Effect Of Hot Isostatic Pressing Research Articles

Effect of HIP temperature on microstructure and tensile properties of 713LC cast superalloy

The effect of hot isostatic pressing (HIP) temperature on mechanical properties of 713LC cast superalloy was investigated; three temperatures (1453, 1468, 1483 K) were tested for a HIP soaking time of 2 h and pressure of 150 MPa. HIP treatment at1453 K was found to be optimal. Extensive γ′ precipitation was observed and the optimal HIP treatment decreased porosity by ∼57·1%. Under tension testing at a fast strain rate (0·001 s−1), the tensile strength was increased by 5·2% at room temperature, 9·8% at 813 K and 7·9% at 923 K, whereas at a very slow strain rate (0·0001 s−1), tensile strength was increased by 1·2% at room temperature and 7·8% at 813 K.

Hot isostatic pressing (HIP) of α-Al2O3 submicron ceramics pressureless sintered at different temperatures: Improvement in mechanical properties for use in total hip arthroplasty (THA)

Abstract The effect of hot isostatic pressing (HIPing) on as-sintered α-Al2O3 ceramics for total hip arthroplasty (THA) was investigated. The sinterability of these powders and the minimum temperature required to obtain closed porosity have been determined by pressureless sintering in air at temperatures between 1280 and 1460 °C for 2 h. Temperatures of 1300 and 1325 °C and applied pressures of 150 MPa for 30 min were utilised in the HIP cycles. Densities >98% of the theoretical density (TD) have been obtained after HIPing, and the grain sizes previously obtained during pressureless sintering increased slightly during the HIP treatment. The microstructures before and after HIP treatments were observed by means of scanning electron microscopy (SEM). The fracture toughness was obtained by the indentation fracture technique using a Vickers hardness tester at a load of 10 N with a dwell time of 15 s for all cases. The ceramics obtained at the lowest HIP temperature (1300 °C) presented a grain size of 0.62 ± 0.04 μm, hardness of 20.5 ± 0.6 GPa, and fracture toughness of 4.8 ± 0.3 MPa m1/2. The reported values were higher than those obtained by other authors and were in concordance with international standards that could make these ceramics available as a replacement for metal-on-polyethylene in orthopaedic surgery.

The effect of hot isostatic pressing on crack healing, microstructure, mechanical properties of Rene88DT superalloy prepared by laser solid forming

Crack characterization in Rene88DT superalloy prepared by laser solid forming (LSF) was investigated; the effect of hot isostatic pressing (HIP) on crack healing, microstructure and mechanical properties was also analyzed. It was found that cracks in LSFed Rene88DT mainly nucleate and propagate in the overlap zone of laser-deposited passes, and can be attributed to the liquation cracks. The size and amount of the cracks in LSFed Rene88DT are significantly affected by the overlap of as-deposited passes. Through HIP processing, crack healing occurred, which leads to a substantial improvement of the mechanical properties of LSFed Rene88DT superalloy. However, the insufficient overlap will result in very large cracks in the deposit, which makes the diffusion bonding during HIP not completely eliminate the local segregation of Ti and Nb in the crack healing region.

CVD-growth of ZnS xSe 1 − x with subsequent hot isostatic pressing

A CVD-technique for preparation of bulk ZnS x Se 1 − x uniform in composition has been proposed. The effect of hot isostatic pressing (HIP) on the optical and structural characteristics of zinc sulfoselenides is examined.

The effect of hot isostatic pressing (HIP) on the fatigue life of A206-T71 aluminum castings

The effect of hot isostatic pressing (HIP) on fatigue properties of A206-T71 castings was investigated. Castings were (i) non-HIPed, or HIPed at (ii) typical HIP temperature, (iii) solution heat-treat temperature and (iv) eutectic melting temperature. HIP conditions were found to increase average and maximum fatigue life. However, the range in fatigue life also increased after HIP, which is attributed to the location of defects as well as HIP's ability to heal porosity and thin bifilms more effectively than thicker bifilms. The mechanism for healing bifilms by HIP appeared to be the fracture of bifilms and partial bonding across their surfaces. Fatigue life data were analyzed using three-parameter Weibull statistics, which showed that HIP significantly increases threshold fatigue life, but increasing HIP temperature has no effect on the threshold fatigue life.

