Impact Toughness Of Specimens Research Articles

Effect of v-notch on impact toughness of fibre reinforced laminates produced by fff method

Effect of v-notch on impact toughness of fibre reinforced laminates produced by fff method

Influence of microstructure on crack initiation and propagation behavior in swaged tungsten heavy alloy during Charpy impact process

In this study, microstructure evolution and mechanical properties of 90W–7Ni–3Fe alloy under different swaging levels were systematically examined, with an emphasis on the relationship between the deformed microstructure and impact failure behavior. The deformed microstructure was characterized by scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) and transmission electron microscopy (TEM), and the impact toughness of specimens were tested using an instrumental Charpy impact machine. Microstructure observations showed that swaging significantly changed shape of W grains and increased the W contiguity. With increasing of deformation levels, microstructure changed from high density dislocations to subgrain structures. Furthermore, pronounced <101> texture is also found in the W phase at the highest deformation level. With increasing of deformation level, the tensile strength sharply increased from 950 to 1313 MPa and the tensile strain decreased from 27% to 9%. The impact test results indicate that the total impact absorbed energy consists of crack initiation energy and crack propagation energy. As deformation level increases, crack initiation energy decreased from 81 J to 23 J, while crack propagation energy first increased to 23 J and then decreased to 10 J. The decrease in crack initiation energy is mainly caused by the increase in dislocation density and W contiguity. The variation of crack propagation energy is relatively complex and influenced by several factors, such as W contiguity, the ability of the matrix phase to resist crack extension, the increased W cleavage event, and so on. Our study provides a deep insight into the relationships between microstructure and impact toughness of swaged tungsten heavy alloys.

Parameter optimization and mechanical properties of 42CrMo4 manufactured by laser powder bed fusion

To study the manufacturability and mechanical properties of a low alloy heat treatable medium carbon steel by additive manufacturing, 42CrMo4 (AISI4140) specimens were manufactured by laser powder bed fusion. Influences of processing parameters on relative density and crack density were investigated. Moreover, Charpy impact tests, microhardness, and tensile tests for specimens with and without preheating were also studied. Results showed that the primary defects in the microstructure of additively manufactured samples were the lack of fusion pores and microcracks. The variation of processing parameters influences the porosity and microcracks prominently. The impact toughness of specimens with preheating is around three times higher than specimens without preheating. However, post heat treatment for as-built specimens, such as tempering at different temperature ranges, did not improve the impact toughness further. The detailed fracture mechanism for the massive difference in the impact toughness was investigated.

Assessment of cold resistance and fracture mechanisms of metals obtained by 3D-printing

The cold resistance and fracture mechanisms of specimens made of 08Г2С and 07Х25Н13 steels obtained by 3D printing by electric arc surfacing at low temperatures are considered. It is determined, that with a decrease in temperature, the impact toughness of steels decreases. The impact toughness of specimens cut along the deposition direction is higher than that of specimens cut in the transverse direction. It is shown, that the brittle component prevails in the fracture of 08Г2С steel at temperatures below –40 °C, and the viscous component is observed in the fracture of 07Х25Н13 steel over the entire temperature range. A relationship is established between the fractal dimension of the fracture surface and the amount of the viscous component. Keywords: 3D printing, cold resistance, fracture mechanisms, ductile-brittle transition, fractal dimension. uru.40@mail.ru

Special Features of the Structure and Properties of Continuously Cast Billet from Steel R6M5

The structure, phase composition and impact toughness of specimens cut from different-thickness regions of a billet with cross section 160 × 160 mm from continuously cast high-speed steel R6M5 are studied. It is shown that the macro- and microstructure, phase composition, and process ductility of the continuously cast high-speed steel R6M5 are substantially higher than those of the steel obtained by traditional casting into molds.

Impact Toughness Anisotropy of TA31 Titanium Alloy Cylindrical Shell after Ring Rolling.

