FR2685348A1 - USE OF STEEL FOR COLD ROLLING. - Google Patents

Abstract

The invention relates to a steel which can be used as a raw material for the manufacture of cold-rolled products. The steel according to the invention contains (in% by mass) (CF DRAWING IN BOPI) the rest of the iron and the impurities due to the production of the steel. Application to rolled products with high wear resistance.

Description

Use of steel For cold laminating.

  The invention relates to the use of a steel for rolling

Cold.

  For cold rolling, steels having the compositions shown in Table 1 below are commercially available. Material Name First Name Chemical Composition% No. 86 Cr Mo V 7 t 123270 85 0.3 0.3 1.8 0.3 0.1 X 210 Cr 12 t 120802.00 12.0 X 155 Cr V Mo 12 1t 23791.55 12.0 0.7 1.0 X 63 Cr Mo V 5 112362 0.63 1 1 0.4 5.2 1.5 05 S 6-5-2 t 133430.90 4.0 5.0 1.9 DE-C-3 006 512 discloses deep wear-resistant cold rolled products which consist of a steel which contains from 0.7 to 0.9% of C, from 0.2 to 2.0% Si, 0.2 to 1.0% Mn, 2.5 to 3.5% Cr, 0.5 to 2.0% Mo, In this case, the safety against breakage of the rolled products is ensured by a mild cooling agent, such as an oil, after the reaction. As a result, these steels must be combined with Ni up to 1.5% to reach the sufficient quenching depth. The wear resistance is obtained by the addition of V up to 0.8%. Vanadium does not form carbides in alloy steels pure vanadium type VC but mixed carbides (MC) in which are also dissolved other alloying elements such as chromium and molybdenum These are partially dissolved during the quenching of rolled products and thus release in their environment high carbon contents in the bottom mass This leads to an undesirable local stabilization of residual austenite Therefore, on the one hand the danger of breaks and stress cracks is increased and, secondly,

  the wear resistance is reduced.

  The object of the invention is therefore to create a steel for

  cold rolling having increased wear resistance.

  According to the invention, it is proposed for this purpose to use a steel containing (in% by weight) more than 0.7 to 1.0% C of 0.1 to 1, 5% Si from 0.1 to 1.5% Mn from 1.8 to 3.5% Cr from 0.1 to 1.0% Mo from 0.1 to 1.0% Ni from 0 , 0.5 to 1.0% of Nb and, where appropriate up to 0.8% of V, up to 2.0% of W, up to 0.05% of B, the balance of iron and impurities due

in the development of steel.

  For the stated purpose, a steel containing (in mass%) is preferred More than 0.70 up to 0.95% C from 0.30 to 1.5% Si from 0.10 to 1.0 % Mn from 2.0 to 3.0% Cr from 0.10 to 0.7% Mo from 0.10 to 0.7% Ni from 0.10 to 0.5% V from 0, 10 to 0.5% Nb, the rest of the iron and the impurities due to the preparation of the steel. It is also proposed, for the indicated use, a steel having the following composition (in% by weight): 0.85% of C 1.0% of Si 0.3% of Mn 2.5% of Cr 0, 5% of Mo 0.3% of Ni 0.2% of V 0.1% of Nb, the rest of the iron and the impurities due to the elaboration of the steel. In particular cold laminates are obtained with cylinder table diameters up to 900 mm and cylinder table widths up to 3000 mm, which after solution annealing (austenisation between 800 and 1000 C) followed by quench hardening, a quenching depth of up to 30 mm, based on 60 Rockwell C hardness (700 Vickers hardness 30) for cylinder diameters of 600 mm. The steel according to the invention has a bottom mass in which are deposited stable niobium carbides (Nb C) almost insoluble Cold rolled products made from this steel, preferably with diameters of cylinder table ranging up to 900 mm and cylinder table widths up to 3000 mm, are annealed in solution between 800 and 1000 ° C and hardened quenched It is thus possible to reach great depths of quenching niobium carbides deposited in the mass of are not influenced by the austenization and in this case do not modify the quenchability of the rolled products nor increase the residual austenite content by the release of carbide This reduces the danger of stress cracks and However, the wear resistance, which is caused by the niobium carbides deposited in the matrix and having a hardness of 10 ° C., can lead to serious accidents and damage. about 3000 Vickers hardness, remains fully achieved. Up to 2.0% addition of tungsten can further increase hardness and wear resistance of rolled products. Addition of up to 0.050% B increases hardness, quenching depth and grain structure purposes

steel.

  FIG. 1 represents the surface hardness and the quenching depth, on the one hand for a steel according to the invention and, on the other hand, for a known steel, the analyzes of which are contained in the following table 2

Table 2

Steel C If Mn Cr Mo Ni V Nb

1.2327 0.85 0.3 0.3 1.8 0.3 0.1 -

  Invention 0.8 1.0 0.3 2.5 0.55 0.2 0.2 0.1 With the same surface hardness of 800 Vickers hardness 30, the hardness falls to 700 Vickers hardness 30, for a rolled product in the steel to be used according to the invention at a depth of 30 mm compared to 20 mm for the steel of

known comparison 1 2327.

  The average increase in yield that has been achieved for the steel rolled products according to the invention as a result of

  reduced abrasion is around 20% when rolling steel.

  Additional benefits result from the fact that longer cylinder life and increased breaking and crack resistance reduce downtime in the cylinders.

  rolling trains related to the exchange of cylinders.

Claims (4)

  1 Steel usable as raw material for the manufacture of cold-rolled products, characterized in that it contains (in% by mass): More than 0.7 up to 1.0% of C from 0.1 to 1, 5% Si from 0.1 to 1.5% Mn from 1.8 to 3.5% Cr from 0.1 to 1.0% Mo from 0.1 to 1.0% Ni from 0 , 0.5 to 1.0% of Nb and, where appropriate up to 0.8% of V, up to 2.0% of W, up to 0.05% of B, the rest of the iron and impurities due in the development of steel.   2 steel according to claim 1, characterized in that it contains (in% by mass): More than 0.70 up to 0.95% of C from 0.30 to 1.5% Si of 0.10 at 1.0% Mn from 2.0 to 3.0% Cr from 0.10 to 0.7% Mo from 0.10 to 0.7% Ni from 0.10 to 0.5% V 0.10 to 0.5% Nb, the rest of the iron and impurities due to the development of steel.   Steel according to one of claims 1 and 2,   characterized in that it has the following composition: 0.85% C 1.0% Si 0.3% Mn 2.5% Cr 0.5% Mo 0.3% Ni 0.2% of V 0.1% Nb, the rest of the iron and the impurities due to the elaboration of the steel.   4 Use of a steel according to one of claims 1 to 3   for the manufacture of cold-rolled products, with cylinder table diameters up to 900 mm and cylinder table widths up to 3000 mm, which reach, after annealing in solution (austenisation between 800 and 1000 C) followed by a hard quench, a quenching depth of up to 30 mm, based on 60 Rockwell C hardness (700 Vickers hardness 30) for cylinder diameters of 600 mm.