The effect of increased HIP temperatures on bifilms and tensile properties of A206-T71 aluminum castings

The effects of hot isostatic pressing (HIP) temperatures on bifilms and tensile properties of A206-T71 castings were investigated. Castings were: (i) non-HIPed, and HIPed at (ii) typical HIP temperature, (iii) solution heat-treat temperature and (iv) eutectic melting temperature. Tensile strength and elongation data were analyzed using Weibull statistics. In all cases, HIP was found to increase the threshold tensile properties. Also, average and maximum tensile properties, as well as variability in elongation were increased by HIP. This was attributed to HIP's ability to heal porosity and thin bifilms more effectively than thicker bifilms. The mechanism for healing bifilms by HIP appeared to be the fracture of thin bifilms and partial bonding across their surfaces. The effect of increased HIP temperature was masked by the presence of spinel bifilms, which resisted the healing effect of HIP.

High temperature ductility and cavitation behaviour of hot isostatically pressed (HIP) ZrO 2/Al 2O 3 composite containing 40 wt.% Al 2O 3

In this study, experiments were conducted to investigate the effect of hot isostatic pressing (HIP) on superplastic ductility of ZrO 2/Al 2O 3 composite containing 40 wt.% Al 2O 3 at a constant strain rate of 1×10 −4 s −1 and 1723 K. The results show that superplastic ductility obtained from HIPed specimen is higher than that of sintered one. The reason for this ductility enhancement is explained in terms of elimination of agglomerates in the sintered specimen. Also the effect of hot isostatic pressing on cavitation behaviour is quantitatively examined. It is shown that extensive internal cavities form during superplastic flow in sintered and HIPed specimens. The amount and size of cavities decrease with hot isostatic pressing stress.

주조된 AI 합금의 기계적 성질에 미치는 HIP의 영향

The present paper investigates the effect of hot isostatic pressing (HIPing) on mechanical properties, e.g., tensile strength, ductility and impact absorption energy of sand and die casted aluminum alloys. After HIPing at various temperatures and pressure conditions, uniaxial tensile test and Izod impact test of the samples were carried out. The experimental results showed improvements in uniaxial tensile strength, elongation and Izod impact toughness of sand casted aluminum alloy, while deterioration of a tensile strength fur die casted aluminum alloy. The effect of HIPing for microstructure of the cast aluminum alloy was also investigated.

The Effect of Hot Isostatic Pressing on Crack Initiation, Fatigue, and Mechanical Properties of Two Cast Aluminum Alloys

This article presents the results of an experimental materials testing program on the effect of hot isostatic pressing (HIP) on the crack initiation, fatigue, and mechanical properties of two cast aluminum alloys: AMS 4220 and 4225. These alloys are often used in castings for high temperature applications. Standard tensile and instrumented Charpy impact tests were performed at room and elevated temperatures. The resulting data quantify improvements in ultimate tensile strength, ductility, and Charpy impact toughness from the HIP process while indicating little change in yield strength for both alloys. In addition standard fracture mechanics fatigue tests along with a set of unique fatigue crack initiation tests were performed on the alloys. Hot isostatic pressing was shown to produce a significant increase in cycles to crack initiation for AMS 4225, while no change was evident in traditional da/dN fatigue crack growth. The data permits comparisons of the two alloys both with and without the HIP process.

Effect of hot isostatic pressing on cast A357 aluminium alloy with and without SiC particle reinforcement

The effect of Hot Isostatic Pressing (HIPping) treatments on porosity in the aluminium casting alloy A357 and stir-cast A357/15 vol % SiC particulate Metal Matrix Composite has been investigated. Densitometry and image analysis have been used to determine the apparent percentage porosity. Four HIPping temperature profiles have been investigated (103 MPa pressure) and mechanical testing has been carried out by single notch four point bending. The bend strength was increased after HIPping relative to as-received. The optimum HIPping cycle involved HIPping for a short time in the semi-solid region followed by a sustain below the solidus.

The effect of hot isostatic pressing on cast aluminum

Aluminum-silicon alloys are the most important commercial aluminum casting alloys, primarily because of their superior casting characteristics. This article discusses the effect of hot isostatic pressing on the mechanical properties of cast aluminum alloy A356. The effect of low-cost Densal hotisostatic pressing is also examined.

