Cold Spray Deposition of Heat-Treated Inconel 718 Powders

Author(s):  
Lorena Perez ◽  
Jake Colburn ◽  
Luke N. Brewer ◽  
Michael Renfro ◽  
Tim McKechnie

Abstract In this work; Inconel 718 gas-atomized powder was successfully heat treated over the range of 700-900°C. As-atomized and as-heat treated powders were cold sprayed with both nitrogen and helium gasses. Cold spray of high strength materials is still challenging due to their resistance to particle deformation affecting the resulting deposit properties. Powder heat treatment to modify its deformation behavior has recently been developed for aluminum alloy powders; however; there is no literature reported for Inconel 718 powders. The microstructural evolution of the powder induced by the heat treatment was studied and correlated with their deformation behavior during the cold spray deposition. Deposits sprayed with heat-treated powders at 800 and 900 °C and nitrogen showed less particle deformation and higher porosity as compare to as-atomized deposit associated to the presence of delta phase in the powders precipitated by the heat treatment. In contrast; deposits sprayed with helium using both powder conditions; as-atomized and as heat-treated powders; showed high particle deformation and low porosity indicating that the type of gas has a greater effect on the particle deformation than the delta phase precipitated in the heat-treated powders. These results contribute to understanding the role of powder microstructure evolution induced by heat treatment on the cold spray deposits properties.

Author(s):  
L. S. Lin ◽  
C. C. Law

Inconel 718, a precipitation hardenable nickel-base alloy, is a versatile high strength, weldable wrought alloy that is used in the gas turbine industry for components operated at temperatures up to about 1300°F. The nominal chemical composition is 0.6A1-0.9Ti-19.OCr-18.0Fe-3Mo-5.2(Cb + Ta)- 0.1C with the balance Ni (in weight percentage). The physical metallurgy of IN 718 has been the subject of a number of investigations and it is now established that hardening is due, primarily, to the formation of metastable, disc-shaped γ" an ordered body-centered tetragonal structure (DO2 2 type superlattice).


2020 ◽  
Vol 405 ◽  
pp. 133-138
Author(s):  
Ludmila Kučerová ◽  
Andrea Jandová ◽  
Ivana Zetková

Maraging steel is an iron-nickel steel alloy, which achieves very good material properties like high toughness, hardness, good weldability, high strength and dimensional stability during heat treatment. In this work, maraging steel 18Ni-300 was manufactured by selective laser melting. It is a method of additive manufacturing (AM) technology, which produces prototypes and functional parts. Sample of additively manufactured and conventional steel with the same chemical composition were tested after in three different states – heat treated (as-built/as-received), solution annealed and precipitation hardened. Resulting microstructures were analysed by light and scanning electron microscopy and mechanical properties were obtained by hardness measurement and tensile test. Cellular martensitic microstructures were observed in additively manufactured samples and conventional maraging steel consisted of lath martensitic microstructures. Very similar mechanical properties were obtained for both steels after the application of the same heat treatment. Ultimate tensile strengths reached 839 – 900 MPa for samples without heat treatment and heat treated by solution annealing, the samples after precipitation hardening had tensile strengths of 1577 – 1711 MPa.


Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1275 ◽  
Author(s):  
Yanjie Mou ◽  
Zhichao Li ◽  
Xiaoteng Zhang ◽  
Devesh Misra ◽  
Lianfang He ◽  
...  

High strength/high elongation continues to be the primary challenge and focus for medium-Mn steels. It is elucidated herein via critical experimental analysis that the cumulative contribution of transformation-induced plasticity (TRIP) and microstructural constituents governs high strength/high elongation in 0.2C–3Al–(6–8.5)Mn–Fe steels. This was enabled by an effective heat treatment involving a combination of intercritical hardening and tempering to obtain high strength/high ductility. An excellent combination of high ultimate tensile strength of 935–1112 MPa and total elongation of 35–40% was obtained when the steels were subjected to intercritical hardening in the temperature range of 700–750 °C and low tempering at 200 °C. The intercritical hardening impacted the coexistence of austenite, ferrite, and martensite, such that the deformation behavior varied with the Mn content. The excellent obtained properties of the steels are attributed to the cumulative contribution of the enhanced TRIP effect of austenite and the microstructural constituents, ferrite and martensite. The discontinuous TRIP effect during deformation involved stress relaxation, which was responsible for the high ductility. Lamellar austenite, unlike the equiaxed microstructure, is envisaged to induce stress relaxation during martensitic transformation, resulting in the discontinuous TRIP effect.


2009 ◽  
Vol 633-634 ◽  
pp. 707-715 ◽  
Author(s):  
Julia Lyubimova ◽  
Jens Freudenberger ◽  
Alexandere Gaganov ◽  
Hansjörg Klauss ◽  
Ludwig Schultz

Recovery, recrystallisation and grain growth processes as well as the formation of a solid solution and the phase separation of a homogeneous material into a heterogeneous one are observed for Cu-Ag-Zr alloys heat-treated at different temperatures by means of mechanical, electrical and microstructural analyses. Heat treatments are shown to be an effective tool to enhance the strain to failure. If applied between several deformation steps the heat treatment causes an increase of both strain and strength limits.


