High-strength cold-roll-forming structural steel and method for producing same

Abstract

The invention discloses a high-strength cool-bent moulding structural steel and manufacturing method, which comprises the following parts: 0.03-0.12% C,0.08-0.50% Si,1.20-1.95% Mn,not more than 0.02% P,not more than 0.006% S, 0.05%-0.15% Mo,0.005-0.055% Als,0.03-0.07% Nb,0.08-0.15% Ti,0.01-0.05% V ,0.0008-0.004% Ca and Fe and inevitable impurity with Ceq not more than 0.42%. The making method is characterized by the following: controlling the fusing point of smolten steel over 15-30 deg.c; casting continuously; setting drawing speed of casting bland at 1.5-4.0m / min and blank thickness between 100 and 200mm; heating in the furnace directly; setting the even heating temperature at 1100-1250 deg.c, fine-rolling temperature at 940-1070 deg.c and outlet temperature at 840-920 deg.c; freezing rapidly after 0-7s; setting the coiling temperature at 500-610 deg.c with yielding strength of steel board over 700Mpa and drawing-proof strength between 750 and 950Mpa and extending rate over 17%.

Description

technical field [0001] The invention relates to a high-strength welding steel plate suitable for cold-bending forming with a yield strength of 700 MPa or more, and the high-strength cold-bending structural steel produced by conventional cast slabs and medium-thin slab continuous casting and rolling production lines method. Background technique [0002] In the past, the micro-alloyed high-strength hot-rolled strip produced by the hot-rolled strip production line through controlled rolling and controlled cooling often needs a higher content of alloying elements to achieve a high strength with a yield strength above 700MPa. A high content of alloying elements will lead to an increase in carbon equivalent and poor welding performance. When reducing the content of alloying elements, in order to achieve high strength requirements, it is necessary to reduce the rolling temperature and coiling temperature, which requires high equipment capacity. The elongation of steel also drops ...

AI Technical Summary

Problems solved by technology

Therefore, the precipitates of Ti, Nb, etc. will be precipitated in the state of large particles. In the subsequent heating process, when the heating time is short and the temperature is low, because the precipitates of Ti, Nb, etc. cannot be completely re-dissolved back into the steel, Reduced its precipitation strengthening effect after rolling

To make the added Ti, Nb and other microalloying elements play a full role after rolling and cooling, it is necessary to increase the heating temperature and prolong the heating time, which will increase the energy consumption even more.

[0005] If it is produced by continuous casting and rolling of thin slabs, due to the high content of Ti, it is easy to cause flow storage accidents, and it cannot guarantee good surface quality and sufficient compression ratio (generally, the thickness of thin slabs is 50-90mm thick). The product is not easy to obtain high strength and toughness matching