Strain Rate Dependence on the Dynamic Recrystallization Phenomena and Processing Map of Low Carbon Q690 V‐N and V‐N‐Cr Microalloyed High‐Strength Steels

2019 ◽  
Vol 90 (8) ◽  
pp. 1900114 ◽  
Author(s):  
Yue Liu ◽  
Lin‐Xiu Du ◽  
Ka‐Bin Tu ◽  
Hong‐Yan Wu ◽  
R. Devesh Kumar Misra
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Processing Map ◽  
High Strength Steels ◽  
High Strength ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Low Carbon

scholarly journals Static and dynamic response of ultra-fast annealed advanced high strength steels

2018 ◽  
Vol 183 ◽  
pp. 03017
Author(s):  
Florian Vercruysse ◽  
Felipe M. Castro Cerda ◽  
Roumen Petrov ◽  
Patricia Verleysen
Keyword(s):  
Strain Rate ◽  
Retained Austenite ◽  
High Strain ◽  
High Strength Steels ◽  
High Strength ◽  
Strain Rates ◽  
Low Carbon ◽  
Heating Rates ◽  
High Strain Rates ◽  
Advanced High Strength Steels

Ultra-fast annealing (UFA) is a viable alternative for processing of 3rd generation advanced high strength steels (AHSS). Use of heating rates up to 1000°C/s shows a significant grain refinement effect in low carbon steel (0.1 wt.%), and creates multiphase structures containing ferrite, martensite, bainite and retained austenite. This mixture of structural constituents is attributed to carbon gradients in the steel due to limited diffusional time during UFA treatment. Quasi-static (strain rate of 0.0033s-1) and dynamic (stain rate 600s-1) tensile tests showed that tensile strength of both conventional and UFA sample increases at high strain rates, whereas the elongation at fracture decreases. The ultrafast heated samples are less sensitive to deterioration of elongation at high strain rates then the conventionally heat treated ones. Based on metallographic studies was concluded that the presence of up to 5% of retained austenite together with a lower carbon martensite/bainite fraction are the main reason for the improved tensile properties. An extended stability of retained austenite towards higher strain values was observed in the high strain rate tests which is attributed to adiabatic heating. The extension of the transformation induced plasticity (TRIP) effect towards higher strain values allowed the UFA-samples to better preserve their deformation capacity resulting in expected better crashworthiness.

Influence of Temperature and Strain Rate on the Plastic Deformation of Two Commercial High Strength Al Alloys

2006 ◽  
Vol 519-521 ◽  
pp. 841-846 ◽  
Author(s):  
Magnus Johansson ◽  
Magnus Hörnqvist ◽  
Birger Karlsson
Keyword(s):  
Strain Rate ◽  
Temperature Sensitivity ◽  
Uniform Elongation ◽  
Rate Sensitivity ◽  
High Strength ◽  
Tensile Tests ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Strain Rates ◽  
Area Reduction

In the present study the influence of strain rate and temperature on the behaviour of two commercial aluminium alloys, 6063-T6 and 7030-T6, was investigated. Both alloys are high strength precipitation hardened alloys that are expected to have low strain rate and temperature sensitivity. Tensile tests were performed at room temperature at strain rates ranging from 10-4 to 102 s-1, and at -40°C and +60°C at strain rates of 10-4 and 10-1 s-1, due to equipment limitations. Both alloys showed low but positive strain rate sensitivity at all temperatures. Also the temperature sensitivity was low, showing negative values in all cases. The dependence of the flow stress on temperature was more pronounced than the strain rate dependence. The area reduction at fracture was higher in 6063 than 7030, although the uniform elongation was larger in 7030. 6063 showed almost no strain rate dependence of the ductility and a limited reduction with increased temperature. 7030 showed markedly increasing area reduction with increasing temperature and decreasing values with increasing strain rate. The energy absorption was higher in 7030 by a factor of approximately three.

scholarly journals Comprehensive Analysis of the Microstructure and Mechanical Properties of Friction-Stir-Welded Low-Carbon High-Strength Steels with Tensile Strengths Ranging from 590 MPa to 1.5 GPa

