scholarly journals Underwater Shock Response of Circular HSLA Steel Plates

2000 ◽  
Vol 7 (4) ◽  
pp. 251-262 ◽  
Author(s):  
R. Rajendran ◽  
K. Narasimhan
Keyword(s):  
Hsla Steel ◽  
Underwater Explosion ◽  
High Strength ◽  
Steel Plates ◽  
Analytical Models ◽  
Second Phase ◽  
Electron Microscopic ◽  
Shock Response ◽  
Slant Fracture ◽  
Two Phases

Studies on shock response of circular plates subjected to underwater explosion is of interest to ship designers. Non-contact underwater explosion experiments were carried out on air backed circular High Strength Low Alloy (HSLA) steel plates of 4 mm thickness and 290 mm diameter. The experiments were carried out in two phases. In the first phase, strain gauges were fixed at intervals of 30 mm from the centre of the plate and strains were recorded for the shock intensity gradually increasing to yielding. Semi-analytical models were derived for the elastic strain prediction which showed good agreement with the experiments. Dynamic yield stress and the shock factor for yielding were established. In the second phase, individual plates were subjected to increasing shock severity until fracture and the apex bulge depth and the thickness strains were measured. Empirical models were derived to predict the plastic deformation which were validated through a fresh set of experiments. Analysis of the fractured surface by visual examination showed that there was slant fracture indicating ductile mode of failure and the same was corroborated by Scanning Electron Microscopic (SEM) examination.

Comparison between Modelled Influence of GMAW Parameters and Corresponding Mechanical Properties of Group 1 and 2 According to ISO/TR 15608 Steel T Joints

2021 ◽  
Vol 890 ◽  
pp. 17-24
Author(s):  
Aurel Valentin Bîrdeanu ◽  
Alin Constantin Murariu ◽  
Horia Florin Daşcău ◽  
Iuliana Duma
Keyword(s):  
Process Parameters ◽  
High Performance ◽  
Hsla Steel ◽  
Welding Process ◽  
High Strength ◽  
Industrial Applications ◽  
Steel Plates ◽  
Experimental Program ◽  
Welding Parameters ◽  
T Joints

Reproducibility in respect to welded structures realization is one of the main requirements for a wide variety of industrial applications. One of the international tendencies regarding the use of the steel is the replacing, in critical areas, of structural steels with high performance steel, e.g. with HSLA steels. The paper presents the results of a factorial designed experimental program focused on determining mathematical correlations between the GMAW process parameters for T joints of 4mm thick steel plates of structural (S235JR+AR according to SR EN 10025-2) and hot-rolled, high-strength low-alloy (HSLA) steel plates (S420MC according to EN 10025-4), respectively. A comparison between the obtained mathematical correlations that connect the welding parameters and the main mechanical characteristics is presented. The correlations can be used for applying the optimal combination of welding process parameters for realizing the T-joints of welded products.

scholarly journals HYDROLYTIC ENZYMES DURING SPERMATOGENESIS IN RAT AN ELECTRON MICROSCOPIC AND HISTOCHEMICAL STUDY

1968 ◽  
Vol 16 (4) ◽  
pp. 249-262 ◽  
Author(s):  
ZOLTAN POSALAKI ◽  
DEZSÖ SZABÓ ◽  
ERNÖ BÁCSI ◽  
ISTVÁN ÖKRÖS
Keyword(s):  
Endoplasmic Reticulum ◽  
Enzyme Activity ◽  
Acid Phosphatase ◽  
Sertoli Cells ◽  
Hydrolytic Enzymes ◽  
Appreciable Amount ◽  
Second Phase ◽  
Nonspecific Esterase ◽  
Electron Microscopic ◽  
Two Phases

The localization of lipids and the activities of nonspecific esterase, aryl sulfatase and acid phosphatase were studied in different stages of spermatogenesis in rats. In addition, the distribution of acid phosphatase activity was demonstrated electron histochemically. The spermatogenetic cycle was divided into two phases—corresponding to the first and the last four stages of Roosen-Runge-Giesel (RG) classification. Spermatids in the first phase contained abundant endoplasmic reticulum with rosette formation and well developed Golgi apparatus with numerous vesicles. They displayed high activity of hydrolytic enzymes but contained no appreciable amount of lipids. The Sertoli cells contained large lipid granules but showed minimal enzyme activity. During the second phase reduction of the cytoplasm of spermatids with fragmentation of the endoplasmic reticulum and Golgi lamellae, accumulation of lipids, aggregation of ribonucleo-protein particles, formation of residual bodies and marked decrease of enzyme activity were seen. The Sertoli cells contained large mitochondria, well developed endoplasmic reticulum and numerous dense bodies and revealed high activities of hydrolytic enzymes and rapid depletion of lipids. These ultrastructural and histochemical findings suggested an interaction between the Sertoli cells and the developing spermatids which probably contributed to the regulation of spermatogenesis.

