Steel Shot Research Articles

Dynamic numerical simulation of plastic deformation and residual stress in shot peening of aluminium alloy

Shot peening is a cold surface treatment employed to induce residual stress field in a metallic component beneficial for increasing its fatigue strength. The experimental investigation of parameters involved in shot peening process is very complex as well as costly. The most attractive alternative is the explicit dynamics finite element (FE) analysis capable of determining the shot peening process parameters subject to the selection of a proper material´s constitutive model and numerical technique. In this study, Ansys / LS-Dyna software was used to simulate the impact of steel shots of various sizes on an aluminium alloy plate described with strain rate dependent elasto-plastic material model. The impacts were carried out at various incident velocities. The influence of shot velocity and size on the plastic deformation, compressive residual stress and force-time response were investigated. The results exhibited that increasing the shot velocity and size resulted in an increase in plastic deformation of the aluminium target. However, a little effect of the shot velocity and size was observed on the magnitude of target´s subsurface compressive residual stress. The obtained results were close to the published ones, and the numerical models demonstrated the capability of the method to capture the pattern of residual stress and plastic deformation observed experimentally in aluminium alloys. The study can be quite helpful in determining and selecting the optimal shot peening parameters to achieve specific level of plastic deformation and compressive residual stress in the aluminium alloy parts especially compressor blades.

Evaluation of microstructural and microchemical aspects of high density concrete exposed to sustained elevated temperature

High density concrete is widely used as a primary material for radiation shielding due to numerous advantageous properties such as, strength, durability and ease of fabrication in comparison with other construction materials. As concrete is subjected even to high temperature environment in a nuclear reactor, the selection of concrete aggregates depends upon the exact application of the concrete. ACI limits the normal operating temperature in concrete structures to 65°C in general and 90°C locally, as exposure of concrete to high temperature induces complex changes in the moisture content as well as chemical composition of the cement paste and mismatch in thermal expansion leads to internal stresses and microcracking in the concrete constituents (aggregate and cement paste). Present research work is to investigate the suitability of concrete ingredients for producing high-performance high density concrete, of different densities using different types of aggregates (heamatite and steel shots) and studying the physicochemical changes in them due to a constant exposure at 120°C as in a sodium cooled reactor. The results indicated heavy moisture loss in the first seven days of exposure and reduction in the mechanical properties, followed by increase in strength on continued exposure. Microstructure and morphological variations in thermally aged fractured specimens were used to explain the above variation in the mechanical properties.

Influence analysis of shot peening on hot forging die

As a common surface mechanical processing method, shot peening got very extensive application because of its low cost and simple operation. This paper gives a comprehensive study on the effects of shot peening on hot forging die based on experimental study and production validation. The effects of shot peening parameters on the distribution of residual stress on surface strengthening layer are studied. Microhardness has an obvious improvement on die surface part after shot peening. By comparing the residual stress distributions on surface strengthening layer, it is found that for 5CrNiMo hot forging die, proper shot peening parameters are cast steel shots with diameter 0.4–0.6 mm, impact velocity 50–75 mm, and coverage rate 100–150 %. Compared with crankshaft forging die without shot peening, microhardness of shot peening die was increased to HV402 on surface part. Under lubricated condition, the abrasion resistance of sample is well improved; friction coefficient finally is close to 0.093 μ and the average friction coefficient is 0.181 μ. Finally, in order to verify experiment results, five sets of module are put into production. Service life of strengthen dies is longer than original dies. The original mold completely was scraped when produced more than 8000 pieces, and shot peening die was scrapped over 9000 pieces.

Influence of Steel Shots Size on Tensile Properties of Magnetic Moulded MMC

The Magnetic moulding process is an extension of lost foam process, in which an Expendable Poly Styrene (EPS) pattern is surrounded by steel shots bonded together by the action of an induced electromagnetic field. Magnetic moulding is a potential alternative for conventional sand casting, which has disadvantages like low thermal conductivity and low permeability, which affects the metallurgical and mechanical properties of the casting. In the present work Al/SiCp metal matrix composite (MMC) samples are moulded by magnetic moulding technique, using different size steel shots viz. 0.18 mm, 0.6mm, 1mm and the tensile properties of the moulded samples were evaluated. The fractured surfaces of the tensile samples were also examined using SEM. The results show that medium size steel shots gives better tensile properties.

