Abstract: The invention relates to a precipitation-hardenable tool steel intended for plastic forming tools manufactured therefrom. The tool steel at the manufacturing of the tool and prior to hardening through ageing treatment but after solution heat treatment and cooling to room temperature has a hardness less than 40 HRC, but after the manufacturing of the tool and the subsequent age hardening treatment, i.e. in the precipitation hardened condition, is harder than 45 HRC and has a high corrosion resistance and a toughness sufficient for plastic forming tools. The steel contains in weight-%:______________________________________ max 0.08 C, max 1 Si, max 2 Mn, 9-13 Cr, 7-11 Ni, max 1 Mo, 1.4-2.2 Al, and ______________________________________balance being essentially only iron, impurities and accessory elements in normal amounts.

Abstract: The invention relates to a precipitation hardening tool steel for mould tools. The steel contains, expressed in weight-%:0.01-0.1 Cfrom traces to max 2 Si0.3-3.0 Mn1-5 Cr0.1-1 Moand Ni as a toughness and hardenability improving element, and Ni and Al as a compound and/or Cu for precipitation hardening purposes, wherein the contents of Ni and Al and/or Cu amount to1-7 Ni1.0-3.0 Al and/or1.0-4.0 Cu,wherein 1.5.times.Al+Cu.gtoreq.2.0, balance essentially only iron, impurities and accessory elements in normal amounts. The invention also relates to a mould tool made from the steel according to the invention.