STEEL FOR WARM WORKING, METHOD OF WARM WORKING OF THE STEEL, AND STEEL MATERIAL AND STEEL PART OBTAINED BY THE SAME

摘要

There are provided a steel for warm working, to be subjected to warm working as various structures, components of cars, and the like, a warm working method thereof, and a steel material and a steel component obtainable from the warm working method. [Solving Means] A steel is to have a particle dispersion type fiber structure formed in the matrix by warm working. The steel is characterized in that the total amount of the dispersed second-phase particles at room temperature is 7 × 10 -3 or more in terms of volume fraction, and the Vickers hardness (HV) is equal to or larger than the hardness H of the following equation (2):
H = (5.2 - 1.2 × 10 -4 ») × 10 2 ... (2)
when the steel is subjected to any of annealing, tempering, and aging treatments in the as-unworked state under conditions such that a parameter » expressed by the following equation (1):
» = T(logt + 20) (T; temperature (K), t; time (hr)) ... (1)
is 1.4 × 10 4 or more in a prescribed temperature range of 350°C or more and Ac1 point or less. This steel is taken as the steel for warm working.