Characteristics of Novel Nuclear-grade Nickel-based Brazing Filler and Microstructure and Properties of Brazed 316L Stainless Steel Joints

DING Huaibo; CHEN Jiacheng; CAI Quan

doi:10.3969/j.issn.1674-6457.2026.06.006

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Journal of Netshape Forming Engineering ›› 2026, Vol. 18 ›› Issue (6) : 56-65. DOI: 10.3969/j.issn.1674-6457.2026.06.006

Joining of New Materials and Dissimilar Materials

Characteristics of Novel Nuclear-grade Nickel-based Brazing Filler and Microstructure and Properties of Brazed 316L Stainless Steel Joints

DING Huaibo, CHEN Jiacheng^*, CAI Quan

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The work aims to design and fabricate a novel Ni-Cr-P-Ta brazing filler and evaluate its application potential in brazing nuclear-grade 316L stainless steel, so as to address the insufficient performance of brazed joints using nuclear-grade Ni-Cr-P filler in new fuel assembly. The Ni-12Cr-10P-4.4Ta filler powder was prepared by vacuum induction melting combined with argon gas atomization, and its morphology, composition, and melting characteristics were characterized by SEM, EDS, and DSC. Vacuum brazing of 316L stainless steel was conducted under different brazing temperature, holding times, and joint gap, followed by analysis of the joint microstructure, as well as the shear strength at room temperature and 350 ℃. The results showed that the filler powder exhibited an amorphous structure with uniform elemental distribution, and its solidus and liquidus temperature ranges from 883 ℃ to 958 ℃. After re-melting, the filler formed a eutectic structure consisting of Ni-based solid solution and (Ni, Cr)₃P, with Ta mainly distributed in the Ni-based solid solution. Under the optimal brazing condition (1 000 ℃, 50 min), (Ni, Cr, Fe)₂P and Ni-based solid solution were uniformly and alternately distributed in the brazed seam, achieving shear strengths of 74.8 MPa at room temperature and 61.9 MPa at 350 ℃. A narrow joint gap (10-30 μm) favored higher strength, whereas the strength decreased significantly when the gap reached 90 μm or above. The newly developed Ni-Cr-P-Ta brazing filler exhibits favorable melting characteristics and gap-filling ability, and sound joints with good mechanical properties can be obtained through process optimization. This study provides a material and process basis for enhancing the long-term service performance of brazed nuclear-grade stainless steel joints.

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brazing / Ni-based filler / microstructure / mechanical properties / nuclear-graded stainless steel

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DING Huaibo, CHEN Jiacheng, CAI Quan. Characteristics of Novel Nuclear-grade Nickel-based Brazing Filler and Microstructure and Properties of Brazed 316L Stainless Steel Joints[J]. Journal of Netshape Forming Engineering. 2026, 18(6): 56-65 https://doi.org/10.3969/j.issn.1674-6457.2026.06.006

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