Hot Isostatic Pressing: HIP’17最新文献

{"title":"Large-Scale and Industrialized HIP Equipment for the Densification of Additive Manufactured Parts","authors":"Hongxia Chen, Deming Zhang, Qing Ye","doi":"10.21741/9781644900031-7","DOIUrl":"https://doi.org/10.21741/9781644900031-7","url":null,"abstract":"Additive manufacturing technology has significant advantages in fabricating parts with complex shape, but the internal defects, such as residual stress, pores and microcracks, would result in critical problems under certain circumstances. To meet the requirement of HIP treatment on additive manufactured parts, we studied the thermodynamic behavior of the gas medium under high temperature and high pressure conditions, explored the deformation discipline of the thin-walled parts and the boundary conditions of controlling deformation, and optimized the process of eliminating residual stress. Based on the above work, a series of HIP equipment were specially designed for the treatment on additive manufactured parts, which could provide solid support for the development of additive manufacturing technology. 1. Advantages of additive manufacturing technology Additive manufacturing is an advanced technology widely developed in the world. Based on the material, it contains rapid forming of plastic, wax, ceramic and metal. Among those, rapid forming of wax-based material combines additive manufacturing and casting technology, which has been widely used for the industrial production of castings. Besides, additive manufacturing of metallic material is the most impressive, which provides universal process for the direct fabricating of key parts with complex shape. With no need of mold and the short manufacturing cycle, it has become the best process for preliminary examination and small-batch production. Recently, additive manufacturing of metallic material mainly focus on super alloy, ultra-high strength steel, titanium alloy and aluminum alloy. Due to the high cost, the application areas are limited in aerospace, military and biomedical industries. In the future, with the development of additive manufacturing and reducing of cost, it will play an important role in more fields. 2. Defects of additive manufactured parts and improvement 2.1 Analysis on defects of additive manufactured parts Compared with traditional technology, additive manufacturing has several advantages. However, due to the uniqueness of the forming process, internal defects tend to appear easily [1]: Types of internal defects result from 1) Residual stress: Thermal strain and residual stress generate due to the high temperature gradient; 2) Spherulization effect: When the laser or electron beam is irradiated, metal powders are partially melted to form a molten pool. Under a certain force, the melt tends to be spherical, resulting in poor surface quality, low density and emergence of pores; 3) Cracks: In the forming process, metal powders undergo rapid heating and cooling. There is no enough liquid metal supplementation during solidification, and the solidification part is bound by the cold substrate, resulting crack. 4) Pore formation: Pores may generate from residual gas during rapid solidification, reaction of carbon and oxygen in the melt, reduction of the metal Hot Isostatic Pressing –","PeriodicalId":202011,"journal":{"name":"Hot Isostatic Pressing: HIP’17","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128581722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microstructural Design of Ni-base Superalloys by Hot Isostatic Pressing","authors":"B. Ruttert, I. Lopez-Galilea, L. M. Roncery, W. Theisen","doi":"10.21741/9781644900031-15","DOIUrl":"https://doi.org/10.21741/9781644900031-15","url":null,"abstract":"Single-crystal Ni-base superalloys (SXs) are used as a first-stage blade material in high-pressure turbines for aero engines or in stationary gas turbines. They operate at temperatures close to their melting point where they have to withstand mechanical and chemical degradation. Casting and extensive solution heat-treatments of such blades introduce porosity that can only be reduced by hot isostatic pressing (HIP). Recent developments in HIP plant technology enable simultaneous HIP-heat-treatments due to rapid quenching at the end of such treatments. This work gives an overview of the opportunities that such a unique HIP offers for the solution heat-treatment of conventionally cast SXs or directionally solidified Ni-base superalloys fabricated by selective electron beam melting (SEBM). The influence of temperature, pressure, and cooling method on the evolution of the γ/γ’-morphology and on the pore shrinkage is investigated. The cooling method has a strong impact on the γ’-particle size and shape whereas the combination of temperature and pressure during the HIP-treatment mainly influences porosity reduction. In a final approach a HIP treatment is satisfactorily used to fully re-establish the γ/γ’-microstructure after high-temperature creep degradation. Introduction SXs are used as a first-stage blade material in modern gas turbines [1]. Their complex composition results in large dendrite arm spacings during the slow Bridgman solidification process, with heavy partitioning of alloy