Development of Hot Isostatic Pressing Technology for Investment Cast Products

2015 ◽  
Vol 830-831 ◽  
pp. 19-22
Author(s):  
S. Dineshraj ◽  
Mayukh Acharya ◽  
Alok Agarwal ◽  
S. Girikumar ◽  
Govind ◽  
...  
Keyword(s):  
Hot Isostatic Pressing ◽  
Microstructural Analysis ◽  
Quality Requirements ◽  
Isostatic Pressing ◽  
Defect Healing ◽  
Aerospace Applications ◽  
Before And After ◽  
Steel Cast ◽  
Stringent Quality ◽  
Pressing Technology

Hot isostatic pressing (HIPping) technology is used for healing the casting defects for aerospace applications. Castings used for aerospace applications like turbo-pumps need to meet very stringent quality requirements. Complexity of the castings used in these applications, makes it difficult to meet the quality requirements in all the areas. Defects like gas holes, shrinkages, cavities etc. may occur in few locations and need to be repaired by welding or healed by HIPping. In the present study, we attempted to simulate the defect healing capability of HIP in a systematic manner. Artificial defects were created in Austenite-Martensite grade stainless steel cast rod. These rods were then subjected to HIP prcoss cycle at 1150 °C and at a pressure of 1620 bar. Healing of the defects was ensured through X-ray radiography. Detailed microstructural analysis using optical metallography and scanning electron microscopy (SEM) with EDX was carried out before and after HIPping, to understand the defect healing mechanisms. These results are discussed in detail here.

scholarly journals Study on the Hot Deformation Characterization of Borated Stainless Steel by Hot Isostatic Pressing

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7110
Author(s):  
Yanbin Pei ◽  
Xuanhui Qu ◽  
Qilu Ge ◽  
Tiejun Wang
Keyword(s):  
Stainless Steel ◽  
Hot Deformation ◽  
True Strain ◽  
Hot Isostatic Pressing ◽  
Microstructural Analysis ◽  
Critical Conditions ◽  
True Strain Rate ◽  
Isostatic Pressing ◽  
Different Temperatures ◽  
Borated Stainless Steel

Borated stainless steel (BSS) specimens have a boron content of 1.86 wt%, and are prepared by hot isostatic pressing (HIP) conducted at different temperatures, ranging from 1000 to 1100 °C and a constant true strain rate (0.01, 0.1, 1 and 10 s−1). These tests, with observations and microstructural analysis, have achieved the hot deformation characteristics and mechanisms of BSS. In this research, the activation energy (Q) and Zener–Hollomon parameter (Z) were contrasted against the flow curves: Q = 442.35 kJ/mol. The critical conditions associated with the initiation of dynamic recrystallization (DRX) for BSS were precisely calculated based on the function between the strain hardening rate with the flow stress: at different temperatures from 1000 to 1100 °C: the critical stresses were 146.69–254.77 MPa and the critical strains were 0.022–0.044. The facts show that the boron-containing phase of BSS prevented the onset of DRX, despite the saturated boron in the austenite initiated DRX. The microstructural analysis showed that hot deformation promoted the generation of borides, which differed from the initial microstructure of HIP. The inhomogeneous distribution of elements in the boron-containing phase was caused by hot compression.

scholarly journals Encapsulation of Electron Beam Melting Produced Alloy 718 to Reduce Surface Connected Defects by Hot Isostatic Pressing

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1226 ◽  
Author(s):  
Yunus Emre Zafer ◽  
Sneha Goel ◽  
Ashish Ganvir ◽  
Anton Jansson ◽  
Shrikant Joshi
Keyword(s):  
Electron Beam ◽  
Electron Beam Melting ◽  
Surface Defects ◽  
High Surface ◽  
Hot Isostatic Pressing ◽  
Coated Sample ◽  
Alloy 718 ◽  
Isostatic Pressing ◽  
Before And After ◽  
X Ray Computed

Defects in electron beam melting (EBM) manufactured Alloy 718 are inevitable to some extent, and are of concern as they can degrade mechanical properties of the material. Therefore, EBM-manufactured Alloy 718 is typically subjected to post-treatment to improve the properties of the as-built material. Although hot isostatic pressing (HIPing) is usually employed to close the defects, it is widely known that HIPing cannot close open-to-surface defects. Therefore, in this work, a hypothesis is formulated that if the surface of the EBM-manufactured specimen is suitably coated to encapsulate the EBM-manufactured specimen, then HIPing can be effective in healing such surface-connected defects. The EBM-manufactured Alloy 718 specimens were coated by high-velocity air fuel (HVAF) spraying using Alloy 718 powder prior to HIPing to evaluate the above approach. X-ray computed tomography (XCT) analysis of the defects in the same coated sample before and after HIPing showed that some of the defects connected to the EBM specimen surface were effectively encapsulated by the coating, as they were closed after HIPing. However, some of these surface-connected defects were retained. The reason for such remnant defects is attributed to the presence of interconnected pathways between the ambient and the original as-built surface of the EBM specimen, as the specimens were not coated on all sides. These pathways were also exaggerated by the high surface roughness of the EBM material and could have provided an additional path for argon infiltration, apart from the uncoated sides, thereby hindering complete densification of the specimen during HIPing.

scholarly journals Trends in hot isostatic pressing technology.

