US20150306736A1 - Surface treatment of a metal part by oblique shot peening - Google Patents

Surface treatment of a metal part by oblique shot peening Download PDF

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Publication number
US20150306736A1
US20150306736A1 US13/977,123 US201113977123A US2015306736A1 US 20150306736 A1 US20150306736 A1 US 20150306736A1 US 201113977123 A US201113977123 A US 201113977123A US 2015306736 A1 US2015306736 A1 US 2015306736A1
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Prior art keywords
particles
hardness
thickness
support
metal part
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Tony Prezeau
Teddy Muller
Joan Samuel
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Winoa SA
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Winoa SA
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
    • B24C1/10—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods for compacting surfaces, e.g. shot-peening
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C3/00—Abrasive blasting machines or devices; Plants
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
    • B24C5/00—Devices or accessories for generating abrasive blasts
    • B24C5/02—Blast guns, e.g. for generating high velocity abrasive fluid jets for cutting materials
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
    • C21D7/04—Modifying the physical properties of iron or steel by deformation by cold working of the surface
    • C21D7/06—Modifying the physical properties of iron or steel by deformation by cold working of the surface by shot-peening or the like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures

Definitions

  • the invention relates to the field of the treatment of metal surfaces, in particular to the treatment by peening.
  • Shot peening is a technique that is widely used for improving certain properties of metal surfaces, such as the fatigue life.
  • a shot-peening treatment is typically characterized by a degree of coverage that describes the proportion of the surface impacted by the peening and an intensity that describes the amount of kinetic energy applied per unit area.
  • the literature in the field of shot peening prescribes limits for the degree of coverage and intensity parameters, beyond which the peened material incurs degradation such as cracking and reduction of the fatigue life. The conditions giving rise to these degradations are commonly denoted by the term “overpeening”.
  • nanostructuring denotes the obtaining of a stable phase, the grain size of which is of the order of a few tens of nanometres. Under certain conditions, it is assumed that the nanostructuring of the material prevents the propagation of microcracks, so that the aforementioned degradations do not occur.
  • the nanostructuring of the material produces advantageous effects such as the increase of the fatigue life, of the hardness, of the corrosion resistance, of the atomic diffusivity, of the biocompatibility, the improvement of the tribological properties, etc.
  • the processes known for producing a nanostructured surface layer note may essentially be taken of:
  • WO02/10461 describes a process for generating nanostructures at the surface of a metal part in which perfectly spherical balls similar to ball bearing balls are projected onto a point of impact of the part under variable incidences. In order to obtain a thickness of nanostructures of a few tens to a few hundreds of microns, it is taught to mechanically and/or thermally stress the surface of the metal part to be treated.
  • WO 02/10462 describes a process for generating nanostructures in which balls are projected onto a point of impact of a part along different and varied directions of incidence by a ball projection source in order to create deformations having any direction.
  • a layer thickness of 10 ⁇ m is obtained with balls having a diameter of 300 ⁇ m and a layer thickness of 20 ⁇ m is obtained with balls having a diameter of 3 mm.
  • WO 02/10463 describes a process for generating nanostructures in which ball motion is triggered by the combination of a circular motion of a chamber containing the balls and a vibrating motion along a direction perpendicular to the plane of the circular motion of the chamber.
  • a nanostructured layer thickness of 10 ⁇ m is obtained with balls having a diameter of 300 ⁇ m and a layer thickness of 20 ⁇ m is obtained with balls having a diameter of 3 mm.
  • EP1577401 describes vibrating rods which produce impacts on a material.
  • the maximum impact speeds are equal to 3.6 m/s.
  • JP2003201549 teaches how to project a stream of particles onto a metal part along a normal incidence.
  • the document teaches how to generate a vibrating motion in order to produce projections, which involves relatively small projection speeds.
  • the invention provides a process for the surface treatment of a metal part, comprising:
  • the surface layer of nanostructures has an average thickness of greater than 50 ⁇ m, the boundary of the surface layer of nanostructures being determined to be a region of the metal part where the hardness is greater than a threshold that is dependent on the metal material from which the part is made.
  • said hardness threshold is defined by a hardening of the material with respect to a prior art upon surface treatment which is equal to 50% of the hardening obtained at the treated surface of the metal part.
  • this threshold may be defined as a function of other parameters, especially the position of a crystalline phase transition in the material when such a transition takes place.
  • such a process may have one or more of the following features.
