Shot Particles Research Articles

Rapid carburizing of low-alloy steel by atmospheric-controlled induction-heating fine-particle peening and investigation of its fatigue properties

Atmospheric-controlled induction-heating fine-particle peening (AIH-FPP) was applied to low-alloy, low-carbon steel AISI 4120 to achieve rapid carburizing within minutes and enhance fatigue strength. The shot particles used during AIH-FPP were specifically created by mechanically milling a mixture of steel particles and carbon powders. The specimens were analyzed using laser microscopy, optical microscopy, X-ray diffraction for residual stress measurement, a micro-Vickers hardness tester, and an electron probe micro-analyzer. Axial fatigue tests and fracture surface analyses via scanning electron microscopy and energy-dispersive X-ray spectroscopy were also conducted. AIH-FPP effectively transferred carbon to the treated surface and facilitated its diffusion in a short period, creating a martensite layer with high hardness and compressive residual stress, which resulted in increased fatigue strength. The fatigue strength of the AIH-FPP-treated specimens was influenced by the conditions of reheating and quenching, which altered the prior austenitic grain size and stress concentration at the specimen surface. Notably, specimens treated with AIH-FPP followed by reheating and water-injection quenching exhibited fatigue strength comparable to that of conventional gas-carburized specimens, owing to the formation of a carburized layer with a small prior austenite grain size.

Analysis of gas-solid two-phase flow characteristics of mobile shot blasting machine recovery device based on CFD-DEM

The shot blasting machine recovery device is an important part of the operation of the shot blasting machine to recover solid particles and reduce environmental pollution. The recovery efficiency of solid particles has an important influence on their processing efficiency and service life. The computational fluid dynamics and discrete element method (CFD-DEM) simulation method is applied to study the gas-solid two-phase flow characteristics and solid particle recovery efficiency of shot pellet recovery unit. The results show that the simulation results of outlet and inlet wind speeds and pressures are in good agreement with the experimental data, which verifies the accuracy of the simulation model. The existence of particle phase divides the recovery pipeline into inner high-speed flow area and outer low-speed flow area, which has little influence on the air flow distribution inside the recovery bin. The results of solid particle recovery efficiency show that with the increase of incident angle, the recovery efficiency of waste particles and shot particles first decreases and then increases, and the recovery efficiency is the lowest when the incident angle is 30°. With the increase of particle formation rate, the efficiency of shot recovery first increases and then decreases. When the particle formation rate is 2000 n/s, the efficiency of shot recovery is the highest, which has little influence on the efficiency of waste recovery.

Analysis of gas–solid two-phase flow and structure optimization of mobile shot blasting machine recovery device

To address the problem of low efficiency of recycling process waste by gas–solid two-phase flow of the shot blasting machine recycling device, a method and structure by increasing the negative pressure value and optimizing the outlet pipe position are proposed. Computational fluid dynamics (CFD), discrete element method (DEM) and discrete phase model (DPM) were used to study the waste recovery efficiency at different pressure outlet conditions and outlet pipe locations. The validity of the model was verified by velocity tests at the outlet and inlet compared with simulations. The effect of particle size and particle generation rate on solid particle recovery efficiency was further investigated by analyzing the flow field distribution of the recovery unit. The results show that the maximum velocity of the gas phase in the recovery device increases with the increase of the absolute value of the outlet pressure, when the outlet pressure is -6500 Pa, the maximum velocity is 67.59 m/s. When the absolute value of the outlet pressure is greater than 6000 Pa, a small amount of steel shot particles is discharged from the recovery bin under the action of the outlet pressure, resulting in the loss of steel shot particles. After the outlet pipe position optimization, the steel shot particle recovery efficiency increased by 10% and the waste particle recovery efficiency increased by 18.9%.