Effect of hot isostatic pressing on the mechanical properties of transformation-strengthened zirconium—Alumina ceramics

The effect of hot isostatic pressing (HIP) on the elastic moduli, strength, and toughness of as-sintered transformation-strengthened zirconium—alumina ceramics was studied. It was established that HIP produces a positive effect on the properties of ceramics provided that the process is carried out at a moderate temperature in a furnace with molybdenum heaters. The positive effect of HIP is manifested most significantly in the statistical strength distribution.

炭化物分散Ti-48Al-1Mnメカニカルアロイング材の組織と機械的性質に及ぼすHIP温度の影響

The effect of hot isostatic pressing (HIP) temperature on the microstructure and mechanical properties of Ti-48 mol%Al-1 mol%Mn compacts fabricated by mechanical alloying was investigated. N-heptane was used as a process control agent for the mechanical alloying. The compacts HIP treated at 1173, 1373 or 1573 K showed an ultra-fine equiaxed grain structure, i.e., a microduplex structure, consisting of TiAl (γ) and Ti2AlC phases, and their average grain sizes were 185 nm, 510 nm and 1.5 μm, respectively. The γ phase was considered to be formed by an α→γ massive transformation during heating. On the other hand, the compacts HIP treated at 1623 or 1673 K showed quite different microstructures from the above HIP compacts. The 1623 K-HIP compact was composed of equiaxed γ grains, whose size was approximately 11.5 μm, rectangular shaped Ti2AlC particles, and a small amount of the grain boundary nucleated α phase. Although the 1673 K-HIP compact showed a microstructure similar to the 1623 K-HIP compact, the γ grains were coarsened to be approximately 27.8 μm in diameter and the Ti2AlC particles were more elongated rectangles. Furthermore, the amount of the grain boundary nucleated α phase was increased and the lamella α phase nucleated at γ twin boundaries was observed in the 1673 K-HIP compact. Mechanical properties determined by compressive testing at various temperatures made clear that the compacts HIP treated at 1173, 1373 or 1573 K have good workability at elevated temperatures and those HIP treated at 1623 or 1673 K have good high temperature strength. These mechanical properties were influenced significantly by the microstructure, especially by the grain size and morphology of the Ti2AlC phase.

Hot isostatic pressing of plasma sprayed Ni-base alloys

This article reports the effects of hot isostatic pressing (HIPing) on the microstructure and properties of plasma sprayed Ni-based alloy coatings. Hot isostatic pressing was used as a post- spray treatment on plasma sprayed Ni-5Al, Ni-20Al, and NiCrAl coatings. The aim was to densify the coatings and modify physical properties such as strength, amount of porosity, and hardness. The coatings were HIPed at 750 to 950 ‡C at pressures of 50 to 200 MPa and held for 1 h. The treated coatings were examined by optical microscopy and scanning electron microscopy (SEM). Coating porosity was determined using a combination of an image analyzer and SEM. Near- zero porosity levels could be obtained, and HIP treatment at increasing temperatures and pressures changed the microstructure and increased the microhardness of the coatings. Mechanical testing of the coatings was performed on a Dynamic Mechanical Analyzer (DMA) from ambient to — 1000 ‡C. The results showed that the elastic modulus of HIPed coatings was greater than as-sprayed coatings up to — 750 ‡C. These changes can be related to plastic flow, interlamellar diffusion, and creep that occur at increased temperatures and pressures.

Fatigue properties of hot isostatically pressed Al–10Mg castings

Constant amplitude fatigue tests have been carried out to assess the effect of hot isostatic pressing (HIP) on the fatigue properties of cast Al–10Mg (wt-%) alloy (AA 520.0). The results showed that HIP treatment can result in large increases in the fatigue life. At a test stress of 106 MN m−2 (60% of proof stress) the average number of cycles to failure increased by 300% following HIP treatment. The magnitude of the increase was significantly greater at a lower test stress of 84 MN m−2 (47% of proof stress). However, the scatter in the results from specimens fatigue tested at 106 MN m−2 following HIP treatment was higher, resulting in a reduction in the safe fatigue life value that could be used for design purposes. Fracture surfaces of these specimens were examined to correlate fatigue life with defect levels. The high scatter can be attributed to the presence of oxide inclusions in the material.MST/1621

Improvement of critical current density in the Bi-Pb-Sr-Ca-Cu-O system through hot isostatic pressing

