We carried out an experimental determination o f the mechanical properties and the low-cycle fa tigue parameters o f the high-strengthsteel SI 100Q. On the basis o f the fracture behavior during the fa tigue tests (the fracture surface was not in-plane for all the tested specimens) it can be concluded that the in v estig ated m aterial show s good fatigue strength. The modulus o f elasticity is, based on fa tigue tests, approximately 7.5% lower compared to the monotonie test. Because o f the low strain-hard ening exponent the cyclic softening o f the material is expected as a result o f fatigue loading.
A large number of experimental and theoretical studies have been conducted in the past examined that used a lot of time and costs. Then numerical simulation was carried out using the explicit non-linear finite element commercial software ANSYS/LS-DYNA as an alternative in the investigation of this paper [13-14]. In the simulation, the property of highstrengthsteel was found to be insensitive to the strain rate, which was consistent with the experimental result [15-16]. One of examined of thick-walled tubes absorber on high-strengthsteel and mild steel used to analyse the axial compression behaviour and energy absorption under an impact load . The hybrid model developed for to reduce weight and to increase strength with added some composite wrap. Some of past investigation of the axial crush performance of square hybrid-aluminium tube with filament wrap with various angles in the overlap between [+/- 30 0 ] and
Deep drawing is a sheet metal forming process that deforms a sheet metal of various shapes, called the blank, by the mechanical action of the punch . A typical deep drawing setup has the following parts: die, blank holder, punch and a blank. These parts are custom made for every deep drawing process based on the shape of the final product as well as the size of the blank. In our analysis we are making use of a circular blank. The die and the blank holder in this case is also circular. The punch in this case is made to be cylindrical to as the inner surface of the cup is also to be cylindrical [1-3]. The other important parameters necessary for deep drawing punch nose radius [13,14], die shoulder radius, blank holder force, punch speed, lubrication at various contact areas, blank thickness, punch force etc. In our analysis we are looking at the effect of punch nose radius, die shoulder radius, punch speed, blank diameter, blank holder force and lubrication at three interfaces; i.e. blank-blank holder, blank-die and blank-punch; on punch force and the stress distribution within the cup. The material for the deep drawing process, HighStrengthSteel has unusually high Ultimate Tensile Strength and Yield Strength value [4-7], hence increasing the chances of defects in the form of tearing and formation of wrinkles because of which final product quality is hindered.
There were two kinds of hydrogen in tested steel which could concentration at crack tips. One came from the cathodic hydrogen charging process. The other came from the corrosion process of the tested steel and tested solution. Hydrogen easily penetrated into the highstrengthsteel. As the increase of amount of hydrogen, the fracture surface ratio for steel increase. As CE proceeded under the repeated stress induced by CE attack, the cracks formed and propagated in fatigue like manner and resulted in the materials loss. Once cracks forming, those cracks were immediately filled with tested solution. Oxygen in the bulk solution was difficult to attain cracks tips by diffusion. So, reduction of water became the dominant cathodic reaction at crack tips. In aqueous solutions hydrogen atoms were generated electrochemically on the metal surface as a partial cathodic reaction in the corrosion process. The basic reactions were represented by:
Ultra HighStrengthSteel (UHSS) has been used in vehicle as it able to improved durability of the vehicle while reducing the mass. Laser cutting process has been an alternative choice in trimming of the UHSS to regain the final shape. This study is intended to study the effect of input parameters of Carbon Dioxide (CO 2 ) laser cutting
Abstract—Application of highstrengthsteel to stiffened girder of cable stayed bridge has the advantage of saving steel. However, it is generally known that the rotational capacity (ductility) of the highstrengthsteel is smaller than that of conventional steel, and application of highstrengthsteel can cause ductility problems in bridge. The rotational capacity of Beam-column is a crucial design parameter in stiffened girder of cable stayed bridge. In this study, highstrengthsteel with yield stress of 690MPa was used. The rotational capacity of the beam-column with highstrengthsteel was derived based on the stress-strain curve of highstrengthsteel. The theoretical model was verified through a series of experimental results and parametric study.
To achieve better structural performance, lesser damage along with minimum residual displacements is a main objective of earthquake resistant design. In ordinary steel reinforced concrete frames, chances of severe damage because of the lower strength of conventional steel are always present during strong earthquakes. With the invention of high-strengthsteel (HSS) it can be anticipated that its introduction in the structures will reduce the degree of damage against strong motions. However, its role towards improved seismic behavior needs to be investigated. In order to realize the response benefits against earthquakes three, six and ten story two bays bare concrete frames reinforced with HSS in columns are compared with the equivalent ordinary steel reinforced frames. Nonlinear static pushover and time history analysis are performed. The results reveal that the HSS reinforced frames have more lateral resistance with reduced residual displacements. Yielding at the column ends and probable story failure mechanisms are prevented. It is envisaged that efficient use of HSS in columns can yield safer structures. Further the potential danger of complete collapse can be reduced.