elements between dendritic and interdendritic regions as well as the formation of large cast pores in interdendritic regions. The presence of porosity reduces the material strength and ductility and results in scattering of the mechanical properties. Pores act as crack initiation sites and promote crack propagation, leading to premature rupture of the components [2-3]. Therefore, it is important not only to reduce the segregation by a heattreatment (solution annealing and aging), but also to reduce the porosity generated during casting and solution annealing by means of HIP. Modern HIP units can provide fast quenching rates that help in designing the desired microstructures starting from material states that feature internal pores, undesirable precipitates, and chemical segregation. The simultaneous application of a high isostatic pressure and a high temperature can eliminate pores by a combination of elementary processes that involve plastic deformation, creep, and diffusion bonding and also simultaneously remove chemical heterogeneities of the alloy. The possibility of controlling the cooling rate after HIP to a certain degree (from quenching to slow cooling) enables establishment of a desired final γ/γ’ microstructure at the end of such an implemented HIP-heat-treatment [4]. Consequently, the combination of HIP and quenching enables integration of the required homogenization of the Hot Isostatic Pressing – HIP‘17 Materials Research Forum LLC Materials Research Proce","PeriodicalId":202011,"journal":{"name":"Hot Isostatic Pressing: HIP’17","volume":"1107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125301247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"HIP Activities for Turbopump Components of Korea Space Launch Vehicle","authors":"S. Yoon, C. Choi, Jinhan Kim","doi":"10.21741/9781644900031-11","DOIUrl":"https://doi.org/10.21741/9781644900031-11","url":null,"abstract":"In Korea, we are developing liquid rockets for commercial launch services, and the government agency, Korea Aerospace Research Institute (KARI), is responsible for main development. Turbopump, which is a key component of liquid rocket engine, is a rotating machine that pressurizes fuel and liquid oxygen in an extreme environment and supplies them to a combustion chamber. Design requirements are very severe because it must maintain lightweight feature while outputting very large power. The HIP (Hot Isostatic Press) method is a near-net shape processing, which makes it easy to mold a material that is difficult to machine, while securing quality comparable to forged products. These advantages are particularly attractive for the aerospace sector. Recently, we tried manufacture of turbopump impellers and turbine discs using HIP technology, and some of the products have been assembled in a turbopump and ground-tested. This will be described in detail in this paper. Introduction There is a series of space launch vehicle programs in Korea and they are named KSLV (Korea Space Launch Vehicle) programs [1]. The first program, KSLV-I was successfully launched in Jan. 2013 after two launch failures. The first stage of KSLV-I was developed in Russia and the upper stage was covered in Korea. Now KSLV-II program is in progress and the launch is scheduled in 2020. The vehicle is composed of three stages, the first stage with four 75 ton thrust engines, the second stage with a single 75 ton thrust engine, and the third one with a 7 ton thrust engine [2]. All of the vehicles are under development by Korea Aerospace Research Institute (KARI) in Korea, requiring precedent development of 75 ton thrust and 7 ton thrust liquid engines. The both engines employ pump-fed gas generator cycle with kerosene/LOx, and the turbopump consists of single-stage centrifugal pumps for each propellant and a single-stage impulse turbine in one axis. An Inter-Propellant-Separator (IPS) is installed between the oxidizer pump and the kerosene pump to avoid any interaction between propellants [3]. Fig. 1 shows 75 ton and 7 ton turbopumps under development in KARI. They completed performance tests and were assembled to engines, now the engines are undergoing ground performance tests. Various materials are utilized to fabricate turbopumps. Especially heat resistant nickel alloys are widely used in oxidizer pump and turbines due to their excellent mechanical properties at extremely low or high temperature condition. These superalloys usually have poor machinability so that casting and powder sintering methods are known to be suitable fabrication methods. In the turbopumps of KSLV-II, the impeller of the oxidizer pump is of Inconel 718 alloy, and is manufactured by machining and brazing process. Also the turbine blisk is of the same material and is manufactured by electric discharge machining and turning operation. In this paper manufacturing of these items with hot isostatic pressing was inves","PeriodicalId":202011,"journal":{"name":"Hot Isostatic Pressing: HIP’17","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131938130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wear of PM HIP Metal Matrix Composites – Influence of Carbide Type","authors":"T. Berglund, Josefin