2021 ◽  
Vol 11 (12) ◽  
pp. 5728
Author(s):  
HyeonJeong You ◽  
Minjung Kang ◽  
Sung Yi ◽  
Soongkeun Hyun ◽  
Cheolhee Kim
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Joint Strength ◽  
Solid Phase ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
Friction Stir ◽  
Welding Processes

High-strength steels are being increasingly employed in the automotive industry, requiring efficient welding processes. This study analyzed the materials and mechanical properties of high-strength automotive steels with strengths ranging from 590 MPa to 1500 MPa, subjected to friction stir welding (FSW), which is a solid-phase welding process. The high-strength steels were hardened by a high fraction of martensite, and the welds were composed of a recrystallized zone (RZ), a partially recrystallized zone (PRZ), a tempered zone (TZ), and an unaffected base metal (BM). The RZ exhibited a higher hardness than the BM and was fully martensitic when the BM strength was 980 MPa or higher. When the BM strength was 780 MPa or higher, the PRZ and TZ softened owing to tempered martensitic formation and were the fracture locations in the tensile test, whereas BM fracture occurred in the tensile test of the 590 MPa steel weld. The joint strength, determined by the hardness and width of the softened zone, increased and then saturated with an increase in the BM strength. From the results, we can conclude that the thermal history and size of the PRZ and TZ should be controlled to enhance the joint strength of automotive steels.

Influence of the contact with friction on the deformation behavior of advanced high strength steels in the Nakajima test

2021 ◽  
pp. 030932472110212
Author(s):  
Mohammad Mehdi Kasaei ◽  
Marta C Oliveira
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Strain Rate ◽  
Contact Pressure ◽  
Deformation Behaviour ◽  
High Strength Steels ◽  
High Strength ◽  
Advanced High Strength Steels ◽  
Deformation Mechanics ◽  
Nakajima Test

This work presents a new understanding on the deformation mechanics involved in the Nakajima test, which is commonly used to determine the forming limit curve of sheet metals, and is focused on the interaction between the friction conditions and the deformation behaviour of a dual phase steel. The methodology is based on the finite element analysis of the Nakajima test, considering different values of the classic Coulomb friction coefficient, including a pressure-dependent model. The validity of the finite element model is examined through a comparison with experimental data. The results show that friction affects the location and strain path of the necking point by changing the strain rate distribution in the specimen. The strain localization alters the contact status from slip to stick at a portion of the contact area from the pole to the necking zone. This leads to the sharp increase of the strain rate at the necking point, as the punch rises further. The influence of the pressure-dependent friction coefficient on the deformation behaviour is very small, due to the uniform distribution of the contact pressure in the Nakajima test. Moreover, the low contact pressure range attained cannot properly replicate real contact condition in sheet metal forming processes of advanced high strength steels.

scholarly journals Reduced preload increases Mechanical Control (strain-rate dependence) of relaxation by modifying myosin kinetics

2021 ◽  
pp. 108909
Author(s):  
Brianna M. Schick ◽  
Hunter Dlugas ◽  
Teresa L. Czeiszperger ◽  
Alexandra R. Matus ◽  
Melissa J. Bukowski ◽  
...  
Keyword(s):  
Strain Rate ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Control Strain ◽  
Mechanical Control

scholarly journals Materials for Automotive Lightweighting

2019 ◽  
Vol 49 (1) ◽  
pp. 327-359 ◽  
Author(s):  
Alan Taub ◽  
Emmanuel De Moor ◽  
Alan Luo ◽  
David K. Matlock ◽  
John G. Speer ◽  
...  
Keyword(s):  
Galvanic Corrosion ◽  
Low Carbon Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
New Materials ◽  
Specific Strength ◽  
Advanced High Strength Steels ◽  
Strength And Stiffness ◽  
The Cost

Reducing the weight of automobiles is a major contributor to increased fuel economy. The baseline materials for vehicle construction, low-carbon steel and cast iron, are being replaced by materials with higher specific strength and stiffness: advanced high-strength steels, aluminum, magnesium, and polymer composites. The key challenge is to reduce the cost of manufacturing structures with these new materials. Maximizing the weight reduction requires optimized designs utilizing multimaterials in various forms. This use of mixed materials presents additional challenges in joining and preventing galvanic corrosion.

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