A PROCESS FOR MANUFACTURING BAKE HARDENING STEEL SHEET AND A BAKE HARDENING SHEET

摘要

Abstract:The invention relates to a process for manufacturing bake hardening steels and tosteel sheet and part obtained by implementing it. The technical problem to be solvedconsists in providing a steel having good mechanical properties, a bake hardeningvalue above 40 Mpa and presenting an improved resistance to natural aging. This isobtained by smelting a steel comprising :0.03 ≤C≤0.060.50 ≤Mn≤1.100.08 ≤Si≤0.200.015 ≤Al≤0.070N≤0.007Ni≤0.040Cu≤0.040P≤0.035S≤0.015Mo≤0.010Ti≤0.005and boron in an amount such that 0.64 ≤ B/N ≤ 1.60then casting a slab of this steel, hot rolling it above Ar3, coilinh it between 500 -700°C, cold rolling it with a reduction of 50 - 80%, continuously annealing it duringless than 15 minutes and skin-passing it at a reduction ratio of 1.2 - 2.5%.