Scholarlink

<p>The present work performs a comparative study on the influence of hydrogen and nitrogen based protective atmospheres on eutectoid steel (0.75–0.8 wt% C) spheroidizing annealing behavior using a convection heating in bell annealing furnace. The same heat treatment cycles—ramp heating to 705&#xa0;°C (which took 3&#xa0;h), 30&#xa0;h isothermal soaking, and furnace cooling up to 650&#xa0;°C for 8&#xa0;h under controlled atmosphere were used on both samples to separate the effect of atmosphere composition and then after open air cooling in both samples. Annealing perform on sample A in nitrogen and Sample B in hydrogen—based bell annealing furnace. Before annealing, the samples A and B had fine pearlitic structures (Interlamellar spacing 0.22–0.23 (μm)) with high hardness (327 HV and 310 HV), tensile strength (972&#xa0;MPa and 930&#xa0;MPa), and low ductility (10% and 11% elongation). Post annealing inspection indicated that the hydrogen atmosphere enhanced a better level of spheroidization (75% vs. 60% for nitrogen), which resulted in improved elongation (22% vs. 16% for nitrogen), better yield strength (483&#xa0;MPa vs. 449&#xa0;MPa for nitrogen), and generally better tensile strength (579&#xa0;MPa vs. 567&#xa0;MPa for nitrogen). The hydrogen treated steel was also more homogeneous and softer (171 HV vs. 179 HV for nitrogen), showing greater stress relief and coarsening of the carbides. The higher outcome under hydrogen is due to its reducing ability, which facilitates oxide removal and improves carbon diffusion. Nitrogen, on the other hand, although inert and inexpensive, does not have this chemical activity, leading to less complete change. Such findings provide significant input to furnace atmosphere optimization for improved mechanical performance in industrial spheroidizing operations.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Comparative Study of Hydrogen and Nitrogen Atmospheres in a Bell Annealing Furnace: Effects on Spheroidization and Mechanical Properties of Eutectoid Steel

  • 期刊论文

  • 发表日期：

    2025年10月27日

查看全文
  • Patel Kishan Jayantibhai,
  • D. B. Jani

摘要

The present work performs a comparative study on the influence of hydrogen and nitrogen based protective atmospheres on eutectoid steel (0.75–0.8 wt% C) spheroidizing annealing behavior using a convection heating in bell annealing furnace. The same heat treatment cycles—ramp heating to 705 °C (which took 3 h), 30 h isothermal soaking, and furnace cooling up to 650 °C for 8 h under controlled atmosphere were used on both samples to separate the effect of atmosphere composition and then after open air cooling in both samples. Annealing perform on sample A in nitrogen and Sample B in hydrogen—based bell annealing furnace. Before annealing, the samples A and B had fine pearlitic structures (Interlamellar spacing 0.22–0.23 (μm)) with high hardness (327 HV and 310 HV), tensile strength (972 MPa and 930 MPa), and low ductility (10% and 11% elongation). Post annealing inspection indicated that the hydrogen atmosphere enhanced a better level of spheroidization (75% vs. 60% for nitrogen), which resulted in improved elongation (22% vs. 16% for nitrogen), better yield strength (483 MPa vs. 449 MPa for nitrogen), and generally better tensile strength (579 MPa vs. 567 MPa for nitrogen). The hydrogen treated steel was also more homogeneous and softer (171 HV vs. 179 HV for nitrogen), showing greater stress relief and coarsening of the carbides. The higher outcome under hydrogen is due to its reducing ability, which facilitates oxide removal and improves carbon diffusion. Nitrogen, on the other hand, although inert and inexpensive, does not have this chemical activity, leading to less complete change. Such findings provide significant input to furnace atmosphere optimization for improved mechanical performance in industrial spheroidizing operations.