Transverse Impact Toughness Research Articles

The Effects of Processing Parameters on the Structure and Mechanical Properties of Structural Pm Steels Containing Mn, Cr and Mo/ Wpływ Parametrów Wytwarzania Na Strukturę I Własności Mechaniczne Spiekanych Stali Konstrukcyjnych Zawierających Mn, Cr I Mo

Abstract The effects of processing parameters on the microstructure and mechanical properties of Fe-Mn-Cr- Mo-C PM steels are described. Pre-alloyed Astaloy CrM and Astaloy CrL, low-carbon ferromanganese and graphite powders were used as the starting materials. After pressing in rigid die, the compacts were conventionally and high temperature sintered at 1120 and 1250°C, respectively. Sintering was carried out for 60 minutes in atmospheres with different H2/N2 ratios. Cooling rate from sintering temperature was 65°C min-1 (convective cooling). The specimens were subsequently tempered at 200°C for 60 minutes in air. All specimens were tested for tensile strength (UTS), elongation (A), offset yield strength (R0:2), transverse rupture strength (TRS), impact toughness and apparent surface hardness (HV 30). After mechanical tests the microstructure of Fe-Mn-Cr-Mo-C PM steels was studied by optical microscopy. These investigations have shown that, by sintering in inexpensive and safe nitrogen-rich atmospheres, it is possible to achieve mechanical properties similar to those of specimens sintered in pure hydrogen and hydrogen-rich atmospheres.

Effects of RE on Inclusions and Mechanical Properties of H13 Die Steel

The effects of RE on the inclusions and the mechanical properties of H13 die steel were studied. The results show that the morphologies and sizes of inclusions in H13 steel are changed, and RE played a very good role of modifying inclusions. Fracture is changed from cleavage to ductile fracture by adding RE to H13 steel. And the mechanical properties of H13 steel are improved. In comparison with H13 steel without RE, the transverse impact toughness of H13 steel with RE is increased 33.61% at 0°C, and the tensile strength and reduction of area have been improved 10.74%, 6.3%, respectively.

Effects of Rare Earth on the Inclusions and Mechanical Properties of Austenitic Stainless Steel

The effects of rare earth metals on the inclusions and the mechanical properties of 21Cr11Ni austenitic steel were studied by scanning electron microscope (SEM) and energy spectrum analysis. The results show that the morphologies and sizes of inclusions in 21Cr11Ni stainless steel are changed, and rare earth played a very good role of modifying inclusions. The fracture mode of 21Cr11Ni stainless steel is typical cleavage fracture, but quasi-cleavage and dimple fracture after adding RE into the steel. The transverse impact toughness of 21Cr11Ni stainless steel is improved obviously by RE. In comparison with 21Cr11Ni stainless steel without RE, the transverse impact toughness of 21Cr11Ni stainless steel with RE is increased 25.33% at-40°C, and the room temperature strength are improved, the elongation and reduction of area have been improved 9.18%, 12.71% respectively.

Effect of Rare Earth on Microstructure and Mechanical Property of Ferrite Stainless Steel

The effect of rare earth element on structure and mechanical properties of the 430 ferrite stainless steel was studied by metallographic examination, scanning electron microscope (SEM), tensile test and impact test. The results show that the proper amount of RE can refine microstructure of 430 ferrite stainless steel. The fracture mode of 430 ferrite stainless steel is typical dimple fracture. 430 ferrite stainless steel containing 0.056% RE can improve its impact toughness and the high temperature strength, and the transverse impact toughness increases 37.2% at 253K respectively comparing with that of 430 ferrite stainless steel without RE. And at 1273K, the high temperature strength increases by 38.3% than that of 430 ferrite stainless steel without RE.

Effect of Rare Earth Metals on Microstructure and Impact Property of Duplex Stainless Steel

The effect of rare earth element on structure and mechanical properties of 2205 duplex stainless steel were studied by metallographic examination, scanning electron microscope (SEM), tensile test and impact test. The results show that the proper amount of rare earth can refine microstructure of 2205 duplex stainless steel. Fracture is changed from cleavage to ductile fracture by adding RE to 2205 duplex stainless steel. 2205 duplex stainless steel containing 0.05% RE can improve its impact toughness, and the transverse impact toughness is increased 15.56% at -20°C respectively comparing with that of 2205 duplex stainless steel without RE.

Effects of RE on Inclusions and Mechanical Properties of Weathering Steel

The effects of RE on the inclusions and the mechanical properties of 10PCuRE steel were studied. The results show that the morphologies and sizes of inclusions in 10PCuRE steel are changed, and RE played a very good role of modifying inclusions. Fracture is changed from cleavage to ductile fracture by adding RE to 10PCuRE steel. And the mechanical properties of 10PCuRE are improved. In comparison with 10PCuRE steel without RE, the transverse impact toughness of 10PCuRE steel with RE is increased 30.15% at -20°C, and the tensile strength and reduction of area have been improved 27.14%, 8.9%, respectively.