This study aims at evaluating the influence of fatigue strain range on hydrogen embrittlement of resulfurized highstrengthsteel on low-cycle fatigue tests. Previously, samples were charged with hydrogen (H) under different conditions. The presence of H causes softening effects on the cyclic behavior and a reduction in fatigue life of samples in comparison with uncharged samples. The explanation of this behavior is based on quantitative analyses of fracture surfaces as well as the microstructure by optical microscopy and scanning electron microscopy (SEM). Moreover, enthalpy changes, associated with the main H trapping sites, were determined by differential scanning calorimetry (DSC).This study has enhanced the understanding of the variables that most influence the fatigue behavior of this type of steel charged with hydrogen.
Abstract. In this paper, the influence of the toolset size on the formability of the highstrengthsteel formability was analyzed. The formability indexes include the thinning rate and springback. The toolset size analyzed in this study includes die corner size and punch corner size. To analyze the above relationship efficiently, the test design and the FE simulation were employed. At the same time, the optimization method was also used. The response surface method can be used to show the effect of the tool size on the formability clearly. It can be seen from the results that the springback increases with the increase of the radius of the toolset punch corner. And the effect of the radius of the toolset die corner shows slight effect on the springback. The radius of the toolset punch corner is more sensitive for the springback than the radius of the toolset die corner. The thinning increases with the decrease of the radius of the toolset punch corner. And the effect of the radius of the toolset die corner shows slight effect on the thinning, the thinning increases with the increase of the radius of the toolset die corner. In terms of the thinning, the punch corner is more sensitive than the die corner, especially when the radius of the toolset die corner is high.
The most common type of rebar is carbon steel, typically consisting of hot-rolled round bars with deformation patterns. Other readily available types include stainless steel, and composite sections made of glass fiber, carbon fiber, or basalt fiber. These alternate types tend to be more expensive or have lesser mechanical properties and are thus more often used in specialty construction where their physical characteristics fulfill a specific performance requirement that carbon steel does not provide. In practice, any material with sufficient tensile strength that is materially compatible with concrete could potentially be used to reinforce concrete, for example bamboo might be considered a viable substitution in regions where steel is not available. Steel and concrete have similar coefficients of thermal expansion, so a concrete structural member reinforced with steel will experience minimal stress as the temperature changes.
Experimental samples were taken from hot rolled steel having chemical compositions modified Si+Mn 0.8-1.3, Cr 0.8, Fe in balance). Two types of samples were prepared, namely blocks in size for standard hardening and tempering treatments and cylindrical bars of 50 mm and 60 mm in length for hardening at The heat treatments were digitally programmed electrical furnace. Table 1 lists the conducted and subsequent analyses, treated surfaces were ground using 120# or 240# abrasive papers to remove the softened layer by For the cylindrical samples, an 8 mm thick slice was taken from the middle length by ection using wire spark erosion technique under cooling, to minimize sample Vickers' hardness tests were carried out on ground sample surfaces being ground using 320# SiC indentation load was made from five indents. XRD and SEM observations were ground and polished following the standard metallographic preparation procedure and finished m diamond slurry. samples were etched using a 2% nital solution. The samples for TEM observations were first ground 150 microns thick, chemical polishing using 5 twinjet electropolishing device using a electrolyte composed of 7% perchloric acid and 93% glacial acetic acid at room temperature and a voltage
During all experiments, the visible cracks were marked at each load increment, and the different crack patterns were observed . Figures 5.33 and 5.34 show the crack patterns and the corresponding loads in kips for all the NWC and LWAC beams respectively. In general, the cracks developed in the pure moment zone were vertical and perpendicular to maximum tensile stress. Outside the constant moment region, the cracks propagated vertically and gradually curved afterwards due to increasing the load which had caused an increase in the shear stress. Furthermore; it can be noted that, the distribution of those cracks were almost symmetrical around the center of the beam. Smaller spacing between cracks was observed in all beams with fibres. Moreover, the trajectories of the beams containing less amount of flexural reinforcement appeared straighter than the others with higher longitudinal reinforcement ratio. The influence of the fibres on the shape of the crack pattern was not evident. On the other hand, the steel fibres had a clear iMPact on reducing the crack widths and increasing number of cracks for all beams. Moreover, the effect of steel fibres extended to slightly control the depth of cracks; where beams with no steel fibres presented a longer crack depth. Crack depth and the number of cracks at ultimate load within the constant moment zone are presented in the Table 5.6. The crack spacing is discussed in section 5.6.4 of this chapter.
AHSS offered the potential for improvement in vehicle crash performance without the extra weight increase because of their excellent strength and formability combinations. Currently, two types of advanced highstrength steels are being used in the automotive industry. One is the dual phase (DP) steel in which ferrite and martensite are the primary phases, and its mechanical properties are controlled by the martensite volume fraction and the ferrite grain size.
At least few methods of identification of J-C material constants may be found in the literature [5-7]. In this work the parameters A, B and n were determined from the true stress-strain curves obtained on the basis of quasi-static compression tests at room temperature. Firstly, the value of A constant was read from the graph as the yield strength. The value of B and n constants were determined by curve-fitting method adjusting the J- C curve (with strain rate hardening and temperature softening effects blocked) to the true stress-strain curve (for data describing the plastic part of the curve) by the least squares method. The curve fitting was performed in the MATLAB software. The correlation coefficient for the curves was R = 0.970.