2012 ◽  
Vol 192-193 ◽  
pp. 556-561 ◽  
Author(s):  
Qiang Zhu ◽  
Stephen Midson ◽  
Chang Wei Ming ◽  
Helen V. Atkinson

Commercial semi-solid cast impellers are produced from Al-Si-Cu alloys heat treated to the T6 temper. The study described in this paper involved the identification of casting and heat treatment parameters to produce semi-solid processed turbocharger impellers from a silicon-free, higher strength 201 alloy. Casting parameters were identified which minimized hot tearing in the alloy 201 impellers. A series of heat treatment studies were performed to determine optimum heat treatment parameters. The T71 temper was identified as the preferred heat treatment condition to produce high strength as well as superior elongation. The results from mechanical property measurements conducted on the T71 heat treated impellers are reported. Optical and scanning electron microscopy (SEM) were also used to characterize the microstructure of alloy 201 impellers before and after heat treatment, and representative microstructures are presented.


2013 ◽  
Vol 376 ◽  
pp. 153-157 ◽  
Author(s):  
Jong Su Ha ◽  
Sun Ig Hong

In this study Cu-Ag or Cu-Cr layer was sandwiched by Ti and Fe plates and the three layers of Ti/Cu-8Ag/S20C were clad by High Pressure Torsioning(HPT). The effect of post-HPT heat treatment on the interfacial reaction products and the mechanical performance in Ti/Cu-Ag/S20C and Ti/Cu-Cr/S20C clad material were studied. Cu4Ti3 and Cu4Ti Intremetallic compound layers were observed at the Ti/Cu-Ag and Ti/Cu-Cr interfaces in the clad heat-treated at 500°C where as no intermetallic compounds were observed at the Cu-Ag/S20C and Cu-Cr/S20C interfaces. The strength of as-HPTed Ti/Cu-8Ag/S20C is much higher than that of Ti/Cu-1Cr/S20C. The strengthening mechanism of Cu-Ag deformed severely is the interface and strain hardening in which dislocations are deposited at the Cu/Ag interfaces and can contribute to the strengthening of the clad composite just after HPT processing, rendering the high strength just after processing. In both clad composites, the strength and ductility increased after heat treatment at 350°C, which are likely caused by the enhanced bonding at the interfaces.


Author(s):  
Yachao Wang ◽  
Jing Shi

Graphene is an ideal reinforcement material for metal matrix composites (MMC) owing to its high strength, high ductility, light weight, as well as good bonding with metal matrix. Additive manufacturing such as selective laser melting (SLM) brings the advantages of low material waste, high flexibility, and short production lead cycle. In this study, graphene nano-platelets (GNPs) reinforced Inconel 718 composites are fabricated by SLM technique and processed under various post heat treatment schemes. It is found that fabrication of GNPs reinforced MMC using SLM technique is a viable approach. The obtained composite possesses dense microstructure and enhanced tensile strength. Post heat treatments at two levels of solution temperature (980 and 1220°C) for 1 hour followed by two-step aging are carried out. The experiment results indicate that addition of GNPs into Inconel 718 matrix results in significant strength improvement. At as-built condition, the ultimate tensile strengths are 997 and 1447 MPa, respectively at 0 and 4.4vol.% GNP content. Moreover, under as-built and solution treated condition, high content of GNPs results in overall higher UTS value and the strengthening effect is most significant at as-built condition. Meanwhile, γ′ and γ″ precipitation hardening is suppressed in the GNPs reinforced composite under aged condition due to the formation of MC carbide and depletion of Nb. Incorporating GNPs in Inconel 718 effectively inhibits the grain growth during post heat treatment.


Coatings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 348 ◽  
Author(s):  
Heli Koivuluoto ◽  
Jussi Larjo ◽  
Danilo Marini ◽  
Giovanni Pulci ◽  
Francesco Marra

Process optimization and quality control are important issues in cold spraying and coating development. Because the cold spray processing is based on high kinetic energy by high particle velocities, online spray monitoring of particle inflight properties can be used as an assisting process tool. Particle velocities, their positions in the spray jet, and particle size measurements give valuable information about spraying conditions. This, in turn, improves reproducibility and reliability of coating production. This study focuses on cold spraying of Al6061 material and the connections between particle inflight properties and coating characteristics such as structures and mechanical properties. Furthermore, novel 2D velocity scan maps done with the HW CS2 online spray monitoring system are presented as an advantageous powder and spray condition controlling tool. Cold spray processing conditions were similar using different process parameters, confirmed with the online spray monitoring prior to coating production. Higher particle velocities led to higher particle deformation and thus, higher coating quality, denser structures, and improved adhesions. Also, deposition efficiency increased significantly by using higher particle velocities.


2019 ◽  
Vol 969 ◽  
pp. 205-210 ◽  
Author(s):  
D. Venkateswarlu ◽  
Muralimohan Cheepu ◽  
P. Nageswara Rao ◽  
S. Senthil Kumaran ◽  
Narayanan Srinivasan

In the present study, aluminum alloy 2219 of two different heat treatment states were selected and welded using the friction stir welding process to evaluate the effect substrate on the joint properties. The microstructural observations have exhibited the difference in their characteristics between two heat treatment conditions of 2219-O and T6 conditions. The tensile strength of the AA2219-T6 joints much higher than the AA2219-O joints. Consequently, the microhardness distribution across the different zones varying with two different heat treated conditions. The failure locations and fracture surface features are revealed the significant differences among these two heat treated conditions with the change in their failure location and the fracture morphologies. The optimal welding conditions were analyzed to determine the high strength of the welds with excellent metallurgical properties of the welds.


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