scholarly journals Tailoring Heterogeneous Microstructure in a High-Strength Low-Alloy Steel for Enhanced Strength-Toughness Balance

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1983
Author(s):  
Yishuang Yu ◽  
Minliang Gao ◽  
Bin Hu ◽  
Chang Tian ◽  
Xuequan Rong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Annealing Temperature ◽  
Volume Fraction ◽  
Hsla Steel ◽  
High Strength ◽  
Back Stress ◽  
Heterogeneous Microstructure ◽  
Hsla Steels ◽  
Two Factors ◽  
Strength And Toughness

The attainment of both strength and toughness is of vital importance to most structural materials, although unfortunately they are generally mutually exclusive. Here, we report that simultaneous increases in strength and toughness in a high-strength low-alloy (HSLA) steel were achieved by tailoring the heterogeneous microstructure consisting of soft intercritical ferrite and hard martensite via intercritical heat treatment. The heterogeneous microstructure features were studied from the perspective of morphology and crystallography to uncover the effect on mechanical properties. Specifically, the volume fraction of martensite increased with increasing annealing temperature, which resulted in increased back stress and effective stress, and thereby an improved strength-ductility combination. The enrichment of carbon and alloying elements in the martensite was lowered with the increase in annealing temperature. As a result, the hardness difference between the intercritical ferrite and martensite was reduced. In addition, the globular reversed austenite preferentially grew into the adjacent austenite grain that held no Kurdjumov-Sachs (K-S) orientation relationship with it, which effectively refined the coarse prior austenite grains and increased the density of high angle grain boundaries. The synergy of these two factors contributed to the improved low-temperature toughness. This work demonstrates a strategy for designing heterostructured HSLA steels with superior mechanical properties.

Electron Microscope studies of the microstructures in as-quenched and aged HSLA-100 production steels and correlation with mechanical properties

1991 ◽  
Vol 49 ◽  
pp. 582-583
Author(s):  
A.G. Fox ◽  
V.R. Mattes ◽  
S. Mikalac ◽  
M.G. Vassilaros
Keyword(s):  
Mechanical Properties ◽  
High Strength ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Solid Solution Strengthening ◽  
Austenite Grain ◽  
Microstructure And Mechanical Properties ◽  
Hsla Steels ◽  
Carbonitride Precipitation ◽  
Strength And Toughness

Because of their excellent weldability, high strength low alloy (HSLA) ultra low carbon bainitic (ULCB) steels are finding increasing applications in ship and submarine construction. In order to achieve the required strength and toughness in ULCB HSLA steels it is necessary to control chemical composition and thermo-mechanical processing very carefully so that the desired microstructure and mechanical properties can be achieved. For instance HSLA 100 ULCB steel (nominal yield strength 100 ksi) used by the U.S. Navy in shipbuilding applications can derive its strength and toughness from the following sources:- (1) solid solution strengthening (2) small prior austenite grain size derived from niobium carbonitride precipitation at austenite grain boundaries (3) dislocation substructure and (4) from copper precipitates (in aged alloys). The object of the present work is to correlate the microstructure and mechanical properties of production batches of HSLA 100 in the quenched and aged conditions. Because many of the salient features of these microstructures are submicron in size it was found necessary to use SEM and TEM.

Effect of Alloying Elements on Mechanical Properties of High-Strength Low-Alloy Steel

2020 ◽  
Vol 1007 ◽  
pp. 41-46
Author(s):  
Ning Li ◽  
Wilasinee Kingkam ◽  
Zi Ming Bao ◽  
Ren Heng Han ◽  
Yao Huang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Hsla Steel ◽  
High Strength ◽  
Ultimate Tensile Stress ◽  
Vacuum Induction Furnace ◽  
Low Alloy Steels ◽  
Hsla Steels ◽  
Different Types ◽  
Calculation Results ◽  
Alloy Steels

In this study, the two types of high-strength low-alloy steels were melted and cast in a vacuum induction furnace. Phase transition temperature of HSLA steel was calculated by JMatPro software. The calculation results show that the two different types of HSLA steels which have equal phase proportions of ferrite and austenite at a temperature of approximately 820 and 800 °C in HSLA-I and HSLA-II, respectively. In addition, the effect of chemical composition on the microstructure and mechanical properties of steels were studied. The results indicate that the ultimate tensile stress value of HSLA-II samples was greater than the HSLA-I samples by about 35%, and the yield stress and breaking strength value of HSLA-II were higher than HSLA-I as well.

