MARAGING STEEL MEANT TO BE USED AT HIGH TEMPERATURES AND METHOD FOR THE THERMAL TREATMENT THEREOF

The invention relates to a new maraging-type steel of increased resistance to heat, which is obtained by bringing its physical properties from the usual temperature range of 20...300A C to the high temperature range, of over 700A C, and to a method for thermally treating the same. According to the invention, the maraging-type steel is characterized in that it has a maximal content of 0.06% C, 0.05...1.2% Si, 0.3...2% Mn, 0.5...1.5% Ti, 0.5...2.5% Nb, less than 0.007% S, 10...14% Ni, 3...6% Mo, 8...12% Co, 0.5...2.5% Al, 0.5% Zr at the most, 0.004...0.01% N, less than 0.004% O2, and Fe for the remainder; the steel composition is balanced so that the steel contains the intermetallic compound Ti3Si3, and the thermal treatment which is different from the classic one shall be achieved by putting it into the solution at the temperature of 950...980A C, with ageing at 650...680A C, thereby resulting a resistance to the temperature of 550A C of at least 1600 N/mm2. Invenţia se referă la un nou oţel de tip maraging, cu rezistenţă mărită la cald, care se obţine prin mutarea proprietăţilor fizice ale acestui oţel din zona temperaturilor obişnuite, de 20...300°C, în zona temperaturilor ridicate, de peste 700°C, şi la o metodă de tratament termic al acestuia. Oţelul de tip maraging, conform invenţiei, este caracterizat prin aceea că are un conţinut de maximum 0,06% C, 0,05...1,2% Si, 0,3...2% Mn, 0,5...1,5% Ti, 0,5...2,5% Nb, mai puţin de 0,007% S, 10...14% Ni, 3...6% Mo, 8...12% Co, 0,5...2,5% Al, nu mai mult de 0,5% Zr, 0,004...0,01% N, nu mai mult de 0,004% O2, restul Fe; compoziţia oţelului se echilibrează astfel încât oţelul să conţină şi compusul intermetalic Ti3Si3, iar tratamentul termic, diferit de cel clasic, se va face prin punere în soluţie la 950...980°C, cu îmbătrânire la 650...680°C, rezultând o rezistenţă la temperatura de 550°C de minimum 1600 N/mm2.