Microalloyed steel for hot forging free of subsequent quenching and tempering, process for producing hot forging, and a hot forging

摘要

PCT No. PCT/JP94/00568 Sec. 371 Date Jan. 5, 1995 Sec. 102(e) Date Jan. 5, 1995 PCT Filed Apr. 5, 1994 PCT Pub. No. WO94/23085 PCT Pub. Date Oct. 13, 1994The present invention provides a steel material for a microalloyed part having a high strength in a hot worked state. A microalloyed steel for a high strength hot forging comprising specified amounts of C, Si, Mn, Cr, S, V and N, and Al and/or Ti, having a carbon equivalent in a definite range, and exhibiting a bainite transformation starting point in a definite range. A microalloyed steel for a high strength hot forging comprising specified amounts of C, Si, Mn, Cr, S, V, N and Ca, and Al and/or Ti, having a carbon equivalent in a definite range, and exhibiting a bainite transformation starting point in a definite range. Said steel material has a tensile strength of at least 900 MPa when it is in a hot forged, and non-quenched and tempered state. Automobile parts can be made small and light by the use of the steel of the invention.