  • the particles have a diameter of greater than 0.3 mm and less than 1.4 mm.
  • the incidences of the particles are distributed substantially continuously in the cone or the conical film.
  • the cone or the conical film has an outer half apex angle of between 10° and 30°.
  • the stream of particles comprises a jet of particles projected along a central direction, the metal part being fixed to a support so as to present said surface oriented obliquely with respect to said central direction, the support being rotated about an axis coaxial with the central direction of the jet of particles.
  • the inclination of the surface of the part with respect to the central direction is between 10° and 30°, preferably close to 15°.
  • the particles are projected at a speed of between 50 and 80 m/s.
  • the particles have a hardness greater than the hardness of the surface of the part before treatment.
  • the invention thus provides a metal part comprising a surface treated by the aforementioned process, said surface comprising a surface layer of nanostructures having an average thickness of greater than 50 ⁇ m, the boundary of the surface layer of nanostructures being determined to be a region of the metal part where the hardness is greater than a threshold that is dependent on the metal material from which the part is made.
  • said hardness threshold is defined by a hardening of the material with respect to a prior art upon surface treatment which is equal to 50% of the hardening obtained at the treated surface of the metal part.
  • the surface layer of nanostructures has an average thickness of greater than 100 ⁇ m.
  • the invention also provides a surface treatment device for a metal part, comprising:
  • a projection means capable of producing a stream of substantially spherical particles having a diameter of less than 2 mm and greater than 0.1 mm and thus are projected at a speed of between 40 m/s and 100 m/s
  • a support capable of holding a metal part, the support comprising a surface exposed to the stream of particles, and an actuator capable of modifying an orientation of the support with respect to the stream of particles so that the primary incidences of the particles on a surface of the support are essentially distributed in a cone or a conical film that has an outer half apex angle of between 10° and 45°.
  • the projection means is capable of producing a jet of particles projected along a central direction, the surface of the support being oriented obliquely with respect to said central direction, the actuator being capable of pivoting the support about an axis that is coaxial with the central direction of the jet of particles.
  • Certain aspects of the invention are based on the idea of designing a process for nanostructuring the material which has a high productivity in order to produce relatively thick nanostructured surface layers in a relatively short time. Certain aspects of the invention are based on the idea of producing relatively homogeneous nanostructured surface layers. Certain aspects of the invention are based on the idea of designing a process for nanostructuring the material which can be applied to varied geometries, in particular concave shapes. Certain aspects of the invention are based on the idea of designing a process for nanostructuring the material which is relatively easy and economical to implement.
  • FIG. 1 is a schematic representation of a process for nanostructuring a metal surface.
  • FIG. 2 is a schematic perspective view of a peening machine suitable for implementing the processes according to the embodiments of the invention.
  • FIG. 3 is a schematic representation of a particle jet produced by the machine from FIG. 2 .
  • FIG. 4 is a diagram of the operation of the machine from FIG. 2 .
  • FIG. 5 is a graph representing the change in the hardness of a metal part as a function of the depth below the treated surface, for several peening conditions.
  • FIG. 6 is a graph representing the change in the thickness of a nanostructured surface layer as a function of the degree of coverage for the peening conditions from FIG. 5 .
  • FIG. 7 is a graph representing the change in the treatment time as a function of the degree of coverage for several shot sizes.
  • FIG. 8 is a graph representing the change in the surface hardness and in the thickness of a nanostructured surface layer as a function of the degree of coverage for a peening condition.
  • FIG. 9 is a graph representing the change in the thickness of a nanostructured surface layer as a function of the degree of coverage for various modes of attachment of the treated part.
  • FIG. 10 is a graph representing the change in the thickness of a nanostructured surface layer as a function of the inclination of a support in the machine from FIG. 2 , for several peening conditions.
  • FIG. 11 is a graph representing the change in the hardness of parts made of various metal materials as a function of the depth below the treated surface.
  • FIG. 12 is a graph representing the change in the thickness of a nanostructured surface layer as a function of the degree of coverage for various metal materials.
  • FIGS. 13 and 14 are graphs representing the change in the surface hardness and in the thickness of a nanostructured surface layer as a function of the degree of coverage for two different rates of projection.
  • FIG. 15 is a graph representing the change in the surface hardness and in the thickness of a nanostructured surface layer as a function of the degree of coverage for another peening condition.
  • FIG. 16 is a schematic cross-sectional representation of a part treated by a peening process representing the region of influence of an impact.
