| 摘要 |
The present invention relates to a process for the production of Carbon steel strips with a mainly fine grained ferrite microstructure, comprising the following steps : transferring a strip, optionally coiled in the form of a coil, having a thickness ranging from 1.5 to 15 mm, of steel having a composition (expressed in mass percent) comprising: C 0.001-0.20; Mn 0.05-1.9; Si 0.002- 0.35; Al<0.06; S<0.03; P<0.1; N 0.003-0.02, the remaining part being, unavoidable impurities apart, substantially Fe, to a first reel placed near the ingoing side of a reversible rolling mill, having at least one stand and equipped at the outgoing side thereof with a second reel; adjusting the temperature of the (optionally rapidly heated and oiled) strip, optionally under inert or non-oxidizing atmosphere, so that the start of the rolling occurs in ferritic field, preferably at a temperature higher than 550 °C and lower than (Ar1 - 20) °C; controlled rolling in ferritic phase at a temperature adjusted in a range of ± 300C, by suitable heating, cooling and/or holding treatments, so as to accumulate an overall deformation etot ranging from 0.7 to 1.6 in a temperature interval ranging from 550 °C to (Ar1 - 2O) °C; in-line treating of the strip, optionally under inert or non-oxidizing atmosphere, upon reaching the desired end thickness, ranging from 0.3 to 7.0 mm, according to one of the following modes: - coiling at a temperature equal to or lower - at most of 40 °C - than the end-of-rolling one, followed by slow cooling of the coil - heating to a temperature 1, and subsequent coiling thereat. - heating the strip up to a temperature in which ferrite and austenite phases coexist, followed by cooling the strip down to coiling temperatures lower than that of the start of martensite formation (Ms). Subject of the present invention are also the strips and the sheets of a thickness ranging from 0.3 to 7 mm, obtainable via said process. |
