Showing papers on "Peening published in 1990"

X-ray diffraction characterization of residual stresses produced by shot peening

Abstract: A brief overview of the theory and practice of x-ray diffraction residual stress measurement as applied to shot peened materials is presented. The unique ability of x-ray diffraction methods to determine both the macroscopic residual stress and the depth and magnitude of the cold worked layer produced by shot peening is described. The need to obtain a complete description of the subsurface residual stress distribution, in order to accurately characterize the residual stress distributions produced by shot peening, is emphasized. Non-destructive surface residual stress measurements are shown to generally be inadequate to reliably characterize the residual stresses produced by shot peening. Practical applications of x-ray diffraction methods for quality control testing are considered. Examples are presented for steel and nickel base alloys.

Fatigue Damage Evaluation of Shot Peened High Strength Aluminum Alloy

Abstract: Shot-peening was applied to high strength aluminum alloy (Al-7050). At various stages during fatigue processes, x-ray diffraction studies including residual stress measurements (by Cr) and dislocation density measurements based on diffraction line analyses (by Cu and Mo) were perfomed. It was found that (1) both surface and interior residual stresses were relaxed as a function of fatigue cycle ratio, (2) relaxation rate of interior residual stress showed a negative slope, (3) the position where the maximum interior dislocation density was developed was close to that where the maximum peak interior residual stresses were generated, (4) surface dislocation density decreases and interior dislocation density increases by increasing fatigue cycles, (5) when ratio of interior to surface dislocation density exceeds 1000, the specimen is close to its fatigue life, and (6) this dislocation density ratio serves a promising fatigue damage indicator.

The effect of heating shot peened sheets and thin plates of aluminium alloys

Abstract: 2024, 7075 and 7475 aluminium alloy sheet and thin plate specimens shot peened to various intensities and subsequently exposed for periods up to 500 h at temperatures up to 120 ° C showed significant decreases in the level of residual stress induced by the shot peening and significant changes in geometrical contour even for exposure temperatures as low as 80 ° C. The higher the intensity of the shot peening, the higher the temperature of exposure and the longer the period of exposure, the greater was the relief of residual stress. After 40 h at 120 ° C the level of residual stress was reduced by more than 60%. Specimens formed to a given curvature by shot peening tended to straighten out on exposure at elevated temperatures. Such significant effects were obtained at temperatures as low as 80 ° C, these increasing with duration and temperature of exposure. The results and the possible effect of a tendency to change the contour of a flight component in service are discussed. Metallurgical ameliorative measures for some of these effects are demonstrated.

Fatigue Fracture and Residual Stress Relaxation in Shot-Peened Components

Abstract: This work is devoted to highlighting the beneficial effects of compressive residual stresses, their relaxation and the associated fatigue crack initiation and propagation in two contrasting materials. Accordingly, rotating bend fatigue tests were conducted on essentially un-notched specimens made from 7075 T7351 aluminium zinc alloy and 080M40 medium carbon steel. The tests involved assessing the life of un-peened, peened, and re-peened specimens where re-peening was applied after the exhaustion of a proportion of the specimens anticipated fatigue life. Whilst the steel demonstrated a very significant recovery of fatigue life associated with the re-peening treatment, this was not the case for the aluminium even though peening had proved highly beneficial. Residual stress measurements and fractographic examination were used to elucidate this discrepancy.

Method and system for monitoring shot peening

Abstract: A method and system for nondestructively measuring surface compression layer depth including obtaining profile data of a peened workpiece surface and determining a total plastic upset depth for a selected dent, the plastic upset depth being approximately equal to the dent diameter. The peening operations may then be adjusted, if needed, so that subsequent peening more closely conforms to predetermined, desired peening results.