The effects of hot isostatic pressing (HIPing) on densification and the superconducting properties of the Bi-Pb-Sr-Ca-O system were investigated. A relative density up to 95% and a critical current density greater than 1100 A/cm 2 at 77 K were achieved through HIPing at 650°C for 2 h under 200 MPa argon. Under these conditions, the product gave a value of J c four times that without HIPing. T o was unaffected by HIPing for samples encapsulated with a combination of glass and silver tubes. However, T o was suppressed from 103 K to 86 K for samples encapsulated with stainless steel and silver tubes while J c increased from 260 A/ cm 2 to 1086 A/cm 2 during HIPing, indicating that the weak links were significantly improved. A new minor phase, having a composition of Bi/Pb/Sr/Ca/Cu=0.58/2.8/3.0/2.1/1.1, was observed in HIPed samples but its effect on J c is not clear.

The effect of post-heat treatment on structure, magnetic and mechanical properties of hot isostatic pressed (HIP) NiZn ferrite

The effects of hot isostatic pressing (HIP) and post-heat-treatment on the structure and the magnetic and mechanical properties of NiZn ferrites were studied. It was found that magnetic and mechanical properties of NiZn ferrites were degraded in the HIP process. X-ray diffraction analysis and magnetic measurements showed that the equilibrium oxygen content of the NiZn ferrites changes during the HIP process, and part of the spinel phase in the surface layer of the sample is decomposed into oxides (Fe/sub 2/O/sub 3/, ZnO, etc.). This leads to a decrease of both the soft magnetic (permeability, B-H loop) and mechanical properties (microhardness, H/sub nu /, and bending strength, sigma /sub f/) of the NiZn ferrites. Therefore, in order to obtain uniform oxygen content and remove the strains from the HIP ferrites, suitable postannealing is indispensable. An HIP ferrite, Ni/sub 0.32/Zn/sub 0.68/Fe/sub 2/O/sub 4/, with B/sub 10/=3100 G, H/sub c/=0.19 Oe, mu ' (1 MHz)=1400, sigma /sub f/=21 kg/mm/sup 2/, and H/sub nu /=850 was obtained.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Effects of thermal and thermomechanical treatments on the mechanical properties of centrifugally cast alloy 718

The ability of thermal and thermomechanical treatments to impart improved microstructural and mechanical properties to nickel-base engine components has been investigated for centrifugally cast alloy 718. The effects of hot isostatic pressing (HIP) or thermal homogenizing treatments on the tensile, creep and fatigue properties of cast alloy 718 were evaluated at 427, 538 and 649°C. The results indicated that either HIP or thermal homogenizing processing of the as-cast alloy, followed by an aging treatment, produced improved fatigue crack propagation resistance when compared on the basis of stress intensity factor range. Creep life and ductility were reduced by both processing treatments but to a lesser degree by the homogenizing treatment. The mechanical behavior of the HIP processed and homogenized material is discussed on the basis of microstructural changes produced in the as-cast alloy by the processing treatments.

Hot Isostatic Pressing of Alumina

Effects of hot isostatic pressing (HIP) conditions on the densification were studied for alumina powder compacts having various particle characteristics. HIP conditions examined are temperature, pressure and time. Powder characteristics were represented by particle size. The results were analyzed with the Ashby's model, and the mechanism of densification as well as the validity of the model was discussed. Alumina densified by the grain boundary diffusion mechanism in HIPing. The densification rate increased markedly with increasing temperature and pressure, and with decreasing particle size. The rates found were much lower than those predicted by the model for all conditions. The difference between the model and the experiment became increasingly significant with decreasing particle size of the powders and with increasing apparent density. The difference is approximately constant for each powder for the apparent density below 90%, but increased markedly with increasing apparent density over 90%. The disagreement between the model and the experiment was attributed to the uncertainty of grain boundary diffusion coefficients applied to the analysis, the agglomeration of powder particles and the grain growth occurring in the final stage of densification.

Densification of sintered lead zirconate titanate by hot isostatic pressing

The effects of hot isostatic pressing (HIPing) on sintered lead zirconate titanate are presented. Densities up to ∼98% were obtained by HIPing for 1 h at 1300°C with argon gas pressures of either 20.7 or 138 MPa. The microstructural changes observed after HIPing, and the rapid initial kinetics for densification and pore shrinkage, indicate that prssure-enhanced grain rearrangement and solution-precipitation processes are primarily responsible for densification. The persistance of large voids after HIPing suggests that it may be impossible to completely eliminate gross processing-related defects in lead zirconate titanate by HIPing.