Influence of Rolling Temperature and Cooling Rate on Microstructure and Properties of Pipeline Steel Grades

2012 ◽  
Vol 706-709 ◽  
pp. 2710-2715 ◽  
Author(s):  
V. Carretero Olalla ◽  
Roumen H. Petrov ◽  
Philippe Thibaux ◽  
Martin Liebeherr ◽  
P. Gurla ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Process Parameters ◽  
Pipeline Steel ◽  
Hsla Steel ◽  
Rolling Temperature ◽  
Air Cooling ◽  
Strong Impact ◽  
Hsla Steels ◽  
Finish Rolling ◽  
Strength And Toughness

Thermo-mechanical control processing (TMCP) is a powerful tool for development of high strength low alloy (HSLA) steels. The understanding of the effect of process parameters on the microstructure of these steels is a key aspect for the optimization of their mechanical properties. The influence of the rolling temperatures and the cooling conditions on the texture, strength and toughness of HSLA steel was investigated. Two stage controlled rolling (roughing and finishing) was carried out on a laboratory rolling mill. Four different compositions were rolled by maintaining same roughing conditions but varying the process parameters of the finish rolling, namely, start finish rolling temperature (SFRT), finish rolling and cooling temperatures. Subsequent to rolling, two different cooling routes were used, namely, air-cooling (AC) and accelerated water cooling (ACC). For the ACC route, the plates were subsequently heat treated to simulate coiling. The microstructure and texture obtained before and after each TMCP schedule were characterized quantifying the phases, grain size and texture by means of EBSD and XRD and associated with the mechanical properties. It was found that SFRT has a strong impact on both strength and toughness if the material was air-cooled. Plates rolled at lower temperature showed better strength and toughness than ones rolled at high temperature in both air-cooling and ACC due to grain refinement. However, for the material that was processed through ACC and coiling simulation, the strength increased without any substantial effect on the toughness. These results provide an interesting insight on the industrial processing of HSLA steels.

Microstructure and Mechanical Properties of Medium Manganese Steel Plate with High Strength and Toughness

2016 ◽  
Vol 879 ◽  
pp. 2293-2299
Author(s):  
Ying Zou ◽  
Yun Bo Xu ◽  
Zhi Ping Hu ◽  
Xiao Long Yang ◽  
Xiao Dong Tan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Retained Austenite ◽  
Annealing Temperature ◽  
Steel Plate ◽  
Volume Fraction ◽  
Manganese Steel ◽  
Uniaxial Tensile ◽  
Medium Manganese Steel ◽  
Strength And Toughness

An intercritical annealing process was applied to a medium manganese steel plate (Fe-0.01C-5.3Mn-1.53Si) after the thermo-mechanical controlled processing (TMCP) and ultrafast cooling (UFC). The microstructures were observed by scanning electron microscopy (SEM) equipped with electron backscatter diffraction (EBSD), electron probe micro-analyzer (EPMA) and transmission electron microscopy (TEM). The retained austenite was measured by XRD and mechanical properties were measured by uniaxial tensile and impact tests. The influence of different annealing temperature was compared and the relationship between microstructures and mechanical properties was investigated. Results showed that the microstructures of the medium manganese steel plate were characterized by ultrafine grained lath-like ferrite and retained austenite and the excellent mechanical properties could be obtained at the annealing temperature of 640°C for 5 h. The volume fraction of the retained austenite reached up to 21%, which could significantly increase the elongation compared with the traditional steel plate. The mechanical property results revealed that the steel possessed adequate ultimate tensile strength of 865MPa and excellent impact energy of 121J (-20°C). The outstanding combination of strength and toughness indicates that the steel has a bright application prospect.

Influence of Grain Size on Corrosion Resistance of a HSLA Steel

2012 ◽  
Vol 557-559 ◽  
pp. 143-146 ◽  
Author(s):  
Yan Tang Chen ◽  
Kai Guang Zhang
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Corrosion Resistance ◽  
Mechanical Performance ◽  
Hsla Steel ◽  
High Strength ◽  
Corrosion Resistant ◽  
Hsla Steels ◽  
Mechanical Properties And Corrosion ◽  
Mn Steel

The mechanical performance, workability, weldability and corrosion resistance of structural high strength low alloy (HSLA) steels used in offshore engineering have been generally required. The effect of grain size on the corrosion resistant performance of a C-Mn structural steel has been investigated with stress on hunting a appropriate grain size to balance mechanical properties and corrosion resistant performance. The results showed that the C-Mn steel with grain size in 10～25μm scope provided expected mechanical properties and corrosion resistance.

scholarly journals Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1988
Author(s):  
Tibor Kvackaj ◽  
Jana Bidulská ◽  
Róbert Bidulský
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
High Strength Steel ◽  
Single Phase ◽  
Hsla Steel ◽  
High Strength ◽  
Strength Properties ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Steel Grades

