scholarly journals Microstructural Stability of Extruded Mg-Mn-Ce Hollow Profiles with Weld Seams

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 547
Author(s):  
Felix Gensch ◽  
Sven Gall ◽  
Stefan Lechner ◽  
Christoph Fahrenson ◽  
Soeren Mueller
Keyword(s):  
Weld Seam ◽  
Strong Dependence ◽  
Heat Treatments ◽  
Fiber Texture ◽  
Extrusion Ratio ◽  
Microstructural Stability ◽  
Subsequent Aging ◽  
Porthole Die ◽  
Free Material ◽  
Weld Seams

Despite aluminum profiles, magnesium profiles have not been well developed due to the low formability. Furthermore, extruded magnesium profiles show a strong dependence on the mechanical properties, according to the loading direction. This is caused by a strong basal texture, which is directly dependent on the process parameters during the extrusion and the subsequent aging. Thus, the present paper focuses on the analysis of the microstructure and its evolution of extruded magnesium hollow profiles, which were subjected to a series of heat treatments at 475 °C up to one hour. The hollow profiles were extruded through a porthole die, thus, containing longitudinal weld seams. These were formed by material that underwent heavy shearing along the tool surface based on the friction conditions in the porthole die. Three extrusion ratios (ER = 8:1, ER = 16:1, ER = 30:1) were applied, resulting in three different wall thicknesses of the profiles. The microstructure of the profiles was analyzed using light-optical microscopy (LOM) and scanning electron microscopy (SEM) coupled with electron backscatter diffraction (EBSD). The analysis revealed no change of the microstructure of the profiles extruded at the two higher extrusion ratios within the time frame of the heat treatment. In contrast, the microstructure and, thus, the micro-texture of the profile with the lowest extrusion ratio (ER = 8:1) has been affected to a great extent. While only small changes in microstructure in the weld-free area were observed, the initial microstructure in the weld seam was transformed from fine recrystallized grains into a significantly bimodal microstructure mainly due to an abnormal grain growth (AGG). These changes were accompanied by a promotion of the rare-earth (RE) texture component for the weld-free material and a change of the overall texture from RE to a typical non-RE double fiber texture for the weld seam due to the intense AGG within the short-time heat treatments. In addition, the influence of the extrusion ratio on particle size and distribution as well as the character of the microstructure governing the behavior during heat treatments was analyzed and discussed.

Improving the tracking quality of the weld seam butt with V-form grooving by using Kalman filter and neural network

2021 ◽  
Author(s):  
Keyword(s):  
Neural Network ◽  
Kalman Filter ◽  
Colored Noise ◽  
Weld Seam ◽  
Vision Sensor ◽  
Laser Vision Sensor ◽  
Characteristic Points ◽  
Laser Vision ◽  
Weld Seams

An algorithm for tracking of the welded seams grooving by using a Kalman filter based on six characteristic points of the profile obtained using the RF627 laser vision sensor is proposed. In order to reduce the error in weld seams control, a multilayer neural network with a backpropagation algorithm is created to compensate for errors caused by colored noise when using the Kalman filter. Experimental results show that when the algorithm is applied, the error in tracking the trajectory of weld seams is reduced. Keywords tracking of weld seams; multilayer/multi-pass welding; Kalman filter; multilayer perceptron

The Creep Behaviors of Two Fine-grained XD TiAl Alloys Produced by Similar Heat Treatments

2004 ◽  
Vol 842 ◽  
Author(s):  
Hanliang Zhu ◽  
Dongyi Seo ◽  
Kouichi Maruyama ◽  
Peter Au
Keyword(s):  
Grain Boundaries ◽  
Creep Resistance ◽  
Lamellar Spacing ◽  
Heat Treatments ◽  
Tensile Creep ◽  
Microstructural Stability ◽  
Creep Tests ◽  
Tial Alloys ◽  
Fine Grained ◽  
Interlocked Grain

ABSTRACTThe microstructural characteristics and creep behavior of two fine-grained XD TiAl alloys, Ti-45Al and 47Al–2Nb–2Mn+0.8vol%TiB2 (at%), were investigated. A nearly lamellar structure (NL) and two kinds of fully lamellar (FL) structures in both alloys were prepared by selected heat treatments. The results of microstructural examination and tensile creep tests indicate that the 45XD alloy with a NL structure possesses an inferior creep resistance due to its coarse lamellar spacing and larger amount of equiaxed γ grains at the grain boundaries, whereas the same alloy in a FL condition with fine lamellar spacing lowers the minimum creep rates. Contrary to 45XD, the 47XD alloy with a NL structure exhibits the best creep resistance. However, 47XD with a FL structure with finer lamellar spacing shows inferior creep resistance. On the basis of microstructural deformation characteristics, it is suggested that the well-interlocked grain boundary and relatively coarse colony size in FL and NL 47XD inhibit sliding and microstructural degradation at the grain boundaries during creep deformation, resulting in better creep resistance. Therefore, good microstructural stability is essential for improving the creep resistance of these alloys.

