马氏体时效钢（英语：Maraging steel）是一种有着高强度韧性，并且同时保留着一定延展性的钢。「时效」意味着经过较长的热处理过程。这种钢一种特别的低碳超高强度钢，其高强度并不来自于碳，而是来自于金属间化合物.其中的主要合金元素为15%到20%的镍。

Maraging steels (a portmanteau of "martensitic" and "aging") are steels (iron alloys) that are known for possessing superior strength and toughness without losing malleability, although they cannot hold a good cutting edge. Aging refers to the extended heat-treatment process. These steels are a special class of low-carbon ultra-high-strength steels that derive their strength not from carbon, but from precipitation of intermetallic compounds. The principal alloying element is 15 to 25 wt.% nickel. Secondary alloying elements, which include cobalt, molybdenum, and titanium, are added to produce intermetallic precipitates,. Original development (by Bieber of Inco in the late 1950s) was carried out on 20 and 25 wt.% Ni steels to which small additions of Al, Ti, and Nb were made; a rise in the price of cobalt in the late 1970s led to the development of cobalt-free maraging steels