scholarly journals Plastic Instability in Medium-Carbon Tempered Martensite Steel

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4609
Author(s):  
Hai Qiu ◽  
Rintaro Ueji ◽  
Tadanobu Inoue ◽  
Yuuji Kimura
Keyword(s):  
Strain Curve ◽  
Local Strain ◽  
Plastic Instability ◽  
Medium Carbon Steel ◽  
Image Correlation ◽  
Tempered Martensite ◽  
Forming Process ◽  
Medium Carbon ◽  
Strain And Strain Rate ◽  
Metal Forming Process

Inhomogeneous plastic deformation damages the surface quality of a product in the metal forming process. Therefore, it is necessary to investigate the plastic instability of a metal. Tempered martensite is a common microstructure of medium-carbon steel. Plastic instability (Lüders phenomenon, Portevin-Le Châtelier phenomenon) in this phase was investigated by a uniaxial tension test performed at room temperature. The formation and propagation of a plastic band were analyzed via two-dimensional digital image correlation, and the strain and strain-rate fields were experimentally evaluated. The results obtained are as follows: (1) there was no clear yield plateau on the stress–strain curve; (2) Lüders phenomenon was present, but the Portevin-Le Châtelier phenomenon was not found; (3) in the Lüders deformation process, local strain distribution in tempered martensite is more complicated than that in ferrite.

The Yield Phenomena of a Medium Carbon Steel under Dynamic Loading

1949 ◽  
Vol 161 (1) ◽  
pp. 165-175 ◽  
Author(s):  
F. V. Warnock ◽  
D. B. C. Taylor
Keyword(s):  
Carbon Steel ◽  
Yield Stress ◽  
Testing Machine ◽  
Strain Curve ◽  
Medium Carbon Steel ◽  
Impact Testing ◽  
Lower Yield ◽  
Lower Yield Stress ◽  
Medium Carbon ◽  
True Shape

The paper describes dynamic tensile tests carried out on a medium carbon steel to determine the true shape of the stress-permanent strain curve for rapid straining. The variation of this curve with change in strain rate, and the progressive deformation of the steel are also studied. An impact testing machine was used, straining being carried out as a series of dynamic loadings, and the stress was measured by means of electrical resistance strain gauges attached directly to the specimens. Comparison is effected between dynamic and static stress-strain curves, the existence of a “dynamic upper yield stress” and a “dynamic lower yield stress” being shown, together with a difference in the rate of strain hardening for the two straining conditions. Non-uniform yielding of the metal is shown to be more pronounced for dynamic straining and, like static yielding, to be an integral part of the lower yield stress phenomenon. The manner in which all these factors are affected by normalizing the steel is shown. A special form of deformation of the steel peculiar to rapid straining is indicated. Theoretical and experimental facts are used to deduce a theory for the observed increases in stress, and the use of these dynamic stresses for design purposes is discussed.

Heat Treatment Effect on the Microstructural, Hardness and Tribological Behavior of A105 Medium Carbon Steel

2021 ◽  
Vol 406 ◽  
pp. 419-429
Author(s):  
Amel Gharbi ◽  
Khedidja Bouhamla ◽  
Oualid Ghelloudj ◽  
Chems Eddine Ramoul ◽  
Djamel Berdjane ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
High Hardness ◽  
Medium Carbon Steel ◽  
Low Friction ◽  
Tempered Martensite ◽  
Medium Carbon ◽  
Friction Resistance ◽  
Heat Treated ◽  
Low Wear

The present work is a contribution in investigating the effect of heat treatment on microstructure, hardness and friction wear of A105N steel. Samples of 25x25 mm2 cross-section and 15mm thickness have been prepared from the as-received material and then heat-treated. The samples were austenitized at 1050°C for 60 minutes followed by water quenching, then tempered at 500 and 700°C for 120 minutes. Microstructural changes and their effect on the wear resistance and hardness were investigated according to the applied heat treatments. The main results show that after quenching the structure is mostly composed of quenched martensite, which confers high hardness and friction resistance to the steel. While the tempered structure is composed of tempered martensite and ferrite. As the temperature rises to 700°C, the tempered martensite decreases and is fully transformed to ferrite and cementite. A good wear resistance expressed by a low friction coefficient and a low wear rate is achieved by tempering at 500°C.

The Combined Effects of Notches and Microstructure on the Performance of Medium Carbon Steel Breakaway Couplings

1994 ◽  
Vol 116 (1) ◽  
pp. 80-84
Author(s):  
D. P. Henkel ◽  
A. W. Pense
Keyword(s):  
Carbon Steel ◽  
Medium Carbon Steel ◽  
Structural Performance ◽  
Strength Increase ◽  
Combined Effects ◽  
Tempered Martensite ◽  
Average Strength ◽  
Medium Carbon ◽  
Aisi 4130 ◽  
Circumferential Notch

Combined effects of notches and microstructure on the structural performance of medium carbon steel breakaway couplings were discussed. Property troughs commonly associated with tempered martensite embrittlement were characterized as a function of temper for AISI 4130 and 4140 steel couplings. It was observed that a circumferential notch could change the fracture mode from ductile to brittle with no change in tempering condition. Notch-strengthening, a second significant effect, was also observed in similar couplings with an average strength increase of thirty percent. A critical assessment was made of the AASHTO specifications on breakaway couplings used for highway structures and of their interpretation by individual states.

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