Thermal treatment technology of ultrahigh-strength stainless steel

The invention relates to a thermal treatment technology of ultrahigh-strength stainless steel for a long blade of a steam turbine. Based on the original thermal treatment technology of a martensite precipitation hardening stainless steel forging, an intermediate treatment process-cold treatment process is added between a solution treatment process and an aging treatment process, and the method specifically comprises the following steps of: performing solution treatment, and cooling; performing cold treatment at (-5)-2 DEG C for at least one hour; and performing aging treatment. The optimized thermal treatment technology solves the problem of low strength caused by incomplete conversion of austenite to martensite in the original technology, and realizes good matching among strength, plasticity and toughness. The production verification test indicates that by adopting the optimized thermal treatment technology, the performance indexes of the material completely meet the usability requirement of the steel for a long blade of a steam turbine.