微量元素对304L不锈钢Hall-Petch关系式的影响研究

Four experimental specimens were prepared from molten 304L austenitic stainless steel, with different trace elements added in it. After cold rolling and recrystallization annealing at different temperatures to cause grain size distribution change to a certain extent, those specimens were annealed again for homogeneity at different temperatures to eliminate the different grain boundary segregation resulting from different annealing temperatures. Then, their mechanical properties were tested with their microstructures observed for grain size statistics, thus getting the Hall-Petch relation through data processing. The effects of such microalloying elements as Nb, B, C and N on Hall-Petch relation were investigated by comparing the results of different specimens and heat-treatments. Conclusions are therefore drawn that: without Nb addition, the trace elements C, N and B have little influence on σ0 in Hall-Petch relation, but N or B can increase grain refinement strengthening coefficient ky. Once Nb is added in the austenitic stainless steel, it compounds with the elements C and N to form the carbonitride of Nb, which has no obvious influence on σ0 but increases ky when reannealing the specimens for homogeneity at 700℃. However, it decreases σ0 but increases ky at 500℃。