Hall","doi":"10.21741/9781644900031-20","DOIUrl":"https://doi.org/10.21741/9781644900031-20","url":null,"abstract":"The type of hard phase in combination with matrix material has a great influence on the wear properties of PM HIP Metal Matrix Composites. The hardness and toughness of the hard phase as well as it ...","PeriodicalId":202011,"journal":{"name":"Hot Isostatic Pressing: HIP’17","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125204248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat Treatment inside the HIP Unit","authors":"N. Wulbieter, Anna Rottstegge, D. Jäckel, W. Theisen","doi":"10.21741/9781644900031-10","DOIUrl":"https://doi.org/10.21741/9781644900031-10","url":null,"abstract":"The possibility of combining densification or compaction of steel parts with a heat treatment has recently evolved due to the production of HIP units with a rapid quenching device. Several studies have already been performed to assess the cooling speed and show possibilities for heat-treating steels. It has already been shown that several alloyed steel grades could be hardened by quenching inside a HIP unit. This study aims to characterize the impact of high isostatic pressure during austenitization and quenching on the transformation behavior and resulting microstructure of hardenable steels. The effect of pressure during quenching was studied using two methods. The first method is to measure the latent heat inside the transforming steel during isothermal holding. The release or uptake of energy reveals information about the transformation sequence taking place. The second method is to use the electrical resistivity of a steel as a sensitive indicator for the existing phases and solution state of the steel during continuous cooling after austenitization. Both experimental methods reveal that an isostatic pressure of 170 MPa is sufficient to shift the transformations to longer times and lower temperatures and hence increase the hardenability of hardenable martensitic steel. Introduction A HIP unit was recently introduced that offers the opportunity to quench inside the pressure vessel [1]. Since the introduction of this URQ method (Uniform Rapid Quenching), various research teams have investigated the possibility to heat-treat steel inside a HIP unit. Mashl showed that hardening of a low-alloyed steel inside a pressure vessel leads to higher hardness compared to quenching in oil [2]. The same result was found by Weddeling [3,4]. Angré et al. have shown that a pressure of 170 MPa prolongs pearlite formation in steel specimens that are austenitized and subsequently hold isothermally in the pearlite region [5]. These findings show that a high isostatic pressure of 170 MPa does have an influence on the phase transformations of steel. Therefore, the TTT (Time-Temperature-Transformation) diagrams of every steel are not applicable for HIP heat treatment. In order to correctly predict the hardness and microstructure resulting from an integrated heat treatment in the HIP unit, the TTT diagram as well as the pressure effect must be known. At ambient pressure, the measurement of variations in length during phase transitions (dilatometric measurements) is utilized to determine the temperature and time of a phase transition; however, this was not possible inside a HIP+URQ unit. In the present study, two methods that are capable of indicating phase transitions in theory are tested in a HIP unit and evaluated for two steels. One method, which also was utilized by Angré et al., is to measure the latent heat. The emission or absorption of heat is an indication for a phase transition. The second method of determining a phase transition is to measure the electrical","PeriodicalId":202011,"journal":{"name":"Hot Isostatic Pressing: HIP’17","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125604551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hot Isostatic Pressing in the Automotive Industry: Case study of Cast Aluminum Alloys for Rims of Car Wheels","authors":"A. Eklund, M. Ahlfors","doi":"10.21741/9781644900031-3","DOIUrl":"https://doi.org/10.21741/9781644900031-3","url":null,"abstract":"Cast aluminum alloys are good candidates for weight saving in many industries, i.e automotive, aerospace, sporting goods and other high-performance application. When HIPing of aluminum alloys is performed the fatigue properties of the casting is greatly improved. That is especially true for rims of car wheels that suffer from high porosity and high scrap rates. After HIP, zero porosity is found and scrap rates drop with 50-90%. Introduction Cast pores are potential crack initiation sites for aluminum alloys and is considered the main influence of poor fatigue properties. Also, the microstructure influences the mechanical behavior of cast alloys, like inclusions, dendrite spacing and grain size. By controlling the cooling rate during solidification of castings, it is possible to control and modify the alloy microstructure and thereby optimizing the mechanical properties. In Fig. 1, AlSi7 cast aluminum alloy is seen before and after HIP. The internal porosity is completely eliminated, but surface connected pores are still visible on the tested samples. The remaining surface pores will disappear after the final