Tensile stress-strain analysis of cold worked metals and steels and dual-phase steels
- PDF / 945,674 Bytes
- 8 Pages / 612 x 792 pts (letter) Page_size
- 31 Downloads / 169 Views
Hollomon analysis to uniaxially prestrained metals and steels and high strength, formable, dual-phase steels. The pure aluminum and copper metals and a series of plain carbon steels with carbon ranging from 0.10 to 1.05 pet were uniaxially prestrained by a given anaount of strain under ambient temperature. A plain carbon steel with carbon of 0.10 pet was utilized in manufacturing the dual-phase s t e e l s . An empirical analysis exhibited the limited applicability of the C-J analysis for the interpretation of the stress-strain relationship of uniaxially prestrained metals and steels. The C-J analysis was also less sensitive to changes in the deformation behavior of the dual-phase steels in which the ferrite matrix and the shape and distribution of the second phase martensite were altered by three heat treatments. The modified C-J analysis was most suitable for describing work-hardening of uniaxially prestrained metals and steels. This analysis revealed that the dual-phase steels deformed in two stages. The first stage was associated with defi)rmation of the ferrite matrix, and the second stage was associated with uniform straining of ferrite and martensite. The more generally used Hollomon curves deviated from linearity over all the uniform strain range regardless of the uniaxially prestrained metals and steels and dual-phase steels. Thus, the Hollomon parameters could not be assigned to an entire curve.
I.
INTRODUCTION
S I N C E the beginning of this century, considerable effort has been directed toward developing empirical laws which describe the work-hardening of polycrystalline metals and alloys, this being reflected by the derivation of the relationships from Ludwik, ~Hollomon, z Voce, 3 Swift-Krupkowski,4 and so forth. The parameters involved in these relationships, particularly the n-value, have been correlated to the changes in the microstructure and processes which occur during deformation.5 17They have also been used extensively to characterize the formability. ~s.19.20Furthermore, the relationship between the n-values and physical properties, e.g., fatigue behavior 'l and fracture toughness, 22 has been investigated. There has recently been an increasing demand for high strength materials, i.e.. cold worked metals and alloys and heat-treated steels from the energy-saving viewpoint. The technical significance of the work-hardening parameters in these high strength materials has also been reported. 2' 26 Unfortunately, in most cases, no correct values have been obtained for these high strength materials. One of the basic problems is that no attention is paid to the facts that these high strength materials have a high proportional limit and that they work-harden immediately without exhibiting the discontinuous-yield phenomenon in their stress-strain curves. The solution to the problem, therefore, is to develop an empirical formula in which the above modifications are made. The present work has been concerned with the applicability of the differential Crussard-Jaoul (C-J) analysis ('7 that a s s u m e s
Data Loading...
