Hardening (metallurgy)

About: Hardening (metallurgy) is a research topic. Over the lifetime, 25584 publications have been published within this topic receiving 376012 citations.

Numerical techniques for cyclic plasticity at variable temperature

Abstract: A formulation of non‐linear kinematic hardening in plasticity is given, with a short description of the model properties under cyclic loading. A resolution algorithm based on the initial stress method is implemented in a two‐dimensional finite element code (ZEBULON). The procedure is tested on examples including mechanical and thermal loading. Some remarks are made on the maximum increment size, the relative efficiency of ‘radial return’ and ‘secant stiffness method’ is discussed. Finally, the possibilities of the model concerning ratchetting, cyclic hardening and softening are shown.

Fatigue Behavior of Stainless Steel 304L Including Strain Hardening, Prestraining, and Mean Stress Effects

Abstract: This paper discusses cyclic deformation and fatigue behaviors of stainless steel 304L and aluminum 7075-T6. Effects of loading sequence, mean strain or stress, and prestraining were investigated. The behavior of aluminum is shown not to be affected by preloading, whereas the behavior of stainless steel is greatly influenced by prior loading. Mean stress relaxation in strain control and ratcheting in load control and their influence on fatigue life are discussed. Some unusual mean strain test results are presented for SS304L, where in spite of mean stress relaxation fatigue lives were significantly longer than fully-reversed tests. Prestraining indicated no effect on either deformation or fatigue behavior of aluminum, while it induced considerable hardening in SS304L and led to different results on fatigue life, depending on the test control mode. Possible mechanisms for secondary hardening observed in some tests, characterized by a continuous increase in the stress response and leading to runout fatigue life, are also discussed. The Smith-Watson-Topper parameter was shown to correlate most of the experimental data for both materials under different loading condition.

Processing, microstructure, and properties of ternary high-strength Cu–Cr–Ag in situ composites

Abstract: A new class of ternary in situ metal matrix composites (MMCs) with high strength and high electrical conductivity consisting of heavily co-deformed Cu, Cr, and Ag is introduced. Three alloys are investigated in detail, namely, Cu‐10wt.%Cr‐3wt.%Ag, Cu‐10wt.%Cr‐1wt.%Ag, and Cu‐4.5wt.%Cr‐3wt.%Ag. The alloys were produced by inductive melting and chill casting. Because Cu‐Cr and Cu‐Cr‐Ag alloys with hypereutectic Cr content are less ductile than previously investigated Cu‐Nb, Cu‐Ag, and Cu‐Nb‐Ag alloys, special attention was placed on optimizing microstructure with respect to both strength and ductility using thermal and thermo-mechanical processing schemes. These included various combinations of swaging, heavy wire deformation (using different lubricants), solution annealing at different temperatures followed by quenching, and aging at different temperatures. Optimized processing allows one to attain maximum wire strains of h 8.48 (h ln(A0:A), A: wire cross-section). The wires have very high strength (for instance Cu‐10wt.%Cr‐3wt.%Ag: 1260 MPa at a strain of h8.48) and good electrical conductivity (62% of the conductivity of pure Cu (IACS) at a strain of h 2.5 after solution treatment). Up to wire strains of h:8.5 the strength is equal to that of Cu‐20wt.%Nb. The wire strength is much higher than predicted by the linear rule of mixtures. The investigation presents the evolution of microstructure during the various thermo-mechanical treatments and relates the results to the observed mechanical and electrical properties. The strength is discussed in terms of Hall‐Petch-type hardening. © 2000 Elsevier Science S.A. All rights reserved.

Simplified Inverse Method for Determining the Tensile Strain Capacity of Strain Hardening Cementitious Composites

Abstract: As emerging advanced construction materials, strain hardening cementitious composites (SHCCs) have seen increasing field applications recently to take advantage of its unique tensile strain hardening behavior, yet existing uniaxial tensile tests are relatively complicated and sometime difficult to implement, particularly for quality control purpose in field applications. This paper presents a new simple inverse method for quality control of tensile strain capacity by conducting beam bending test. It is shown through a theoretical model that the beam deflection from a flexural test can be linearly related to tensile strain capacity. A master curve relating this easily measured structural element property to material tensile strain capacity is constructed from parametric studies of a wide range of material tensile and compressive properties. This proposed method (UM method) has been validated with uniaxial tensile test results with reasonable agreement. In addition, this proposed method is also compared with the Japan Concrete Institute (JCI) method. Comparable accuracy is found, yet the present method is characterized with much simpler experiment setup requirement and data interpretation procedure. Therefore, it is expected that this proposed method can greatly simplify the quality control of SHCCs both in execution and interpretation phases, contributing to the wider acceptance of this type of new material in field applications.