Effect of fine particle shot peening on surface friction of stainless steel and ceramic bracket slots

This study aims to compare the static friction of untreated and fine particle shot peening (FPSP) treated stainless steel and ceramic bracket slots. A total of 60 pieces of stainless steel and 60 pieces of ceramic brackets (Roth prescription, 0.022×0.028 in2) were divided into 3 groups: control (n=20), silica glass bead particle surface treatment (n=20) and stainless steel (SUS316L) particle surface treatment (n=20). Ten brackets of each group were combined with 0.019×0.025 in2 orthodontic stainless steel arch wires and were analyzed for static friction. The remaining 10 brackets of each group were tested for slot surface roughness and hardness. The result shows that stainless steel brackets treated with FPSP exhibited lower static friction, with smoother and harder surfaces than the control group (p<0.05). In contrast, treated ceramic brackets showed no difference from the control group in terms of static friction, roughness, and hardness (p>0.05).

Molecular modeling of Ti-6Al-4V alloy shot peening: the effects of diameter and velocity of shot particles and force field on mechanical properties and residual stress

Shot peening is a surface treatment process that is used for the improvement of the mechanical properties of metallic alloys. The effects of sphere particle diameter and impact velocity on residual stress and mechanical properties of Ti-6Al-4V as titanium alloy are investigated in this study using molecular dynamics simulation. In this research, titanium atoms are simulated as a surface layer and the carbon steel atomic structure is modeled as the impacting particle in the shot peening process. Two types of molecular potential functions including embedded atom method (EAM) and Lennard-Jones (LJ) are used for molecular modeling of colliding atoms and the effect of these force fields on residual stress, hardness, surface roughness is investigated. Moreover, the effects of impacting particle velocity and diameter on these parameters are studied. The results show the amount of residual stress in the titanium surface layer increased by increasing the particle diameter and velocity of particles. The diameter and velocity of particles in the shot peening process has a significant effect on the mechanical behavior of the simulated titanium surface layer. The value of maximum compressive residual stress is −413 MPa which occurs in depth of 10 Å from the surface layer for 1 Å fs−1 velocity and 10 Å diameter of shot particle. Furthermore, the results show that the Vickers hardness of the titanium is increased by increasing the size and velocity of the carbon steel particle in both EAM and LJ potential functions.

772-P: Portability of Nasal Glucagon for the Rescue of Severe Hypoglycemia: Stability and Performance Evaluation across a Broad Range of Temperatures

Background and Aims: Nasal glucagon is a ready-to-use, drug-device combination therapy for the treatment of severe hypoglycemia. Portability is key, as nasal glucagon should be carried by persons with diabetes at all times. In designing for portability, the medication must allow for exposure to a broad range of temperatures without significant adverse effect on product quality/performance. In this study, we evaluated the stability and performance of nasal glucagon at temperatures ranging from -20 to +30 °C (-4 to +86 °F) in order to mimic real world situations. Methods: Testing focused on characterization of drug product (glucagon amount) and combination product performance (consistent delivery to nasal cavity). Critical quality elements, including chemical purity and content, particle size, actuation force, delivered dose, shot weight, spray pattern and plume geometry, were evaluated after being exposed to temperatures from -20 and +30 °C, a range broader than a typically controlled room temperature product [i.e., Store at Controlled Room Temperature, 20° to 25°C (68° to 77°F); excursions permitted between 15° and 30°C (59° and 86°F)], such as glucagon for injection. Results: All testing demonstrated that 100% of critical quality elements were satisfied. Nasal glucagon could be exposed to frozen (-20 °C), refrigerated (2 to 8°C), and up to 30 °C conditions for the 2-year shelf life. The degradation of glucagon followed Arrhenius kinetics (i.e., slower degradation rates at lower temperatures). Temperature cycling studies showed no significant changes in the chemical/product performance attributes. Conclusions: These analyses indicate no adverse impact to nasal glucagon from the chemical and physical perspective when exposed to frozen, refrigerated, and up to 30 °C conditions. The stability across a broad range of temperatures facilitates the portability of nasal glucagon as a rescue medication for severe hypoglycemia. Disclosure B. W. Pack: Employee; Self; Eli Lilly and Company, Stock/Shareholder; Self; Eli Lilly and Company. J. Melnick: Employee; Self; Eli Lilly and Company, Employee; Spouse/Partner; Eli Lilly and Company. C. Breen: Employee; Self; Eli Lilly and Company. R. Allen: Employee; Self; Eli Lilly and Company. Funding Eli Lilly and Company