Effects of Ce on the Inclusions and Mechanical Properties of 2Cr13 Stainless Steel

The effects of rare earth metals on the inclusions and the mechanical properties of 2Cr13 stainless steel were studied by metallographic examination, scanning electron microscope (SEM) and energy spectrum analysis. The results show that the morphologies and sizes of inclusions in 2Cr13 stainless steel are changed, and rare earth metals played a very good role of modifying inclusions. The fracture mode of 2Cr13 stainless steel is typical cleavage fracture, but quasi-cleavage and dimple fracture after adding Ce into the steel, and the spherical inclusions of rare earth oxysulfide in the dimple are the main factors for this transformation. The transverse impact toughness of 2Cr13 stainless steel is improved obviously by Ce. In comparison with 2Cr13 stainless steel without Ce, the transverse impact toughness of 2Cr13 stainless steel with Ce is increased 54.55% at -40°C, and the room temperature strength are improved, the elongation and reduction of area have been improved 11.90%, 16.67 respectively.

Effects of Rare Earth Addition on the Inclusions and Mechanical Properties of 2205 Duplex Stainless Steel

The effects of rare earth metals on the inclusions and the mechanical properties of 2205 duplex stainless steel were studied by metallographic examination, scanning electron microscope (SEM) and energy spectrum analysis. The results show that the morphologies and sizes of non-metallic inclusions in 2205 duplex stainless steel are changed, and rare earth metals played a very good role of modifying inclusions. The fracture mode of 2205 duplex stainless steel is typical cleavage fracture, but quasi-cleavage and dimple fracture after adding RE into the steel, and the spherical inclusions of rare earth oxysulfide in the dimple are the main factors for this transformation. The transverse impact toughness of 2205 duplex stainless steel is improved obviously by RE. In comparison with 2205 duplex stainless steel without RE, the transverse impact toughness of 2205 duplex stainless steel with RE is increased 20.49% at -40°C, and the room temperature strength are improved, the elongation and reduction of area have been improved 11.67%, 24.55% respectively.

Influence of grain refining elements on mechanical properties of AISI 430 ferritic stainless steel weldments – Taguchi approach

The effect of grain refining elements such as copper, titanium and aluminum on transverse tensile strength, ductility, impact toughness, microhardness and austenite content of AISI 430 ferritic stainless steel welds through Gas Tungsten Arc Welding (GTAW) process in as-welded condition was studied. Taguchi method was used to optimize the weight percentage of copper, titanium and aluminum for maximizing the mechanical properties and austenite content in the weld region of ferritic stainless steel welds. Based on Taguchi orthogonal array the regression equations were developed for predicting the mechanical properties of ferritic stainless steel welds within the range of grain refining elements. The observed mechanical properties and austenite content have been correlated with microstructure and fracture features.

Effect of rare earth element yttrium addition on microstructures and properties of a 21Cr–11Ni austenitic heat-resistant stainless steel

In this comparative study, the microstructure and the mechanical properties of a 21Cr–11Ni austenitic heat-resistant stainless steel with and without addition of rare earth (RE) element yttrium have been investigated. The results show that a number of fine spherical yttrium-rich oxide particles are not uniformly distributed in the matrix of steel with yttrium; instead, they are aligned along the rolling direction. The grains surrounding the alignment are nearly one order of magnitude smaller than those farther away from the alignment. The approximate calculation results indirectly show that the grain refinement may be mainly attributed to the stimulation for nucleation of recrystallization rather than to pinning by particles. Furthermore, the alignment has resulted in significant loss in transverse impact toughness and tensile elongation at room temperature. There is a trough in the hot ductility–temperature curve, which is located between 973 and 1173K. The ductility trough of steel with yttrium becomes shallow within a certain temperature range, especially around 1073K, indicating that improvement on hot ductility is achieved by yttrium addition. The results may be attributed to the increase of grain boundary cohesion indicated by the effective improvement on intergranular failure tendency, and the inhibitory effect of yttrium on sulfur segregation to grain boundaries is believed to be an important cause.

PREDICTION OF MECHANICAL PROPERTIES OF 25CrMo48V SEAMLESS TUBE USING NEURAL NETWORK MODEL

In this investigation, a neural network model was established to predict mechanical properties of 25 CrMo 48 V seamless tubes. The sensitivity analysis was also performed to estimate the relative significance of each chemical composition in mechanical behavior of steel tubes. The results of this investigation show that there is a good agreement between experimental and predicted values indicating desirable validity of the model. Among those alloying elements, the elements of carbon, silicon and chromium tended to play a more important role in controlling both the yielding strength and the Charpy-V-Notch transverse impact toughness. In comparison, the impurities such as O , N , S and P have a relatively weak impact. More detailed dependences of mechanical properties on each chemical composition in isolation can be revealed using the established model. The well-trained neural network has a great potential in designing tough and ultrahigh-strength seamless tubes and modeling the on-line production parameters.

