Showing papers on "Peening published in 1984"

Method of coating a substrate with a rapidly solidified metal

Abstract: A method for coating a substrate with rapidly solidified metal which comprises spraying a mixture of rapidly solidified metal powder and small peening particles at high velocity against the substrate, said velocity being sufficient for the rapidly solidified metal powder and peening particles to impact the substrate and simultaneously bond the metal powder to the substrate. If the substrate is metallic, the method may provide the simultaneous mechanical working of the substrate surface.

System for the monitoring and control of flow of particulate material in impact treatment equipment

Abstract: Air blast peening equipment includes a flow density transducer and a pressure or velocity transducer for measuring flow velocity. Measured values are compared during peening with predetermined desired values. Operation of the apparatus is automatically adjusted, if necessary, by adjustment of flow density and/or flow velocity to maintain these parameters at desired values.

The fatigue of an aluminium alloy produced by fretting on a shot peened surface

Abstract: An Al-4.2%Cu-0.7%Mg-0.7%Si age hardening alloy (2014A) has been shot peened and subjected to plain and fretting fatigue. The shot peening improves both plain and fretting fatigue strengths, and in particular the fretting fatigue strength of the alloy in the fully aged condition is increased by 130%. The improvement in fretting fatigue properties is largely due to the residual compressive stresses induced into the surface by the shot peening process. Surface roughening also has a small beneficial effect but work hardening of the surface does not influence the fretting fatigue properties.

Improvement of the fatigue life for offshore welded connections

Abstract: The advantages provided by using high strength structural (HSS) steels for offshore construction might be limited by the fatigue resistance properties of the welded connections. Since fatigue crack propagation characteristics are not significantly different between low and high strength structural steels, the best way to improve the fatigue resistance of welded joints in HSS steels is to introduce a longer initiation period. For this purpose, we developed two complementary procedures: an improved weld procedure, and a global post weld improvement technique. The overall geometry of the fillet weld is controlled to obtain the best stress flow and the lowest stress concentration in the weld toe region. Furthermore the weld toe run is done at the beginning of the welding. This improved weld procedure gives smaller global and local stress concentrations. The second step to improve the fatigue resistance of such welded joints is post weld shot peening. Such a technique has the advantage of being a “global treatment”, not only localized at the weld toe. The compressive residual stress field induced by shot peening has been studied at the surface of the specimen and in depth. By measuring the initial stress field (prior to fatigue testing) and the redistribution of these residual stresses during fatigue, optimum parameters of shot peening (ALMEN intensity, shot diameter, coverage rate, etc) may be chosen. Fatigue tests were carried out on 30 mm thick T shape welded joints. Comparative results between as-welded and shot peened specimens show the efficiency of the improved weld procedure and of shot peening in improving the fatigue resistance of welded structures.

Spray welding of metals

Abstract: A butt weld is made between components having scarves. Three work stations AB, CD and EF advance from right to left, all in a non-oxidising atmosphere. AB, a plasma scarf melting step, precedes and is overlapped by CD, a spray deposition step, which applied a molten spray of filler metal to form the weld. THe step CD precedes and is overlapped by EF, a peening step, which consolidates the weld as it freezes. The peening EF does not overlap the scarf melting AB.

Simultaneous spray deposition and peening of metals (SSP)

Abstract: A new process, simultaneous spray peening (SSP), is described which comprises the spray deposition of metals together with simultaneous shot peening. This combined incremental operation allows either thick or thin deposits to be made in ferrous or non-ferrous metals. The deposits are hot worked and densified during the process so improving their properties compared with more conventional spray deposits. An additional advantage is that the inherent residual tensile stresses of spray deposition are counter-balanced by the compressive stresses caused by peening. By control of the simultaneous peening operation it is shown that the residual stresses in SSP deposits can be maintained at any required positive or negative level. Examples and structures are shown of SSP products made from gas-atomized melts, by arc spray, and by plasma spray.

Manufacture of machine parts made of precipitation hardening alloy

Abstract: PURPOSE:To obtain machine parts made of a precipitation hardening alloy with corrosion resistance and high strength, by forming a worked layer on the surface of a precipitation hardening alloy in a solubilized state and by subjecting the alloy to age heat treatment. CONSTITUTION:A precipitation hardening material such as an Ni or Cr alloy is forged or mechanically worked and subjected to soln. heat treatment. A worked layer having >= about 50mum thickness is formed on the surface of the material by peening or other method, and the material is subjected to age heat treatment. By this method a layer with superior mechanical strength remains on the surface, superior mechanical strength is provided as a whole, and machine parts with improved corrosion resistance and stress corrosion cracking resistance are obtd.

Delivery system for ball peening or forming apparatus

Abstract: A ball peening machine used for forming or surface treatment is constructed with a unique delivery system. The peening media is loaded by gravity from a hopper to a conveyor belt which is constructed with paddles extending transverse to the direction of travel. The media is delivered to the work piece at the end of the conveyor where it turns sharply downward. The paddles tend to propel the media downward.