Effect of Fine Particle Peening Using Hydroxyapatite Particles on Rotating Bending Fatigue Properties of β-Type Titanium Alloy

Fine particle peening (FPP) using hydroxyapatite (HAp) shot particles was performed to improve the fatigue strength and form a HAp transfer layer on a beta titanium alloy (Ti–22V–4Al). The surface microstructures of the FPP-treated specimen were characterized using scanning electron microscopy, micro-Vickers hardness testing, energy dispersive X-ray spectrometry, X-ray diffraction, and electron backscattered diffraction. A HAp transfer layer with a thickness of 5.5 μm was formed on the surface of the Ti–22V–4Al specimen by FPP. In addition, the surface hardness of the Ti–22V–4Al was increased, and high compressive residual stress was generated on the specimen surface by FPP. Rotating bending fatigue tests were performed at room temperature in laboratory air over a wide cycle-life region (103–109 cycles). In the long cycle-life regime, the fatigue strength at 107 cycles of the FPP-treated specimen became higher than that of the untreated specimen. This result is attributed to the formation of a work-hardened layer with high compressive residual stress by FPP. However, the fatigue strength was not improved by FPP in the short cycle-life regime, because fatigue cracks were initiated at surface defects formed during the FPP process. The fatigue fracture mode of the FPP-treated specimens shifted from surface-initiated fracture to subsurface-initiated fracture at a stress amplitude level of 600 MPa.

Smart tribo-peening process for surface functionalization through digital twin concept

Tribo-peening is a unique derivative process of shot peening to produce functional surface with fully localized or distributed deformation induced by the impact and friction of activated formed and dispersed shot particles. This research paper discusses a methodology to develop a smart tribo-peening of surface functionalization with the aim of controlling tribo-peening operations through integration of sensors and taking advantage of information including data-driven simulation for shot peening process. A digital twin of high-fidelity computational model that simulates the tribo-penning process is hence designed to combine multi-sensory data insights, multiscale surface quality control, and physical processing capabilities. To drive the tribo-peening process, elementary areal surface representative (EASR) concept that involves multi-scale surface characterization is used to describe functionally the areal blasted surface and to create its representative digital twin. Results emphasize the ease with which tuning tribo-peening for surface functionalization may occur using digital twin concept. It shows also clearly that the design of shots operating under controlled impulsive loading is of considerable importance in tribo-peening process.

Magnetic Field Simulation for Design of Shot Particle Removal Device

Magnetic Field Simulation for Design of Shot Particle Removal Device

Shot velocity measurement using particle image velocimetry and a numerical analysis of the residual stress in fine particle shot peening

Abstract Fine particle shot peening has the advantages of producing compressive residual stress, microscale work hardening near the surface, and minimal surface roughness. Therefore, fine particle shot peening has been applied to numerous parts to improve fatigue strength. In this study, the shot velocity of fine zircon and stainless steel shots at four values of air pressures were precisely measured using particle image velocimetry. The shots were accelerated to a standoff distance of approximately 80 mm from the nozzle outlet. The shot velocity of the zircon shots is faster than that of the stainless steel shots. The measured shot velocity for both shots is almost proportional to the 0.5th power of the air pressure. To investigate the effect of the measured shot velocity on the residual stress distribution in an aluminum alloy (A5052) plate, a finite element model was developed for fine particle shot peening. The analyzed residual stress distributions using the accurately measured shot velocity agreed well with those measured in four test pieces using the zircon and stainless steel shots at two air pressures. The shot velocity measurement method and numerical analysis model for residual stress were both validated.

