• Proceedings of the Materials Research Society of Korea Conference
• /
• 2001.11a
• /
• pp.37-37
• /
• 2001

• Transactions of Materials Processing
• /
• v.32 no.3
• /
• pp.114-121
• /
• 2023

During rolling, rolling mill rolls endure wear when shaping metal billets into a desired form, such as bars, plates, and shapes. Such wear affects the lifespan of the rolls and product quality. Therefore, in addition to rigidity, wear performance is a key factor influencing the performance of rolling mill rolls. Conventional methods such as casting and forging have been used to manufacture rolling mill rolls. However, powder alloying methods are increasingly being adopted to enhance wear resistance. These powder manufacturing methods include atomization, canning to shape the powder, hot isostatic pressing to combine the powder alloy with conventional metals, and various wear performance tests on rolls prepared with powder alloys. In this study, numerical simulations and experimental tests were used to develop and elucidate the wear analysis mechanism of rolling mill rolls. The wear characteristics of the rolls under various rolling conditions were analyzed. In addition, experimental tests (wear and surface analysis tests) and wear theory (Archard wear model) were used to evaluate wear. These tests were performed on two different materials in various powder states to evaluate the different aspects of wear resistance. In particular, this study identifies the factors influencing the wear behavior of rolling mill rolls and proposes an analytical approach based on the actual production of products. The developed wear analysis mechanism can serve the future development of rolls with high wear resistance using new materials. Moreover, it can be applied in the mechanical and wear performance testing of new products.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.2
• /
• pp.217-223
• /
• 1999

In this study, the effects of the content of $ZrO_{2}$ in $Si_{3}N_{4}$ on mechanical and wear properties were investigated. $Si_{3}N_{4}$ based composites containing 0~40 wt% $ZrO_{2}$ powders were fabricated using hot isostatic pressing (HIP), at $1750^{\circ}C$, 172 MPa for 1 hour in $N_{2}$ gas. Mechanical properties and wear properties of composites were examined. Mechanical properties (hardness, strength, and fracture toughness) of $Si_{3}N_{4}-ZrO_{2}$ composite were decreased with increasing the amount of $ZrO_{2}$, but relative density of composites were increased. Further, the increase in amount of $ZrO_{2}$, reduced wear rates in air. It was found that wear behaviors in air were related to microcracking.

• Korean Journal of Materials Research
• /
• v.16 no.6
• /
• pp.341-345
• /
• 2006

[ $Ni_2Si$ ] mixed powders were mechanically alloyed by a ball mill and then processed by hot isostatic pressing (HIP) and spark plasma sintering (SPS). In the powder that was mechanically alloyed for 15minutes(MA 15 min), only Ni and Si were observed but in the powder that was mechanically alloyed for 30minutes(MA 30 min), $Ni_2Si$, Ni and Si were mixed together. Some of the MA 15 min powder and MA 30 min powder were processed by HIP under pressure of 150MPa at the temperature of $1000^{\circ}C$ for two hours and some of them were processed by SPS under pressure of 60 MPa at the temperature of $1000^{\circ}C$ for 60 seconds. Both methods completely compounded the powders to $Ni_2Si$. The maximum density of sintered lumps by HIP method was 99.5% and the maximum density of the sintered lump by SPS method was 99.3%. with the hardness of HRc 66 with the hardness of HRc 63. Therefore, the SPS method that can sinter in short time at low cost is considered to be more economical that the HIP method that requires complicated sintering conditions and high cost and the sintering can produce target materials in desired sizes and shapes to be used for thin film.

• International Journal of Precision Engineering and Manufacturing-Green Technology
• /
• v.5 no.5
• /
• pp.605-612
• /
• 2018

This work investigates the relationships between the static mechanical properties of Ti-6Al-4V manufactured through selective laser melting (SLM) and post-process heat treatments, namely stress relieve, annealing and hot isostatic pressing (HIP). In particular, Ti-6Al-4V parts were fabricated in three different build orientations of X, Z, and $45^{\circ}$ to investigate the multi-directional mechanical properties. The results showed that fully densified Ti-6Al-4V parts with densities of up to 99.5% were obtained with optimized SLM parameters. The microstructure of stress relieved and mill annealed samples was dominated by fine ${\alpha}^{\prime}$ martensitic needles. After HIP treatment, the martensite structure was fully transformed into ${\alpha}$ and ${\beta}$ phases (${\alpha}+{\beta}$ lamellar). Within the realm of tensile properties, the yield and ultimate strength values were found statistically similar with respect to the built orientation for a given heat treatment. However, the ductility was found orientation dependent for the HIP samples, where a lower value was observed for samples built in the X direction.