Abstract—Concrete as one of the most used materials has been widely studied on its behavior, strength, etc. Concrete characteristic could be observed from the cracks that are commonly found in concrete. Micro crack is one of the types of the concrete cracks. The appearance of micro cracks in the mortar aggregate interface is caused by the inherent weakness of plain concrete. The weakness can be reduced by randomly spreading micro reinforcement into the mixture. This study aimed to investigate the effects on the use of steel fiber on the strength of concrete with planned characteristic compressive strength of 60 MPa. Mix Design on this study referred to ACI 211 4R-08 and 4 (four) varieties of the concrete mixture is used. The varieties in the mixture will be determine by steel fiber content on the mixture, which is 0%, 1%, 2% and 3% of concrete volume. The mechanical properties to be tested in this study are compressive test, split tensile test, shear test and flexural test were conducted. Result data obtained has been analysed and compared with a control specimen which is concrete with 0% steel fiber. The specimen planned characteristic compressive strength is not achieved. The largest compressive strength obtained from this test is 56.38 MPa obtained from concrete with a 2% steel fiber mixture. However, result data clearly shows percentage increases in compressive strength, split tensile strength, shear strength and flexural strength due to the increases of the used steel fiber on concrete, while the ductility effect start occurred on the use of 2% steel fiber.
There is general agreement in the experimental literature that the frictional work done does not signi ﬁ cantly in ﬂ uence the macroscopic temperature of the contact [35,36]. However, model- ling has indicated that high ﬂ ash temperatures ð 4 1000 1 C Þ may exist at asperities which would be expected to in ﬂ uence the evolution of the debris bed [37,38]. Experimental evidence and modelled predictions indicate that the resulting thermal ﬁ elds extend in the order of microns; it has been shown that over 90% of the frictional energy is dissipated within 5 μ m of the surface [39,40]. These surface ﬂ ash temperatures may be one of the reasons why oxide debris is observed at such low temperatures in any fretting contact; however, the effect of these ﬂ ash tempera- tures does not (in itself) explain the change in behaviour on raising the bulk temperature from room temperature to 85 1 C.
With the increasing development of welding technology, people require increasingly high welding performance, especially for hull highstrengthsteel requirements. Its performance directly affects the safety of the hull, and welds on the welding performance plays a vital role . In recent years, domestic and foreign scholars Zhang Lin et al  Gandin CA et al  using cellular automata method to simulate the alloy solidification process; Yan Weidong, Rappaz M. et al [13-14] using solidification temperature field simulation and grain The results show that the simulation process of the actual solidification process of the alloy is similar to that of the alloy, which proves that the simulation can approximate the grain structure solidification process. The results show that the solidification process of the alloy is similar to that of the solidification process. However, the simulation of the solidification process of the weld metal is not yet ripe. Based on the requirements of development, in order to study the solidification process of weld metal structure more deeply, a cellular automata model of weld metal structure solidification was established. It is an inevitable trend to improve the welding performance by using the computer simulation to study the solidification process of the weld.
In the case of using conventional steel bars in ﬂexural members, it has been shown that during the second stage of cracking, when steel strains are usually greater than 0.0005, the presence of existing primary cracks affects the formation of secondary cracks under increasing moment. Away from a primary crack, stresses are transferred by bond from the reinforcement to the concrete. If enough force is transferred from the steel at the crack to the concrete away from the crack, the strains that are developed may exceed the strain capacity or the tensile strength of the concrete at a section and another crack will form perpendicular to the reinforce- ment. Theoretically, the section at which secondary crack formation occurs is midway between existing cracks. This mechanism continues until the tensile forces developed through bond transfer are insufﬁcient to produce additional cracks. To compare and demonstrate the crack behavior of members reinforced with conventional steel bars and mem- bers reinforced with high-strengthsteel bars, a relatively complex material modeling in a simple direct tension model is used.
At 450°C, the relative residual compressive strength showed respectively a decrease of 56%, 65% and 35% for C2, CP2-2 and CS2-30 concretes while the porosity increase was respectively 5%, 7% and 6%. Until the temperature of 450°C, slight strength decrease was noticed when using polypropylene fibres (10% in compression for CP2-2). Relative residual strength of the concretes with or without polypropylene fibres were almost the same at the temperature of 600°C. The polypropylene fibres did not improve the residual mechanical properties of the concrete exposed to high temperature. The addition of steel fibres in the concrete limited the strength loss. The profit of relative residual strength was more important in tension. At 600°C, the profit of residual tensile strength was more than 30% for the CS2-40 concrete. In compression, the profit was 14%. For all the heating-cooling cycles, an improvement of relative residual strength in compression and tension was observed. An improvement was also noticed when studying the relative modulus of elasticity until the temperature of 450°C. At a minimum amount of 20 kg, the steel fibres improved the concrete residual mechanical properties. A conservation of the concrete residual ductility was also noticed.