HIP Process Research Articles

Welding techniques development of CLAM steel for Test Blanket Module

Fabrication techniques for Test Blanket Module (TBM) with CLAM are being under development. Effect of surface preparation on the HIP diffusion bonding joints was studied and good joints with Charpy impact absorbed energy close to that of base metal have been obtained. The mechanical properties test showed that effect of HIP process on the mechanical properties of base metal was little. Uniaxial diffusion bonding experiments were carried out to study the effect of temperature on microstructure and mechanical properties. And preliminary experiments on Electron Beam Welding (EBW), Tungsten Inert Gas (TIG) Welding and Laser Beam Welding (LBW) were performed to find proper welding techniques to assemble the TBM. In addition, the thermal processes assessed with a Gleeble thermal-mechanical machine were carried out as well to assist the fusion welding research.

Auswertung der durch den HIP-Prozess diffusions- geschweissten CMU- und FW-Testproben

To manufacture a cooling plate and a first wall with internal cooling channels for a fusion reactor, several diffusion bonding attempts with the material EUROFER97-2 have been so far conducted systematically. Some bonding parameter sets are predicted according to a diffusion bonding model. These predictions have then been verified in laboratory experiments with different samples. Beginning with unstructured samples up to samples with cooling channels, the experiments have been conducted in a uniaxial diffusion bonding device. The optimal parameter set has been determined. For the technological transfer to the real components two diffusion bonding samples (a compact mock-up (CMU) and a first wall (FW)) have been manufactured. Due to the large format of the FW test sample, the diffusion bonding by the HIP process is used. The process parameter set is modified from the optimal parameter set determined before. The cleaning method of the surfaces which will be diffusion bonded has been changed to the dry ice cleaning procedure. The bonding samples are examined first by a leakage test with helium. With a pressure of 130 bar and test duration of 2 h, leakage rate smaller than 10- 9 mbar I/s is detected. The measurements at the ligament of the channels after the bonding process show excessive inelastic deformations, which are even non uniform for the FW test sample. The microscopic investigations show the variation of bonding quality on each of the examined bars from CMU and FW. This is confirmed by investigation of the remaining voids in the bonding seam. The grain coarsening due to the additional thermal treatment stage for 2 h and those approx. 1 h extended bonding duration at 1050 °C is also observed. With the AES analysis at the fracture surface no precipitations of the alloying elements are observed. Furthermore some detached dirt particles, which contain a large quantity of atoms of oxygen, aluminum and sulfur, are found. The investigation of the mechanical behaviour of the diffusion bonded Material in a temperature range of RT ≤ T ≤ 700 °C shows that the 0.2 % yield strength (R p0,2 ) and the tensile strength (R m ) of the base material drop due to the grain coarsening. However at the same time the ultimate strains increase over the entire test temperature range. The samples with bonding seam have values of R p0,2 and R m that lie in the range of the values of the base material. The varied bonding quality of each ligament from CMU and FW is shown in the curve of the ultimate strain. This will be also verified by the impact tests in a temperature range of -150 < T ≤ RT. No evidence of USE and DBTT show the sample with bonding seam. Their impact energy has a linear dependency on the test temperatures. The results show, that the ligament 1 (edge region) of CMU with the impact energy of 4.12 J (47% the USE of the base material) and the ligament 6 (in the middle of the region) of FW with the impact energy of 3.2 J (33% the USE of the base material) at RT have the best bonding behaviour.

Idiopathic Transient Osteoporosis of the Pelvis in a Non-Pregnant Young Woman: A Case Study

Idiopathic transient osteoporosis of the hip is a rare condition that was first described in a series women in their third trimester of pregnancy. The clinical course is usually benign and self-limiting. Magnetic resonance is very useful for the diagnosis. Differential diagnoses include avascular necrosis of the femoral head, septic arthritis of the hip, osteomyelitis, stress fractures, primary or secondary neoplastic processes, and referred pain from the spine or genitourinary tract in pregnant women. The authors present a case of idiopathic transient osteoporosis of the pelvis in a young nonpregnant woman with insidious hip pain with no antecedent infection or trauma.