Shot peening treatment for rail-welded joint

Abstract: PURPOSE: To improve fatigue strength at a welded joint by welding a rail, subjecting the resulting weld zone to heat treatment, and then carrying out shot peening under specific conditions CONSTITUTION: After a rail is welded at the job site of laying, heat treatment consisting of holding at 500-650°C for ≥30sec is carried out, and then, shot peening treatment is applied to both sides of a web lower than the bending neutral axis in the weld zone and the surface and rear surface of a rail foot by projecting steel shots having 10-18mm diameter and C scale HRC 48-60 hardness by Rockwell hardness under the conditions of 400-1000kgf/m 2 projection density and 60-100m/sec projection rate By this method, fatigue strength at a welded joint of rail can be improved, and the rail-welded joint excellent in reliability can be obtained COPYRIGHT: (C)1991,JPO&Japio

Manufacturing of high strength bolt

Abstract: PURPOSE:To obtain a serration bolt capable of withstanding the increasing output and revolution of an engine by peening the serrated section of the serration bolt with shots each of which is Hv700 to 900 in hardness and 0.18 to 3.3 in a ratio of a grain size (d) to a fillet R, for a specified time. CONSTITUTION:Peening is, of course effective for improving fatigue strength even with shots each of which is less than Hv700 in hardness, shots with the thickness value equal to or more than Hv700 are however actually desirable. The use of the shots with the hardness value of Hv900 is sufficiently effective since the use of the shots with the harness value equal to or more than Hv900 results in the markedly shortened life of shot grains, the use of the hardness value less than Hv900 is appropriate. As for the shot size, grains with 50mu to 200mu in diameter can be used and are affected by relation with the radius of a fillet R section. Let the shot size be (d), and let the fillet radius be (R), it is desirable that d/R is 0.18 to 3.3. As for shot peening time, time less than 30 seconds by the use of the hardness value of Hv800 is insufficient to keep residual compression stress which is considered effective to improve fatigue strength in bending, time equal to or more than 90 seconds however saturates residual compression stress increasingly on the contrary.

Fine particle steel shot and manufacture thereof

Abstract: PURPOSE:To simply manufacture fine particle steel shorts for shot peening at a low cost by charging granules of white pig iron series hard cast irons into a heating furnace, heating them while supplying oxygen-containing gas and executing decarbonizing treatment to the surfaces of the granular cast irons CONSTITUTION:The while pig iron is charged into a cupola, and after heating and melting at 1,300 - 1,400 degC, this is atomized into water to manufacture the granular cast irons having 2 - 4% C and 01 - 20mm particle diameter This granular cast irons are charged into inner part 9 in a vessel 1 providing the refractory brick 7 having gas vent hole 8 and this vessel 1 is charged into the heating furnace 2 and rotated with a rotating shaft 5 having gas supplying hole 6 as the same as the above While supplying oxygen gas or oxygen- containing gas of the air, etc, into the inner part 9 in the vessel 1 through the gas vent holes 6, 8, these are heated in the heating furnace 2 at 800 - 1,000 degC for 05 - 10hr and the decarbonizing treatment is executed to the surface of the granular cast irons to manufacture the fine particle steel shots for peening having 01 - 10% C and 01 - 20 mm particle diameter

Shot Peen Controls and Aircraft Engine Requirements

Abstract: New shot peening requirements are emerging which are driven by aircraft engine customers. These include the military services and commercial air framers. The interest is in enhanced life engine components produced through quantified, verifiable benefits obtained by controlled, repeatable shot peen processes. These new requirements have the potential to greatly change the way peening is defined, and used in aircraft engine applications.

