Effect of Sampling Methods on N Detection in High Nitrogen Steel

Abstract

The effect of sampling methods on the detection of N content in the high nitrogen steel (HNS) was studied by variance analysis method. In the experiments, two kinds of samples (rod sample and chip sample) were chosen. It was showed that when the N content was in the range of 0.06%∼0.4%, the results obtained by two methods were almost the same, indicating that both were suitable to identify the N in the steel. However, when the N content was higher than 0.4%, the result obtained using chips as sample was lower than that using rod. The N2 bubble in the rod sample might cause error since it didn't comprise the N content. Hence, the N content could be reflected more accurately by the chip samples. Based on the difference of N content detected by two methods, the shrinkage rate was analyzed theoretically and found to be inversely proportional to the pressure of N2 bubbles in steel.