Characterization of novel W alloys produced by HIP

W and W alloys containing 0.5 wt% Y 2O 3, x wt% Ti and ( x wt% Ti + 0.5 wt% Y 2O 3) have been prepared, x = 2 or 4. Elemental powders were blended or ball milled, canned, degassed and finally consolidated by a two-stage HIP process under a pressure of 195 MPa. It is found that Ti addition favours the densification attaining a fully dense material. XRD, SEM and EDX analyses of the material with Ti addition reveal the formation of a microstructure consisting of tungsten particles embedded in a W-Ti matrix. The microhardness of these materials increased noticeably with the titanium content.

Influence of Manufacturing Process and Alloying Element Content on the Tribomechanical Properties of Cobalt-Based Alloys

Manufacturing process routes of materials can be adapted to manipulate their microstructure and hence their tribological performance. As industrial demands push the applications of tribological materials to harsher environments of higher stress, starved lubrication, and improved life performance, manufacturing processes can be tailored to optimize their use in particular engineering applications. The aim of this paper was therefore to comprehend the structure-property relationships of a wear resistant cobalt-based alloy (Stellite 6) produced from two different processing routes of powder consolidated hot isostatic pressing (HIPing) and casting. This alloy had a nominal wt % composition of Co–28Cr–4.5W–1C, which is commonly used in wear related applications in harsh tribological environments. However, the coarse carbide structure of the cast alloy results in higher brittleness and lower toughness. Hence this research was conducted to comprehend if carbide refinement, caused by changing the processing route to HIPing, could improve the tribomechanical performance of this alloy. Microstructural and tribomechanical evaluations, which involved hardness, impact toughness, abrasive wear, sliding wear, and contact fatigue performance tests, indicated that despite the similar abrasive and sliding wear resistance of both alloys, the HIPed alloy exhibited an improved contact fatigue and impact toughness performance in comparison to the cast counterpart. This difference in behavior is discussed in terms of the structure-property relationships. Results of this research indicated that the HIPing process could provide additional impact and fatigue resistance to this alloy without compromising the hardness and the abrasive/sliding wear resistance, which makes the HIPed alloy suitable for relatively higher stress applications. Results are also compared with a previously reported investigation of the Stellite 20 alloy, which had a much higher carbide content in comparison to the Stellite 6 alloy, caused by the variation in the content of alloying elements. These results indicated that the fatigue resistance did not follow the expected trend of the improvement in impact toughness. In terms of the design process, the combination of hardness, toughness, and carbide content show a complex interdependency, where a 40% reduction in the average hardness and 60% reduction in carbide content had a more dominating effect on the contact fatigue resistance when compared with an order of magnitude improvement in the impact toughness of the HIPed Stellite 6 alloy.

An empirical investigation of labor income processes

In this paper, I reassess the evidence on labor income risk. There are two leading views on the nature of the income process in the current literature. The first view, which I call the “Restricted Income Profiles” (RIP) process, holds that individuals are subject to large and very persistent shocks, while facing similar life-cycle income profiles. The alternative view, which I call the “Heterogeneous Income Profiles” (HIP) process, holds that individuals are subject to income shocks with modest persistence, while facing individual-specific income profiles. I first show that ignoring profile heterogeneity, when in fact it is present, introduces an upward bias into the estimates of persistence. Second, I estimate a parsimonious parameterization of the HIP process that is suitable for calibrating economic models. The estimated persistence is about 0.8 in the HIP process compared to about 0.99 in the RIP process. Moreover, the heterogeneity in income profiles is estimated to be substantial, explaining between 56 to 75 percent of income inequality at age 55. I also find that profile heterogeneity is substantially larger among higher educated individuals. Third, I discuss the source of identification—in other words, the aspects of labor income data that allow one to distinguish between the HIP and RIP processes. Finally, I show that the main evidence against profile heterogeneity in the existing literature—that the autocorrelations of income changes are small and negative—is also replicated by the HIP process, suggesting that this evidence may have been misinterpreted.