Effect of heat treatment on neutron attenuation characteristics of high density concretes (HDC)

In nuclear reactor and fuel cycle facilities, apart from ordinary concrete (2300 kg/m3) various special types of concrete of density varying in range 3600–4600 kg/m3have been effectively employed to achieve less shielding thickness. Radiation attenuation in concrete mainly depend on types of aggregate used; water to cement ratio, elemental composition and moisture content apart from density of concrete. In addition to this, operating temperature also plays a vital role in deciding its shielding properties due to loss of water content and microcracking. The effect of heat on neutron attenuation properties of HDC upon heat exposure is the scope of the study in this paper. Four types of concrete made of granite and having hematite and steel shots as aggregate were prepared with density varying from 2300 to 4300 kg/m3and exposed to 120 °C for durations (14, 28 and 56 days). Neutron Attenuation Factor (NAF) was obtained from experimental study and compared with results obtained with neutron transport calculations. The results of this study clearly indicate that the sustained and cyclic heat treatment at 120 °C up to 56 days reduced the neutron attenuation factor by a factor of two.

Physical incorporation of particles in a porous media: a path to a smart wood

The aim of this work is to develop a functional wood incorporating, in its surface, physical and chemical properties that meet society demand. For instance: fire resistance, magnetic electrical conduction (metal-wood particles), antibacterial reaction (copper-wood), anti-pollution (zeolite-wood), dry coloring, reflective effects (minerals-wood). As part of the research on wooden materials, the technique of “JAZOLTHOP” driving micrometric particles before combining them and moving in supersonic speeds was used in the framework of enriching a wooden substrate. Various tests were conducted on two wooden materials (fir and ash tree) submitted to four typologies of particles (steel shot, garnet, corundum and glass beads). The surfaces of the test samples were machined beforehand for a use of conventional smooth quality, thus defining a reference surface before incorporation. The enriched samples were characterized by using two optical techniques; firstly a surface technique through macroscopy Leica 110X ZP, then a volume technique through tomography. Subsequently, volume simulations (wood-inclusions) were implemented to study the thermal transfer. The obtained results showcase the existence of certain set conditions to reach the critical fluency of incorporation and to localize the enrichment on a parallel plan to the sample surface. The results show also the influence of particles concentration and the kind of the chosen wood on the final composite matrix/particle media.

Influence of steel shot size on the permeability of mould

Summary Casting is one of the commonly used techniques in industries for the manufacturing of metal products. Although sand is used as a mould material for casting, its permeability and thermal conductivity are very low and hence affects the microstructure and mechanical properties of the cast product. Therefore using alternate material for the mould may result in better permeability, heat transfer rate and thereby better properties. In the present work, steel balls are used as mould material and the effect of grain size on the permeability of the mould material is studied. Steel balls of different diameters namely 0.18 mm, 0.6 mm and 1 mm which are commercially available were used. From the experiments conducted, it is confirmed that coarser steel balls showed more permeability and thereby can help in easy escape of hot gases (from the molten metal and mould material) during pouring of molten metal into the mould.

Assessing the heterogeneity of residual stress for complementing the fatigue performance comprehension

The residual stress analysis is a well-established method for predicting fatigue failures of mechanical components. Within industrial constraints, the X-ray diffraction is a technique usually applied to measuring a small spot of the workpiece surface. This punctual and averaged outcome does not allow the proper representation of the residual stress. The objective of this study is to define a feasible method for assessing the heterogeneity of the surface residual stress state. The proposal is based on the theoretical relationship between the deviation of the residual macrostress and the intensity of the microstress. Steel shot peened gears were produced and their microstresses were assessed by means of the diffraction profiles broadening. The reference database was composed of topography measurements, metallographic analyses and residual macrostress maps. The stress heterogeneity was reasonably correlated to the intensity of the Gauss integral breadth. Applied to ground parts, the correlation’s parameter filled a comprehension gap between the measured residual stress intensity and observed contact fatigue failures. Using the same data from the macro residual stress measurement, the method proved to be feasibly applied. Moreover, by providing a deviation perspective to the residual stress state, the heterogeneity assessment enhances the analysis of a fatigue failure.