Formation of intermetallic compounds through transfer and diffusion of shot particle element using AIH-FPP system

Formation of intermetallic compounds through transfer and diffusion of shot particle element using AIH-FPP system

Influences of tooth flank finishing after fine particle shot peening on tooth surface texture and fatigue life of vacuum carbonitrided gears

Influences of tooth flank finishing after fine particle shot peening on tooth surface texture and fatigue life of vacuum carbonitrided gears

Ridge-Texturing for Wettability Modification by Using Angled Fine Particle Peening

The industrial demand for wettability control has been increasing because wettability is a key factor for achieving novel anti-contaminant surfaces and related products. In this paper, the potential of angled fine particle peening (angled-FPP) was explored as a method of surface modification to control wettability. Angled-FPP, which is an abrasive jet machining process conducted using a peening nozzle set at an angle inclined to the material surface, is a potential texturing technique. With it, it is possible to create periodically aligned peaks and valleys (“ridges”) on the peened surface. Because control of wettability could possibly be achieved by varying the geometric characteristics of the texture, an attempt was made to vary ridge texture by conducting angled-FPP using three kinds of shot particles: steel, glass, and alumina grit. Thereafter, changes in the wettability owing to creation of a ridge texture on the surfaces were evaluated, with focus on the geometric and morphological features of the ridge texture. The results indicate that the size of the ridges depends on the size and shape of the shot particles, and the angled-FPP conducted using finer angular particles created densely concentrated ridges. The superficial appearance of the ridge texture differed depending on the shot particles used for angled-FPP. The topographies created by angled-FPP using steel particles and alumina grit were “hierarchical” (i.e., the ridge structure was overlapped by finer-scale roughness). In contrast, angled-FPP conducted using glass particles created ridge structure with a quite plain surface. Measurement of the water drop contact angle revealed that the surface became less hydrophilic after creation of the hierarchical topography. It was concluded that the predominant influence on the wettability of the angled-FPP surfaces came from the superficial morphology of the ridge texture.

Formation of a hydroxyapatite layer on Ti–29Nb–13Ta–4.6Zr and enhancement of four-point bending fatigue characteristics by fine particle peening

A hydroxyapatite (HAp) surface layer was generated at room temperature on a beta-titanium alloy (Ti-29Nb-13Ta-4.6Zr, TNTZ) using fine particle peening (FPP), as a means of enhancing fatigue resistance. This material is commonly employed in bio-implants, but has a suboptimal Young's modulus. Treated specimens were assessed using scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and electron backscatter diffraction, as well as by measuring the Vickers hardness. Performing FPP using shot particles made of HAp was found to transfer the particles to the TNTZ surface to rapidly produce a HAp layer that became thicker as the FPP process progressed. Room-temperature four-point bending fatigue tests in air showed that the HAp layer resulting from the FPP process increased the endurance limit of test specimens. This improved performance is ascribed to the appearance of a hardened surface layer having a significant degree of compressive residual stress.

Effect of Surface Treatment on Physical and Mechanical Properties of Nickel-Titanium Orthodontic Archwires by Fine Particle Shot Peening Method

Surface treatment on metal can alter physical and mechanical properties. Understanding the physical and mechanical properties of the archwires is essential for the management of orthodontic treatment. Methods: This study used digital micrometer, universal testing machine, and surface hardness tester for measuring dimension, unloading force, and surface hardness of two different type of nickel-titanium (Ni-Ti) archwires: commercially available Ni-Ti (NT-N) and surface treated Ni-Ti by fine particle shot peening (FPSP) method (NT-F). Statistical analysis was undertaken using a paired T-test (α=0.05). Results: No significant difference was found on both vertical and horizontal dimensions of NT-N and NT-F (p= 1.00 and 0.796 respectively). For bending and surface hardness test, significance difference was found (p&lt;0.001 and p&lt;0.001 respectively). Conclusions: The NT-F archwire provided lower unloading force and surface hardness but there was no change in size when compared with NT-N.

Effects of Fine Particle Shot Peening Treatment on Fatigue Properties of Al-7Si-0.3Mg Alloy

In this study, two different fine particle shot peening (FPSP) treatments were performed on Al-7Si-0.3Mg alloy specimens to evaluate their effects on fatigue properties. After the treatment, the microstructure morphology of the specimens was observed, and the surface roughness and residual stress distribution were measured. Rotating bending fatigue tests were conducted, and the fatigue fracture surfaces were observed using scanning electron microscopy (SEM). The crack initiation and propagation behavior were investigated using the replica method. The results indicate that FPSP can introduce residual stress on the surface layer of the material and refine the surface microstructure, and also change the surface roughness. At low stress amplitude levels, FPSP can improve fatigue life significantly. At 5 × 107 cycles, the fatigue strength of shot-peened specimens increased by 33% compared to unpeened specimens. In unpeened and steel shot-peened (SSP) specimens, both crystal slip and casting defects can induce fatigue failure, while only casting defects can cause failure in the case of ceramic shot-peened (CSP) specimens. Moreover, FPSP can move the crack initiation site to the subsurface from the surface. The range of threshold stress intensity factor of the material can be improved significantly by this treatment. Casting defects have a significant influence on fatigue strength; the effect on fatigue strength can be well evaluated by the modified Murakami equation.

