Effect of grain-boundary characteristics on castability of nickel-base superalloys

Zhang, Jian; Singer, Robert F.

doi:10.1007/s11661-004-0018-7

Cited by 49 publications

(29 citation statements)

References 14 publications

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“…1 12 It should be emphasized that the material and geometry of the alumina tubes used as molds are exactly the same in the present work as in our earlier work, 12 i.e., the tube-like castings have exactly the same inner and outer diameters as well as wall thickness in both works. The only difference is that the inner alumina is placed at a higher position in the present work, and this change in the test set-up does not influence the level of hot tearing, as will be seen later.…”

Section: A Castability Testsmentioning

confidence: 53%

“…SC seeds from superalloy CMSX-4 and PWA1483 were used to initiate the development of CMSX-4 and IN792 SC or BC tube castings, respectively. In our previous work, 12 it was reported that PWA1483 seeds do not influence the nominal composition of IN792 after casting because PWA1483 is the SC equivalent of IN792 having almost the same composition except the minor elements such as B and Zr.…”

Section: A Castability Testsmentioning

confidence: 94%

“…The aim of the present work was to explore the hot tearing susceptibility of high-refractory superalloy CMSX-4 as a function of the GB misorientation in a similar vein as in Ref. 12. The comparison of CMSX-4 and IN792 is helpful in understanding the hot tearing performances in both alloys.…”

Section: Introductionmentioning

confidence: 92%

“…In our previous work, 12 the effects of GB misorientation on castability were examined by casting SC and bi-crystal (BC) samples. It was found that the hot tearing susceptibility of DS superalloy IN792 is a function of the GB misorientation, i.e., the hot tearing tendency of the alloy increases with increasing GB misorientation.…”

Section: Introductionmentioning

confidence: 99%

“…Superalloy CM247 was chosen as a reference material in our previous works 12,14,15 because of its well-known good castability. The microstructural characteristics of this alloy are recalled in the present work to obtain better insight into the relationship between the microstructural parameters and castability.…”

Section: Introductionmentioning

confidence: 99%

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Effect of grain boundary characteristics on hot tearing in directional solidification of superalloys

2006

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The effect of grain boundary (GB) misorientation on hot tearing susceptibility of directionally solidified (DS) nickel-based superalloys was explored. We found that the castability of second generation nickel-based superalloy CMSX-4 is inferior to DS superalloy IN792, an alloy well known for bad castability. The castability of CMSX-4 is somewhat improved at a higher solidification rate. The hot tearing tendency increases with increasing GB misorientation angle. As feeding tendency becomes greater with increasing misorientation, this points to the importance of GB cohesion for solidification cracking in the alloy. Microstructure investigation reveals that hot tearing is associated with formation of continuous gamma and gamma prime eutectic films at the GB in CMSX-4. We assume that the gamma and gamma prime eutectic, which reflects the remaining liquid at the end of solidification, prevents the impinging dendrite arms from touching and in this way decreases cohesion.

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Section: A Castability Testsmentioning

confidence: 53%

Section: A Castability Testsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of grain boundary characteristics on hot tearing in directional solidification of superalloys

2006

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Laser Powder Bed Fabrication of Nickel‐Base Superalloys: Influence of Parameters; Characterisation, Quantification and Mitigation of Cracking

2012

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The use of a selective laser melting (SLM) powder-bed method to manufacture Ni-based superalloys components provides an economic approach for low production run components that operate under a high-temperature and stress environment. A major concern with the SLM of precipitation hardenable Ni-based superalloys is their high susceptibility to cracking, which has been heavily documented in the field of welding. Weld cracking may occur either during processing (hot cracking, liquation cracking and ductility-dip cracking) or during the post weld heat-treatment stage (strain-age cracking). Due to the complex thermal history of SLM fabricated material there is the potential for all of these mechanisms to be active.In this investigation, cuboidal coupons of the Ni-based superalloy CM247LC were fabricated by the SLM of argon gas atomised powder. Parametric studies were performed to investigate the influence of the process parameters (laser scan speed, power and scan spacing) on the cracking density and morphology through conducting a stereological study of scanning electron microscope (SEM) micrographs. Further microstructural evidence is presented, illustrating the different crack morphologies observed as well as suggesting the responsible mechanisms. Finally a postfabrication Hot Isostatic Pressing (HIP) treatment was performed to investigate its utility in 'healing' the internal cracks, and providing a route to retro-fix the cracking problem in the heat treatment stage of production. The findings highlight the need for process models of the SLM method in order to understand the thermal history and the laser fabricated structures observed.

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Crack‐Free Welding of a Co‐Base Superalloy with High γ' Precipitate Fraction

et al. 2022

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Laser cladding of superalloys provides an attractive and cost‐efficient technique for near‐net shape manufacturing, remanufacturing, or individualized repair of components. While the weldability of γ' hardened Ni‐base superalloys is limited, Co‐base superalloys should have a lower susceptibility for cracking during welding due to a lower γ' solvus temperature and less segregation than Ni‐base superalloys. The weldability of the Co‐base superalloy CoWAlloy2Mod and the resulting mechanical properties at 950 °C are investigated. In the as‐welded condition of CoWAlloy2Mod, a fine dendritic microstructure without forming cracks and limited porosity is found. After a three‐step heat treatment, recrystallized, equiaxed grains and a high γ' volume fraction are obtained leading to a very good strength. CoWAlloy2Mod shows a significantly higher strength and creep strength than the conventional weld filler Co‐alloy PWA795.

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Effect of grain-boundary characteristics on castability of nickel-base superalloys

Cited by 49 publications

References 14 publications

Effect of grain boundary characteristics on hot tearing in directional solidification of superalloys

Effect of grain boundary characteristics on hot tearing in directional solidification of superalloys

Laser Powder Bed Fabrication of Nickel‐Base Superalloys: Influence of Parameters; Characterisation, Quantification and Mitigation of Cracking

Crack‐Free Welding of a Co‐Base Superalloy with High γ' Precipitate Fraction

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