  • FIGS. 17 to 20 are optical micrographs of nanostructured surface layers.
  • FIG. 21 is a graph representing the change in the hardness of a metal part as a function of the depth below the treated surface, for several peening conditions with another hardness measurement method.
  • FIG. 22 is a schematic cross-sectional representation of a metal part having a nanostructured surface layer as a function of the depth below the treated surface on which the measured hardness curve is superposed.
  • FIG. 23 is a graph representing the change in the surface hardness of a part treated by peening and the change in the thickness of a nanostructured surface layer as a function of the degree of coverage.
  • a process for nanostructuring a metal surface 1 is schematically represented.
  • the size of the grains 2 of the material all the way to the surface 1 is typically a few tens to a few hundreds of ⁇ m.
  • the grain size of the material at a surface layer 3 is reduced to a few tens of nm, for example around 20 nm, whilst grains of larger size continue to exist more deeply in the material.
  • an axis z perpendicular to the surface 1 and oriented towards the inside of the material starting from the surface is defined.
  • the surface serves as a reference of the dimensions. The transition of the size of the grains between the surface layer 3 and the unmodified deep material is in reality more gradual than in the drawing.
  • the nanostructuring of the material in the layer 3 is stable up to a temperature of at least 600° C.
  • a metal part coated with such a nanostructured layer may be used in various industries, for example in applications where the wear resistance and the fatigue resistance are critical properties.
  • the machine 10 comprises a projection nozzle 11 supplied from a shot reservoir and from an air compressor (which are not represented) in order to produce a jet of shot projected at a speed V which may vary depending on the size of the shot particles.
  • the projection of the shot particles may also be carried out using a vane turbine, according to the known art. Common peening equipment makes it possible to obtain speeds ranging from 20 m/s to around 120 m/s.
  • the shot used preferably consists of particles obtained by atomization. Such particles may be produced in a large amount at a relatively advantageous cost and have quite good sphericity, for example greater than or equal to 85%. Their cost is substantially lower than that of ball bearing balls, the process for the manufacture of which is virtually unitary in order to achieve a sphericity of greater than 99%.
  • peening media such as conditioned cut wire, glass beads or ceramic beads.
  • the projection nozzle 11 is fixed facing a mobile support device 12 constructed in the following manner: a metal disk 13 is mounted on the shaft of a rotary motor that is not represented, for example an electric motor, in order to be able to pivot with respect to a fixed frame 19 .
  • the central pivoting axis of the disk 13 is coaxial with a central projection axis of the nozzle 11 .
  • Positioned on the disk 13 is an inclinable support 14 , the angle of inclination of which with respect to the disk 13 can be adjusted by means of a screw.
  • Fastened around a central portion of the inclinable support 14 are fastening clamps 15 provided with screws 16 parallel to the support 14 .
  • the screws 16 may be tightened onto a part to be treated in order to fasten the part between the clamps 15 and may be loosened in order to withdraw the part after treatment.
  • a jet of particles 20 produced by the projection nozzle 11 is schematically represented.
  • the jet 20 has an approximately conical shape with a half apex angle ⁇ .
  • the angle ⁇ may be measured, for example, as the ratio between the radius p of an impacted region 21 and the distance L from the region 21 to the orifice 22 of the nozzle 11 .
  • the surface portion located around the central axis 25 of the jet 20 receives the particles at an angle of incidence a with respect to the local normal direction 26 .
  • the surface portion located around an edge of the jet receives the particles at an angle of incidence ( ⁇ ) with respect to the local normal direction 27 .
  • the surface portion located around the opposite edge of the jet 20 receives the particles at an angle of incidence ( ⁇ + ⁇ ) with respect to the local normal direction 28 .
  • any portion of the sample located in the jet 20 is hit at incidences located in a more or less wide conical film.
  • This conical film is thin towards the centre of the jet where it coincides exactly with the angle ⁇ and broader towards the periphery of the jet, where it includes all the angles between ( ⁇ ) and ( ⁇ + ⁇ ). If ⁇ , the conical film degenerates into a cone.
  • a treated surface region may be hit at all the angle of elevation values located in the conical film.
  • This property of the machine 10 makes it possible to produce nanostructured layers on different metals with a relatively high productivity, as will be recounted in the tests below. In the tests below, the angle ⁇ is equal to around 8° and the distance L to around 300 mm. Of course, it is not excluded for a small portion of the particles to be projected along atypical trajectories outside of the main directions of the jet 20 .