• Journal of Powder Materials
• /
• v.31 no.1
• /
• pp.1-7
• /
• 2024

This study explores the profound impact of varying oxygen content on microstructural and mechanical properties in specimens HO and LO. The higher oxygen concentration in specimen HO is found to significantly influence alpha lath sizes, resulting in a size of 0.5-1 ㎛, contrasting with the 1-1.5 ㎛ size observed in specimen LO. Pore fraction, governed by oxygen concentration, is high in specimen HO, registering a value of 0.11%, whereas specimen LO exhibits a lower pore fraction (0.02%). Varied pore types in each specimen further underscore the role of oxygen concentration in shaping microstructural morphology. Despite these microstructural variations, the average hardness remains consistent at ~370 HV. This study emphasizes the pivotal role of oxygen content in influencing microstructural features, contributing to a comprehensive understanding of the intricate interplay between elemental composition and material properties.

• Journal of Powder Materials
• /
• v.27 no.5
• /
• pp.373-380
• /
• 2020

The purpose of this study is to investigate the densification behavior and the corresponding microstructural evolution of tantalum and tantalum-tungsten alloy powders for explosively formed liners. The inherent inhomogeneous microstructures of tantalum manufactured by an ingot metallurgy might degrade the capability of the warhead. Therefore, to overcome such drawbacks, powder metallurgy was incorporated into the near-net shape process in this study. Spark plasma-sintered tantalum and its alloys with finer particle sizes exhibited higher densities and lower grain sizes. However, they were contaminated from the graphite mold during sintering. Higher compaction pressures in die and isostatic compaction techniques also enhanced the sinterability of the tantalum powders; however, a full densification could not be achieved. On the other hand, the powders exhibited full densification after being subjected to hot isostatic pressing over two times. Consequently, it was found that the hot isostatic-pressed tantalum might exhibit a lower grain size and a higher density as compared to those obtained in previous studies.

• Composites Research
• /
• v.20 no.4
• /
• pp.9-17
• /
• 2007

Powder metallurgy has been employed for the development of SiC particle reinforced aluminum metal matrix composites by means of hot isotropic pressing and vacuum hot pressing. A material model based on micro-mechanical approach then has been presented for the processes. Densification occurs by the inelastic flow of matrix materials during the consolidation, and consequently it depends on many process conditions such as applied pressure, temperature and volume fraction of reinforcement. The model is implemented into finite element software so that the process simulation can be performed enabling the predicted relative density to be compared with experimental data. In order to determine the performance of finished products, further tensile test has been conducted using the developed specimens. The effect of internal void of the materials on mechanical properties therefore can be investigated.

• Korean Journal of Materials Research
• /
• v.10 no.4
• /
• pp.312-316
• /
• 2000

A study has been made to investigate the effects of hot isostatic pressing(HIP ping) on bond strength and elevated temperature characteristics of thermal barrier coating(TBC). The specimens were prepared by HIPping of TBC which is composed of the ceramic top coat(8wt%$Y_2$$O_3$-$ZrO_2$) and the metallic bond coat on the matrix of IN738LC superalloy. The results showed that the porosity and microcracks in the ceramic top coat of TBC were significantly decreased by HIP. As a result, the bond strength of the HIPped coating was increased above 48% compared to that of as-coated specimen and microstructure was homogenized. It was found that the thermal cycle resistance of HIPped coating was inferior to that of as-coated specimen. It was considered that this result was mainly caused by the reduction of internal defects in the top coat layer which could play a role in relaxing the thermal stress due to a large difference in thermal expansion between TBC and matrix.

• Journal of Powder Materials
• /
• v.20 no.4
• /
• pp.264-268
• /
• 2013

Nickel-based superalloy IN 713C powders have been consolidated by hot isostatic pressing (HIPing). The microstructure and mechanical properties of the superalloys were investigated at the HIPing temperature ranging from $1030^{\circ}C$ to $1230^{\circ}C$. When the IN 713C powder was heated above ${\gamma}^{\prime}$ solvus temperature (about $1180^{\circ}C$), the microstructure was composed of the austenitic FCC matrix phase ${\gamma}$ plus a variety of secondary phases, such as ${\gamma}^{\prime}$ precipitates in ${\gamma}$ matrix and MC carbides at grain boundaries. The yield and tensile strengths of HIPed specimens at room temperature were decreased while the elongation and reduction of area were increased as the processing temperature increased. At $700^{\circ}C$, the strength was similar regardless of HIPing temperature; however, the ductility was drastically increased with increasing the temperature. It is considered that these properties compared to those of cast products are originated from the homogeneity of microstructure obtained from a PM process.