Improving Shot Sleeve Life Through Selected Surface Heat Treatment of H13 Steel

A common problem seen in the die-casting aluminum automotive industry is the dissolution of the steel diecasting shot sleeve that holds molten aluminum prior to it being shot into the mold. Dissolution shortens the life of the shot sleeve by changing the geometry of the sleeve due to the washout effect. A solution is needed to retard the dissolution of the steel shot sleeves. The application of non-reactive surface treatments to the sleeve surface is thought to prevent dissolution. This experiment looked at two different methods of coating application: diffusion and layered coatings.

Shot Ingestion by Wintering Female Northern Pintails (Anas acuta) in the Texas Coastal Plain, 2012–14

Historically, lead poisoning through lead shot ingestion was one of the largest health issues affecting waterfowl in North America. Lead shot was banned for use in waterfowl hunting in the US in 1991 and was banned in Canada in 1997. However, biologists need to understand how, and if, lead shot remaining in the environment will continue to impact waterfowl. Our goal was to estimate lead and nontoxic shot consumption by female Northern Pintails (Anas acuta) wintering along the Texas coast. We found shot or metal fragments (or both) in the gizzards of 39 (17%) of 227 female Northern Pintails collected along the Texas coast. Of these, lead shot was found in seven gizzards, steel shot was found in 24 gizzards, and other metal and fragments were found in 20 gizzards. Some females consumed multiple shot types. Overall, shot (lead and nontoxic combined) ingestion rates were similar to those found prior to the lead shot ban in Texas (14%) and Louisiana (17%); however, lead shot ingestion rates were considerably lower, suggesting that it is becoming less available over time. All Northern Pintails that had lead shot in their gizzards were collected from coastal habitats. While it seems that lead shot ingestion by Northern Pintails has decreased since the ban was put in place, monitoring lead shot ingestion rates from different regions will provide insight into its availability in different habitats and under various environmental conditions.

Influence of Process Parameter on Grit Blasting as a Pretreatment Process for Thermal Spraying

In thermal spraying, uncoated substrates usually require roughening. As the most common roughening method, grit blasting increases the surface area and produces undercuts in almost all cases, which facilitate mechanical interlocking and thus promote the bonding between the substrate and coating. The effects of grit blasting parameters, i.e., the particle size, the blasting angle, the stand-off distance, and the pressure, on the resulting surface topography are investigated. Furthermore, the efficiency and wear behavior of the blasting media are analyzed. Influences of three different blasting media, corundum, alumina zirconia, and steel shot, on the surface roughening, are compared. By varying adjusted blasting parameters, different initial conditions (surface topography) are created. Subsequently, the substrate is coated, and the coating bond strength is measured. One of the main results of this publication is that alumina zirconia and steel grit show a longer lifetime than pure alumina as a blasting media. Moreover, it has been shown that the blasting parameters such as grain size, working pressure, and history (wear status) of the abrasive particles have a significant effect on the resulting surface topography. Additionally, systematical analysis in this study shows that the blasting parameters such as stand-off distance and blasting angle have a small influence on the results of the blasting process. Another important conclusion of this study is that the conventional surface parameters that have been analyzed in this study did not turn out to be suitable for describing the relationship between the surface topography of the substrate and resulting bond strength.

Room Temperature Case Carburizing of a Ni–Cr–Mo Steel Through Shot Peening/Blasting Techniques

Controlled shot-peening/blasting is an operation which is used largely in the manufacturing industry. An attempt is made to create a case-hardened surface by the shot peening technique on a Ni–Cr–Mo steel. Steel shots with activated carbon powders were introduced at the surface of the samples for different periods of time, i.e. for 5, 10, 15 and 20 min. The microstructure, chemical composition, and hardness were investigated by optical microscopy, SEM, OES, XRF, XRD and micro-Vickers hardness tester, respectively. An effective diffusion of carbon atoms was found in the samples subjected to shot peening for 10 min. and above. However, the hardness values were found to be non-uniform and showed a maximum hardness of 300 HV0.3 at activated spots. The microstructural studies revealed formation lamellar-shaped cells consisting of nano grains at the shot peened surface. A close observation of these lamellae shows α-ferrite and cementite (Fe3C) formed by diffusion of carbon into iron at room temperature. XRD results confirmed the formation of Cr23C6 and Fe3C by shot peening with activated carbon.

