'alliage de plomb. Ledit procédé peut être mis en oeuvre avec un seul cycle de travail et de recuit, ou avec une pluralité de cycles de ce type. Le degré de déformation, la durée et la température de recristallisation et le nombre de répétitions de ces étapes sont sélectionnés de manière à garantir une augmentation substantielle de la population des joints de grains spéciaux dans la microstructure, afin d'améliorer la résistance au fluage, la corrosion intergranulaire et le fendillement intergranulaire des collecteurs et connecteurs de courant pendant le fonctionnement de l'accumulateur, offrant ainsi une durée de vie prolongée de l'accumulateur ainsi que l'opportunité de réduire la taille et le poids dudit accumulateur.
EP01989121A 2001-11-26 2001-11-26 Alliages de plomb traites de maniere thermo-mecanique Withdrawn EP1461470A4 (fr)

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PCT/US2001/044061 WO2003046243A1 (fr) 2001-11-26 2001-11-26 Alliages de plomb traites de maniere thermo-mecanique

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EP1461470A2 true EP1461470A2 (fr) 2004-09-29
EP1461470A4 EP1461470A4 (fr) 2005-09-14

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EP (1) EP1461470A4 (fr)
JP (1) JP2005510628A (fr)
KR (1) KR20040066847A (fr)
AU (1) AU2002243237A1 (fr)
BR (1) BR0117183A (fr)
CA (1) CA2468022A1 (fr)
MX (1) MXPA04004943A (fr)

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JP5322423B2 (ja) 2007-11-05 2013-10-23 古河電池株式会社 鉛電池用鉛基合金基板の製造方法
KR101900506B1 (ko) * 2009-11-25 2018-09-19 코닝 인코포레이티드 내크리프성의 내화성 금속 구조 제조방법
JP6326928B2 (ja) * 2013-05-07 2018-05-23 株式会社Ｇｓユアサ 制御弁式鉛蓄電池
JP2015088289A (ja) * 2013-10-30 2015-05-07 株式会社Ｇｓユアサ 制御弁式鉛蓄電池及びその鋳造集電体
KR101493944B1 (ko) * 2013-11-06 2015-02-17 한국과학기술원 전자후방산란회절 기법을 이용한 재결정율 측정 방법
WO2020111017A1 (fr) * 2018-11-30 2020-06-04 Ｊｆｅスチール株式会社 Procédé pour améliorer une propriété de résistance à la fatigue pour joint soudé
AU2021387363A1 (en) * 2020-11-30 2023-07-06 Furukawa Electric Co., Ltd. Lead alloy, lead storage battery electrode, lead storage battery, and power storage system
CN113667913B (zh) * 2021-06-11 2022-07-08 上海大学 提高Hastelloy N合金ΣCSL晶界比例的工艺方法

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WO2000060677A1 (fr) * 1999-04-03 2000-10-12 Exide Technologies Procede de production de grilles positives et elements et batteries au plomb utilisant ces grilles
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WO2001026171A1 (fr) * 1999-10-06 2001-04-12 Integran Technologies Inc. Plomb et alliages au plomb presentant une meilleure resistance au fluage et/ou a la corrosion intergranulaire, particulierement pour les batteries plomb-acide, et electrodes a cet effet

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WO2000060677A1 (fr) * 1999-04-03 2000-10-12 Exide Technologies Procede de production de grilles positives et elements et batteries au plomb utilisant ces grilles
WO2001026171A1 (fr) * 1999-10-06 2001-04-12 Integran Technologies Inc. Plomb et alliages au plomb presentant une meilleure resistance au fluage et/ou a la corrosion intergranulaire, particulierement pour les batteries plomb-acide, et electrodes a cet effet

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See also references of WO03046243A1 *

Also Published As

Publication number Publication date
KR20040066847A (ko) 2004-07-27
AU2002243237A1 (en) 2003-06-10
EP1461470A4 (fr) 2005-09-14
JP2005510628A (ja) 2005-04-21
BR0117183A (pt) 2004-11-03
MXPA04004943A (es) 2005-04-08
CA2468022A1 (fr) 2003-06-05

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