  • the nominal diameter of a type of shot is defined as the median diameter of the distribution: 50% by weight of the particles of the type of shot considered have a diameter of less than the nominal diameter, and 50% have a larger diameter.
  • the degree of coverage R is a measurement of the proportion of the surface impacted by the peening. In the present description, it is defined as follows: the reference 100% indicates that an amount of shot which is statistically sufficient to impact 98% of the exposed surface was projected. Beyond 100%, a linear law is applied with respect to this reference amount. A degree of coverage of 1000% therefore indicates that ten times the reference amount has been projected. At constant flow rate, the degree of coverage is therefore also a measurement of the treatment time of the sample.
  • the thickness of the nanostructured layer zn was obtained by two methods: observation by optical microscopy and observation of the hardness profile of the material as a function of the depth z.
  • the thickness measured is an arithmetic mean of nine observations of the thickness of the visually amorphous layer corresponding to the nanostructured region 3 .
  • the width of the sample treated is scanned over three regions and three measurements are taken per region, which ensures the reproducibility of the measurement method.
  • the microscope observations are then correlated to hardness profiles, in order to confirm that the visually amorphous region observed indeed corresponds to the peak of hardness originating from the hardening by the effect of the nanometre-sized grains.
  • the method used for producing the hardness profile consists in making an indentation line with a step of 50 ⁇ m starting from the outermost surface with a micro Vickers hardness tester having a pyramidal tip with a load of 100 g (HV 0.1) which possesses a lens.
  • the surface of the sample and the nanostructured layer are visualized as in optical microscopy.
  • the hardness profile is thus obtained from a depth of 50 ⁇ m to 500 ⁇ m.
  • the values communicated are an average of three indentation lines in order to have a reliable and reproducible measurement.
  • the curve 30 corresponds to the type S170 shot.
  • the curve 31 corresponds to the type S280 shot.
  • the curve 32 corresponds to the type S330 shot.
  • the curve 33 corresponds to the type S550 shot.
  • a region of very high hardness 34 appears, which corresponds to the nanostructured layer 3 and a second region 35 appears where the hardness decreases more gradually with the depth and which corresponds to the strain hardening of the material.
  • the boundary of the nanostructured layer 3 must therefore correspond to a steep change of slope of the hardness. This point is verified in FIG. 5 where the thicknesses z n obtained by visual observation have been plotted as a dot-and-dash line for each type of shot.
  • the nanostructured layer 3 is the region in which the hardening of the material produced by the peening treatment is greater than or equal to 50% of the maximum hardening obtained at the surface of the sample. This empirical definition has been verified experimentally for the degrees of coverage of greater than 750%, as will be explained below.
  • FIG. 6 represents the change in the thickness z n observed visually as a function of the peening treatment time, measured by the degree of coverage R, by the four types of shot.
  • Curve 36 corresponds to type S170 shot.
  • Curve 37 corresponds to type S280 shot.
  • Curve 38 corresponds to type S330 shot.
  • Curve 39 corresponds to type S550 shot.
  • FIG. 6 demonstrates that all the shots from test 1 make it possible to obtain a thickness z n that exceeds 100 ⁇ m, or even 140 ⁇ m.
  • This figure also demonstrates two advantages of the type S280 and S330 shots (curves 37 and 38 ).
  • the nanostructured layer 3 appears significantly at a lower degree of coverage R, around 300%, than with the larger particles (S550) or smaller particles (S170).
  • the thickness z n reaches its peak at a higher level than that obtained with larger particles (S550) or smaller particles (S170).
  • FIG. 16 This competition is illustrated schematically in FIG. 16 , where the region of influence of an impact, also referred to as the nanocrystallization lobe, is represented by a semisphere.
  • the region of influence of an impact also referred to as the nanocrystallization lobe
  • impacts that are relatively spaced apart give rise to edge regions where the material is deformed over a relatively small thickness z 0 and central zones where the material is deformed over a relatively large thickness z 1 .
  • the thickness z n that can be observed lies between z 0 and z 1 .
  • Another property on which the size of the particles has an observable effect is the uniformity of the thickness z n along the treated surface. This property may be characterized by the standard deviation C of the thickness z n . Table 3 recounts the values measured in the samples from test 1, micrographs of which are reproduced in FIGS. 17 to 19 . For the chosen degree of coverage, it appears that the largest type S550 shot provides a mean thickness z n comparable to the thickness obtained with the type S330, but a doubling of the standard deviation C. FIGS. 17 to 19 also make it possible to observe nanocrystallization lobes.