painting step. Figure 1. Material before HIP (in the middle) and after HIP (top/bottom). Hot Isostatic Pressing – HIP‘17 Materials Research Forum LLC Materials Research Proceedings 10 (2019) 18-23 doi: http://dx.doi.org/10.21741/9781644900031-3 19 Production route for rims for car wheels Two different production routes have been considered for the manufacturing of rims for car wheels. In Fig. 2, the HIP is used to treat the aluminum alloy directly after solidification to eliminate porosity and improve the machined surface quality to lower the scrap rate, see Fig. 3. The best way to control the cooling rate is achieved with a HIP-system equipped with uniform rapid cooling (URCTM), see Fig. 4. Uniform rapid cooling was introduced in the 1980’s for enhancement of the productivity making it possible to double the production due to shorter cycle times. Another advantage was the better control of the cooling rate, which makes it possible to optimize the pressure-temperature ratio which enables optimization of the material properties. Figure 2. Possible production route for HIP after casting. Hot Isostatic Pressing – HIP‘17 Materials Research Forum LLC Materials Research Proceedings 10 (2019) 18-23 doi: http://dx.doi.org/10.21741/9781644900031-3 20 Figure 3. Improved machined surface quality, before HIP (left), and after HIP (right). Figure 4. Typical HIP cycle times without and with rapid cooling. The second possible production route can be seen in Fig. 5. Here, the HIP will replace even more process step, i.e. the solution heat treatment (SHT) and the quenching, by utilizing the possibility the combine HIPing and heat treatment, HPHT. The latest developments in HIP technology, Uniform Rapid Quenching (URQ), have made it possible to achieve cooling rates up and over 2000 °C/min. The same quench rates as you experience in oiland water bath quenching","PeriodicalId":202011,"journal":{"name":"Hot Isostatic Pressing: HIP’17","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131850806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"HIP for AM - Optimized Material Properties by HIP","authors":"M. Ahlfors, Fouzi Bahbou, A. Eklund, U. Ackelid","doi":"10.21741/9781644900031-1","DOIUrl":"https://doi.org/10.21741/9781644900031-1","url":null,"abstract":"An investigation of HIP parameters for EBM Ti-6Al-4V has been performed by Arcam AB and Quintus Technologies AB with the aim to maximize the strength of the HIP:ed material. A lower HIP temperature of 800 °C and a higher pressure of 200 MPa gives the highest strength and is also enough to eliminate all internal defects. By printing material with intentionally induced porosity combined with an optimized HIP cycle the highest strength can be obtained. Introduction Hot isostatic pressing (HIP) is widely used today to eliminate internal defects in metallic materials produced by powder bed fusion. The internal defects are mostly lack-of-fusion defects generated during the printing process and entrapped gas porosity coming from the powder particles. These defects act like stress concentrations and crack initiation points in the material, which decreases the material properties. By eliminating these defects within the material, the ductility and especially the fatigue properties are improved [1-5]. Figure 1 shows a cross section of an EBM Ti-6Al-4V material before and after HIP where the typical effect of HIP:ing in terms of defect elimination can be seen. In Figure 2, typical fatigue data of as printed and HIP:ed material of EBM Ti-6Al-4V is shown and it is evident that the HIP process gives much improved fatigue properties compared to as-printed material. This data is generated by Arcam. Figure 1 Micrographs of EBM Ti-6Al-4V before HIP to the left and after HIP to the right Hot Isostatic Pressing – HIP‘17 Materials Research Forum LLC Materials Research Proceedings 10 (2019) 1-10 doi: http://dx.doi.org/10.21741/9781644900031-1 2 Figure 2 Fatigue data for EBM Ti-6Al-4V, courtesy of Arcam The solidification rates in the EBM process are in the order of 10 – 10 K/s which is very high [6]. The extremely fast solidification generates a very fine microstructure which gives the material a high strength. Any conventional heat treatment at an elevated temperature for a significantly long time, like HIP:ing, will coarsen the microstructure due thermodynamic driving forces. This coarsening of the microstructure will decrease the strength of the material, which is not preferable. The development within EBM printing equipment over the last years has made the as-printed microstructures even finer, which makes this challenge even more significant for the modern EBM machines. In Figure 3 a) and b) the microstructure of as printed material compared to HIP:ed EBM Ti-6Al-4V is shown. The coarsening of the microstructure after HIP is evident. Figure 3 a) and c) shows the difference between the microstructures produced by an older Arcam s12 machine compared to a newer Arcam Q10 machine. Figure 3 Microstructures of EBM Ti-6Al-4V a) As-printed with Arcam s12 b) After HIP (920°C, 1000bar, 2h) with Arcam s12 c) As-printed with Arcam Q10 For Ti-6Al-4V produced by selective laser melting (SLM), the same coarsening of the microstructure and thus