Effects of heat treatment on microstructure and mechanical properties of Fe-Co-Ni-Cr-Mo-C alloy

A kind of Fe-Co-Ni-Cr-Mo-C alloy was designed for valve seat use. The effects of the quenching temperature, tempering time and tempering temperature on the mechanical properties and microstructure of the alloy were investigated. The results show that the hardness decreases, while tensile strength (σb), transverse rupture strength (σbb) and impact toughness (K ic) increase after the alloy is quenched and tempered. The best complex property (σb, 446 MPa; σbb, 793 MPa; K ic, 2. 96 J/cm2) can be obtained when the alloy is quenched at 1100°C and tempered at 650°C. The results of X-ray diffraction and energy dispersive X-ray analysis (EDX) show that the major strengthening phases are carbides such as (Fe, Cr)7C3 and Fe2MoC. The obvious secondary hardening appears when the alloy is tempered at 550°C, which results from the precipitated carbides of Cr and Mo in the alloy from the matrix and the heat-resistant retained austenite.

Application of Barium-bearing Alloys in Steelmakig.

Based on the understanding of the physico-chemical properties of alkaline earth metals, an overview on the investigation of application of Ba-bearing alloys in steel is given in the paper. As calcium it is, barium has a strong affinity for oxygen and sulfur in steel; barium can also modify the inclusions in the steel. The barium-bearing inclusions easily float out from steel. The residual barium-bearing inclusions exist in spherical complex aluminates and randomly distribute in the steel. The mechanical properties such as fatigue, transverse impact toughness and anisotropic properties of steels treated with barium-bearing alloys are improved. The effect of calcium and barium on microstructure of steel is discussed. Some characteristics of production of barium-bearing alloys are also discussed.

Quantitative study of modification of sulphide inclusions by calcium and its effect on the impact toughness of a resulfurised alloy steel

In this paper, the mechanisms of the shape control of sulphide inclusions by calcium in a resulfurised alloy steel and the quantitative effect of the shape factor, the size and the quantity of sulphide inclusions on the transverse impact toughness are investigated. There are three different types of sulphide inclusions in the calcium‐treated resulfurised alloy steel, 58CrNiMnMoVSCa, namely elongated MnS, oval (Mn,Ca)S with and without any calcium aluminate nucleus. The proportion of the former is reduced while that of the two latter raised as the ratio of Ca/S in steel increases. The mechanisms of the shape control of sulphide inclusions by calcium are mainly due to its solid solution hardening effect. Besides, the calcium aluminate, existing as the nucleus of the oval (Mn,Ca)S, restricts the hot deformation of the sulphide inclusions and as a result, enhances further the shape control. Based on the solid solution effect of calcium on sulphide inclusions, the quantitative relationship between the shape factor Λ of sulphide inclusions and the ratio of Ca/S in steel at a hot forging reduction of 85 is developed. Finally, the quantitative relationship between the transverse impact toughness and the parameters of sulphide inclusions, namely the shape factor (Λ), the size (L) and the quantity (N) is also developed.

Cast gun tube by electroslag refining

Cast steels made by electroslag refining have been shown to be capable of meeting the mechanical-property specification for forged gun tubes. Not only were the transverse ductility and impact toughness well within the specified minima, but also the degree of directionality between the transverse and longitudinal properties was much lower than for conventionally cast and forged gun barrels. An 81 mm dia. mortar made from an as-cast ESR ingot stood up well under the high impulsive loads imposed during firing tests with charges of up to 143% of normal.

Production of high tensile Nb-V microalloyed, 20-40mm thick pipe steel plates through controlled rolling

The authors have examined a Nb- V microalloyed steel annealed at 1120°C and controlled rolled to 20-40 mm thick, the finish rolling temperatures TF ranging between 805° and 680°C. Mechanical properties were studied as well as microstructure. The steel plates showed high strength combined with good low-temperature toughness. The 40 mm plates met the requirements of grade X60, American Petroleum Institute Standard 5LX. The transverse impact toughness in the Charpy V-notch test was >50J at -60° C and the 50% fracture appearance transition temperature was -75°C. A distinct change in microstructure and mechanical properties occurred when the finish rolling temperature was reduced from about 800° to 680° C. Depending upon the temperature for the final passes, the following terms were adopted in the discussion of the results:(i) normal controlled rolling (TF > 800° C)(ii) slight thermomechanical rolling (TF =800°-750°C)(iii) heavy thermomechanical rolling (TF < 750°C).The third type of rolling produced the best strength-toughness combination.