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<p>High-speed steel is one of the most widely used materials in machining tools. However, applications, such as dry machining, demand properties superior to those of conventional tools. Plasma nitriding emerges as a promising surface treatment to enhance these properties. This study investigates the application of plasma nitriding, at temperatures of 300&#xa0;°C, 350&#xa0;°C, and 400&#xa0;°C, with a treatment time of 2&#xa0;h. Typically, nitriding temperatures (between 400 and 500&#xa0;°C) significantly increase surface roughness, which is detrimental to tool performance. The objective of using lower temperatures in this work was to mitigate this effect. Furthermore, the nitrogen concentration in the nitriding atmosphere was kept below 10% to ensure the formation of a layer without a compound zone, thereby promoting greater mechanical stability. The treatments were applied to N-type drills (diameter of 8&#xa0;mm) using a maximum power source of 3000 W. The samples were characterized by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) with Rietveld refinement, surface microhardness, microhardness profile, and average surface roughness (Ra) measurements. In addition, the performance of the treated tools was evaluated through simulation in a CNC machining center. This evaluation was based on the evolution of flank wear, the required electric current by the machine during cutting times, and the diameter and surface roughness of the machined holes. The results revealed that tools treated at 400&#xa0;°C exhibited 30% more flank wear compared to untreated tools, despite the observed surface hardening. Conversely, tools treated at lower temperatures demonstrated less flank wear than their untreated tools, suggesting that improved wear resistance is not solely dependent on surface hardness. Another significant finding was the enhancement in the dimensional quality of the machined holes, as all holes machined with the treated tool conformed to established tolerance limits. Consequently, treatments performed at lower temperatures were found to yield a more favorable balance between hardness and surface roughness, thereby contributing to superior wear resistance.</p>

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Study of the plasma nitriding effect on high-speed steel drills: performance in dry machining

  • 期刊论文

  • 发表日期：

    2025年8月8日

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  • Petteson Linniker Carvalho Serra,
  • Weslley Rick Viana Sampaio,
  • Patrick Abreu de Oliveira,
  • Renan Matos Monção,
  • José Ribamar do Carmo Pereira Júnior,
  • Paulo Roberto Queiroz de Almeida,
  • Wenio Fhara Alencar Borges,
  • Thércio Henrique de Carvalho Costa,
  • Marcos Guilherme Carvalho Braulio Barbosa,
  • Rômulo Ribeiro Magalhães de Sousa

摘要

High-speed steel is one of the most widely used materials in machining tools. However, applications, such as dry machining, demand properties superior to those of conventional tools. Plasma nitriding emerges as a promising surface treatment to enhance these properties. This study investigates the application of plasma nitriding, at temperatures of 300 °C, 350 °C, and 400 °C, with a treatment time of 2 h. Typically, nitriding temperatures (between 400 and 500 °C) significantly increase surface roughness, which is detrimental to tool performance. The objective of using lower temperatures in this work was to mitigate this effect. Furthermore, the nitrogen concentration in the nitriding atmosphere was kept below 10% to ensure the formation of a layer without a compound zone, thereby promoting greater mechanical stability. The treatments were applied to N-type drills (diameter of 8 mm) using a maximum power source of 3000 W. The samples were characterized by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) with Rietveld refinement, surface microhardness, microhardness profile, and average surface roughness (Ra) measurements. In addition, the performance of the treated tools was evaluated through simulation in a CNC machining center. This evaluation was based on the evolution of flank wear, the required electric current by the machine during cutting times, and the diameter and surface roughness of the machined holes. The results revealed that tools treated at 400 °C exhibited 30% more flank wear compared to untreated tools, despite the observed surface hardening. Conversely, tools treated at lower temperatures demonstrated less flank wear than their untreated tools, suggesting that improved wear resistance is not solely dependent on surface hardness. Another significant finding was the enhancement in the dimensional quality of the machined holes, as all holes machined with the treated tool conformed to established tolerance limits. Consequently, treatments performed at lower temperatures were found to yield a more favorable balance between hardness and surface roughness, thereby contributing to superior wear resistance.