The impact toughness of a TA31 titanium alloy cylindrical shell was investigated systemically after ring rolling. The impact toughness of specimens with different notch orientations shows obvious anisotropy. The microstructure of the cylindrical shell and the impact fracture were characterized by an optical microscope and scanning electron microscope. The results show that cracks are easier to propagate in the equiaxed α phase than the elongated α phase. This is because the expanding cracking path in the equiaxed α phase is shorter than that in the elongated α phase, and thereby the cracks are easier to propagate in the equiaxed α phase than the elongated α phase. More specifically, the α phase on the RD-TD plane was obviously isotropic, which makes it easy for the cracks to propagate along α grains in the same direction. However, the α phase on the RD-ND plane has a layered characteristic, and the direction of the α phase varies from layer to layer, thus it requires higher energy for cracks to propagate across this layered α phase. Therefore, the cracks propagating in the same α phase orientation take easier than that in the layered α phase, so it has lower impact toughness.

Development of Wear Resistant Cast Steel and Its Study on Mechanical Properties

This paper mainly through the experimental study on the heat treatment process and mechanical properties of cast steel 35CrMnSiMo.According to the effect of alloy elements in design of a high-toughness abrasion-resistant cast steel, Cr, Mn, Si, as the main alloy elements, supplemented by a small amount of Mo, the casting molding, for hardness and impact toughness test of mechanical properties of experimental steel. The results show that, the as-cast 35CrMnSiMo by 880 °C, quenching for 20min then, the same quenching temperature, quenching hardness of materials is far greater than the oil quenching hardness. Water quenching hardness up to 25% higher than the oil quenching hardness, The impact toughness of specimen is inversely proportional to the contrast relationship Hardness.

Impact toughness of specimens cut out from the rollers of machines for continuous casting of blanks with fused layers

We study the impact toughness of three batches of Charpy specimens cut out from the rollers of continuous-casting machines. We determine the stages of dynamic deformation and fracture of bimetallic and monometallic specimens on the micro-, meso-, and macrolevels. With the help of scanning and transmission microscopies, we study the specific features of the micromechanisms of plastic deformation and fracture for steels with ferrite-pearlite (35G2) and ferrite-martensite (18Kh11MNFB) structures. In addition, we analyze their impact toughness with regard for these features.

Effect of out-of-furnace treatment on the chemical composition, mechanical properties, and microstructure of cast steel for the car-building industry

The mechanical properties, chemical composition, microstructure, and nonmetallic inclusions in steel 20GL subjected to out-of-furnace treatment in an AKP installation (furnace-ladle unit) and melted by the standard process are studied. The effect of the out-of-furnace treatment on the content of sulfur, on the contamination of the metal with nonmetallic inclusions, and on the impact toughness of specimens with U-and V-notches at a test temperature of + 20 and − 60°C is determined.

Microstructural characterization and impact toughness of intercritically annealed PM steels

Abstract In this study, atomized iron powder (Ancorsteel 1000) was mixed with 0.3 and 0.5 wt.% graphite powder. After sintering at 1120 °C, coarse and fine ferrite and martensite (dual phase) microstructures were produced through intercritical annealing heat treatment at different temperatures. Specimens with various martensite volume fraction and size were impact tested. Impact toughness increased with increasing martensite volume fraction and decreasing martensite size. It was also seen that the impact toughness of specimens with 0.3 wt.% graphite was higher than those specimens with 0.5 wt.% graphite. Furthermore, the impact toughness of intercritically annealed specimens with fine ferrite and martensite microstructure was compared with a specimen that was conventionally quenched and tempered after sintering. The results showed that especially for high intercritical annealing temperatures, the impact toughness of intercritically annealed specimens was higher than that of conventionally heat-treated ones.

Effect of strain aging on the strength and impact toughness of specimens with stress raisers

Effect of strain aging on the strength and impact toughness of specimens with stress raisers