Annealing behaviour of nitrogen-ion-implanted 304 stainless steel

We studied the modification of 304 stainless steel following nitrogen ion implantation. We used grazing incidence X-ray diffraction. Nitride formation is enhanced in specimens containing a significant amount of martensite formed by surface finishing. We report for the first time an increase in surface hardness at depths larger than the implantation depth following annealing of such implanted specimens. This effect correlates with the release of nitrogen from nitrides. The nitrogen appears to diffuse inwards and strengthen the martensite phase

Wear behaviour of nitrogen implanted stainless steel

Samples of 304 stainless steel were implanted with N2+ ions. Wear tests were carried out on a sample implanted with a dose of 5 × 1016 N2+ cm-2 at 130 keV and stored at room temperature for 10 months. Several other samples were tested within a few days after implantation. The former showed remarkable wear resistance whereas the latter failed to exhibit wear resistance. X-ray diffraction revealed the formation of γ'-Fe4 N in the aged sample whereas other samples showed little or no evidence of it. Artificial aging of one of the discs was also tried by heating it at various temperatures in the range 85-135°C but it failed to exhibit wear resistance. The oxide on each sample is found to contain Fe3O4 and/or Cr3O2. The existence of oxide is confirmed by Auger electron spectroscopy

Intensity modulated radiation therapy (IMRT) is not superior to three-dimensional conformal radiation (3DCRT) for adjuvant gastric radiation: A matched pair analysis

Aims: To compare three-dimensional conformal radiation (3DCRT) and Intensity Modulated Radiation Therapy (IG-IMRT) for adjuvant gastric irradiation. Subjects and Methods: From Jan 2010-Aug 2013, all patients undergoing 3DCRT and IG-IMRT were included. Systemic chemotherapy included 1 cycle before and 2 cycles after chemoradiation. Planning Target Volume (PTV) received 45 Gy/25 fractions/5 weeks with concurrent capcetabine 825 mg/m2 bid. Matched pair analysis was performed to evaluate imbalance in two cohorts if any. Common Toxicity Criteria for Adverse Event (CTCAE) vs 3.0 was used to record gastrointestinal (GI), hematological (HL), and renal toxicity during treatment and follow-up. Patterns of recurrence were documented. Mann-Whitney U test was used for statistical comparison. Results: Of the 51 patients, 26 received 3DCRT and 25 IMRT. IMRT led to decrease in dose received by right and left kidney (12.4 Gy and 7.1 Gy and 29 Gy vs 8.2 Gy; P < 0.001). Overall, 17.6% and 19.6% patients had grade II GI and HL toxicity and 3.9% and 5.9% had grade III GI and HL toxicity. No difference was observed in acute grade II-V GI or HL toxicity (11.5% vs 24%, P = 0.07; 7.6% vs 20% P = 0.20) or late GI, HL, or renal toxicity between 3DCRT and IMRT. No difference was observed in patterns of local relapse (11.5% vs 12%, P = 0.14) or overall survival (39% and 38% (P = 0.97)) between 3DCRT and IMRT. Conclusions: 3DCRT and IMRT are equivalent in terms of toxicity and local control