Peening methods for improvement of fatigue strength

Abstract: Keywords: 230/ICOM Note: Paper XIII-WG2-2-90 presented at the meeting of the IIW Commission XIII, Working Group 2 : Improvement methods. Lyon, France, 8-9 March 1990. Paris, Institut international de la soudure (IIW) Reference ICOM-REPORT-1990-002 Record created on 2008-01-24, modified on 2016-08-08

Sealing treatment for sprayed deposit

Abstract: PURPOSE:To maintain the attractive appearance of a thermally sprayed layer through many years while obviating the necessity of resin coating by applying peening treatment to a thermally sprayed layer formed on the surface of a base metal. CONSTITUTION:A thermally sprayed layer of metal is formed on the surface of a base metal of an exterior material, such as steel, for the purpose of improving attractive appearance and durability. Shot peening treatment is applied to the above thermally sprayed layer by using glass beads, etc., by which the porous thermally sprayed layer is sealed and the vicinity of the surface of the thermally sprayed layer is strengthened. Since the surface of the thermally sprayed layer is hardened by means of compaction by the above peening treatment and superior durability is provided, an exterior material free from deterioration in attractive appearance due to penetration of rainwater and sticking of soil can be formed.

Shot peening method for gear

Abstract: PURPOSE:To process a pair of gears in the same degrees and simultaneously by independently supporting plural gears of different radii biting in a pair each other on a concentric circle, respectively adjusting the peripheral speeds of plural gears by each rotating means provided respectively in the specified peripheral speed and processing by a single shot peening device. CONSTITUTION:Plural gears 4, 5 of different radii biting in a pair each other are independently supported on a concentric circle. Then in the state of respectively adjusting the peripheral speeds of the plural gears 4, 5 to the specified peripheral speed by each rotating means(motor) 10, 17 provided respectively, a shot peening treatment is simultaneously executed by a single shot peening device (projector) 23.

Some Theoretical Problems of Shot Peening

Abstract: Shot peening has long been used both for cleaning component surfaces and for improving the properties of surface layers. This paper reviews various ways of calculating the sizes of dimples formed by shot impacts under various conditions, dimple depths, the generation and magnitude of stresses and their effect on the deflection of a thin strip shot peened from one side only. The calculation results have been tested experimentally on an AlCu4Mgl alloy; this work has allowed detailed analyses of the coverage, dimple sizes and distribution patterns, and the amount of deflection. Stress calculations were based on the plastic deformation of the surface layer. In the discussion, the newly applied methods are compared with previously published approaches; the relationships between results obtained on flat strips and on cylindrical bars are examined; and procedures are described for determining the peening process parameters by calculations.

Manufacture of magnetostrictive torque sensor shaft

Abstract: PURPOSE:To give the magnetic anisotropy caused by a compression residual stress to a shaft body by constituting this shaft so that the total of a tensile strain caused by the torsion torque and the tensile strain which is not caused by the torsion torque to the shaft body becomes larger than the strain at the time of tensile yield of a shaft material. CONSTITUTION:When the torsion torque is applied to the shaft body 1, tension main stress and a compression main stress are generated by the shearing stress and the tensile strain and the compression strain are generated. In this state, when the tensile strain which is not caused by the torsion torque is generated by shot peening 5, the total of tensile strains is generated in the direction of the tension main stress caused by the torsion torque. Also, its value is allowed to become larger than the strain at the time of tensile yield of the material of the shaft body 1. Subsequently, when the torsion torque and the tensile strain of the peening 5 are eliminated, consequently, the shaft body 1 is brought to plastic working to the tension side by a portion by which the strain generated on the surface exceeds the strain at the time of tensile yield. Also, on the compression side, the compression strain and the tensile strain are offset and no plastic working is executed. In such a manner, the magnetic anisotropy caused by the compression residual stress can be given to the shaft body.

Effect of Pre- and Post-Processing upon Shot-Peening Residual Stresses

Abstract: The process of shot-peening finds extended use in industry to combat fatigue fracture in engineering components. The introduction of compressive residual stresses increases the fatigue life considerably and forms an integral part of the design process. Although the benefits of the shot-peening process are well established, all investigations overlook the history of the component being treated. This increases the scatter in the results and makes them unreliable. Also, although researchers are aware that post-processes performed on treated components reduce and redistribute the peening compressive residual stresses, no experimental confirmation exists.

