| Title |
Effects of N Concentration on the Tensile and Impact Properties of 9Cr-1W Steels |
| Authors |
박상민(Sang Min Park); 홍순익(Sun Ig Hong); 김태규(Tae Kyu Kim) |
| DOI |
https://doi.org/10.3365/KJMM.2014.52.9.713 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
9Cr-1W steel; V-rich MX; ferritic/martensitic steel; tensile strength; impact toughness |
| Abstract |
The effects of nitrogen concentration on the tensile and impact properties of 9Cr-1W steels were evaluated. The 9Cr-1W alloy ingots containing nitrogen concentrations of 110, 280 and 500 ppm were fabricated by a vacuum induction melting process. The alloy ingots, with a 30 kg scale each, were hot-rolled at 1150 ℃ up to 15 mm in thickness, which was followed by normalizing at 1050 ℃ for 1 hour and tempering at 760 ℃ for 1 hour. M23C6, V-rich MX and Ta-rich MC precipitates were observed in all the alloys. We found that the increased nitrogen concentration led to increased V-rich MX carbonitrides. When the nitrogen concentration was increased from 110 ppm to 500 ppm, the tensile strength increased while the impact toughness remained almost constant. We thus concluded that the V-rich MX carbonitrides in 9Cr-1W steels mainly act to improve the tensile strength rather than the impact toughness. (Received October 30, 2013) |