Application of the hot isostatic pressing process on a thermally sprayed coating layer on copper dies

Recent research has shown that copper-alloy dies sprayed with a protective steel layer can potentially replace steel dies in the pressure die casting process for the purpose of rapid heat extraction. The deposited layer is required to withstand abrasion, thermal shock, and cyclic loading, and be resistant to debonding from the copper-die substrate. This paper is concerned with an experimental investigation into the application of the HIP process to ascertain its effectiveness towards enhancing the bond strength, hardness, and densification of chrome steel coatings on a copper substrate. A particular focus of the paper is on the use of partial encapsulation coupled with the use of ceramic paper whose purpose is to transfer the loading pressure and prevent bonding between the die and the encapsulation container. It is shown in the paper that partial encapsulation is effective and can be used to HIP localized regions of a die. The ceramic paper was shown to be effective in transmitting loading and has the added advantage of providing relatively good surface finish as compared with that obtained with ceramic powder. The results of the experimental trials show reduced porosity and increased bond strength with application of the HIP process. In addition hardness values are shown to be reduced to levels typically found in traditional die-tool steels.

Rudimentary investigation of the HIP process for tungsten target

Zr alloy and 316-Ti stainless steel (S.S.) were selected as cladding materials for a W target. The HIP processes were performed at 1200, 1300 and 1400 °C and 180 MPa. The observation and determination for micro-morphology of the interface, diffusion depth and composition as well as their micro-hardness were conducted. The results indicated that the bonding of W–Zr and W–S.S. was good under the testing conditions. No pores or micro-cracks in the interface were observed. Grain growth of W was not observed at 1200 and 1300 °C, but it was observed at 1400 °C. The diffusion of Zr–W on the interface of W–Zr was preferred during the HIP process. The diffusion layer was 6–13 μm in thickness for W–Zr, and 13 μm for W–S.S. A peak of the hardness was observed at the interface of W–Zr or W–S.S. A part of the stainless steel cladding melted after HIP using an oxygen absorber (Zr) at 1300 °C and 180 MPa. The conditions of 1200 °C and 180 MPa without using an oxygen absorber Zr are suitable for W–S.S. bonding, while 1300 or 1400 °C and 180 MPa are better for W–Zr bonding.

Effect of preforms on the synthesis of micro .BETA.-SiC from phenol resin and silicon

The aim of present study is to investigate the effect of preforms on the synthesis of micro β-SiC. For this purpose, preforms were prepared from commercially available phenol resin and silicon powders by pyrolysing at 650°C and 750°C in vacuum. Then, preforms were hot isostatically pressed (HIPed) at 1400°C for 10 min in an argon atmosphere of 50 MPa to synthesize micro β-SiC. X-ray diffraction analyses showed that the formation of β-SiC was enhanced in the specimens prepared by HIPing the preforms pyrolyzed at 750°C, which might be due the more carbonization and the development of porous structure in the range 600-800°C. Scanning electron microscopy observations revealed the formation of micro-crystals (up to 8 μm in size) with facets in the HIPed specimens. In addition, the degree of crystallites in the specimen obtained from the preforms pyrolyzed at 750°C was higher than the preforms pyrolyzed at 650°C. The energy dispersive spectroscopy showed that crystals were of SiC because the atomic ratio of silicon and carbon atoms in the crystals was almost 1 : 1. The density of the specimens obtained by HIPing the preforms pyrolyzed at 750°C was (3.11 g/cm3) more than the specimens obtained by HIPing preforms pyrolyzed at 650°C (2.95 g/cm3). The HIPing process, in addition to densification, led to the formation and growth of β-SiC.

