Abstract
The effect of boron (B) and silicon (Si) additions on the liquid-phase sintering behavior and corrosion resistance of P/M ferrite type stainless steel (SUS430L) was investigated. As a result, the addition of B improved the sintering of specimens, and the relative sintered density of 0.2mass%B and 0.2mass%B+2mass%Si added steel sintered at 1573 K were more than 97%. The high tensile strength was obtained on 0.2mass%B+2mass%Si added specimens sintered at 1473, 1523 and 1573 K, and the maximum strength was 508 MPa obtained at 1573 K. The reason was considered due to the high density of the matrix obtained by the eutectic reaction between the matrix and borides and the solid-solution hardening of matrix by Si element. On the other hand, the ductility was not improved by the addition of B and Si. This results may be due to grain coarsening and borides precipitated along the grain boundary. The specimen with 0.2mass%B and 0.2m, -ss%B+2mass%Si sintered at 1573 K were found to have an excellent corrosion resistance in a pitting corrosion test of a solution of 6 % FeCl3 (N/20 HC1). Especially, the corrosion rate of the 0.2mass%B + 2mass%Si added steel sintered at 1573 K is smaller by one sixth compared of the non-added steel. However, in the case of steels sintered at lower than 1523 K, the corrosion resistance of 0.2mass%B and 0.2mass%B+2mass%Si added steels was similar to that of the non-added steel. This tendency was probably due to a low sintered density in similar to the non-added P/M steel.
