Yielding- and fracture behaviour of ferritic steels in the transition region of quasistatic to dynamic loading

Hesse, Werner; Brüninghaus, K; Dahl, Winfried

doi:10.1016/0029-5493(86)90258-x

Cited by 8 publications

(3 citation statements)

References 6 publications

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“…A strong reciprocity between strain rate and temperature is characteristic for dynamic deformation according to the theory of thermal activated plastic deformation 15–25. Plastic deformation in metals is controlled by the interaction of dislocations and microstructural obstacles.…”

Section: Discussionmentioning

confidence: 99%

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Influence of Pre‐Straining and Bake Hardening on the Strain Rate Sensitivity of Automotive Sheet Steels

Larour

Dahmen

Bleck

2011

steel research int.

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The present investigation deals with the influence of pre-straining with or without bake hardening on the strain rate sensitivity of automotive sheet steels in typical crash conditions. The strain rate sensitivity m has been determined by means of dynamic tensile tests in the strain rate range 0.005-1000 s À1 and in the temperature range 233-373K. A bake hardening heat treatment at 170 8C for 20 min without pre-straining does not influence the m-value in comparison to the base material condition. A small pre-straining near plane strain condition, as commonly found in outer door panels, or a 10% uniaxial, plane strain and biaxial pre-straining, as typically used in formed automotive crash components, without bake hardening does not affect the m-value of sheet steels in comparison to the base material condition. Uniaxial 2% to 10% pre-straining, longitudinal or transverse to rolling direction with subsequent bake hardening, does not clearly change the m-value in comparison to the base material condition either. Small differences in the strain rate sensitivity behaviour are rather attributed to experimental scattering without real physical background.

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Section: Discussionmentioning

confidence: 99%

“…Combining equations (4) and (5) gives: Equation (6) can be simplified as proposed in 22–24: with m' strain rate exponent.…”

Section: Discussionmentioning

confidence: 99%

Influence of Pre‐Straining and Bake Hardening on the Strain Rate Sensitivity of Automotive Sheet Steels

Larour

Dahmen

Bleck

2011

steel research int.

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“…The applied external flow stress σ can be decomposed in two additive athermal σ i and thermally activated σ * components 19. The effective stress σ * is modeled, based on a simplified Kocks approach 1, 12, 30, 31. The yield strength R p0.2 is expressed as follows: …”

Section: Thermally Activated Deformationmentioning

confidence: 99%

Influence of Strain Rate, Temperature, Plastic Strain, and Microstructure on the Strain Rate Sensitivity of Automotive Sheet Steels

Larour

Bäumer

Dahmen

et al. 2012

steel research int.

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This work identifies the influence of strain rate, temperature, plastic strain, and microstructure on the strain rate sensitivity of automotive sheet steel grades in crash conditions. The strain rate sensitivity m has been determined by means of dynamic tensile tests in the strain rate range 10 À3 -200 s À1 and in the temperature range 233-373 K. The dynamic flow curves have been tested by means of servohydraulic tensile testing. The strain rate sensitivity decreases with increasing plastic strain due to a gradual exhausting of work hardening potential combined with adiabatic softening effects. The strain rate sensitivity is improved with decreasing temperature and increasing strain rate, according to the thermally activated deformation mechanism. The m-value is reduced with increasing strength level, this decrease being most pronounced for steels with a yield strength below 400 MPa. Solid solution alloying with manganese, silicon, and especially phosphorous elements lowers the strain rate sensitivity significantly. Second phase hardening with bainite and martensite as the second constituent in a ferritic matrix reduces the strain rate sensitivity of automotive sheet steels. A statistical modeling is proposed to correlate the m-value with the corresponding quasistatic tensile flow stress.

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Institute of Ferrous Metallurgy of the Technical University, RWTH, Aachen - IEHK - Part 4: Division of Materials Engineering

Dahl

1989

Steel Research

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Yielding- and fracture behaviour of ferritic steels in the transition region of quasistatic to dynamic loading

Cited by 8 publications

References 6 publications

Influence of Pre‐Straining and Bake Hardening on the Strain Rate Sensitivity of Automotive Sheet Steels

Influence of Pre‐Straining and Bake Hardening on the Strain Rate Sensitivity of Automotive Sheet Steels

Influence of Strain Rate, Temperature, Plastic Strain, and Microstructure on the Strain Rate Sensitivity of Automotive Sheet Steels

Institute of Ferrous Metallurgy of the Technical University, RWTH, Aachen - IEHK - Part 4: Division of Materials Engineering

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