熱間等方加圧（ＨＩＰ）法による開気孔質多孔体の作製とその焼結メカニズム

Open-pore porous materials can be produced by the capsule-free Hot Isostatic Pressing (HIPing) process. In this paper, sintering mechanisms, features and applications of capsule-free HIPed open-porous materials are discussed. During sintering powder compacts by capsule-free HIPing process, high pressure gas penetrates inside of the green bodies, and forms pores. There are two mechanisms to explain this phenomenon. Surface-diffusion is enhanced during capsule-free HIPing, because high frequency gas-collision with pore surfaces, forms grown necks between raw powder particles, and enhances pore formation. Another possible mechanism is the matter of spatial compatibility of gas atoms and sintered material. For the shrinkage of pores, i. e., for the densification of the green bodies, the high pressure gas, or the high density gas must be removed from inside of pores. The higher density requires the higher energy to remove high density gas. At the end of the sintering process, the gas must be removed from pores to ambient pressure to make those pores to be open pores. The above mentioned sintering mechanisms provide higher open porosity, more grown necks, smoother pore surfaces and narrower pore size distribution in capsule-free HIPed materials compared with those in conventionally sintered porous materials. As a consequence, high Young's modulus, high fracture strength, high fluid permeability are obtained by the capsule-free HIP process. The porous materials fabricated by the capsule-free HIPing can be applied for filters, grinding wheels, electrochemical electrodes and others with better performance than conventional products.

진공 소결공정에 의한 고밀도 바인더리스 및 극저바인더 초경합금의 제조

【Pure WC or WC with low Co concentration less than 0.5 wt.% is studied to fabricate high density WC/Co cemented carbide using vacuum sintering and post HIP process. Considering the high melting point of WC, it is difficult to consolidate it without the use of Co as binder. In this study, the effect of lower Co addition on the microstructure and mechanical properties evolution of WC/CO was investigated. By HIP process after vacuum sintering, hardness and density was sharply increased. The hardness values was $2,800kgf/mm^2$ using binderless WC.】

The HIP way to make cleaner, better steels

Hot isostatic pressing has emerged as a very important technique in the PM ‘toolbox’ of manufacturing options. The fully dense high alloyed steels produced via HIP processing are estimated to have created a $500 million market, says consultant Olle Grinder…

Effect of γ′ precipitation during hot isostatic pressing on the mechanical property of a nickel-based superalloy

The effect of the precipitation of γ′ phase during hot isostatic pressing (HIPing) on the mechanical property of a nickel-based superalloy, GTD-111, was evaluated by conducting tensile and creep-rupture tests at 871 °C. In the 4-h two-step HIP process, the coupons were isostatically compressed (at 120 MPa) and heated to 1230 °C, well above the dissolution temperature of γ′ precipitates into the γ matrix, for the first 2 h, and cooled down to a temperature to induce the precipitation of γ′ phase and held for the last 2 h at 120 MPa or at ambient pressure. The precipitates were controlled in size by varying the temperature for the last half of the process. According to the result of the tensile test, the mechanical properties of the alloy were varied upon the microstructural evolution, and improved more than 40%, compared to those of the untreated ones. The precipitation of γ′ phase under high pressure further improved in the properties, suggesting that the precipitation of γ′ phase at high pressure provides an advantage for the rigidity of the structure. Based on these findings, a 6-h three-step HIP process was tried, and proved to be an effective substitute for the normal heat treatment, especially in terms of creep properties. This feature was mostly attributed to the homogenized microstructure of HIPed ones, as evidenced by the X-ray diffraction patterns.

Preparation of ultra-fine TiC0.7N0.3-based cermet

Abstract Since ultra-fine Ti(C, N) has large surface and high activity, preparation of high performance cermets using ultra-fine Ti(C, N) powders is very difficult at the present. In the paper, deoxidation process of ultra-fine TiC0.7N0.3 powder is carried out firstly, and the oxygen content of ultra-fine TiC0.7N0.3 powder can be decreased from more than 1 wt% to 0.06 wt%; milling technology of ultra-fine TiC0.7N0.3-based cermet is studied in the paper, the results show that the optimum milling time is 45 h and the ball to powder weight ratio is 15:1, and the dispersant helps to achieve a homogeneous distribution of the ultra-fine powder; during vacuum sintering of ultra-fine cermet, pores tend to form, hence NT6B shows relatively lower properties than NT6A. After HIP process (1350 °C, 90 min, 70 MPa), the porosity can be largely decreased. The prepared ultra-fine cermet has typical core–rim microstructure, finer grain size and enhanced properties.

