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Micro-alloyed steels with optmised mechanical properties

Selection of micro-alloying additions combined with optimal forming and heat treatment conditions will be used to enhance end-use properties of steel products: forgings, sheets, strips and tubes.

The evolution of prices of raw materials dictates the application of new structural materials. Trends in manufacturing of steel products lead to production of high-strength non-alloyed and low-alloyed steels and to utilisation of micro-alloying and optimised heat treatment cycles. The properties of specially alloyed - micro-alloyed materials, which are typical materials in aviation and automotive industries, are today also required in structural steels in power generation, chemical and construction industries. Synergic effects in interdisciplinary applications and in the use of principles of the appropriate manufacturing and processing technologies can be expected to be found with manufacturers of forgings and castings (ZDAS, a. s., CZ), tubes (ZELEZIARNE PODBREZOVA, a. s., SK), sheets and strips (ACRONI, d. o. o., SLO) and in cooperation with research institutions (COMTES FHT, s. r. o., CZ, IMT Ljubljana, SLO) and higher education institutions (VSB TU Ostrava, CZ, VUT Kosice, SK). The activities related to development and optimisation of the micro-alloying methods will be focused on determination of the influence of micro-alloying elements on mechanical properties and on the microstructure of steels. The effects of the following single elements or their combinations and the influence of their concentrations will be examined: Al 0.0010 to 0.1000 wt. % B 0.0001 to 0.0100 wt. % Ca 0.0001 to 0.0050 wt. % N 0.0030 to 0.0250 wt. % Nb 0.0030 to 0.1000 wt. % Ti 0.0030 to 0.1500 wt. % V 0.0010 to 0.2000 wt. % Zr 0.0010 to 0.1500 wt. % KVZ 0.0001 to 0.0100 wt. % The joint effects of residual elements (Bi, Al, Sn, Sb, Pb, P, S) on mechanical properties of micro-alloyed steels will also be investigated. The activities related to designing and optimisation of chemical compositions, selection of micro-alloying additions and to forming and heat treatment will be focused on certain types of products and specific grades of steels. A: Open-die forgings (ZDAS, a.s., CZ) A1) HSLA (High Strength Low Alloyed Steels) grades F42 to F70 according to ASTM (American Society for Testing and Materials) and equivalent grades for forgings of flanges, fittings, valves and components for high pressure conveyance. The aim is to achieve high absorbed impact energy values > 50 J/cm2 at temperatures below -46 degrees Celsius while maintaining the prescribed high yield strength and ultimate strength of the material. A2) Carbon and low-alloyed steels with considerably higher than common values of mechanical properties across the cross-section of the forging produced by the effects of micro-alloying elements and the heat treatment. Research into the influence of micro-alloying elements on hardenability of structural steels for sizable forgings with nominal dimensions exceeding 250 mm. B: Hot-drawn or cold-drawn tubes (Zeleziarne Podbrezova, a.s., SK) Development of micro-alloyed steel tube manufacturing technology while achieving parameters in agreement with requirements for AHSS. B1) AHSS (Advanced High Strength Steels): DP (Dual Phase) - two-phase micro-alloyed steels with ferrite-martensite microstructure. CP (Complex Phase) - steels with ferrite-bainite-martensite microstructure. Optimisation of the micro-alloying parameters and advanced treatment methods for processing of AHSS-type steels aimed at achieving the parameters required by the group of customers buying HSLA tubes for use in the automotive industry, in particular: B2) HSLA - (High Strength Low Alloyed Steels): High-strength low-alloyed steels with 0.1 - 0.17% carbon showing significant influence of micro-alloying additions on their mechanical properties. The heat treatment produces material with yield strength of 400 to 700 MPa and ultimate tensile strength of 480 to 900 MPa. C: Sheet and strip (ACRONI, d.o.o., SLO) Development and designing of optimised alternatives of HSLA and AHSS steel compositions, steelmaking technology and treatment of thick sheet and strip. Keywords: high strength steel, micro-alloyed steel, forgings, tubes, sheet.
Acronym: 
MICROST
Project ID: 
4 092
Start date: 
01-01-2008
Project Duration: 
48months
Project costs: 
1 770 000.00€
Technological Area: 
Iron and Steel, Steelworks
Market Area: 
Motor Vehicles, Transportation Equipment and Parts

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