Magnetic Field Simulation for Design of Shot Particle Removal Device

Magnetic Field Simulation for Design of Shot Particle Removal Device

Improvement of the electrochemical characteristics of medium carbon steel using atmospheric-controlled induction-heating fine particle peening

Atmospheric-controlled induction-heating fine particle peening (AIH-FPP) using Cr and Mo shot particles was introduced to improve the electrochemical characteristics of AISI 1045 medium carbon steel in NaCl solution. AIH-FPP can form transferred and diffused layers of shot particles on the surface of carbon steel. The corrosion potential of the AIH-FPP-treated steel was higher than that of the untreated steel in a NaCl environment. Furthermore, a passivation region was observed in the carbon steel treated with AIH-FPP using Cr shot particles after peening with Mo shot particles through the formation of a surface-modified layer with high Cr and Mo concentrations in 20% NaCl solution.

An efficient and accurate hybrid method for simulating non-linear neutrino structure

We present an efficient and accurate method for simulating massive neutrinos in cosmological structure formation simulations, together with an easy to use public implementation. Our method builds on our earlier implementation of the linear response approximation (LRA) for neutrinos, coupled with an N-body code for cold dark matter particles. The LRA's good behaviour at early times and in the linear regime is preserved, while better following the non-linear clustering of neutrinos on small scales. Massive neutrinos are split into initially "fast" and "slow" components. The fast component is followed analytically with the LRA all the way to redshift zero. The slow component is evolved with the LRA only down to a switch-on redshift $z_\nu = 1$, below which it is followed with the particle method, in order to fully account for its non-linear evolution. The slow neutrino particles are initialized at $z = 99$ in order to have accurate positions and velocities at the switch-on time, but are not used to compute the potential until $z \leq 1$, thus avoiding the worst effect of particle shot noise. We show that our hybrid method matches (and for small neutrino masses, exceeds) the accuracy of neutrino particle simulations with substantially lower particle load requirements.

INFLUENCE OF MILK THISTLE SHOT ON QUALITY PARAMETERS OF THE SOUR-MILK BEVERAGE

Modern complicated ecological conditions cause a general necessity in improving the food structure of the population due to improving the quality, biological value and taste characteristics of products. Just that is why, the aim of the work was to study the influence of milk thistle shot on quality parameters of the sour-milk beverage – kefir. It was established, that it had the homogenous consistence with a broken clot and color from white to creamy with shot particles. The increase of the milk thistle shot dose to 3 % and 4 % results in the taste with the brightly expressed milk thistle smack and brown color with the expressed milk thistle content. The viscosity of kefir with fms 2,5 % changes during seven days of storage, although remains rather high at 8 day, namely 47 s. The increase of the viscosity of kefir with milk thistle shot is explained by its hygroscopic properties, in which result free moisture of the product is bound. The analysis of microbiological parameters in the process of storage of kefir with milk thistle shot allows to make a conclusion about the satisfactory sanitary condition of the new product and its harmlessness for consumer’s health. In the kefir with milk thistle shot the general amount of amino acids grew by 11,6 %, including irreplaceable ones – by 10,1 %, replaceable – by 12,6 %, that indicates its biological value. Addition of milk thistle shot to kefir didn’t cause changes of the biological value of the protein component of the combined product. It is testified by the mean value of amino acid scores of control (129,3 %) and experimental (127,9 %) samples of kefir. Some growth of the valine score (3,6 %) can be noted. So, the combined product is characterized by the balanced amino acid composition. Due to adding milk thistle shot, consumption of amino acids, necessary for synthesis of proteins and essential number of compounds, vitally important for the human organism, grew.