Specifically, it contains C: 0.02% or less, N: 0.02% or less, Cr: 11% or more and less than 17%, appropriate content of Si, Mn, P, S, Al, Ni, and satisfies 12≤Cr Mo 1.5Si≤ 17. Stainless steel plates with 1≤Ni 30 (CN) 0.5 (Mn Cu) ≤4, Cr 0.5 (Ni Cu) 3.3Mo≥16.0, 0.006≤CN≤0.030 are heated to 850 ～ 1250 ℃, and then carried out at 1 ℃ / s Cooling heat treatment at the above cooling rate. In this way, it can become a high-strength stainless steel plate with a martensitic structure with a volume fraction of 12% or more, high strength of 730 MPa or more, corrosion resistance and bending workability, and toughness in the welding heat affected zone. Reusing Mo, B, etc. can significantly improve the stamping performance of welded parts.
The oxygen plus gas flame cannot cut stainless steel because stainless steel is not easily oxidized.