On the Microstructure of Plate Steels for API-5L X120 Applications

2012 ◽  
Vol 706-709 ◽  
pp. 17-23 ◽  
Author(s):  
C. Isaac Garcia ◽  
Ming Jian Hua ◽  
X. Liang ◽  
P. Suikannen ◽  
Anthony J. DeArdo
Keyword(s):  
Hsla Steel ◽  
High Strength ◽  
Steel Plates ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Direct Quenching ◽  
Prior Austenite Grain Size ◽  
Optical Examination ◽  
Very High

The very high strength now achievable in low carbon HSLA steel plates is caused by the formation of bainite or martensite during the post-hot rolling cooling in interrupted direct quenching. Modern electron optical examination, especially FEG-SEM, has allowed the microstructural features such as packet, block and lath dimensions and crystallography to be quantitatively determined. Several recent studies have attempted to relate the strength and toughness to these features, with limited success. However, one observation is clear, these microstructural features scale with the prior-austenite grain size and state of recrystallization. The role of microalloying, beyond grain refinement, remains inconclusive. This paper will discuss these microstructures and suggest possible ways of further refining them.

As-Rolled High-Strength Plate Grades for Navy Shipbuilding Applications

1989 ◽  
Vol 5 (03) ◽  
pp. 200-205
Author(s):  
J. G. Speer ◽  
S. S. Hansen
Keyword(s):  
Microalloyed Steel ◽  
Hsla Steel ◽  
High Strength ◽  
Steel Plates ◽  
Low Carbon ◽  
Heat Treated

As-rolled high-strength, low-alloy (HSLA) steel plates offer a number of benefits compared with heat-treated plates, and this paper discusses laboratory and production experiments which have been conducted to develop as-rolled grades for high-strength Navy shipbuilding applications (for example, HSLA-65 and HSLA-80). A low-carbon niobium/vanadium microalloyed steel is shown to offer favorable combinations of strength, toughness, and weldability. The results indicate that an as-rolled grade which meets the current HSLA-80 strength and impact requirements can be produced in thicknesses up to approximately 19 mm (3/1 in.); HSLA-65 plates can be produced up to about 51 mm (2 in.) thick. This grade is generally weldable without preheat using HY-80 consumables.

scholarly journals Metallurgical Investigation of HSLA Steel Subjected to Underwater Explosion

1994 ◽  
Vol 1 (4) ◽  
pp. 385-394
Author(s):  
V. Bhujanga Rao ◽  
R. Rajendran ◽  
A.V. Jaykumar ◽  
K.H.B.S. Satyanarayana
Keyword(s):  
Hsla Steel ◽  
Underwater Explosion ◽  
Underwater Vehicles ◽  
Steel Plates ◽  
Ductile Deformation ◽  
Metallurgical Investigation ◽  
Adiabatic Shearing ◽  
Structural Applications ◽  
Mode Of Failure ◽  
Fractographic Examination

The metallurgical behaviour of HSLA steel subjected to underwater explosion is of prime importance because of its structural applications in underwater vehicles. HSLA steel plates 300 × 250 × 4 mm were subjected to single and repetitive shock loadings and the point of rupture was identified. Test plates exhibited mode-I (large ductile deformation) and mode-II (tensile tearing) macroscopic failures. Electron micrographic and fractographic examination showed that the initiation of fracture was due to adiabatic shearing and the microscopic mode of failure was ductile. Plates subjected to single shock showed an increase in residual hardness and at the point of rupture it was approximately one-third higher than the initial residual hardness.

scholarly journals CYTOPLASMIC FILAMENTS OF AMOEBA PROTEUS

1970 ◽  
Vol 46 (2) ◽  
pp. 267-289 ◽  
Author(s):  
Thomas D. Pollard ◽  
Susumu Ito
Keyword(s):  
Electron Microscopy ◽  
Normal Structure ◽  
Amoeba Proteus ◽  
Second Phase ◽  
Polarization Microscopy ◽  
Electron Microscopic ◽  
Thin Filaments ◽  
Cytoplasmic Filaments ◽  
Two Phases ◽  
Birefringent Fibrils

