Martensite stainless steel and preparation method for flat strip of martensite stainless steel

The invention discloses martensite stainless steel and preparation method for flat strips of martensite stainless steel. The martensite stainless steel comprises following chemical components by weight percentage: C 0.02 to 0.06%, Si 0.3 to 0.5%, Mn 1.0 to 1.5%, Ni 8.5 to 9.0%, Cr 17.5 to 18.5%, Ti 0.4 to 0.6%, P no more than 0.009% and S no more than 0.009%, with the balance being Fe. The preparation method for flat strips of the martensite stainless steel comprises the following steps: a) weighing above-mentioned chemical components at desired weight percentage; b) carrying out vacuum induction melting; c) carrying out casting to obtain remelt electrode bars; d) carrying out electroslag remelting to obtain steel ingots; e) forging steel ingots into billets; f) processing billets into round strips; g) carrying out solid solution treatment; h) drawing treated blanks into wires; i) preparing flat strips. According to the invention, equivalents of nickel and chromium are strictly controlled, the ratio of C to Ti and alloy elements are optimized, EVR smelting is carried out and such alloying elements as C, Si, Mn and Ti are added, thereby enabling formation of a metastable austenite structure; a predeformed phase-changed martensite wire material is obtained by wire drawing; and the ultra high strength deformed flat strips of martensite stainless steel are obtained by flat strip rolling.