Steel for press hardening and press hardened part manufactured from such steel

US11319610B2 · kind B2 · utility

Assignee

• ArcelorMittal · LI

Inventors

• Pascal Drillet · Rozérieulles, FR
• Maria Poirier · Villers-Saint-Paul, FR
• Sujay Sarkar · Sherghati, IN

Key dates

• Filing date: Jun 10, 2016
• Grant date: May 3, 2022
• Expiry date: Dec 8, 2037

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/008
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A process for manufacturing a press hardened steel part is provided. The steel of the part has a chemical composition including, in weight: 0.062%≤C≤0.095%, 1.4%≤Mn≤1.9%, 0.2%≤Si≤0.5%, 0.020%≤Al≤0.070%, 0.02%≤Cr≤0.1%, wherein: 1.5%≤(C+Mn+Si+Cr)≤2.7%, 0.040%≤Nb≤0.060%, 3.4×N≤Ti≤8×N wherein: 0.044%≤(Nb+Ti)≤0.090%, 0.0005≤B≤0.004%, 0.001%≤N≤0.009%, 0.0005%≤S≤0.003%, 0.001%≤P≤0.020%, optionally: 0.0001%≤Ca≤0.003%, and the remainder being Fe and unavoidable impurities. The process includes hot forming the heated blank in the forming press so as to obtain a formed part and cooling the formed part at a cooling rate CR1 between 40 and 360°C/s in a temperature range from 750 to 450°C. and at a cooling rate CR2 between 15 to 150°C/s in a temperature range from 450°C to 250°C. wherein CR2<CR1.