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Method for manufacturing high-strength steel sheet parts subject in use to fatigue stresses

a technology of high-strength steel and fatigue stress, which is applied in the direction of shaping tools, heat treatment equipment, furnaces, etc., to achieve the effects of reducing costs, reducing time, and high mechanical properties

Inactive Publication Date: 2013-12-12
SISTEMI SOSPENSIONI SPA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention provides a method for making steel sheets that can be used for things like vehicle suspension systems. This method makes these sheets have very strong mechanical properties, which are better than what can be achieved using regular steels that have to be heat treated. However, this method takes less time and is less expensive than using heat treatment steels.

Problems solved by technology

Moreover, the quenching and tempering treatment significantly changes the metallographic structure of the material and therefore requires special quality controls on the finished part to check the treatment has been correctly carried out.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0017]The manufacturing method according to the invention provides first of all for obtaining a part, such as for instance a vehicle suspension part, by means of one or more forming operations starting from a sheet of high-strength steel, in particular of high-strength low-alloy steel, such as for instance S600MC steel. The part may be for instance a cross-member for a twist-beam axle suspension, a longitudinal or transverse arm for an independent suspension or for an interconnected suspension, a frame for a front suspension, etc. In case of a tubular or profiled part, such as for instance a cross-member for a twist-beam axle suspension, the method will include first a tube making process (or, more generally, a shaping process) such as the one described in the introductory part of the description of the present application, so as to obtain a tube blank which will be then subjected to the outright forming process. The forming process may be performed by cold-stamping and / or by hydro-...

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Abstract

The manufacturing method comprises the steps of: carrying out one or more forming operations so as to give the desired geometry to the part; and subjecting the part thus formed to a single heat treatment having only a stress relieving treatment, which is preferably carried out at a temperature in the range from 530° C. to 580° C. for a time in the interval from 45 to 60 minutes and is followed by cooling of the part in air. By virtue of the formed part being subjected to a stress relieving heat treatment, the residual stress state due to the initial forming process and to the bead welding, if any, is eliminated or at least significantly reduced.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a “national phase” application based upon International Patent Application PCT / EP2012 / 052757 filed on Feb. 17, 2012, which, in turn, claims priority to Italian Patent Application TO2011A 000139 filed on Feb. 18, 2011.BACKGROUND OF INVENTION 1. Field of Invention[0002]The present invention relates to a method for manufacturing high-strength steel sheet parts suitable for fatigue applications, i.e. parts which are subject in use to fatigue stresses. In particular, although not exclusively, the invention relates to the manufacturing of high-strength steel sheet parts intended to be used on vehicle suspension systems. In the following description and claims, the expression “high-strength” is to be intended as referred to a steel having a yield strength greater than 420 MPa.[0003]2. Description of Related Art[0004]As is known, plastic forming operations carried out on steel sheets leave stress states in the material, the so...

Claims

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Application Information

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IPC IPC(8): B21D31/00
CPCB21D31/00B60G7/001B60G2206/722C21D1/30C21D8/0205C21D8/105C21D9/0068C21D9/08C21D9/46C21D9/50C21D8/02F16L9/02B21C37/08B23K2101/06
Inventor SANTINI, ANDREABORGNA, GUIDOMONCHIERO, PIERO
Owner SISTEMI SOSPENSIONI SPA