Search for new technological methods of strengthening treatment of crankshafts

The work objective is searching new methods of strengthening processing of the cranked shaft. Modern constructive and processing methods of increasing the durability of the engine cranked shaft are considered. Some features of the key processing methods - nitriding, riveting on, steel shot blasting of fillets - are identified. The main task of the constructive methods to increase strength -crankshaft shaping that provides a more uniform stress distribution on shaft volume - both in the stress concentration zones, and outside them is considered. The required design shapes of the shaft are determined experimentally. New installation diagrams for the strengthening and stabilizing vibrowave and shock-vibrating machining of the engine crankshafts are proposed. It is experimentally established that the shock-vibrating machining allows the following: uniform hardening of the surface layer of all part features; sharp edge finishing and rounding; smooth transitions; avoidance of non-rigid shaft distortion that takes place at the local rolling of large part fillets.

The Small Road Surface Shot Blasting Cleaning Machine Design

The design of a small road surface shot blasting cleaning machine, using the motor driven wheel blasting high-speed rotation, the pellet material (steel shot or sand) at high speed and certain Angle to throw, throw rock formed certain fan type flow, impact to the road to play the role of a blasting and removing the effect of the residue .Then, projectile and dust into the separator, separator will be tiny and dust separation, dust into the dust collector, and the projectile into the shot blasting machine to recycle. Complete road surface shot blasting cleaning machine of shot blasting machine, sand pill purification plant design. By using solid works 3D drawing software of 3D modeling and virtual assembly.

A comparison of lead and steel shot loads for harvesting mourning doves

ABSTRACTWith approximately 100 million shots fired at mourning doves (Zenaida macroura) annually, it is incumbent on managers to determine whether changes in ammunition will substantially alter harvest metrics or hunter satisfaction. We compared mourning dove harvest metrics for 1 lead (Pb 7½, 32 g) and 2 steel (Fe 7 and Fe 6, 28 g) 12‐gauge ammunition types using a double‐blind field test in central Texas, USA. There were no differences in the number of attempts, or number of shots fired among ammunition types. Hunters were unable to distinguish the ammunition type being used in the field, and we detected no relationship between ammunition type and level of hunter satisfaction. Field analyses detected no difference in doves bagged per shot, wounded per shot, bagged per hit, or wounded per hit among the 3 ammunition types. Necropsy analyses detected no difference in the proportion of birds with through‐body strikes, mean penetration depth of through‐body strikes, or mean embedded pellet depth among ammunition types. Ammunition and choke combinations that produced higher pattern densities yielded more hits per shot and produced more total strikes per bird, resulting in a higher percentage of birds with embedded pellets, more embedded pellets per bird, and a higher proportion of birds with broken legs. All 3 ammunition types retained sufficient lethality to harvest mourning doves under typical hunting conditions. Our results demonstrate that when the ammunition type used provides sufficient lethality for pellets to penetrate vital organs, pattern density becomes the primary factor influencing ammunition performance. © 2014 The Authors. The Wildlife Society Bulletin is published by The Wildlife Society

Hardfacing using ferro-alloy powder mixtures by submerged arc welding

In this study, we investigated the microstructure and properties of hardfacing coatings produced using Submerged Arc Welding (SAW) process. Powder mixtures of ferro-chrome powder, cast iron chip or stainless steel shot were used as alloying source to form Fe–Cr–C coating. Modified alloys were also produced by the addition of boron-containing powder to partially or fully replace carbon in the carbide-based coatings. Microstructural examination of produced samples showed the formation of carbides and borides of different morphologies which were best interpreted as microstructures of undercooled alloys. Abrasive wear and impact testing were also performed on the coatings as a measure of process effectiveness. By adjusting the amount of powder input and process variables, hypoeutectic, eutectic and hypereutectic alloys were successfully produced.

