42CrMo4 and 42CrMo4V are alloy steels commonly used in various engineering applications. The equivalent of 42CrMo4 is AISI 4140, which shares similar mechanical properties and chemical composition. For 42CrMo4V, the discussion highlights its substitutes in different standards, emphasizing the importance of understanding material equivalencies. Resources are available online for further information on these materials and their specifications. Accurate identification of these equivalents is crucial for material selection in manufacturing processes.