Towards Predictive Control of Extrusion Weld Seams: An Integrated Approach

2009 ◽  
Vol 424 ◽  
pp. 9-17 ◽  
Author(s):  
Andrew J. den Bakker ◽  
Robert J. Werkhoven ◽  
W.H. Sillekens ◽  
Laurens Katgerman
Keyword(s):  
Weld Seam ◽  
Computer Modelling ◽  
Microstructural Analysis ◽  
Hot Extrusion ◽  
Integrated Approach ◽  
Plastic Instability ◽  
Experimental Results ◽  
Process Conditions ◽  
Local Conditions ◽  
Weld Seams

Longitudinal weld seams are an intrinsic feature in hollow extrusions produced with porthole dies. The formation of longitudinal weld seams is a solid bonding process, controlled by the local conditions in the extrusion die. Being the weakest areas within the extrusion cross section, it is desirable to achieve adequate properties of these weld seams. In our research, the concept of a weld seam integrity indicator as a means of quantifying bonding efficiency is introduced. The value of this indicator depends on a number of factors: the material flow within the die weld chambers, an adequate pressure level acting on the weld planes and finally the evolution of the metal microstructure. Optimisation of the welding conditions leads to a higher value of the weld seam integrity indicator and thus to improved weld seam properties. The objective of the research presented in this paper is to assess the feasibility of this concept. In lab-scale experiments, AA6060 and AA6082 aluminium alloy billets were formed into strips by means of the direct hot extrusion process. By utilising porthole dies a central longitudinal weld seam is formed. The effect of different geometries of the weld chamber and the processing conditions on the quality of the weld seam are investigated. Characterisation of these weld seams through mechanical testing, focusing on the ability of the weld seam area to accommodate plastic deformation following the onset of plastic instability, and microstructural analysis provides insight into bonding performance. The outcome of this characterisation provides a basis for an estimation of the weld seam indicator. Through computer modelling, the particular process conditions related to weld seam formation are calculated and correlated with the experimental results. The experimental results clearly demonstrate that weld seam formation is controlled by a combination of factors as described above. Inadequate fulfilment of these conditions, verified by the FE-simulations, is the cause of inferior weld seams, associated with low values of the weld seam integrity indicator. Through further elaboration of the concepts presented in this work, the weld seam integrity indicator is to be developed, with the future aim of predicting the weld seam performance through finite element simulations.

Low Cycle Fatigue Behavior of Welded Components: A New Approach — Experiments and Numerical Simulation

2012 ◽  
Author(s):  
Eliane Lang ◽  
Jürgen Rudolph ◽  
Thomas Beier ◽  
Michael Vormwald
Keyword(s):  
Fatigue Life ◽  
Thermal Loading ◽  
Weld Seam ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Strain Curve ◽  
Life Assessment ◽  
New Approach ◽  
Elastic Plastic ◽  
Weld Seams

Nuclear power plant components are often subjected to local plastic deformations due to low cycle operational thermal loading conditions. The fatigue behavior of weld seams is of particular interest in this context. Applicable design codes for fatigue life assessment use factors (e.g. Fatigue strength reduction factors – FSRF) within the simplified elastic-plastic or general elastic-plastic analysis in connection with the design fatigue curves for non-welded components. This way, the influence of the weld seam on the fatigue behavior is approximately considered. Emanating from this status quo ideas for a new approach considering the particularities of the fatigue behavior of the weld seam in more detail are developed. The proposed approach is based on material mechanics and constitutes a combination of experimental findings and numerical calculations in order to determine the local strains and the fatigue relevant influence of geometrical and metallurgical notches induced by the weld seam. Experiments on welded specimens provide the fatigue life as well as the stabilized cyclic stress-strain curve as relevant input parameters for the finite element analyses. The proposed model is capable of considering the exact geometry of the weld seam obtained by 3D scanning with very high resolution and the different material strengths due to the weld. The consideration of the principal influences on the fatigue behavior of weld seams paves the way to the application of established damage parameters such as PJ with the future objective to transfer the results also on arbitrary proportional and non-proportional loadings with variable amplitudes.

