Determination of true stress by tensile tests and hardness indentation tests

Keywords: Vickers indentation test, tensile test, plastic deformation In steel fastener design for the cold heading process, material characterization is very important stage for the traditional design and the studies of computer simulations. Generally tensile and compression tests are using for the material characterization. In last years hardness tests which are more convenient for the material characterization become center of interest by the researchers. In this study, it is researched that true stres-true strain curves can be obtained from Vickers hardness(indentation) tests or not. In the experimental work, true stress-true strain curves of steel fastener raw materials QSt32-3, 20MnB4, 30MnB3 and 42CrMo4 are obtained from tensile tests and, strength coefficients and strain hardening exponents are appointed from these curves. The relationship between true stres-true strain curves which are obtained from tensile tests and force-penetration depth curves obtained from Vickers indentation tests are also investigated. The values over 0,05 true strain get relations have agreeable results for every material used in experiments.