  • FIG. 7 represents, for a conventional peening nozzle model, the change in the degree of coverage R with the projection time t for two different particle sizes, all conditions being otherwise equal.
  • Curve 40 relates to type S550 and curve 41 to type S280.
  • test 1 in order to form a thickness of 100 ⁇ m, 107 s are needed with type S550 versus 30 s with type S330 and 75 s with type S280. It is therefore seen that the optimal type of shot in terms of productivity, that is to say that produces the greatest nanostructured thickness per unit time, lies below the S550 particle size.
  • Test 1 therefore shows that counter-productive effects of the large particles begin to arise with the type S550 shot and that it is not advantageous to use even larger sizes.
  • FIG. 8 demonstrates the relationship between the nanostructured thickness z n and the hardening observed at the surface of the treated sample.
  • Curve 42 represents the thickness z n (left-hand axis) and the curve 43 the Vickers hardness at the surface (right-hand axis) as a function of the coverage R for type S280 in test 1.
  • Curve 43 demonstrates a strain-hardening effect which causes a first increase in hardness in a region 45 starting from the initial hardness 44 without however forming nanometre-size grains, and an effect of the nanostructuring of the material which causes a second increase in the hardness in a region 46 .
  • FIG. 9 shows the change in the thickness z n as a function of the coverage R in test 2 (square symbols) superposed on curve 42 from test 1. No significant difference emerges between the results of the two tests, neither in the thickness measurements, nor in the hardness measurements, which means that the fastening of the part by clamping in test 1 has no causal relationship with the nanostructuring effects observed.
  • test 3 was carried out with the type S170, S280 and S330 shots under conditions similar to test 1 by varying the angle ⁇ between 0° and 45° and the rotation of the support device 12 .
  • the nanostructured thicknesses obtained in this test 3 are recorded in Table 4.
  • FIG. 10 graphically represents the results from Table 4 with rotation of the support.
  • Curve 50 corresponds to type S170 shot.
  • Curve 51 corresponds to type S280 shot.
  • Curve 52 corresponds to type S330 shot.
  • Curve 53 corresponds to the 304L stainless steel.
  • Curve 54 corresponds to the 32CDV13 structural steel.
  • the hardness profiles of these materials correspond to the trends observed in test 1. Regions 34 and 35 of FIG. 11 have the same meaning as in FIG. 5 .
  • Curve 31 from test 1 (E24 steel) is plotted by way of comparison.
  • the thicknesses z n observed are visually 143 ⁇ m for E24, 176 ⁇ m for 32CDV13 structural steel and 155 ⁇ m for 304L stainless steel.
  • This definition clearly corresponds to curve 53 (304L steel) when the reference for the hardening is chosen at a depth of 300 ⁇ M.
  • the choice of reference is explained by the change of microstructure specific to the 304L steel, during the peening of the material, and more particularly during a first step of the peening corresponding to a step of strain-hardening of the material.
  • the sample of 304L steel has its original hardness of the austenite and for a thickness of less than 300 ⁇ m the hardness of the material is increased both by the nanostructured layer and by the presence of strain-induced martensite.
  • the reference hardness used for determining the nanostructured layer is the hardness at the deepest layers of the strain-induced martensite, which is here around 300 ⁇ m.
  • test 1 In order to evaluate the effect of smaller particles, tests were carried out with samples of pure iron containing 0.03C (99.8% Fe) and type S070 shots. The other conditions are similar to test 1.
  • Test 6 demonstrates the obtaining of a greater nanostructured thickness with a degree of coverage, a particle size and a projection speed that are all lower than in this publication. It is noted that the comparison of degrees of coverage requires a calibration due to different definitions in the two cases. The use of a lower projection speed may prove advantageous for reducing the roughness of the treated sample or protecting a material more vulnerable to microcracks.
  • Test 7 was carried out with samples of pure iron containing 0.03C (99.8% Fe) and type S170 shots. The other conditions are similar to test 1.
  • Curve 64 represents the Vickers hardness at the surface and curve 65 the thickness z n .
  • the numbers 44 , 45 and 46 have the same meaning as in FIG. 8 . It is observed that the thickness z n saturates at a level close to 100 ⁇ m.
  • Table 3 recounts the results of the second series of tests carried out according to the same conditions as test 1 presented in Table 2.