decrease of strength has been seen.","PeriodicalId":202011,"journal":{"name":"Hot Isostatic Pressing: HIP’17","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129986422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of the Design and Technological Solutions for Manufacturing of Turbine Blisks by HIP Bonding of the PM Disks with the Shrouded Blades","authors":"L. Magerramova, E. Kratt","doi":"10.21741/9781644900031-6","DOIUrl":"https://doi.org/10.21741/9781644900031-6","url":null,"abstract":"A bimetallic turbine blisk with shrouded blades had been designed in order to enhance the gas-dynamic and strength characteristics of the wheels of the gas turbine engines and reduce their weight. The separately cast nickel superalloy shrouded blades are joined to disc made of the heat-resistant alloy powder using a method of hot isostatic pressing (HIP). The problem of such joint is complicated by the presence of the shrouds on the periphery of the blades. This design should provide a good contact on the working faces of the shrouds during the operation. In order to solve this problem, a capsule for manufacturing of the disk piece and a process flow diagram for calculation of shaping such a capsule during hot isostatic pressing have been developed. Introduction In various fields of technology, the need for high performance parts and components is constantly increasing. The shape and dimensions of blanks for such parts need to be close to the geometry of the final parts (the near net shape for the disk and net shape geometry for the blades). Traditional technology based on casting or forging and machining have serious limitations in the production of such blanks, due to the considerable difficulties in ensuring the requirements of geometrical complexity and required accuracy and distribution of performance and technological characteristics in the material. The development of new technologies for the creation of bimetallic wheel structures, based on the processes of diffusion bonding of dissimilar alloys now allows us to meet the extremely high (and increasingly stringent) requirements for safe operation and economic efficiency of Gas Turbine Engines (GTE). Various methods are used to connect the blades to the disks; for example, electrochemical and mechanical methods of disk manufacture with blades from one forging, or blade connection to the disc by indentation at high temperature, soldering, friction welding, or hot isostatic pressing [1-4]. During the recent decades worldwide a progressive technological method based on Hot Isostatic Consolidation of rapidly solidified powders of advanced alloys into various shapes has been developed. Hot isostatic pressing (HIP) of powder materials is a process of high-temperature consolidation of porous workpieces under a high pressure. This process eliminates the abovementioned restrictions, allowing obtaining a workpiece of the required complex configuration. Such parts as impellers, diffusers, turbines are produced by hot isostatic pressing. Hot isostatic pressing is advantageous due to its ability to produce complex shape parts earlier available only Hot Isostatic Pressing – HIP‘17 Materials Research Forum LLC Materials Research Proceedings 10 (2019) 39-46 doi: http://dx.doi.org/10.21741/9781644900031-6 40 by casting from difficult to process alloys, and possessing mechanical properties of the wrought materials. In the variety of technological parameters influencing the final shape of the product the deci","PeriodicalId":202011,"journal":{"name":"Hot Isostatic Pressing: HIP’17","volume":"154 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131856680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oxygen Content in PM HIP 625 and its Effect on Toughness","authors":"T. Berglund, Fredrik Meurling","doi":"10.21741/9781644900031-19","DOIUrl":"https://doi.org/10.21741/9781644900031-19","url":null,"abstract":"Oxygen control during powder manufacturing and handling is crucial when manufacturing HIPed parts. The influence of elevated oxygen content on mechanical properties is something that has been debated and investigated for many years. The general consensus in the industry is that oxygen has a very detrimental effect on the toughness of the material if present in excessive amounts. The detrimental effect of oxygen content on the impact toughness of the material has resulted in HIPed specifications, both existing and under development, with limits on the oxygen content in the material. Many specify a relatively low limit on oxygen content at e.g. 120 ppm which can have adverse effects on yield in powder manufacturing which might increase costs without accomplishing the desired effect of ensuring sufficient toughness. As this study show, oxygen content and chemistry alone is not enough to describe the effect of oxygen content on the HIPed material. Setting a limit at e.g. 120 ppm will not guarantee that one gets better properties or even reaches the desired properties of the material. The study show it is important where the oxygen is located in the powder and to separate bulk oxygen content and the surface oxygen content, where the latter has a more pronounced effect on toughness. In the study four batches of