scholarly journals WAAM-Fabricated Laminated Metal Composites

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1948
Author(s):  
Niclas Spalek ◽  
Jakob Brunow ◽  
Moritz Braun ◽  
Marcus Rutner
Keyword(s):  
Material Properties ◽  
High Strength Steel ◽  
Bulk Material ◽  
High Strength ◽  
Fatigue Loading ◽  
Metal Composites ◽  
Static Tensile ◽  
Ductile Steel ◽  
High Level ◽  
Wire Arc Additive Manufacturing

Laminated metal composites are a promising design since the hybrid design enables superior and tailorable material properties compared with bulk material. The article introduces for the first time, laminated metal composites consisting of multiple bilayers of alternating layers of ductile and high-strength steel processed by wire arc additive manufacturing (WAAM). The layup of the laminated metal composites is built up by alternating deposits made of ductile steel and high-strength steel type wires. Governing parameters in the fabrication process affecting the material properties, such as dilution, are discussed. Enhanced material properties of the laminated metal composites fabricated by WAAM are investigated under static tensile, impact and tension-tension high-cycle-fatigue loading and compared to the relating homogenous weld metal. Potential reasons for the retardation of crack propagation in laminated metal composites fabricated by WAAM compared to findings in roll-bonded laminated metal composites are discussed. WAAM is conducted by a collaborative robot providing a high level of flexibility in respect to geometry and scalability. Tailorability of material properties through WAAM-fabricated laminated metal composites adds an important layer of flexibility which has not been explored yet.

scholarly journals The effect of mean axial and torsional stresses on the fatigue strength of 34CrNiMo6 high strength steel

2019 ◽  
Vol 300 ◽  
pp. 16004
Author(s):  
Luis Pallarés-Santasmartas ◽  
Joseba Albizuri ◽  
Nelson Leguinagoicoa ◽  
Nicolas Saintier ◽  
Jonathan Merzeau
Keyword(s):  
High Strength Steel ◽  
Fatigue Behavior ◽  
High Strength ◽  
Fatigue Loading ◽  
Experimental Results ◽  
Shear Stresses ◽  
Mean Stress ◽  
Theoretical Predictions ◽  
Loading Case ◽  
Fracture Appearance

The present study consists of a theoretical, experimental and fractographic investigation of the effect of superimposed static axial and shear stresses on the high cycle fatigue behavior of a 34CrNiMo6 high strength steel in quenched and tempered condition (UTS = 1210 MPa), commonly employed in highly stressed mechanical components. The Haigh diagrams for the axial and torsional cases under different values of mean stress were obtained. In both cases, experimental results showed that increasing the mean stress gradually reduces the stress amplitude that the material can withstand without failure. The results of the present tests are compared with the theoretical predictions from Findley, based on the maximum damage critical plane; and the methods of Marin and Froustey, which are energetic based criterions. Froustey’s method shows the best agreement with experimental results for torsional fatigue with mean shear stresses, showing a non-conservative behaviour for the axial fatigue loading case. Macro-analyses and micro-analyses of specimen fracture appearance were conducted in order to obtain the fracture characteristics for different mean shear stress values under torsion fatigue loading.

scholarly journals Mechanical properties of wire and arc additively manufactured high-strength steel structures

2021 ◽  
Author(s):  
Johanna Müller ◽  
Jonas Hensel ◽  
Klaus Dilger
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Yield Strength ◽  
High Strength Steel ◽  
Energy Input ◽  
High Strength ◽  
Accelerated Cooling ◽  
Active Cooling ◽  
Wire Arc Additive Manufacturing ◽  
Interpass Temperature

AbstractAdditive manufacturing with steel opens up new possibilities for the construction sector. Especially direct energy deposition processes like DED-arc, also known as wire arc additive manufacturing (WAAM), is capable of manufacturing large structures with a high degree of geometric freedom, which makes the process suitable for the manufacturing of force flow-optimized steel nodes and spaceframes. By the use of high strength steel, the manufacturing times can be reduced since less material needs to be deposited. To keep the advantages of the high strength steel, the effect of thermal cycling during WAAM needs to be understood, since it influences the phase transformation, the resulting microstructure, and hence the mechanical properties of the material. In this study, the influences of energy input, interpass temperature, and cooling rate were investigated by welding thin walled samples. From each sample, microsections were analyzed, and tensile test and Charpy-V specimens were extracted and tested. The specimens with an interpass temperature of 200 °C, low energy input and applied active cooling showed a tensile strength of ~ 860–900 MPa, a yield strength of 700–780 MPa, and an elongation at fracture between 17 and 22%. The results showed the formation of martensite for specimens with high interpass temperatures which led to low yield and high tensile strengths (Rp0.2 = 520–590 MPa, Rm = 780–940 MPa) for the specimens without active cooling. At low interpass temperatures, the increase of the energy input led to a decrease of the tensile and the yield strength while the elongation at fracture as well as the Charpy impact energy increased. The formation of upper bainite due to the higher energy input can be avoided by accelerated cooling while martensite caused by high interpass temperatures need to be counteracted by heat treatment.