The role of filaments in consistency changes and movement in a motile cytoplasmic extract of Amoeba proteus was investigated by correlating light and electron microscopic observations with viscosity measurements. The extract is prepared by the method of Thompson and Wolpert (1963). At 0°C, this extract is nonmotile and similar in structure to ameba cytoplasm, consisting of groundplasm, vesicles, mitochondria, and a few 160 A filaments. The extract undergoes striking ATP-stimulated streaming when warmed to 22°C. Two phases of movement are distinguished. During the first phase, the apparent viscosity usually increases and numerous 50–70 A filaments appear in samples of the extract prepared for electron microscopy, suggesting that the increase in viscosity in caused, at least in part, by the formation of these thin filaments. During this initial phase of ATP-stimulated movement, these thin filaments are not detectable by phase-contrast or polarization microscopy, but later, in the second phase of movement, 70 A filaments aggregate to form birefringent microscopic fibrils. A preparation of pure groundplasm with no 160 A filaments or membranous organelles exhibits little or no ATP-stimulated movement, but 50–70 A filaments form and aggregate into birefringent fibrils. This observation and the structural relationship of the 70 A and the 160 A filaments in the motile extract suggest that both types of filaments may be required for movement. These two types of filaments, 50–70 A and 160 A, are also present in the cytoplasm of intact amebas. Fixed cells could not be used to study the distribution of these filaments during natural ameboid movement because of difficulties in preserving the normal structure of the ameba during preparation for electron microscopy.

Correlation between GMAW Parameters and Mechanical Properties of Hot-Rolled, High-Strength Low-Alloy (HSLA) Steel Butt Joints

2021 ◽  
Vol 890 ◽  
pp. 25-32
Author(s):  
Alin Constantin Murariu ◽  
Aurel Valentin Bîrdeanu
Keyword(s):  
Mechanical Properties ◽  
Welded Joints ◽  
Hsla Steel ◽  
Gas Metal Arc Welding ◽  
High Strength ◽  
Steel Plates ◽  
Experimental Program ◽  
Welding Parameters ◽  
Main Process ◽  
Hot Rolled

In all industrial fields, the product requirements are more and more demanding. HSLA steels are designed to provide higher atmospheric corrosion resistance and improved mechanical properties than structural steels. The paper presents the results of an experimental program based on factorial design, applied to predict the mechanical properties of butt-welded joints of S420MC and S460MC hot-rolled, high-strength low-alloy (HSLA) steel plates with 2mm, 4mm and 8mm thickness. Gas Metal Arc Welding (GMAW) was used and correlations between the main process parameters and the related mechanical properties of the welded joints were found. Obtained mathematical correlations can be exploited to provide optimal combination of welding parameters to fit the quality requirements of the end-users for envisaged welded product.

scholarly journals The Effect of Ca Content on the Formation Behavior of Inclusions in the Heat Affected Zone of Thick High-Strength Low-Alloy Steel Plates after Large Heat Input Weldings

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1328 ◽  
Author(s):  
Yinhui Zhang ◽  
Jian Yang ◽  
Longyun Xu ◽  
Yunlong Qiu ◽  
Guoguang Cheng ◽  
...  
Keyword(s):  
Heat Affected Zone ◽  
Heat Input ◽  
Hsla Steel ◽  
Solidus Temperature ◽  
High Strength ◽  
Steel Plates ◽  
Ca Addition ◽  
Formation Behavior ◽  
Large Heat ◽  
Molten Liquid

Ca deoxidation has been acknowledged recently as an effective oxide metallurgy technology that improves the toughness of the heat affected zone (HAZ) in high-strength low-alloy (HSLA) steel plates after large heat input welding. This paper describes the effect of Ca concentrations on the formation behavior of the non-metallic inclusions in the HAZs of a series of thick HSLA steel plates after large heat input welding at 400 kJ cm−1. The quantitative statistics on the inclusions show that the Ca addition significantly decreases the quantity of the pure MnS sulfide, but increases that of the complex oxysulfide. The pure MnS sulfide precipitates below the solidus temperature, while the complex oxysulfide forms in the molten liquid, leading to the core (oxide) and shell (sulfide) structure. The Ca addition proportionally improves the HAZ toughness of these thick HSLA steel plates, primarily owing to the positive effect of the complex oxysulfides on the refinement of the HAZ microstructure.

