2001 Volume 48 Issue 8 Pages 758-763
The objective of this study is mainly to elucidate the effect of N addition on DC magnetic properties of Fe-Cr type PM stainless steels bearing Cr of 9-24wt%. The magnetic measurement was practically carried out about specimens before and after the heat-treatment upto 1173 K in a N atmosphere. Finally, these data were evaluated in the terms of degradation of magnetic properties by N absorption, together with residual pores.
The results obtained were summarized as follows:
(1) Fe-Cr alloys, heated at 673 K in a N gas show higher magnetic induction (B)/maximum permeability (μm) and also, lower coercive force (Hc) in the vicinity of Cr: 12wt%, as well as as-sintered ones.
(2) When Fe-Cr alloys are heated upto 1173 Kin a N gas, the magnetic properties, especially μm, are wholly degraded, and the peak values mentioned-above are shifted to Cr rich region.
(3) For the degradation ratio, ΔB/B increases abruptly at 1073 K corresponding to N absorption, while Δμm/μm linearly increases with the rise of heat-temperature though fairly scattered due to being structure-sensitive.
(4) Roughly evaluated including HIPed materials, magnetic properties are degraded with the rise of amount of N, austenite-former, in relation to ferrite-former and also, non-magnetic Cr constituent.
(5) Specimens sintered at higher temperature tend to absorb small amount of N and hence, show better magnetic properties, although the correlation of N content to sintered density (ρ) is not apparently larger.