CORROSION MINERALOGY OF COMMON BIRD SHOT TYPES IN NORTH CAROLINA, USA, ENVIRONMENTS

This study compared corrosion of lead, steel, copper-coated lead, tungsten-steel, and bismuth varieties of shot in different sedimentary and aquatic environments in North Carolina. Sets of individual plastic vials containing all five types of shot were placed in the following environments: marine beach, marine dune/soil, barrier island lagoonal mud, saltwater, running (stream) freshwater above and below sediment surface, still (pond) freshwater above and below sediment surface, and forest soil and surface. After approximately 4.5 years exposure, samples were collected and analyzed with scanning electron microscopy/energy dispersive spectrometry (SEM/EDS) and powder X-ray diffraction (XRD). Samples that were placed in saltwater environments were the most severely corroded, while those in terrestrial or freshwater environments were much less corroded. Similarly, buried samples were generally more corroded than samples placed at or above the water table. Analyses reveal the production of Pb oxide, hydroxide, chloride, carbonate, sulfide, and sulfate compounds in lead and copper-coated lead shot. Steel and tungsten-steel shot exhibited a surface layer of Fe oxides/hydroxides. Bismuth shot and tungsten-steel shot showed little corrosion, limited to small amounts of oxide/chloride and oxide only in two of the sampled environments. In all shot types, 19 minerals and one non-mineral compound [Zn 4 (CO 3 )(OH) 6 •H 2 O] were identified as corrosion products.

A study of the effect of surface pre-treatment on the adhesion of coatings

This paper deals with the study of effects of mechanical surface preparation on the adhesion of coating with high content of zinc dust. Five kinds of mechanically blasted surfaces were studied. The following were used as abrasives: steel shot, steel grit, brown corundum oxide and zirblast. The last surface type was modified by MBX Blaster technology (mechanical bristle blasting). The surfaces topography was quantified by a roughness profilometer. The shape and size of the incurred inequalities on the modified surfaces were studied using 3D microscope images of the surface. The purity of the surfaces after pre-treatment was evaluated by impurity glued on the tape and measuring the reflection of light from the surface. Fractal analysis was used to evaluate the diversity of inequalities on the prepared surfaces. Cross-sections were also taken of the prepared surfaces. The prepared surfaces were coated with zinc-filled coating. The adhesion of the coating to the substrate was evaluated by a pull-off test after curing the coating (as sprayed), as well as after exposure to severe corrosive environments. The best adhesion of the coating was found for the coating applied to the substrate which had been pre-treated with brown corundum and steel grit.

Energy-dispersive X-ray diffraction mapping on a benchtop X-ray fluorescence system

A method for energy-dispersive X-ray diffraction mapping is presented, using a conventional low-power benchtop X-ray fluorescence spectrometer, the Seiko Instruments SEA6000VX. Hyper spectral X-ray maps with a 10 µm step size were collected from polished metal surfaces, sectioned Bi, Pb and steel shot gun pellets. Candidate diffraction lines were identified by eliminating those that matched a characteristic line for an element and those predicted for escape peaks, sum peaks, and Rayleigh and Compton scattered primary X-rays. The maps showed that the crystallites in the Bi pellet were larger than those observed in the Pb and steel pellets. The application of benchtop spectrometers to energy-dispersive X-ray diffraction mapping is discussed, and the capability for lower atomic number and lower-symmetry materials is briefly explored using multi-crystalline Si and polycrystalline sucrose.

The Need to Intensify Research Efforts in the Alternative to Lead Shot

The problem of lead poisoning resulting from the use of lead shot in hunting waterbirds and shooting sports has led to the partial ban, voluntary restriction and complete ban of lead shot in some countries. The ban resulted in the alternatives like copper shot, tungsten-tin shot, bismuth-tin, steel shot, etc. These alternatives are still expensive and other possible alternatives have not been explored up to date. There is therefore need to ban lead shot world-wide and step up research into the alternatives (green shot).