Abstract
The objective of this study is mainly to elucidate the effect of sulfuric acid corrosion on DC/AC magnetic properties of 434L-type PM stainless steels with Si of 1 and 2 wt%. DC/AC magnetic measurements were experimentally carried out before and after the boiling test in 5% of sulfuric acid, together with the radial crushing strength test. Finally, these data were numerated in terms of degradation ratio (ΔX/X).
The result obtained were summarized as follows:
(1) As for sintered and HIPed materials, corrosive weight loss (ΔW) wholly decreased with the rise of sintered density (ρ) except for the passivative region of p=7-7.5 Mg/m3, though there is a little difference of ΔW in the addition of Si 1 to 2wt%.
(2) DC magnetic properties, especially magnetic induction (B) was linearly degraded with the rise of ΔW, where ΔB/B was extrapolated to nearly zero when satisfying ΔW=0.
(3) As an example experiment of maximum permeability (μm), Δμm/μm was extensively scattered in the region of 0.1-0.3 though μm almost bears no correlation to ΔW.
(4) The fraction of specific permeability (μa), typical of AC magnetic properties, Δμa/μa also had more extensively scattered at higher frequency -100 kHz.
(5) Radially crushed strength (σ) shows the degradation ratio of as much as 0.6 regardless of weight loss, probably because of being sensitive to surface conditions.
