Novel carbon-plus-nitrogen corrosion-resistant ferrous and austenitic alloys, apparatus incorporating an inventive alloy, and methods of making and using the apparatus are described. The corrosion-resistant ferrous and austenitic alloys comprise no greater than about 4 wt. % nickel, are characterized by a strength greater than about 700 MPa (100 ksi), and, when being essentially free of molybdenum (<0.3 wt. %), have minimum Pitting Resistance Equivalence (PRE) numbers of 20 and minimum Measure of Alloying for Corrosion Resistance numbers (MARC) of 30 because of the use of both carbon and nitrogen. The ferrous and austenitic alloys are particularly formulated for use in oilfield operations, especially sour oil and gas wells and reservoirs. This abstract allows a searcher or other reader to quickly ascertain the subject matter of the disclosure. It will not be used to interpret or limit the scope or meaning of the claims.