  • the method used for producing the hardness profile during this second series of tests consists in making an indentation line with a step of 10 ⁇ m starting from 20 ⁇ m from the outermost surface to a depth of 100 ⁇ m.
  • the indentation line is then continued with a step of 50 ⁇ m to a depth of 300 ⁇ m.
  • the indentation line is made with a micro Vickers hardness tester having a pyramidal tip with a load of 25 g (HV 0.025) which possesses a lens.
  • HV 0.025 a Buehler Micromet 5104 microhardness tester comprising a motorized table having a step of 1 ⁇ m and Buehler Omnimet Mhtsa control and measurement software.
  • the hardness profile is thus obtained from a depth of 20 ⁇ m to 300 ⁇ m.
  • the values communicated are an average of three indentation lines in order to have a reliable and reproducible measurement.
  • the surface of the samples and the nanostructured layer are visualized by optical microscopy. The observation of the samples is carried out using a Zeiss axio scope A1 microscope, a Qimaging Micropublisher 5.0 RTV camera, a Zeiss EC EPIPLAN X10/0.2HD lens and Axiovision 4.8 software.
  • the first three columns of Table 3 correspond to the first three columns of Table 1
  • the fourth column mentions the thickness of the nanostructured layer, denoted by z nh with reference to the hardness. Indeed, in test 8, the thickness of the nanostructured layer z nh was obtained by a method solely based on the hardness profile as a function of the depth z. For this, a hardness threshold is determined by calculating the median value of the hardness between the hardness measured on the surface layer and the hardness of the sample in the deep layer in which the material is not substantially modified by the peening.
  • the thickness of the nanostructured layer z nh therefore corresponds to the depth at which the increase in the hardness is equal to half of the increase in hardness observed at the surface of the sample after treating this surface.
  • the fifth and sixth columns mention the hardness at the surface of the sample on the treated face and on the untreated face. These values correspond to the first measurement points of the measured hardness curve, that is to say to a depth of 20 ⁇ m.
  • the hardness is measured closer to the surface than in test 1, so that the hardness value is higher than in Table 2.
  • the size of the grains in the vicinity of the surface varies according to a gradient.
  • the size of the grains varies between 10 and 50 nm, and in a deeper region, the size of the grains varies between a few tens of nanometres to a few hundreds of nanometres.
  • the hardness is measured with a larger load in test 1 than in test 1 The impression made in the material therefore has larger dimensions in test 1 and therefore generates a less precise measurement.
  • the last column from Table 3 mentions the uncertainty margin of the thickness measurement z nh resulting from the uncertainty margin of the microhardness tester.
  • the hardness measurements have an uncertainty of around ⁇ 10 Vickers for the E24 steel, ⁇ 9.5 Vickers for the 32CDV13 steel and ⁇ 13.5 Vickers for the 304L steel.
  • the hardness tester load is adapted as a function of the hardness of the material: a greater load is used for harder materials.
  • a load of 50 g (HV 0.050) is used for the 32CDV13 steel and for the 304L steel.
  • Curve 70 corresponds to type S170 shot.
  • Curve 72 corresponds to type S330 shot.
  • Curve 73 corresponds to type S550 shot.
  • a zone of very high hardness appears which corresponds to the nanostructured layer 3 and a second zone appears where the hardness decreases more gradually with the depth and which corresponds to the strain hardening of the material.
  • the hardness value 74 measured in the deep layer and the maximum hardness value 75 measured on the surface layer of the sample associated with curve 70 are respectively equal to 142 and 300 Vickers.
  • the corresponding threshold 71 has a value of 221 Vickers, which corresponds to the median value between the hardness value 74 measured in the deep layer of the sample and the maximum hardness value 75 measured on the surface layer of the sample.
  • This threshold makes it possible to determine a thickness z nh of the nanostructured layer having a value approximately equal to 81.5 ⁇ m for the test corresponding to the S170 shot.
  • An uncertainty range of the thickness z nh of the nanostructured layer is therefore determined from the hardness threshold and from the uncertainty range of the hardness.
  • the boundary values of the thickness of the nanostructured layer are plotted for hardness values 85 and 86 respectively of 231 Vickers and 211 Vickers.
  • the thickness of the nanostructured layer lies within a range of around 69 to 92 ⁇ m.
  • the uncertainty ranges of the thickness of the nanostructured layer are presented in Table 3.
  • the thickness of the nanostructured layer measured graphically itself also has a measurable uncertainty.
  • the hardness profile 70 as a function of the depth z from the surface of the sample is plotted on the schematic representation of these regions.