Development of an Ultrasonic Phased Array Testing System That Can Evaluate Quality of Weld Seam of High-Quality ERW Pipes

2012 ◽  
Author(s):  
Yutaka Matsui ◽  
Yukinori Iizuka ◽  
Masahito Suzuki ◽  
Eiichi Urahata ◽  
Tomohiro Inoue ◽  
...  
Keyword(s):  
Ultrasonic Testing ◽  
Phased Array ◽  
Weld Seam ◽  
Testing System ◽  
Beam Size ◽  
High Quality ◽  
Ultrasonic Phased Array ◽  
Weld Seams ◽  
Focused Beam

A high sensitivity ultrasonic testing system for inspection of the weld seam of ERW pipes was developed. The factors that affect the quality of the weld seam were investigated using an ultrasonic C-scan method with a focused probe and samples sliced from weld seams. As the result, it was found that a scattered-type penetrator consisting of micro oxides is a key factor in the quality of the weld seam. Absorbed energy in the Charpy impact test can be evaluated by the ultrasonic echo amplitude with the optimized focused beam size (about 1mm2) to detect the scattered-type penetrator. In order to evaluate the density of the scattered-type penetrator in weld seams with the optimum focused beam size for pipe, a point focused beam tandem method was developed by applying the ultrasonic phased array technique. The sensitivity of the developed method is 20dB higher for a standard artificial through drilled hole whose diameter is 1.6mm. A precise seam tracking system was also developed for application of the point focused beam tandem method to the actual ERW pipe manufacturing process. Since the allowance for applying the focused beam to the weld seam is very narrow, i.e., about 1mm, a circumference multi-point simultaneous receiving technique and thermal image-type seam detection technique were developed. The developed ultrasonic testing system has been in operation at the 24″ ERW mill at East Japan Works (Keihin District) of JFE Steel Corporation since March 2011. The combination of the ultrasonic testing system and an oxide control technique now contributes to production of high-performance, high-quality ERW pipe “Mighty Seam®” for use in frigid environments.

Non-Destructive Detection of Weld Seams in Extruded Aluminum Profiles

2013 ◽  
Vol 585 ◽  
pp. 103-110 ◽  
Author(s):  
Marcus Engelhardt ◽  
N. Grittner ◽  
Wilfried Reimche ◽  
Friedrich Wilhelm Bach
Keyword(s):  
Room Temperature ◽  
Current Sensor ◽  
Non Destructive Testing ◽  
Testing Methods ◽  
Destructive Testing ◽  
Porthole Die ◽  
Different Types ◽  
Aluminum Profiles ◽  
Non Destructive ◽  
Weld Seams

The present study focuses on the feasibility of non-destructive testing methods for the detection of transverse and longitudinal weld seams in extruded aluminum alloys. Two extrusion trials using billet on billet extrusion with a porthole die producing both types of weld seams were conducted. First, two billets of different types of alloy, AlMgSi1 (EN AW-6082) and AlZn4.5Mg1 (EN AW-7020), were extruded. In a second trial, two billets of AlZn4.5Mg1 were processed. The produced profiles were then tested by non-destructive testing using a tactile eddy current sensor as well as an encasing sensor at room temperature. The measured signals of both sensors were then evaluated and compared. Microstructural analyses have been carried out to correlate the occurrence of transverse and longitudinal weld seams with the results of the non-destructive testing.

Numerical and experimental study on the extrusion through a porthole die to produce a hollow magnesium profile with longitudinal weld seams

2008 ◽  
Vol 29 (6) ◽  
pp. 1190-1198 ◽  
Author(s):  
L. Li ◽  
H. Zhang ◽  
J. Zhou ◽  
J. Duszczyk ◽  
G.Y. Li ◽  
...  
Keyword(s):  
Experimental Study ◽  
Porthole Die ◽  
Weld Seams

scholarly journals The Effect of Extrusion Temperatures on Microstructure and Mechanical Properties of Mg-1.3Zn-0.5Ca (wt.%) Alloys

Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1228
Author(s):  
Honglin Zhang ◽  
Zhigang Xu ◽  
Laszlo J. Kecskes ◽  
Sergey Yarmolenko ◽  
Jagannathan Sankar
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Volume Fraction ◽  
Fiber Texture ◽  
Extrusion Ratio ◽  
Tensile Yield Strength ◽  
Microstructure And Mechanical Properties ◽  
Average Size

The present work mainly investigated the effect of extrusion temperatures on the microstructure and mechanical properties of Mg-1.3Zn-0.5Ca (wt.%) alloys. The alloys were subjected to extrusion at 300 °C, 350 °C, and 400 °C with an extrusion ratio of 9.37. The results demonstrated that both the average size and volume fraction of dynamic recrystallized (DRXed) grains increased with increasing extrusion temperature (DRXed fractions of 0.43, 0.61, and 0.97 for 300 °C, 350 °C, and 400 °C, respectively). Moreover, the as-extruded alloys exhibited a typical basal fiber texture. The alloy extruded at 300 °C had a microstructure composed of fine DRXed grains of ~1.54 µm and strongly textured elongated unDRXed grains. It also had an ultimate tensile strength (UTS) of 355 MPa, tensile yield strength (TYS) of 284 MPa, and an elongation (EL) of 5.7%. In contrast, after extrusion at 400 °C, the microstructure was almost completely DRXed with a greatly weakened texture, resulting in an improved EL of 15.1% and UTS of 274 MPa, TYS of 220 MPa. At the intermediate temperature of 350 °C, the alloy had a UTS of 298 MPa, TYS of 234 MPa, and EL of 12.8%.

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