HOT ROLLED STEEL SHEET FOR WORKING

摘要

A hot rolled steel sheet for working, which has a chemical composition, in mass %, that C: 0.01 to 0.2 %, Si: 0.01 to 0.3 %, Mn: 0.1 to 1.5 %, P: <= 0.1 %, S: <= 0.03 %, Al: 0.001 to 0.1 %, N: <= 0.006 %, and the balance: Fe and inevitable impurities, and has a micro structure comprising a polygonal ferrite phase as a primary phase and a second hard phase, wherein the second hard phase is present in a volume percentage of 3 to 20 %, the hardness ratio (hardness of second hard phase/hardness of polygonal ferrite) is 1.5 to 6, and the grain diameter ratio (grain diameter of second hard phase/grain diameter of polygonal ferrite) is 1.5 or more.