Stainless steel poles

This invention provides a high-nitrogen austenitic stainless steel superior to the conventional one both in the corrosion resistance and strength, despite a low Ni content, characterized in having a Fe content of 50% by mass or more; containing Cr: 15.0% by mass to 35.0% by mass, Stainless steel poles Mo: 0.05% by mass to 8.0% by mass %, Mn: 0.2% by mass to 10.0% by mass, Cu: 0.01% by mass to 4.0% by mass and N: 0.8% by mass to 1.5% by mass, both ends inclusive, having a C content of 0.20% by mass or less, a Si content of 2.0% by mass or less, a P content of 0.03% by mass or less, a S content of 0.05% by mass or less, a Ni content of 0.5% by mass or less, an Al content of 0.03% by mass or less, and an 0 content of 0.020% by mass or less; wherein the contents of Cr, Mo, N and Mn are adjusted so that a compositional parameter ¦Ç expressed by the equation:

A high-nitrogen austenitic stainless steel having a Fe content of 50% by mass or more, and containing: Cr: 15.0% by mass to 35.0% by mass; Mo: 0.05% by mass to 8.0% by mass; Mn: 0.2% by mass to 10.0% by mass; Cu: 0.01% by mass to 4.0% by mass; and N: 0.8% by mass to 1.5% by mass, both ends inclusive, having a C content of 0.20% by mass or less, a Si content of 2.0% by mass or less, a P content of 0.03% by mass or less, a S content of 0.05% by mass or less, a Ni content of 0.5% by mass or less, an Al content of 0.03% by mass or less, and an 0 content of 0.020% by mass or less; wherein the contents of Cr, Mo, N and Mn are adjusted so that a compositional parameter expressed by the equation:
¡Ô(WCr+3.3WMo+16WN)/WMn where WCr is Cr content (% by mass), WMo is Mo content (% by mass), WN is N content (% by mass) and WMn is Mn content (% by mass) has a value of 5 or above; and optionally further containing either one of, or both of: W: 0.01% by mass to 1.0% by mass; and Co: 0.01% by mass to 5.0% by mass, both ends inclusive; and optionally further containing at least one of: Ti: 0.01% by mass to 0.5% by mass; Nb: 0.01% by mass to 0.5% by mass; V: 0.01% by mass to 1.0% by mass; and Ta: 0.01% by mass to 0.5% by mass, both ends inclusive; and optionally further containing at least one of: B: 0.001% by mass to 0.01% by mass; Zr: 0.01% by mass to 0.50% by mass; Ca: 0.001% by mass to 0.01% by mass; and Mg: 0.001% by mass to 0.01% by mass, both ends inclusive; and optionally further containing either one of, or both of: Te: 0.005% by mass to 0.05% by mass; and Se: 0.01% by mass to 0.20% by mass, both ends inclusive.

As described in the above, Outdoor lighting is effective as a deoxidizing element, but considerably lowers the corrosion resistance through formation of AlN in the high-nitrogen steel, even under a slight excess of the Al content. In this invention, the Al content is limited to 0.03% by mass or less, in view of avoiding the nonconformity and of raising the amount of N solubilization into the austenite phase as possible. The Al content is preferably limited to 0.025% by mass or less, and more preferably to 0.020% by mass or less.