scholarly journals Effects of Pressure on Microstructure and Residual Stresses during Hot Isostatic Pressing Post Treatment of AISI M50 Produced by Laser Powder-Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 596
Author(s):  
Siyuan Qin ◽  
Simone Herzog ◽  
Anke Kaletsch ◽  
Christoph Broeckmann
Keyword(s):  
Residual Stresses ◽  
Microstructure Evolution ◽  
Thermal Stresses ◽  
Hot Isostatic Pressing ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
X Ray ◽  
Isostatic Pressing ◽  
Conventional Heat Treatment

Laser powder-bed fusion (LPBF) enables the production of difficult-to-machine materials with near-net shape and complex geometries. Components made of tool steels produced by LPBF, even using high preheating temperature, tend to show residual porosity, cracks, and high residual stresses. Hot isostatic pressing (HIP) is able to densify components and modify their microstructure. Moreover, compared to conventional heat treatment at ambient pressure, rapid cooling within the HIP vessel can alleviate thermal stresses, warping or cracking during quenching. In this study, the effects of isostatic pressure on microstructure evolution and residual stresses are investigated. Samples were produced by LPBF. Partly, they were conventionally heat treated by austenitizing, quenching, and tempering, partly using a HIP-device with an integrated quenching facility. The microstructure was characterized by optical microscopy, scanning electron microscopy employing energy-dispersive X-ray spectroscopy, and X-ray diffraction analysis. The results showed that besides the densification of the material to the porosity of 0.001%, HIP influenced the microstructure evolution by retarding recrystallization during austenitization due to the pressure and led to slight compressive residual stresses around 11 MPa on the surface of components.

Surface pick-up of argon during hot isostatic pressing of material built by laser powder bed fusion

2021 ◽  
Vol 38 ◽  
pp. 101763
Author(s):  
Emil Strandh ◽  
Pelle Mellin ◽  
Sophie Dubiez-Le Goff ◽  
Johannes Gårdstam ◽  
Magnus Ahlfors ◽  
...  
Keyword(s):  
Hot Isostatic Pressing ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Isostatic Pressing

Hot isostatic pressing of MRI compatible Zr-1Mo components manufactured by laser powder bed fusion

2020 ◽  
Vol 169 ◽  
pp. 110657
Author(s):  
Xiaohao Sun ◽  
Debao Liu ◽  
Minfang Chen ◽  
Weiwei Zhou ◽  
Naoyuki Nomura ◽  
...  
Keyword(s):  
Hot Isostatic Pressing ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Isostatic Pressing

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.

scholarly journals Structure and Properties of Ti/Ti64 Graded Material Manufactured by Laser Powder Bed Fusion

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6140
Author(s):  
Evgenii Borisov ◽  
Igor Polozov ◽  
Kirill Starikov ◽  
Anatoly Popovich ◽  
Vadim Sufiiarov
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Additive Manufacturing ◽  
Hot Isostatic Pressing ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Isostatic Pressing ◽  
Graded Material ◽  
Single Part

Multimaterial additive manufacturing is an attractive way of producing parts with improved functional properties by combining materials with different properties within a single part. Pure Ti provides a high ductility and an improved corrosion resistance, while the Ti64 alloy has a higher strength. The combination of these alloys within a single part using additive manufacturing can be used to produce advanced multimaterial components. This work explores the multimaterial Laser Powder Bed Fusion (L-PBF) of Ti/Ti64 graded material. The microstructure and mechanical properties of Ti/Ti64-graded samples fabricated by L-PBF with different geometries of the graded zones, as well as different effects of heat treatment and hot isostatic pressing on the microstructure of the bimetallic Ti/Ti64 samples, were investigated. The transition zone microstructure has a distinct character and does not undergo significant changes during heat treatment and hot isostatic pressing. The tensile tests of Ti/Ti64 samples showed that when the Ti64 zones were located along the sample, the ratio of cross-sections has a greater influence on the mechanical properties than their shape and location. The presented results of the investigation of the graded Ti/Ti64 samples allow tailoring properties for the possible applications of multimaterial parts.

scholarly journals The Effect of Hot Isostatic Pressing on Surface Integrity, Microstructure and Strength of Hybrid Metal Injection Moulding, and Laser-Based Powder Bed Fusion Stainless-Steel Components

2021 ◽  
Vol 11 (16) ◽  
pp. 7490
Author(s):  
Aldi Mehmeti ◽  
Donal Lynch ◽  
Pavel Penchev ◽  
Rafael Martinez Ramos ◽  
Denis Vincent ◽  
...  
Keyword(s):  
Surface Integrity ◽  
Injection Moulding ◽  
Hot Isostatic Pressing ◽  
Post Treatment ◽  
Powder Bed Fusion ◽  
Powder Bed ◽  
Isostatic Pressing ◽  
Treatment Techniques ◽  
Metal Injection Moulding ◽  
Conventional Heat Treatment

Hybrid manufacture of components by combining capabilities of replication and additive manufacturing processes offer a flexible and sustainable route for producing cost-effectively small batches of metal parts. At present, there are open issues related to surface integrity and performance of such parts, especially when utilising them in safety critical applications. The research presented in this paper investigates the ductility amplification of hybrid components produced using metal injection moulding to preform and then build on them customisable sections by laser-based powder bed fusion. The properties of such hybrid components are studied and optimised through the use of non-conventional post treatment techniques. In particular, hot isostatic pressing (HIP) is employed to improve mechanical strength and to produce hybrid components that have consistent properties across batches and throughout the samples, minimising microstructural heterogeneities between fabrication processes. Thus, the investigated post-processing method can offer an extended service life of hybrid components, especially when operating under severe conditions. The optimised post treatment was found to increase the hybrid components’ strength compared to as-built ones by 68% and ~11% in yield strength (YS) and ultimate tensile strength (UTS), respectively. Subsequently, leading to a great pitting resistance, thus, making HIP samples suitable for corrosive environments. The advantages of the HIP treatments in comparison to the conventional heat treatment of hybrid components are discussed and also some potential application areas are proposed.

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