Hole Expansion Performance of Three High Strength Steels: Observation of Room Temperature Strain Aging Phenomena

2021 ◽  
Author(s):  
Rachael Stewart ◽  
◽  
Robert Comstock ◽  
Keyword(s):  
Strain Aging ◽  
Room Temperature ◽  
High Strength Steels ◽  
High Strength ◽  
Hole Expansion ◽  
Aging Phenomena ◽  
Temperature Strain

Development of Low Carbon Microalloyed Ultra High Strength Steels

2005 ◽  
Vol 500-501 ◽  
pp. 551-558 ◽  
Author(s):  
A. Ghosh ◽  
Brajendra Mishra ◽  
Subrata Chatterjee
Keyword(s):  
Room Temperature ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
Hsla Steels ◽  
Finish Rolling ◽  
Ultra High Strength Steels ◽  
Rolling Temperatures ◽  
Carbon Microalloyed ◽  
Carbon Concentrations

In the present study HSLA steels of varying carbon concentrations, alloyed with Mn, Ni, Cr, Mo, Cu and micro-alloyed with Nb and Ti were subjected to different finish rolling temperatures from 850oC to 750oC in steps of 50oC. The microstructure of the steel predominantly shows martensite. Fine twins, strain induced precipitates in the martensite lath along with e-Cu precipitates are observed in the microstructure. With an increase in carbon content the strength value increases from 1200MPa UTS to 1700MPa UTS with a negligible reduction in elongation. Impact toughness values of 20-26 joules at room temperature and −40oC were obtained in sub-size samples.

Strain aging of high-strength steels

1969 ◽  
Vol 11 (10) ◽  
pp. 792-797
Author(s):  
N. G. Orekhov ◽  
L. M. Pevzner ◽  
A. S. Tarantova ◽  
S. T. Kishkin
Keyword(s):  
Strain Aging ◽  
High Strength Steels ◽  
High Strength

scholarly journals Microstructure–property relation and machine learning prediction of hole expansion capacity of high-strength steels

2021 ◽  
Author(s):  
Wei Li ◽  
Martina Vittorietti ◽  
Geurt Jongbloed ◽  
Jilt Sietsma
Keyword(s):  
Machine Learning ◽  
High Strength Steels ◽  
High Strength ◽  
Experimental Procedure ◽  
Hole Expansion ◽  
Metal Sheets ◽  
Chemical Content ◽  
Property Relation ◽  
Expansion Capacity ◽  
The Relationship

Abstract The relationship between microstructure features and mechanical properties plays an important role in the design of materials and improvement of properties. Hole expansion capacity plays a fundamental role in defining the formability of metal sheets. Due to the complexity of the experimental procedure of testing hole expansion capacity, where many influencing factors contribute to the resulting values, the relationship between microstructure features and hole expansion capacity and the complexity of this relation is not yet fully understood. In the present study, an experimental dataset containing the phase constituents of 55 microstructures as well as corresponding properties, such as hole expansion capacity and yield strength, is collected from the literature. Statistical analysis of these data is conducted with the focus on hole expansion capacity in relation to individual phases, combinations of phases and number of phases. In addition, different machine learning methods contribute to the prediction of hole expansion capacity based on both phase fractions and chemical content. Deep learning gives the best prediction accuracy of hole expansion capacity based on phase fractions and chemical composition. Meanwhile, the influence of different microstructure features on hole expansion capacity is revealed. Graphical abstract

scholarly journals Hole Expansion Characteristics of Ultra High Strength Steels

2014 ◽  
Vol 81 ◽  
pp. 718-723 ◽  
Author(s):  
Xinping Chen ◽  
Haoming Jiang ◽  
Zhenxiang Cui ◽  
Changwei Lian ◽  
Chao Lu
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Hole Expansion ◽  
Ultra High Strength Steels