scholarly journals Compressive Deformation Behavior of Thick Micro-Alloyed HSLA Steel Plates at Elevated Temperatures

2017 ◽  
Vol 62 (2) ◽  
pp. 1191-1196
Author(s):  
J.-H. Lee ◽  
D.-O. Kim ◽  
K. Lee
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Elevated Temperatures ◽  
Hsla Steel ◽  
High Strength ◽  
Steel Plates ◽  
Compression Tests ◽  
Rate Dependent ◽  
Strength Constant

Abstract The hot deformation behavior of a heavy micro-alloyed high-strength low-alloy (HSLA) steel plate was studied by performing compression tests at elevated temperatures. The hot compression tests were carried out at temperatures from 923 K to 1,223 K with strain rates of 0.002 s−1 and 1.0 s−1. A long plateau region appeared for the 0.002 s−1 strain rate, and this was found to be an effect of the balancing between softening and hardening during deformation. For the 1.0 s−1 strain rate, the flow stress gradually increased after the yield point. The temperature and the strain rate-dependent parameters, such as the strain hardening coefficient (n), strength constant (K), and activation energy (Q), obtained from the flow stress curves were applied to the power law of plastic deformation. The constitutive model for flow stress can be expressed as σ = (39.8 ln (Z) – 716.6) · ε(−0.00955ln(Z) + 0.4930) for the 1.0 s−1 strain rate and σ = (19.9ln (Z) – 592.3) · ε(−0.00212ln(Z) + 0.1540) for the 0.002 s−1 strain rate.

The Thinking on Multiphase Materials

2007 ◽  
Vol 351 ◽  
pp. 233-237
Author(s):  
Jing Kun Guo ◽  
Hua Min Kou ◽  
Yu Bai Pan
Keyword(s):  
Shell Structure ◽  
Phase Particle ◽  
High Strength ◽  
Ceramic Matrix ◽  
Solid Particles ◽  
Second Phase ◽  
Two Phase ◽  
Multiphase Materials ◽  
Nano Scale ◽  
Two Phases

The main problems for multiphase materials are the even mixing and the bonding or reacting among two or more phases, as well as the states of their grain boundaries. The mixing of two phases is usually effective by using liquid medium. The technology of second phase coating for the original particles or so call nucleo-shell structure is a well approach for the even mixing. For ceramic matrix multiphase materials low sintering temperature is the effective way to avoid the occurring of reaction between different phases. The design of grain boundary and its stress is important for their bonding states. The thinking for above problems would be described briefly in this paper. The purpose of multiphase materials design is expected that every phase will be playing its role, combining together and then given out a comprehensive performances. So it is necessary to consider the following problems. 1. Even mixing Even mixing between each other material is important for multiphase materials. It’s the better when the processing is carrying on in the liquid state for the even mixing of two phase materials. Using physical or chemical method could be formed the fine solid particles with even dispersion of two or more phases materials. Usually it could be obtained nano-scale particles. The application of nano-technology is necessary. The nano-scale mixing of two phases materials would be greatly increased the contacting surface of each other particles without agglomeration. Of course, if one phase of material is fine solid particle which disperses in another phase of material solution, the even mixing of two phases is obtained similarly. Making a coating to other phase particle is a very good approach for the two phases even mixing. Coating process is attracting more and more attention in the preparation of composite materials mainly due to its predominance in the improvement of the uniformity for different phases [1]. The thickness of coating material determines the amount proportion of two phases which is able to be control. Two examples of so-called “nucleo-shell structure” will be introduced in the following parts. Cermet composites have been widely studied due to their potential for achieving higher toughness and reasonable strength compared with ceramic matrix. But except for numbered systems, such as Co/WC and Ni/TiN, few systems have reached the people’s expectation mainly for the poor wettability between metal and ceramic. Al/Al2O3 cermet is a low density and high strength material, and it has many potential and actual applications in military, industrial and consumer regions. To improve the dispersive uniformity of the two phases, coating aluminum with alumina may be a good candidate since such coatings not only stabilize aluminum dispersions but also make it possible to control inter-particle and particle-matrix interactions [2]. Figure1a-c shows the images

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