Przedmiotem wynalazku jest stal martenzytyczna chromowo-kobaltowo-molibdenowa, odporna na korozje, przeznaczona na narzedzia do pracy na goraco. Znana jest stal martenzytyczna, odporna na korozje, przeznaczo¬ na na narzedzia do pracy na goraco, zawierajaca wagowo: wegla do 0,03%,manganu do 0,1%, krzemu do 0,1%, fosforu do 0,01%, siarki do 0,01%, chromu od 14% do 16%, niklu do 0,3%, kobaltu od 19% do 21% i molibdenu od 2,6% do 3,2%, reszta zelazo i nieuniknione zanieczyszczenia. Stal ta po obróbce cieplnej wykazuje Rm okolo 1600 MPa i HRC 47-48.Celem wynalazku jest poprawienie wlasnosci uzytkowych stali martenzytycznej chromowo-kobaltowo- molibdenowej. Cel ten uzyskano wedlug wynalazku przez wprowadzenie w sklad tej znanej stali aluminium w ilosci wagowej od 0,05% do 0,20%. Stal wedlug wynalazku wykazuje po obróbce cieplnej nastepujace wlasnos¬ ci mechaniczne: R0#2 = 1400 MPa, Rm = 1650-1700 MPa, A = 19-20%, Z = 65-70%, KCU = 70-100 J/cm2 i HRC = 49-50.Przyklady skladów stali c I Mn Si P S Cr Ni Co Mo I Al I 0,02% 0,08% 0,06% 0,009% 0,008% 15,2% 0,2% 19,3% 2,9% 0,12% II 0,03% 0,06% 0,07% 0,009% 0,009% 14,8% 0,3% 19,6% 3,0% 0,09% Zrobione ze stali wedlug przykladu I matryce do kucia na goraco daja do czasu calkowitego zniszczenia ponad 4500 odkuwek. Natomiast kowadla zrobione ze stali wedlug przykladu 11 pracuja ponad 150 godzin.2 137536 { Zastrzezenie patentowe ) Stal martenzytyczna chromowo-kobaltowo-molibdenowa odporna nc} korozje, skladajaca sie wagowo zwegla do 0,3%, manganu do 0,1%, krzemu do 0,1%, fosforu do 0,01%, sijirki do 0,01%, chromu od 14% do 16%, niklu do 0,3%, kobaltu od 19% do 21% i molibdenu od 2,6% do \3,2%, reszta zelazo i nieuniknione zanieczyszczenia, znamienna tym, ze zawiera wagowo aluminium od fif05% do 0,20%.Pracownia Poligraficzna UP PRL. Naklad 100 egz.Cena 100 zl PLThe subject of the invention is chromium-cobalt-molybdenum martensitic steel, resistant to corrosion, intended for hot work tools. Known is a martensitic steel, resistant to corrosion, intended for hot work tools, containing by weight: carbon up to 0.03%, manganese up to 0.1%, silicon up to 0.1%, phosphorus up to 0.01%, sulfur up to 0.01%, chromium from 14% to 16%, nickel to 0.3%, cobalt from 19% to 21% and molybdenum from 2.6% to 3.2%, the rest iron and the inevitable impurities. This steel, after heat treatment, has an Rm of about 1600 MPa and an HRC of 47-48. The aim of the invention is to improve the performance properties of the martensitic chrome-cobalt-molybdenum steel. This object is achieved according to the invention by incorporating aluminum in this known steel in an amount by weight ranging from 0.05% to 0.20%. The steel according to the invention shows, after heat treatment, the following mechanical properties: R0 # 2 = 1400 MPa, Rm = 1650-1700 MPa, A = 19-20%, Z = 65-70%, KCU = 70-100 J / cm2 and HRC = 49-50 Examples of steel compositions c I Mn Si PS Cr Ni Co Mo I Al I 0.02% 0.08% 0.06% 0.009% 0.008% 15.2% 0.2% 19.3% 2 , 9% 0.12% II 0.03% 0.06% 0.07% 0.009% 0.009% 14.8% 0.3% 19.6% 3.0% 0.09% Made of steel according to example I Hot forging dies give more than 4,500 forgings until complete destruction. In contrast, anvils made of steel, according to example 11, work more than 150 hours.2 137536 {Patent claim) Martensitic chrome-cobalt-molybdenum steel resistant to corrosion, consisting of carbon up to 0.3% by weight, manganese up to 0.1%, silicon up to 0.1%, phosphorus up to 0.01%, sieves up to 0.01%, chromium from 14% to 16%, nickel up to 0.3%, cobalt from 19% to 21% and molybdenum from 2.6% to \ 3.2%, the rest is iron and unavoidable impurities, characterized by the fact that it contains aluminum from fif05% to 0.20% by weight. Printing studio of the Polish People's Republic of Poland. Mintage 100 copies Price PLN 100 PL