  • a nanostructured surface layer 77 corresponding to a region in which the material is substantially amorphous and homogeneous.
  • Layer 77 corresponds to the darker zone observed in FIGS. 17 to 19 .
  • Layer 77 extends from the surface 76 of the part to a second layer 78 ,
  • This second layer 78 corresponds to the region in which grain boundaries are observed and in which the size of the grains delimited by the grain boundaries increases with the depth.
  • layer 78 corresponds to the region which extends from a sudden change in contrast starting from layer 77 .
  • This second layer 78 corresponds to the strain-hardening region of the material.
  • a third layer 79 comprises a region where the size of the grains remains constant.
  • the hardness threshold 71 agrees substantially with the boundary 84 observed visually between the nanostructured surface layer 77 and the layer 78 .
  • the method of measuring thickness based on the hardness described above may display a difference with the optical observation when the thickness of the nanostructured layer is thin, which corresponds to the case of the samples from test 8 at a degree of coverage of less than 750%. Another method for determining the thickness of the nanostructured layer may then be used. This other method is also based on the principle of determining the thickness of the nanostructured layer from a hardness threshold. This method starts from the observation that, when it appears on the sample and therefore when it has a very thin thickness, the nanostructured layer 3 has a hardness value at the surface which corresponds to this threshold.
  • a hardness threshold By way of illustration, with reference to FIG.
  • curve 80 represents the thickness of the nanostructured layer as a function of the coverage and curve 81 represents the surface hardness of the sample as a function of the coverage for the S170 peening test.
  • a minimum detectable thickness 82 of the nanostructured layer appears for a coverage of 150%.
  • the surface hardness 83 measured during this appearance of the nanostructured layer is 226 Vickers.
  • This hardness threshold of 226 constitutes a realistic value of the hardness threshold for determining the thickness of the nanostructured layer after treatment with a coverage of less than 750%.
  • test 8 listed in Table 3 the hardness thresholds were determined with this other method for coverage values of less than 750%. In Table 3, the values determined with this other method have an asterisk.
  • the processes used are applicable to metal parts of any shape.
  • the expression “successive portion” is understood here to mean a surface portion that is relatively small with respect to the local radius of curvature, so that an average orientation of the surface portion can be defined, and relatively large with respect to the size of the shots projected, so that a large number of impacts can statistically be envisaged.
  • Certain non-planar geometries are capable of producing multiple impacts by one and the same particle on the part, that is to say rebounds. However, given that the rebounds lead to very high energy losses, it is assumed that it is the primary incidence of the particle, that is to say the incidence before the first impact on the part which is the most significant.
  • the working surfaces of a gear pinion are generally the bases of the teeth.
  • the nanostructuring treatment of a pinion can therefore be carried out, in one particular embodiment, by successively orienting the tooth base surfaces facing the particle jet, so as to carry out the particular orientation of the primary incidences of the particles on the tooth base surface.
  • a single projection nozzle has been presented in the embodiment of the machine from FIG. 2 .
  • a peening machine with several projection nozzles.
  • These projection nozzles may especially be arranged so as to target the same surface of the part along several different incidences.
  • Projection nozzles may also be arranged so as to target various surfaces of the part to be treated.