Influence of Microstructure on Damage in Advanced High Strength Steels

2012 ◽  
Vol 706-709 ◽  
pp. 925-930 ◽  
Author(s):  
Frank Hisker ◽  
Richard Thiessen ◽  
Thomas Heller
Keyword(s):  
Work Hardening ◽  
Tensile Testing ◽  
Failure Modes ◽  
Tensile Elongation ◽  
High Strength Steels ◽  
High Strength ◽  
Body Parts ◽  
Hole Expansion ◽  
Advanced High Strength Steels ◽  
Dp Steels

AHSS (Advanced High Strength Steels) combine high strength and good ductility. Their outstanding forming and work-hardening behavior predestines these steels for fabrication of strength relevant structural elements and automobile body parts. To characterize a material, not only tensile, but also hole-expansion and bending behavior are important and help predict the stretch-flange-formability. In this study, detailed analyses of the correlation between these three tests and the damage mechanisms during forming have been performed for selected steels. The results show that for AHSS one should differentiate between “local” and “global” failure. Furthermore, not only are certain materials more sensitive to local or global damage, but also various testing methods tend to provoke either local or global damage. Tensile testing provokes global failure whereas hole-expansion tends to induce local failure. A specimen fails during bending with a mixture of local and global modes. These failure modes are strongly attributed to the microstructure. DP-steels yield high elongation during tensile testing and poorer hole-expansion values. High-resolution EBSD has revealed that the microstructure of DP-steels is sensitive to localized damage, which is compensated by work-hardening around damaged regions and thus shifts the loading to un-hardened regions. This makes DP-microstructures well-suited to tensile loading but sensitive to hole-expansion. CP-steels of comparable strength show poorer tensile elongation and higher hole-expansion ratios due to a microstructure which is not sensitive to localized failure (but has limited capacity for work-hardening). The failure mode in TRIP-steels exhibits a similar character as in DP-steels, but only after the martensitic transformation of retained austenite.

Rate Controlling Steps of SCC of High Strength Steels

CORROSION ◽  
1979 ◽  
Vol 35 (9) ◽  
pp. 397-402 ◽  
Author(s):  
B. STELLWAG ◽  
H. KAESCHE
Keyword(s):  
Stress Intensity ◽  
Crack Growth ◽  
Room Temperature ◽  
High Strength Steels ◽  
High Strength ◽  
Intensity Curve ◽  
Plateau Region ◽  
The Common ◽  
Cracking Process ◽  
Emission Studies

Abstract Stress corrosion crack velocities have been measured for a high strength steel in 0.5N NaCI solution at room temperature without potentiostatic control. Changing the strength level of the steel alters the shape of the SCC velocity vs stress intensity curve distinctly. With increasing strength, the common plateau region (so called stage II) disappears, and SCC velocity becomes exponentially dependent on stress intensity. Additional experiments (acoustic emission studies, crack growth incubation measurements, load change tests, fractography) confirm the current understanding, that absorbed hydrogen is the damaging species. The results can be well interpreted by assuming that lattice decohesion of the metallic bonds by absorbed hydrogen is a fundamental feature of the cracking process. Conclusions can be drawn as to the rate controlling steps of crack growth.

Effect of Prestrain at Elevated Temperature on the Fracture Behavior of High Strength Steels

1983 ◽  
Vol 105 (1) ◽  
pp. 16-20 ◽  
Author(s):  
K. Satoh ◽  
M. Toyoda ◽  
Y. Mutoh
Keyword(s):  
Elevated Temperature ◽  
Cleavage Fracture ◽  
Fracture Mechanism ◽  
Strain Aging ◽  
Fracture Behavior ◽  
Present Report ◽  
High Strength Steels ◽  
High Strength ◽  
Fracture Initiation ◽  
Initiation And Propagation

It is well known that fracture initiation behavior is influenced by weld thermal straining. In the present report, attention is focused on the influence of weld thermal straining on the fracture mechanism. The influence of prestrain at elevated temperature or strain-aging on the initiation and propagation behaviors of ductile and cleavage fracture in KD32 and HT80 steels is investigated. A relationship between the increase in the lowest temperature at which a tear dimple region can be observed (Ti) or the decrease in stretched zone width and the increase in hardness at the notch tip is found.

Sign in / Sign up

Export Citation Format

Share Document