Shot peening device

Abstract: PURPOSE:To grasp work strength electrically at real time and to increase the accuracy of the work stage control of a shot peening device by installing a collision energy detector generating an electric output toward the nozzle direction inside the shot zone of a processing room. CONSTITUTION:By a collision energy detector 6 faced to a nozzle 3a for shot injection, the electric output corresponding to the energy owned by the shot S colliding therewith is generated and due to the energy owned by the shot S being high at its correlation with the work strength in spot peening the work strength is electrically grasped at real time. The accuracy in the work stage control of a shot peening device 1 can be increased by electrically processing and utilizing that.

Stresses In Amorphous Gd-Fe Alloy Thin Films Deposited By Magnetron Sputtering

Abstract: Amorphous Gd-Fe alloy thin films were made by D.C. planar magnetron sputtering under various deposition conditions (e.g., film thickness, composition, working pressure of Ar, negative bias voltage and deposition rate). The stress, the film composition and the content of entrapped Ar in the films were measured respectively. The experimental results showed that in this case the working pressure of Ar and the negative bias voltage did not change the composition of the films, and the stresses were all compressive except for the films deposited in a very high working pressure of Ar. The origin of the compressive stress can be attributed to the atomic peening effect produced by fast neutral working gas atoms rebounded from the sputtering target. The magnitude of the compressive stress depends not only on the amount of Ar atoms incorporated in the films but also on the film microstructure such as the packing density.

Method and device for shot blasting

Abstract: PURPOSE:To increase the machining depth of peening, make the compressed residual stress on a surface uniform, and improve surface roughness by carrying out the peening machining of a cylindrical workpiece by using heavy-weight and light-weight shot grains. CONSTITUTION:A blasting shot gun 3 has a flow passage 15 for introducing shot 6, conveying fluid 7, and a jet stream 10 to a nozzle 14, while being rotatable around a connecting rod 5 and further being fitted to the connecting rod 5 so as to be movable also in the axial direction together with a thrust bearing 16. By inserting the nozzle 14 into a cylindrical workpiece 8, heavy-weight rough-grain shot from a blasting machine 24, together with the conveying fluid 7, is injected toward and made collide with the inner face of the workpiece 8 from the nozzle 14 to carry out deep layer peening. Then, light-weight fine- grain shot from the blasting machine 24, together with the conveying fluid 7 is injected out of the nozzle 14 to carry out surface layer peening. In this case, the space including the machining position of the workpiece 8 is closed up by means of a shielding mechanism (cylinder) 14.

Manufacture of thin wall tube

Abstract: PURPOSE:To join both edges of a thin metal sheet formed into a tubular shape by grinding or peening one surface of the sheet whose thickness is <=3.5mm. CONSTITUTION:A sheet thickness is limited to be <=3.5mm because forming effect reduces if a thickness of a thin metal sheet S exceeds 3.5mm. The strip S wound on a reel 1 is transferred with the strip S restricted in a flat shape between pinch rolls 3, 3'; in that time, an elastic wheel 4 is rotated at a prescribed number of rotations, the strip S is uniformly ground or peened in the width direction by pressing pinch rolls 5 onto the wheel 4. The strip S delivered from the rolls 3, 3' is released from restriction and is formed into a tubular shape. Then, a thin tube P is obtained by joining both edge thereof between pressing rolls 6, 6'. A ground or stain finished tube P having good designing capability is obtained because the tube P is formed by bringing the ground or peened surface to be the outside. Further, fatigue strength of the tube P is increased by peening.

Process and machine for peening the surface of fabrics.

Abstract: The machine for peening the surface of fabrics has a grit-blasting chamber (3), a belt (6) for moving the fabric (5) to be treated through the grit-blasting chamber (3), and a centrifugal turbine (16) arranged in the grit-blasting chamber (3) and fed with grit. The centrifugal turbine (16) is arranged so that its ejection outlet faces the fabric (5) to be treated in order to eject the grit onto the side of the fabric (5) which is to be subjected to the treatment so as to obtain particular finishing effects.