Thermomechanical behavior of advanced manufactured heat-resistant alloys and their weldments

This work investigates the impacts of additive manufacturing (AM), explosion welding (EXW) cladding, and subsequent arc welding on the performance of a selected group of heat-resistant alloys under service conditions of generation 3 concentrated solar power (Gen3 CSP) systems. The performance aspects investigated include isothermal low cycle fatigue (LCF), corrosion resistance, and elevated temperature strength. The data generated in this work plays a pivotal role in de-risking Gen3 CSP systems by identifying and validating suitable alloys for various subcomponents. The findings provide essential performance metrics critical for accurate component design and service life predictions under the demanding conditions of Gen3 CSP applications. The isothermal LCF behavior of Haynes 282 (H282) was evaluated under four material conditions: wrought, AM, and gas tungsten arc weldments (GTAW) of both. LCF testing at 750°C across four strain ranges (0.6-1.2%) revealed shorter fatigue lives in AM samples compared to wrought ones. Welded specimens exhibited greater data scatter and most failures occurred within the fusion zone. The fatigue performance was similar in welded AM and welded wrought, regardless of the presence of minor weld defects. The corrosion behavior of AM-to-wrought welded coupons for H282 and IN740H was examined in molten chloride salt (MgCl₂–KCl–NaCl) at 750°C for 100 hours. Laser powder bed fusion (LPBF) and wire-fed electron beam additive manufacturing (EBAM) processes introduced unique microstructures affecting corrosion resistance. While no significant difference was observed in corrosion rates between AM and wrought materials of H282 and IN740H, the alloys displayed different corrosion mechanisms. H282 showed more surface oxidation and intergranular attack, whereas IN740H exhibited internal nitridation and more uniform corrosion. EBAM-to-wrought H282 welds showed the highest corrosion rate due to elevated iron content, reduced Al content and different grain morphology. Explosion welding (EXW) cladding was explored as a cost-effective method for molten salt pipes, using C22 and Ni201 clads on 304H and Grade 91 backers. The EXW process produced defect-free metallurgical bonds with minimal interdiffusion. Elevated temperature tensile testing of transverse weld samples revealed better mechanical performance of the 304H-C22 clad couple than the others. Severe grain coarsening and microcracks were observed in the Ni201 clad heat affected zone and fusion boundary, respectively, limiting the mechanical properties of the cladded components.

Name thesis:degree_name

Doctor of Philosophy (Ph.D.)

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Metallurgical and Materials Engineering

Grantor dc:publisher

Colorado School of Mines. Arthur Lakes Library

Year dc:date.issued

2024

Author dc:creator

• Abdelmotagaly, Abdelrahman

Advisor dc:contributor.advisor

• Yu, Zhenzhen

Committee members dc:contributor.committeemember

• Gockel, Joy
• Findley, Kip Owen
• Vidal, Judith

• additive manufacturing
• concentrated solar power
• corrosion
• explosion welding cladding
• low cycle fatigue
• welding

Statement dc:rights

• Copyright of the original work is retained by the author.

Language dc:language.iso

eng, English

Dc Identifier Other

T 9923

OAI identifier oai:identifier

oai:repository.mines.edu:11124/180337