  • the embodiments described in the examples relate to initially homogeneous materials on which the peening processes described make it possible to form relatively thick nanostructured surface layers. It is possible to characterize the degree of coverage applied to a given material by the thickness of the nanostructured layer that this coverage made it possible to obtain. Hence, the application of a similar degree of coverage to a material having undergone other prior treatments is also capable of effectively producing nanostructured surface layers, even if this pretreated material does not correspond to the examples described, for example a heterogeneous material.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
  • Laser Beam Processing (AREA)
  • Powder Metallurgy (AREA)
US13/977,123 2010-12-30 2011-12-29 Surface treatment of a metal part by oblique shot peening Abandoned US20150306736A1 (en)

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FR1061373 2010-12-30
FR1061373A FR2970006B1 (fr) 2010-12-30 2010-12-30 Traitement de surface d'une piece metallique
PCT/FR2011/053210 WO2012089989A1 (fr) 2010-12-30 2011-12-29 Traitement de surface d'une piece métallique par grenaillage oblique

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CA (1) CA2822186C (fr)
DE (1) DE11815553T1 (fr)
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US10000822B2 (en) 2013-09-02 2018-06-19 Blanco Gmbh + Co Kg Method for hardening sheet metal material
FR3082446A1 (fr) * 2018-06-14 2019-12-20 Psa Automobiles Sa Procede de texturation d’une surface sollicitee en frottement lubrifie et surface ainsi obtenue

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FR3004729A1 (fr) * 2013-04-23 2014-10-24 Peugeot Citroen Automobiles Sa Procede de traitement d'une piece en acier fritte
JP7377113B2 (ja) * 2020-01-27 2023-11-09 山陽特殊製鋼株式会社 ショットピーニング用粉末
CN114117680B (zh) * 2021-12-02 2024-05-07 中航飞机起落架有限责任公司 具有可转动工作台的喷丸用装置模型构建方法及系统
CN116652841B (zh) * 2023-07-31 2023-10-17 河南师范大学 一种物理实验用金属器具加工设备

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JP3765376B2 (ja) * 2000-03-29 2006-04-12 オリエンタルエンヂニアリング株式会社 ショットピーニング装置及び方法
FR2812284B1 (fr) * 2000-07-28 2003-03-07 Univ Troyes Technologie Procede de mecanique de generation de nanostructures et dispositif mecanique de generation de nanostructures
FR2812285B1 (fr) * 2000-07-28 2003-02-07 Univ Troyes Technologie Procede de traitement de nanostructures et dispositif de traitement de nanostructures
US7147726B2 (en) * 2000-07-28 2006-12-12 Universite De Technologie De Troyes Mechanical method for generating nanostructures and mechanical device for generating nanostructures
US6570125B2 (en) * 2001-08-31 2003-05-27 General Electric Company Simultaneous offset dual sided laser shock peening with oblique angle laser beams
JP3879059B2 (ja) * 2002-01-07 2007-02-07 財団法人理工学振興会 ナノ結晶構造金属材料の製造方法及びナノ結晶構造金属材料
JP4112952B2 (ja) * 2002-11-19 2008-07-02 新日本製鐵株式会社 表層部をナノ結晶化させた金属製品の製造方法
JPWO2004059015A1 (ja) * 2002-12-25 2006-04-27 新東工業株式会社 金属表面の微細化方法及びその金属製品
JP4168342B2 (ja) * 2004-02-12 2008-10-22 トヨタ自動車株式会社 高硬度高磁気特性鋼材及びその製造方法
JP2006125530A (ja) * 2004-10-29 2006-05-18 Kanai Hiroaki ピストンリングおよびその製造方法
FR2925378B1 (fr) * 2007-12-20 2012-06-15 Saint Gobain Ct Recherches Particules de grenaillage.
RU2354715C1 (ru) * 2007-12-24 2009-05-10 Государственное образовательное учреждение высшего профессионального образования Томский политехнический университет Способ упрочнения деталей из конструкционных материалов
CN101580940B (zh) * 2009-06-10 2010-09-15 广东巨轮模具股份有限公司 一种汽车轮胎模具的快速节能气体软氮化方法

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10000822B2 (en) 2013-09-02 2018-06-19 Blanco Gmbh + Co Kg Method for hardening sheet metal material
US20180237873A1 (en) * 2013-09-02 2018-08-23 Blanco Gmbh + Co Kg Method for hardening sheet metal material and hardened metal sheet material
US10837070B2 (en) 2013-09-02 2020-11-17 Blanco Gmbh + Co Kg Method for hardening sheet metal material and hardened metal sheet material
FR3082446A1 (fr) * 2018-06-14 2019-12-20 Psa Automobiles Sa Procede de texturation d’une surface sollicitee en frottement lubrifie et surface ainsi obtenue

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JP5857070B2 (ja) 2016-02-10
CA2822186A1 (fr) 2012-07-05
RU2579323C2 (ru) 2016-04-10
MX2013007448A (es) 2013-12-06
BR112013017012A2 (pt) 2016-10-25
JP2014501182A (ja) 2014-01-20
FR2970006A1 (fr) 2012-07-06
FR2970006B1 (fr) 2013-07-05
KR20130132968A (ko) 2013-12-05
EP2659010B1 (fr) 2018-03-28
CN103403196A (zh) 2013-11-20
EP2659010A1 (fr) 2013-11-06
ES2672928T3 (es) 2018-06-18
DE11815553T1 (de) 2014-02-27
CA2822186C (fr) 2019-03-12
WO2012089989A1 (fr) 2012-07-05
KR101843606B1 (ko) 2018-03-29

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