Ferrite stainless steel with low black spot generation
View Patent ↗This ferrite stainless steel includes: by mass %, C: 0.020% or less; N: 0.025% or less; Si: 1.0% or less; Mn: 0.5% or less; P: 0.035% or less; S: 0.01% or less; Cr: 16% to 25%; Al: 0.15% or less; Ti: 0.05% to 0.5%; and Ca: 0.0015% or less, with the balance being Fe and inevitable impurities, wherein the following formula (1) is fulfilled, BI=3Al+Ti+0.5Si+200Ca≦0.8 (1) (wherein Al, Ti, Si, and Ca in the formula (1) represent contents (mass %) of the respective components in the steel).
1. A ferrite stainless steel with low black spot generation in welded portions, comprising: by mass %,
C: 0.020% or less;
N: 0.025% or less;
Si: 0.25% or less;
Mn: 0.5% or less;
P: 0.035% or less;
S: 0.01% or less;
Cr: 19.1 to 22.6%;
Al: 0.04% to 0.13%;
Ti: 0.05% to 0.19%;
Ca: 0.0003% to 0.0015%;
either one or both of V: 0.05% to 0.2% and Zr: 0.05% to 0.2%; and
a balance of Fe and unavoidable impurities,
wherein the stainless steel has a BI value ≦0.8, and
BI=3Al+Ti+0.5Si+200Ca.
2. The ferrite stainless steel with low black spot generation in welded portions according to claim 1 , wherein the ferrite stainless steel further comprises, by mass %, Nb: 0.6% or less.
3. The ferrite stainless steel with low black spot generation in welded portions according to claim 1 , wherein the ferrite stainless steel further comprises, by mass %, Mo: 3.0% or less.
4. The ferrite stainless steel with low black spot generation in welded portions according to claim 1 , wherein the ferrite stainless steel further comprises, by mass %, either one or both of Cu: 2.0% or less and Ni: 2.0% or less.
5. The ferrite stainless steel with low black spot generation in welded portions according to claim 1 , wherein the ferrite stainless steel further comprises, by mass %, B: 0.005% or less.
6. The ferrite stainless steel with low black spot generation in welded portions according to claim 2 , further comprising at least one element selected from the group consisting of Mo: 3.0% or less, Cu: 2.0% or less, Ni: 2.0% or less, and B: 0.005% or less.