A Parametric Study on Buckling Response of High Strength Steel Pipes With Anisotropic Material Properties

2012 ◽  
Author(s):  
Ali Fathi ◽  
J. J. Roger Cheng
Keyword(s):  
Yield Strength ◽  
Material Properties ◽  
High Strength Steel ◽  
Transverse Direction ◽  
Kinematic Hardening ◽  
High Strength ◽  
Longitudinal Direction ◽  
Operating Pressure ◽  
Material Anisotropy ◽  
Hardening Material

Highly pressurized pipelines crossing harsh environments need to have two chief materials properties; they should have high strength in transverse direction to resist high operating pressers; and high deformability in the longitudinal direction to accommodate externally induced deformations. Pipeline producers try to deal with this dual demand in their high strength steel (HSS) linepipe products by enhancing the yield strength in the transverse direction and maintaining deformability in the longitudinal direction. This practice results in significant level of anisotropy in yielding and early plastic regions. The effects of material anisotropy on complex pipeline limit states such as local bucking is not fully understood. This paper presents the results of a numerical study on the effects of material anisotropy on the buckling response of HSS pipes. The effects of operating pressure, diameter-to-thickness ratio, material grade, strain hardening and the ratio of longitudinal-to-transversal yield strength were taken into account. Combined (isotropic-kinematic) hardening material modeling technique — previously introduced by the authors — was employed in this study. The results of this study are presented in several graphs showing the variation of the critical buckling strain versus the level of material anisotropy of HSS pipes with different geometry, material and operation conditions. These results provide an insight into the effects of material properties on the buckling resistance of pipes, especially when anisotropy is present.

Bond Strength and Damage of Long Rebar Anchored in HPC under Static and Fatigue Loading

2006 ◽  
Vol 324-325 ◽  
pp. 867-870 ◽  
Author(s):  
Jian Zhuang Xiao ◽  
Chuan Zeng Zhang ◽  
Horst Falkner
Keyword(s):  
Static Loading ◽  
High Strength Steel ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Fatigue Loading ◽  
Element Analysis ◽  
Bond Behaviour ◽  
Steel Bar ◽  
Reinforcement Bar

This paper presents an experimental study on the anchorage behaviour of long high-strength steel rebars embedded in high-performance concrete (HPC) under both static loading and fatigue loading. The HPC was designed as C60 with its cube compressive strength larger than 60 MPa, and the high-strength steel bar was adopted as HRB500 with its characteristic yield strength equals 500 MPa. Under 3×106 fatigue loading cycles and then followed by a monotonous static loading, the strain and the stress state of the reinforcement bar, and the bond stress between the concrete and the 700 mm-long bar were investigated. Based on the test results and the ANSYS finite element analysis, the bond behaviour between HPC and long high-strength steel bars is discussed.

Fatigue Analysis of Multi-Lap Spot Welding of High Strength Steel by Quasi Static Tensile- Shear Test

2007 ◽  
Vol 345-346 ◽  
pp. 251-254
Author(s):  
Su Rok Sin ◽  
Sung Mo Yang ◽  
Hyo Sun Yu ◽  
Chai Won Kim ◽  
Hee Yong Kang
Keyword(s):  
Fatigue Life ◽  
High Strength Steel ◽  
Shear Test ◽  
Welding Current ◽  
High Strength ◽  
Tensile Shear ◽  
Life Evaluation ◽  
Static Tensile ◽  
Fatigue Life Evaluation

The welding quality of spot weldment is an important factor that significantly affects the strength, stiffness, safety, and other performance characteristics of vehicles. Therefore, quality control and fatigue life evaluation of spot weldment are necessary processes. This paper presents a method for determining the fatigue life of multi-lap spot weldment of a high strength steel sheet. In this method, the fatigue life is estimated by using the lethargy coefficient, which is the total defect coefficient according to rupture stress and time obtained by the quasi static tensile-shear test. Also, in this study, we modified the lethargy coefficient by using the welding current. And, we define a specific lapping constant, which is a characteristic constant of 2 or 3 lap weldments. The fatigue life obtained by the fatigue estimate equation, which contains a specific lapping constant was compared and verified with an experimental value. And we analyzed the relation of lap number, welding current and fatigue life. This method can save processing time and cost for predicting the life cycle of a structure.

scholarly journals The effect of kinematic hardening on the fatigue behaviour of bent high strength steel

2021 ◽  
Author(s):  
Sanjay Gothivarekar ◽  
Sam Coppieters ◽  
Reza Talemi ◽  
Dimitri Debruyne
Keyword(s):  
High Strength Steel ◽  
Predictive Accuracy ◽  
Numerical Study ◽  
Kinematic Hardening ◽  
Kinematic Model ◽  
Dynamic Strength ◽  
High Strength ◽  
Fatigue Loading ◽  
Fatigue Behaviour ◽  
Forming Simulation

The integration of forming in the fatigue modelling of cold-formed components significantly improves the predictive accuracy of the estimated life. The current study investigated the fatigue behaviour of a bent specimen made from a 5 mm thick, S900MC high strength steel plate. Because of its superior static and dynamic strength, this grade is progressively used for hollow cold-formed sections in mobile applications. However, it exhibits a strong stress saturation as well as limited formability. In this regard, a finite element modelling framework was adopted from previous research and further developed to integrate bending in the fatigue modelling and life estimation procedure. However, this framework currently ignores the possible influence of kinematic hardening and associated Bauschinger effect. For this reason, a numerical study was performed that compares isotropic with kinematic hardening for this specific application. First, the characteristic behaviour of these models was verified in a virtual tension-compression test. Subsequently, they were implemented in forming simulation followed by fatigue loading. Herein, the stress-strain evolution was investigated and a multi-axial fatigue criteria was used to map the sensitivity of the estimated life to the type of hardening. In general, the stress that entered the fatigue calculation was at least 21% lower for the kinematic model. As a result, a significant increase of 65% was observed for the estimated fatigue life, yielding a better comparison with experimental data.

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