Fraunhofer Institute for Machine Tools and Forming Technology
Fraunhofer Institute for Machine Tools and Forming Technology

Press hardening

The process of press hardening

One successful example for the manufacturing of super high strength car body parts is press hardening: a production process for hot forming of sheet metals. It is also called form hardening and combines shaping and heat treatment of sheet metal components in one single process step. The process involves inserting sheets or closed profiles, which have been heated beyond the austenitization temperature, into a cooled forming tool, where they are quenched. This heat treatment, which is integrated into the forming process, produces a martensitic structure that provides the press-hardened parts with an extremely high tensile strength of up to 1,800 MPa. Such components can be used in crash-relevant structures, for instance A-pillars and B-pillars, bumpers or sills, or they can be applied in the powertrain, for example as camshafts.

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  • Press hardened structural components
  • Press hardening of hollow profiles by hydroforming
  • Partial press hardening – generating graded component properties
  • Adapted thermal management in the forming tool
  • Tribological investigations
  • Energy-efficient process chains in hot sheet metal forming
  • Fast and graded heating of blanks
  • Intelligent press hardening

  • Use of super high strength materials in car bodies
  • Weight reduction of body-in-white
  • Reduction of steel required for car manufacturing
  • Reduction of fuel consumption and CO2 emissions during vehicle utilization
  • Development of reliable manufacturing strategies ready for mass production
  • Design of energy- and resource-efficient processes and process chains

Development of processes and technologies

  • Numerical and experimental feasibility studies
  • Component design
  • Analyses and design of forming and cutting processes
  • Numerical process simulations
  • Determination of optimum process parameters
  • Technological design of process chains
  • Evaluating energy and resource efficiency of processes and process chains
  • Process integration
  • Assessment of economic efficiency

Tool development

  • Calculation and design of hot forming tools
  • Numerical and experimental analysis of tool loads
  • Sensitivity analysis
  • Investigations on tool life

Determination of characteristic values

  • Determination of mechanical characteristic material values (stress-strain curve, flow curves, among others)
  • Determination of thermal characteristic material values (coefficient of heat transfer, analyses of dilatometry and calorimetry)
  • Metallography (investigations of macro and micro structures)

Machine technology

  • Multi-servopress MSP4-2000-2.5x1.2-400 (4 main drives, maximum compressive force 2,000 kN)
  • Hydraulic tryout press EHP4-1600 with multi-point die cushion and high-speed-system
  • Hydraulic double-column frame press, hydraulic double-column press, hydraulic C-stand press
  • Shape rolling system (up to 11 profiling frames,for metal sheets up to a width of 500 mm)
  • Hydroforming presses (closing forces 15,000 kN and 50,000 kN with gas compressor control module up to 120 MPa, active medium: nitrogen)
  • Induction units for medium and high frequency, each with 25 kW output power, and for medium frequency of 50 kW; magnetic forming system (105 kJ pulse energy)

Software

  • Design: Creo Elements / Pro (Pro / ENGINEER), CATIA V5, Autodesk®, Inventor®, AutoCAD®
  • Simulation: PAM-STAMP, DEFORM, LS-DYNA, AutoForm, simufact, Abaqus, ANSYS®

Testing technology

  • Tensile testing machine Zwick 1475 with optical strain rate measurement, high temperature capability of up to 1,100 °C and a maximum force of 100 kN
  • Tensile testing machine UTS 20 with vacuum / inert gas oven of up to 1,600 °C
  • Tempered strip draw tester with 90 °C bending angle
  • FLC test station (tool temperatures up to 500 °C)
  • Testing technology for determining thermal characteristic material values (dilatometer, calorimeter)
  • Test station for determining the coefficient of heat transfer between different materials at high surface pressures