Learning Your Earning: Are Labor Income Shocks Really Very Persistent?

The current literature offers two views on the nature of the labor income process. According to the first view, individuals are subject to very persistent income shocks while facing similar life-cycle income profiles (the RIP process, Thomas MaCurdy 1982). According to the alternative, individuals are subject to shocks with modest persistence while facing individual-specific profiles (the HIP process, Lee A. Lillard and Yoram A. Weiss 1979). In this paper we study the restrictions imposed by these two processes on consumption data—in the context of a life-cycle model—to distinguish between the two views. We find that the life-cycle model with a HIP process, which has not been studied in the previous literature, is consistent with several features of consumption data, whereas the model with a RIP process is consistent with some, but not with others. We conclude that the HIP model could be a credible contender to—and along some dimensions, a more coherent alternative than—the RIP model. (JEL D83, D91, E21, J31)

“To Us Writers, the Differences Are Obvious”

“To Us Writers, the Differences Are Obvious”

Mechanical and microstructural behaviour of Y 2O 3 ODS EUROFER 97

Two small ingots of the steel EUROFER 97, one containing 0.25 wt% Y 2O 3 and the other Y 2O 3 free, have been produced by consolidating mechanically milled powder by hot isostatic pressing at 1373 K for 2 h under 200 MPa. For comparison, a third ingot was consolidated under identical conditions but using un-milled EUROFER powder. Microhardness, tensile and Charpy tests, along with TEM observations, have been performed on these materials in the as-HIPed condition and after different heat treatments. The mechanical behaviour and the microstructural characteristics of these materials suggest that the origin of the reduced impact properties of the oxide dispersion strengthened EUROFER could be the premature formation of carbides during quenching following the HIP process. This would be enhanced by the high density of structural defects produced by milling, as these favour the fast diffusion and segregation of carbon.

Effect of 12 Heat Treatment Conditions After HIP Process on Microstructural Refurbishment in Cast Nickel-Based Superalloy, GTD-111

Effect of 12 Heat Treatment Conditions After HIP Process on Microstructural Refurbishment in Cast Nickel-Based Superalloy, GTD-111

Microstructure and mechanical properties of hot isostatically pressed cermets with TiN coatings

To increase the adhesion strength between the coating and the substrate, sintered Ti(C, N)-based cermets were selected and deposited with monolayer TiN using a multiarc ion-plating technique; subsequently, hot isostatic pressing (HIP-ing) treatment was performed at 1000°C using nitrogen pressure up to 110 MPa. The mechanical properties of cermets after a coating process and subsequent HIPing treatment have been evaluated with respect to the hardness, the residual stress, and the coating adhesion. The results show that after the HIPing process, there was a higher increase in critical load in the TiN-coated cermets with lower surface roughness compared with those with higher surface roughness. In all cases, the residual stress was found to be compressive. The effects of substrate surface roughness and posttreatment on the adhesion strength of the coatings were thus investigated. It was also found that the HIPing posttreatment process is well suited for increasing the adhesion strength between the coating and the substrate.

Evaluation of Mechanical Properties and Microstructure of a High Carbon-Vanadium Tool Steel Produced by Powder Metallurgy

Tool steels have important participation in the worldwide market of steels. They are used by metal-mechanical industry as cutting tools, molds, punches, etc. Because the use is of great responsibility, it is important to discuss the relationship between microstructure and mechanical properties. The starting material was powder of a commercial tool steel with the composition (wt%) 2.5%C, 5.25%Cr, 0.9%Si, 9.75%V, 0.5Mn, 1.3%Mo and balance Fe. The samples were obtained by hot isostatic pressing (hip) process, and than were austenitizing at 1120°C and submitted to tempering in the temperature range varying from 430° to 550°C. The aim of this work was to evaluate the correlation between heat treatment, microstructure and mechanical properties. Results of toughness and hardness are presented.