SE526120C2 - Process for the manufacture of an ultra-high-strength stretched or stretched product of steel - Google Patents

Abstract

A method for manufacturing an ultra-high-tensile sheet method product of steel, at which the initial work piece used is constituted of a metal work piece of iron, alloyed with chromium, nickel and carbon in predetermined proportions. The initial work piece is wholly or partially plastically cold worked by stretch forming or stretch bending at a predetermined temperature and/or deformation degree, that determines and is determining for the yield point of the final product, in providing a strong deformation hardening, that gives the final product a totally or partially many times increased strength or higher yield point, as compared to the yield point of the initial work piece.

Description

-rnfa qng and also values far beyond that, for example 1500 MPa. This result with a strong and controlled deformation hardening of all or parts of the product is achieved during the stretch pressing or stretch bending operation by plastically cold working the product in at least one step in one or more directions in combination with the alloy maintaining a good ductility during the stretch pressing operation. temperature adjusted to the yield strength of the final product and at the same time to a degree of deformation adapted to the yield strength of the like product desired. If you have a low or moderate degree of deformation and want a high strength, you can compensate for this with a lower temperature, ie. by cooling the metal blank before, during and / or after the machining operation, by cooling all or part of the stretch pressing or stretch bending tool, or by a combination of these measures during the machining operation. If you have a high degree of deformation, you can counteract a deformation hardening by allowing the workpiece and / or the tool to maintain a higher temperature.

The invention is described in more detail below with the aid of the following exemplary embodiments.

In the preferred embodiment according to the invention, the stretch-pressed or stretch-bent product, which is manufactured according to the invention, consists of a metal blank of iron, alloyed with chromium, nickel and carbon in predetermined proportions.

In the selected example, the iron has been alloyed with 17% Cr, 7% Ni and 0.1% C or to these adjacent alloys and the temperature of the substance before and / or during the manufacturing process has been maintained or maintained at a controlled level, which is -196 ° C <= T <= 70 ° C in order to achieve during the stretch pressing or bending operation a strong but controlled deformation hardening during a plastic cold working of the blank in combination with the alloy maintaining good ductility.

Furthermore, the temperature of the pre-formed, stretch-pressed or stretch-bent product can be controlled directly after the processing process itself. The alloy metal blank, which forms the constituent material according to the invention, can be molded or plastically cold processed in traditional machines, but with modified tools, for stretch pressing or stretch bending to raise its yield strength from an initial low yield strength of about 300 MPa to a final product, which completely or partially has a yield strength of more than 700 MPa.

The procedure works even if you go from an e.g. medium yield strength of say 700 MPa to a higher say 1000 MPa or more.

A stronger deformation hardening is obtained in all the cases described above if the pressing or bending is done in two or more steps.

Claims (7)

Patent claims Process for the manufacture of an ultra-high-strength steel product, in which the constituent metal substance used is iron, alloyed with 17% chromium, 7% nickel and 0.1% carbon or related alloys, characterized in that the constituent metal substance completely or partially plastically cold-worked by stretch-pressing or stretch-bending at a predetermined temperature and / or to a degree of deformation which determines and is decisive for the yield strength of the final product to obtain a strong deformation hardening which gives the final product a fully or partially multiple strength or higher tensile strength. limit, compared with the yield strength of the constituent substance, which original, low yield strength amounts to approx. 300 MPa and which elevated yield strength amounts to over 700 MPa or from an elevated level of approx. 700 MPa to a higher level of approx. 1000 MPa or higher, while the temperature at which the constituent metal blank is completely or partially cooled or the temperature T maintained wholly or partially during processing is -l96 ° C <= T <= 70 ° C to obtain a controlled, high hold - strength regardless of degree of deformation. Method according to claim 1, characterized in that the alloyed metal blank is formed in traditional machine types for stretch pressing or bending but with a modified tool to obtain a suitable deformation of the metal blank to raise its yield strength from an initial low yield strength to a final product as a whole or partially has a high yield strength; Method according to claim 1 or 2, characterized in that the alloyed metal blank is formed in traditional machine types for stretch pressing or stretch bending but with a modified and fully or partially temperature-controlled tool to obtain an off-A-adjusted temperature in relation to the deformation which occurs during stretch pressing. or the bending operation, _ for rrw / fl nm 5 v ~ 1 .... v '_ __, to raise its yield strength from an initially low yield strength to an end product which. in whole or in part has an increased yield strength. Method according to one of the preceding claims, characterized in that the stretch pressing or bending is carried out in two or more steps, whereby a stronger deformation hardening is obtained. Process according to one of the preceding claims, characterized in that the constituent is cooled in whole or in part to or kept at a controlled temperature range before and during processing in order to obtain a controlled, high strength regardless of degree of deformation. Process according to one of the preceding claims, characterized in that the finished product is cooled completely or partially or is kept at a controlled temperature in order to obtain a controlled increase in strength, regardless of the degree of deformation during processing. Process according to Claim 6, characterized in that the temperature at which the finished product is completely or partially cooled or the temperature maintained after processing is -196 ° C <= T <= 70 ° c. V