25CrMnSi (A) of the carbon content higher than 20 CrMnSi steel, and lower than 30 CrMnSi steel, strength and toughness in between the two. After appropriate heat treatment, both in the high-temperature tempering or hypothermia after tempering can be strength plastic toughness of the three with good overall performance of 25 CrMnSi steel can be used to make connections, important pieces of welding and stamping parts.