alloy 625 have been investigated, all with only relatively small variations in oxygen content but with drastically different toughness and differences in how oxygen is distributed in the material. Introduction Powder Metallurgical (PM) materials are sensitive to oxygen due to the large surface area of the fine powder. In some PM processes e.g. press & sinter and Metal Injection Molding, oxygen content can be reduced in sintering by performing it in hydrogen. However, when consolidating the material using Hot Isostatic Pressing (HIP) the consolidation occurs with vacuum the capsule which has little or no effect on the oxygen content. Therefore, oxygen control throughout the manufacturing process is important as any adsorbed oxygen cannot be removed in the later stages of manufacturing. Other studies have investigated the influence of oxygen on mechanical properties on HIPed austenitic and duplex stainless steel. In general the studies show a correlation between oxygen content and impact toughness, especially at lower temperatures [16]. Usually it is toughness that is reduced by excessive oxygen in the material but also welding properties of the material can be affected. Currently there are few material specifications on HIPed material and most that exist are project or product specific. There are a few specifications and standards covering PM HIP material e.g. ASTM (A988, A989 and B834), ASME code cases (N-834 and 2840) as well a mention in API 6A. However, more specs are in the works and many of them specify maximum oxygen content in the material. There is a trend to set lower and lower maximum allowable oxygen content which in turn can have a n","PeriodicalId":202011,"journal":{"name":"Hot Isostatic Pressing: HIP’17","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122070992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Overview of Properties, Features and Developments of PM HIP 316L and 316LN","authors":"Martin Östlund, T. Berglund","doi":"10.21741/9781644900031-17","DOIUrl":"https://doi.org/10.21741/9781644900031-17","url":null,"abstract":"PM HIP 316L is an alloy that is of increased intere st for nuclear applications since its recent ASME code case approval. Over the years, com prehensive data and understanding of the properties and features have been collected and evaluated which will be summarized in this article. Since the early developments of the P M HIP technology it has been observed that PM HIP alloys generally exhibit higher yield streng ths compared to their conventional counterparts, a feature that applies well for 316L. In this article this is demonstrated, both by using the Hall-Petch relationship as well as Picker ing ́s and Irvine ́s empirically derived relationship between composition and grain size for austenitic stainless steels. Furthermore, a mechanism generating the increased yield strength i n PM HIP 316L vs conventionally manufactured 316L will be proposed. Results also sh ow t at low oxygen contents itself is not a guarantee for good or increased performance in fo rm of mechanical properties, but that there are other features that is of similar or perhaps ev en higher importance in order to achieve good properties. The results of this article includ e microstructural properties derived from EBSD measurements as well as tensile and impact pro perties in a wide range of test temperatures of PM HIP 316L from several powder bat ches manufactured at different locations and processed with various HIP and heat t r ment procedures. Finally, some results regarding creep properties of PM HIP 316L is presen ted. Introduction Austenitic stainless steel 316L is one of the most c mmonly known and used stainless steel grades and the performance and properties of this a lloy in different product forms is well known. Powder Metallurgical manufacturing via Gas A tomization and Hot Isostatic Pressing is a manufacturing technology known to generate iso tropic microstructures, high cleanliness and often improved mechanical properties. In light of he recent ASME code case approval for PM HIP 316L [1], the properties of this alloy v ia this manufacturing process has become of increasing interest [2-4]. This article will giv e an overview of the properties of PM HIP 316L/316LN, how properties can be affected by varyi ng manufacturing process parameters and compare how they differ from the conventionally manufactured counterparts. Microstructure One of the large benefits with PM HIP manufacturing s that the microstructures of the manufactured components are homogeneous, isotropic and have high cleanliness. All these features apply also for PM HIP 316L/316LN and trans l tes into excellent ultrasonic inspectability [4]. Regarding cleanliness, the clea r majority of the non-metallic inclusions found in PM HIP 316L/316LN are well below 2.8 μm in size and are predominately constituted by oxides [2,3]. The oxides can origina te either from the melt which are later trapped within the powder particles (bulk oxides) o r fr m the surface oxide layer and oxide","PeriodicalId":202011,"journal":{"name":"Hot Isostatic Pressing: HIP’17","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128864609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}