This review paper concerns the development of the chemical compositions and controlled processes of rolling and cooling steels to increase their mechanical properties and reduce weight and production costs. The paper analyzes the basic differences among high-strength steel (HSS), advanced high-strength steel (AHSS) and ultra-high-strength steel (UHSS) depending on differences in their final microstructural components, chemical composition, alloying elements and strengthening contributions to determine strength and mechanical properties. HSS is characterized by a final single-phase structure with reduced perlite content, while AHSS has a final structure of two-phase to multiphase. UHSS is characterized by a single-phase or multiphase structure. The yield strength of the steels have the following value intervals: HSS, 180–550 MPa; AHSS, 260–900 MPa; UHSS, 600–960 MPa. In addition to strength properties, the ductility of these steel grades is also an important parameter. AHSS steel has the best ductility, followed by HSS and UHSS. Within the HSS steel group, high-strength low-alloy (HSLA) steel represents a special subgroup characterized by the use of microalloying elements for special strength and plastic properties. An important parameter determining the strength properties of these steels is the grain-size diameter of the final structure, which depends on the processing conditions of the previous austenitic structure. The influence of reheating temperatures (TReh) and the holding time at the reheating temperature (tReh) of C–Mn–Nb–V HSLA steel was investigated in detail. Mathematical equations describing changes in the diameter of austenite grain size (dγ), depending on reheating temperature and holding time, were derived by the authors. The coordinates of the point where normal grain growth turned abnormal was determined. These coordinates for testing steel are the reheating conditions TReh = 1060 °C, tReh = 1800 s at the diameter of austenite grain size dγ = 100 μm.

scholarly journals Properties of High-Strength Flowable Mortar Reinforced with Palm Fibers

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Eethar Thanon Dawood ◽  
Mahyuddin Ramli
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Test Results ◽  
Palm Fiber ◽  
Toughness Index ◽  
Strength And Toughness

This study was conducted to determine some physical and mechanical properties of high-strength flowable mortar reinforced with different percentages of palm fiber (0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, and 1.6% as volumetric fractions). The density, compressive strength, flexural strength, and toughness index were tested to determine the mechanical properties of this mortar. Test results illustrate that the inclusion of this fiber reduces the density of mortar. The use of 0.6% of palm fiber increases the compressive strength and flexural strength by about 15.1%, and 16%, respectively; besides, the toughness index (I5) of the high-strength flowable mortar has been significantly enhanced by the use of 1% and more of palm fiber.

High-Strength Steels Produced by Advanced Metallurgical Processes

1988 ◽  
Vol 4 (03) ◽  
pp. 169-185
Author(s):  
I. L. Stern ◽  
M. Wheatcroft ◽  
D. Y. Ku ◽  
R. F. Waite ◽  
W. Hanzalek
Keyword(s):  
Mechanical Properties ◽  
Heat Input ◽  
High Strength Steels ◽  
High Strength ◽  
Marine Industry ◽  
Metallurgical Processes ◽  
Strength And Toughness

Advanced metallurgical processes have made possible the manufacture of steels that—in addition to possessing high strength and toughness characteristics—maintain modest carbon equivalents for good weldabiiity results. These steels show promise of application in the marine industry because of their potential relative insensitivity to heat input and hardening and their potential for reduced requirements for preheat. This paper reviews several candidate steels, their composition, metallurgy and mechanical properties, and analyzes the results of a series of weldabiiity and toughness tests.

Microstructure Evolution and Mechanical Properties of 67GPa•% Grade Medium Manganese Steel

2021 ◽  
Vol 1035 ◽  
pp. 404-409
Author(s):  
Zhe Rui Zhang ◽  
Ren Bo Song ◽  
Nai Peng Zhou ◽  
Wei Feng Huo
Keyword(s):  
Mechanical Properties ◽  
Microstructure Evolution ◽  
Annealing Temperature ◽  
High Strength ◽  
Total Elongation ◽  
Manganese Steel ◽  
Experimental Steel ◽  
Medium Manganese Steel ◽  
Hot Rolled ◽  
Hot Rolled Steel

In this study, a new Fe-6Mn-4Al-0.4C high strength medium manganese hot rolled steel sheet was designed. The influence mechanism of the intercritical annealing (IA) temperature on microstructure evolution and mechanical properties of experimental steel were studied by SEM and XRD. The experimental steel was held for 30 minutes at 640°C, 680°C, 720°C, 760°C, 800°C, respectively. When the annealing temperature was 640°C, cementite particles precipitated between the austenite and ferrite phase boundary. As the annealing temperature increased, the cementite gradually dissolved and disappeared, the fraction of lamellar austenite increased significantly. When the annealing temperature is 800°C, the coarse equiaxed austenite and ferrite appeared. The yield strength (YS) decreased, the product of strength and elongation (PSE) and total elongation (TE) both increased first and then decreased, while the ultimate tensile strength (UTS) showed the opposite trend. The experimental steel exhibited excellent comprehensive mechanical properties after held at 760°C for 30 min. The UTS was 870 MPa, the YS was 703 MPa, and the TE was 77 %, the PSE was 67 GPa·%.

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