Decorative nickel-chromium electroplated surfaces with patterned finishes

Abstract: SummaryDecorative nickel-chromium plated surfaces with patterned finishes can be produced using a process which selectively applies the patterning, in the form of a satin texture, to the chromium plated surface by peening with a slurry of glass beads in water. The equipment and techniques needed to ensure successful results in production are described. The results of accelerated corrosion testing and outdoor exposure tests show that the process has no adverse effect on the corrosion resistance of the plated finish. Metallographic examination of the chromium plated surface, after peening, shows the deformation and change in topography, which gives a more diffuse scattering of reflected light, resulting in a lustrous, satin finish. The deformation also introduces a fine crack pattern into the chromium plated layer.

Decision method of result from peening work

Abstract: PURPOSE: To enable a result of work to be decided for whether it is good or bad with no necessity of skill, by irradiating light from a gloss sensor to a surface, immediately after it is processed by peening work, and comparing a quantity of reflected light with the quantity of reflected light from a standard workpiece so as to decide whether the result of work is good or bad. CONSTITUTION: If short peening work is finished for a workpiece 22, it is carried outside a blast chamber 8 by a grip 23 of a workpiece attitude control device 7 and positioned to a gloss sensor 6 immediately after a time for which gloss of the workpiece is not changed. This gloss sensor 6, placing the workpiece 22 approaching to an optical fiber 27 in a distance l about 3cm, measures the gloss of a processed surface by a light emitting and a light receiving element 29, 30. And a quantity of reflecting light from a standard workpiece, set by previously studying a condition of compressed air pressure, machining time, etc. obtaining a predetermined peening effect, serves as a reference deciding a result of peening work for whether it is good or bed. COPYRIGHT: (C)1986,JPO&Japio

Manufacture of rear axle housing

Abstract: PURPOSE:To increase fatigue strength of a rear axle housing by removing unevenness due to mold deviation, burrs, traces of welding correction, traces of grinding etc. caused in manufacturing a rear axle housing made of cast steel by blasting work. CONSTITUTION:After casting a rear axle housing as a cast steel product M, the gate 2 is ground by a grinder 3 or acute angled part 2a is ground by welding correction. Then, blasting work by shot peening is performed on the whole body of the rear axle housing 1. Shot peening is performed by blasting about 0.3-4mm. steel shots at blasting speed of 10-50m/sec. Compressive stress is caused on the surface of the rear axle housing by spot peening and internal tensile stress is cancelled by this and concentration of stress is prevented. Consequently, fatigue strength is increased.

Treatment in weld zone of nickel alloy

Abstract: PURPOSE:To improve the corrosion resistance in the weld zone of an Ni alloy contg. Cr by subjecting the weld zone thereof to strong plastic working then heating the weld zone so as to form a fine granular structure by a primary recrystallization. CONSTITUTION:The respective surfaces in the weld metal and weld heat affected zone of a weldment made of an Ni alloy contg. Cr are sujbected to strong plastic working and thereafter the strong-plastically worked parts are heated to form the fine granular structure by a primary recrystallization, whereby the corrosion resistance in the weld zone is improved while a mechanical property such as high temp. strength is maintained. The above-mentioned weldment is preferably formed of a welding base metal produced by subjecting the same to an immunization treatment for >=10hr at 650-850 deg.C to deposit thoroughly Cr carbide and to decrease intergranular corrosion. The above-mentioned strong plastic working is accomplished adequately by shot peening or wire peening and the heating in the strong-plastically worked parts is acoomplished preferably at 700-850 deg.C by high frequency induction heating, laser beam heating or IR heating.

Surface treatment of ferrous metallic parts

Abstract: PURPOSE:To prevent the generation of the blown-out matter after mechanical removal of the infiltrated matter, by subjecting porous ferrous parts to a surface treatment by a nitriding treatment with a salt bath then heating the same to a specific temp. to blow out forcibly the infiltrated matter and removing mechanically the same. CONSTITUTION:A hard nitride layer is formed by a nitriding method with a salt bath on porous metallic parts such as ferrous sintered parts in order to improve the wear resistance thereof. Since the salt in the bath used in this case is infiltrated into the inside of the porous material, the parts are heated for 30- 60min at 200-300 deg.C to blow out forcibly the infiltrated matter onto the surface. The blown-out matter is thoroughly removed by shot blasting or shot peening. The generation of the succeeding blow-out is thoroughly prevented by such treatment, and the surface hardness of the sintered parts is further improved by a peening effect as a secondary effect.

The Behaviour of Fatigue Cracks in Shot-Peened Components

Abstract: The present work has been directed towards an understanding of the effect of shot-peening on fatigue properties in terms of the propagation of fatigue cracks through the surface zones of peened samples. Measurements of the residual stress distribution below the surface of peened specimens of a martensitic 12% Cr steel along with results from fatigue crack growth experiments at different mean stresses have been used to determine the relative defect tolerance of peened and untreated fatigue-loaded components. A considerable improvement of up to a factor of 4 can be expected.