| 摘要 |
PROBLEM TO BE SOLVED: To provide a free cutting stainless steel material, which prevents environmental pollution caused by Pb and decrease of corrosion resistance caused by MnS, and can be hot-formed. SOLUTION: The free cutting stainless steel material comprises including 1.0 mass% or less B and 0.5 mass% or less N, and dispersing boron nitride particles in the metallic matrix at a volume ratio of 0.1% or more, preferably 0.5% or more, and, in some cases, further dispersing the metal boride particles at the volume rate of 5.0% or less, preferably 3.0% or less. The method for manufacturing the steel material comprises when adding B and N to molten stainless steel including 11-25 mass% Cr, controlling an additive quantity of B and N so as to make a value of N-content/B-content to be 0.5 or more, preferably be 0.7-2.0, in a range of 0.005-1.0 mass% B, preferably of 0.005-0.7 mass% B, and 0.003-0.5 mass% N, and heating the ingot at 1,000-1,300 deg.C for 0.5-3 hours before hot working.
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