1991 ◽  
Vol 38 (1) ◽  
pp. 16-22
Author(s):  
Katsuhiro Uehara ◽  
Kazuhiko Nakajima
Keyword(s):  
Hot Isostatic Pressing ◽  
Isostatic Pressing ◽  
Pressing Technology

scholarly journals Study of Microstructure Features and Properties of Metals Obtained by Hot Isostatic Pressing

2021 ◽  
Vol 24 (4) ◽  
pp. 4-10
Author(s):  
A.A. Khlybov ◽  
D.A. Ryabov ◽  
M.S. Anosov ◽  
E.S. Belyaev
Keyword(s):  
Fractal Dimension ◽  
Relative Density ◽  
Metal Powder ◽  
Hot Isostatic Pressing ◽  
Microstructural Analysis ◽  
Fractal Dimensionality ◽  
Spherical Particles ◽  
Metal Powders ◽  
Isostatic Pressing ◽  
Different Temperatures

The aim of this research is to study the features of the structure and properties of alloys obtained using the technology of hot isostatic pressing (HIP) of metal powders. The study was carried out in the temperature range of interruption of the HIP cycle from 670 to 1150 °C on alloys 08Cr18Ni10Ti and Cr12MoV. For processing images of microstructures and assessing their fractal dimension, software has been developed in the MATLAB environment. The results of microstructural analysis of the metals under study showed that complete sintering of powders is observed at a HIP temperature of 1150 °C; at lower temperatures, pores and unsintered spherical particles of metal powder are observed in the microstructure of the alloys. The grain size of alloys obtained by HIP is determined, first of all, by the size of the initial fraction of the metal powder. Based on the results of evaluating the density of alloys obtained at different temperatures of the HIP, a relationship was established between the relative density of the alloy and the process temperature. Based on the results of fractal analysis, the relationship between the fractal dimensionality of the microstructure of the alloy and the HIP temperature and the relative density of the metals under study has been established. The obtained dependences are linear. The error in estimating the relative density from the obtained dependencies is, on average, 5 %. The data obtained in the course of the study make it possible to estimate the density of metals obtained by hot isostatic pressing of metal powders by evaluating the fractal dimension of the microstructure image.

Fabrication of BN-AlN-TiB2 Compound Conductive Ceramics by Self-Propagating High Temperature Synthesis and Hot Isostatic Pressing

2007 ◽  
Vol 336-338 ◽  
pp. 786-789 ◽  
Author(s):  
Li Juan Zhou ◽  
Yong Ting Zheng ◽  
Shan Yi Du
Keyword(s):  
High Temperature ◽  
Composition Dependence ◽  
Bending Strength ◽  
Hot Isostatic Pressing ◽  
Microstructural Analysis ◽  
Temperature Synthesis ◽  
Powder Mixtures ◽  
Isostatic Pressing ◽  
High Temperature Synthesis ◽  
Conductive Ceramics

BN-AlN-TiB2 compound conductive ceramics from powder mixtures of BN, Al, and TiB2 was fabricated by self-propagating high temperature synthesis (SHS) and hot isostatic pressing (HIP). The powder mixtures were shaped by isostatic cool pressing at 5-10MPa and the combustion reaction was carried at 100-200 MPa N2 by an ignitor. XRD experiments confirmed that the reaction was complete and only AlN, BN and TiB2 were detected. Optical microscopy as well as SEM with an electron probe microanalysis was used for microstructural analysis and revealed a relatively uniform distribution of particulates. The temperature-dependence and composition-dependence of the electrical resistivity of BN-AlN-TiB2 ceramics were studied. The results showed that the optimum composition was 5-10wt% BN, 30-55wt% Al and 60-40wt% TiB2, and the products had the density of 90% of the theoretical, resistivity of 80-1000 μ⋅cm and bending strength of 100-200 MPa.

scholarly journals On the Hot Isostatic Pressing of Inconel 625 Structures built using Laser Powder Bed Fusion at Higher Layer Thickness

2021 ◽  
Author(s):  
Saurav Kumar Nayak ◽  
Arackal Narayanan Jinoop ◽  
Christ Prakash Paul ◽  
Vesangi Anil Kumar ◽  
Dineshraj Subburaj ◽  
...  
Keyword(s):  
Layer Thickness ◽  
Volume Fraction ◽  
Hot Isostatic Pressing ◽  
Microstructural Analysis ◽  
Inconel 625 ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Isostatic Pressing ◽  
Elemental Segregation

Abstract This paper reports the effect of Hot Isostatic Pressing (HIPing) on the porosity, microstructure and mechanical properties of Laser Powder Bed Fusion (LPBF) IN625 structures built at a higher layer thickness of 100 µm. It is observed that the process-induced pores/voids of volume fraction (Vf) 0.43% in as-built IN625 structures are reduced significantly to ~ 0.01% after HIPing treatment. The microstructure is changed from fine columnar dendrites to coarse equiaxed dendrites. The microstructural analysis of as-built structures reveals the presence of cellular/ dendritic growth along with elemental segregation of Nb, Si and C and precipitation of Nb-rich carbides. Whereas, coarse recrystallized microstructure along with elemental segregation of Si and precipitation of Nb, Mo and Cr rich carbides are observed in Hot Isostatic Pressed (HIPed) samples. HIPed structures exhibit lower tensile s trength, higher ductility, and lower anisotropy as compared to LPBF built structures. There is a reduction in the Vickers micro-hardness of IN625 samples after HIPing and the values are observed to be similar to their conventional counterparts. Further, an increase in the energy storage capacity of the material is observed after HIPing treatment through Automated Ball Indentation (ABI®) studies. The study paves a way to develop ~100% dense, defect-free and isotropic engineering components using LPBF.

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