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<p>High-temperature vacuum brazing is recognized as an effective method for making homogeneous joints in multi-component heat-resistant nickel alloys, particularly those with high-chromium content, which are prone to hot cracking during welding and heat treatment. This study focuses on overcoming these challenges by Ni–Cr-Co-(Ti, Al, Ta)-Si-B filler metals with varying silicon content and evaluating the structural characteristics and long-term strength of brazed joints in the high-chromium heat-resistant nickel alloy SM88U-VI. The research examined how silicon content influences the solidus and liquidus temperatures of the filler metal. Micro-X-ray analysis revealed that increasing the silicon content reduces the formation of needle-like boride phases, while promoting the formation of nickel silicides and a eutectic structure, which in turn enhances the microhardness of the joint. Initially, the brazed joints exhibited a microhardness of HV 550–600, exceeding that of the base metal. A combination of brazing and heat treatment improved the homogeneity of the joint, reducing microhardness to 450–500 HV. The results of tests for long-term strength at elevated temperatures (900&#xa0;°C) of brazed joints from the SM88 alloy obtained by vacuum brazing using Ni–Cr-Co-(Ti, Al, Ta)-(5…6)Si-B brazing filler metal showed good performance for 114&#xa0;h at a load of 140&#xa0;MPa while maintaining structural integrity.</p>

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Brazing of heat-resistant nickel alloy SM88-VI

  • 期刊论文

  • 发表日期：

    2025年7月8日

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  • Svitlana Maksymova,
  • Vitalii Voronov,
  • Petro Kovalchuk,
  • Oleksii Malyi

摘要

High-temperature vacuum brazing is recognized as an effective method for making homogeneous joints in multi-component heat-resistant nickel alloys, particularly those with high-chromium content, which are prone to hot cracking during welding and heat treatment. This study focuses on overcoming these challenges by Ni–Cr-Co-(Ti, Al, Ta)-Si-B filler metals with varying silicon content and evaluating the structural characteristics and long-term strength of brazed joints in the high-chromium heat-resistant nickel alloy SM88U-VI. The research examined how silicon content influences the solidus and liquidus temperatures of the filler metal. Micro-X-ray analysis revealed that increasing the silicon content reduces the formation of needle-like boride phases, while promoting the formation of nickel silicides and a eutectic structure, which in turn enhances the microhardness of the joint. Initially, the brazed joints exhibited a microhardness of HV 550–600, exceeding that of the base metal. A combination of brazing and heat treatment improved the homogeneity of the joint, reducing microhardness to 450–500 HV. The results of tests for long-term strength at elevated temperatures (900 °C) of brazed joints from the SM88 alloy obtained by vacuum brazing using Ni–Cr-Co-(Ti, Al, Ta)-(5…6)Si-B brazing filler metal showed good performance for 114 h at a load of 140 MPa while maintaining structural integrity.