Characterisation of Residual Stresses by X-Ray Diffraction of Laser Welded AZ91 Magnesium Alloy

This study looks at the effect of laser welding on residual stresses in sheets of moulded magnesium alloy (AZ91). The modifications are significant even though they are localised along the weld line. The welding process produces a gradient of residual stresses from the weld line to the base metal and throughout the thickness of the weld zone. The distribution of these residual stresses has been qualitatively explained by the kinetics of cooling and by the nature of the multiphase material. Finally, it has been demonstrated that a pronounced crystallographic texture modifies local distribution of residual stresses. These results show that there is a complex coupling between the metallurgical, thermal and mechanical aspects generated by high power welding procedures.

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Fe-Based Amorphous/Nanocrystalline Coating on AZ91 Magnesium Alloy Substrate Deposited by Automatic High Velocity Arc Spraying

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.418-420.786 ◽

2011 ◽

Vol 418-420 ◽

pp. 786-791 ◽

Cited By ~ 1

Author(s):

Lin Lei Wang ◽

Xiu Bing Liang ◽

Shi Cheng Wei ◽

Yong Xiong Chen ◽

Wei Guo ◽

...

Keyword(s):

Electron Microscopy ◽

Elastic Modulus ◽

Magnesium Alloy ◽

High Velocity ◽

Arc Spraying ◽

Az91 Magnesium Alloy ◽

X Ray ◽

Nanocrystalline Coating ◽

High Velocity Arc Spraying ◽

Az91 Magnesium

An automatic high velocity arc spraying process was used to deposit a type of FeCrBSiMoNbW amorphous/nanocrystalline coating with substrate of AZ91 magnesium alloy. The microstructure of the coating was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDAX). The coating is about 250μm in thickness with low porosity and oxids. The results show that the microstructure of the coating can be classified into two regions, namely, a full amorphous phase region and homogeneous dispersion of α-Fe (Cr) nanocrystals with 30-80 nm in a residual amorphous region. Mechanical properties, such as nano-hardness, elastic modulus, were analyzed. The experimental results show that the coating has high nano-hardness and elastic modulus. The friction and wear experiments were operated on UMT-2 micro friction tester. The relative wear resistance of the FeCrBSiMoNbW coating is about 2 times higher than that of the conventional 3Cr13 coating under the same conditions. The main wear mechanism of the amorphous/nanocrystalline coating is the typical brittle spalling.

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X-Ray Fractography on Fatigue Fracture Surfaces of Mg-9mass%Al-1mass%Zn Alloy

Advances in X-ray Analysis ◽

10.1154/s0376030800022916 ◽

1995 ◽

Vol 39 ◽

pp. 491-498

Author(s):

Yoichi Kishi ◽

Shigenobu Takahashi ◽

Yukio Hirose

Keyword(s):

Residual Stress ◽

Magnesium Alloy ◽

Fracture Surface ◽

Fatigue Fracture ◽

Fracture Analysis ◽

Fatigue Fracture Surface ◽

Az91 Magnesium Alloy ◽

X Ray ◽

Fracture Surfaces ◽

Az91 Magnesium

X-ray diffraction observation of fracture surfaces provides fracture analysis with useful information on the mechanisms and mechanical conditions of fracturing. This method is called ” X-ray fractography “ and has been developed especially in Japan as a new engineering tool for fracture analysis.In the present paper, X-ray fractography is applied to fatigue fracture surfaces of AZ91 magnesium alloy which are used for machine parts. The X-ray stress constant, H,was first determined. The fatigue tests were conducted by using compact tension ( CT ) specimens of AZ91 magnesium alloy. The residual stress was measured on and beneath the fatigue fracture surface. The depth of the plastic zone left on the fatigue fracture surface was evaluated from the residual stress distribution. The results are discussed on the basis of fracture mechanics.

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Microstructure and Mechanical Properties of FeCrNiCoCu(B) High-Entropy Alloy Coatings

Materials Science Forum ◽

10.4028/www.scientific.net/msf.694.502 ◽

2011 ◽

Vol 694 ◽

pp. 502-507 ◽

Cited By ~ 1

Author(s):

Xiu Bing Liang ◽

Wei Guo ◽

Yong Xiong Chen ◽

Lin Lei Wang

Keyword(s):

Mechanical Properties ◽

Arc Spraying ◽

High Entropy Alloy ◽

X Ray Diffraction ◽

Az91 Magnesium Alloy ◽

X Ray ◽

High Entropy ◽

High Velocity Arc Spraying ◽

Az91 Magnesium ◽

Electronic Microscope

Two kinds of high-entropy alloy coatings of FeCrNiCoCu and FeCrNiCoCuB were deposited on AZ91 magnesium alloy substrate using high velocity arc spraying technology. Microstructure and general mechanical properties of the coatings were investigated with Scanning Electronic Microscope (SEM), X-Ray Diffraction instrument (XRD), microhardness tester and strength bond tester. The results show that the two kinds of coatings exhibit compact layered microstructure and the phase lattice type are both FCC, the microhardness of the FeCrNiCoCu and FeCrNiCoCuB coatings are 414HV0.1 and 342HV0.1 respectively, the bond strength are 36.9 MPa and 33.6 MPa respectively.

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Sealing of PEO Coated AZ91 Magnesium Alloy Using La-Based Solutions

International Journal of Corrosion ◽

10.1155/2017/5305218 ◽

2017 ◽

Vol 2017 ◽

pp. 1-13 ◽

Cited By ~ 12

Author(s):

Luca Pezzato ◽

Katya Brunelli ◽

Riccardo Babbolin ◽

Paolo Dolcet ◽

Manuele Dabalà

Keyword(s):

Corrosion Resistance ◽

Magnesium Alloy ◽

Photoelectron Spectroscopy ◽

Az91 Alloy ◽

Az91 Magnesium Alloy ◽

Corrosion Properties ◽

X Ray ◽

Different Temperatures ◽

Az91 Magnesium ◽

Sealing Treatment

In this work, solutions containing lanthanum salts were used for a post-treatment of sealing to increase the corrosion resistance of PEO coated AZ91 alloy. PEO coatings were produced on samples of AZ91 magnesium alloy using an alkaline solution containing sodium hydroxide, sodium phosphates, and sodium silicates. The sealing treatment was performed in a solution containing 12 g/L of La(NO3)3at pH 4 at different temperatures and for different treatment times. Potentiodynamic polarization test, an EIS test, showed that the sealing treatment with solution containing lanthanum nitrate caused a remarkable increase in the corrosion resistance. The corrosion behavior was correlated with the surface morphology and elemental composition evaluated with scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). In particular, the sealing treatment at 50°C for 30 min resulted in being the most promising to increase the corrosion properties of PEO treated samples because of the formation of a homogeneous sealing layer, mainly composed of La(OH)3.

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Effects of the drill flute number on drilling of a casted AZ91 magnesium alloy

Materials Testing ◽

10.3139/120.111315 ◽

2019 ◽

Vol 61 (3) ◽

pp. 260-266 ◽

Cited By ~ 3

Author(s):

Ugur Koklu ◽

Sezer Morkavuk ◽

Levent Urtekin

Keyword(s):

Magnesium Alloy ◽

Az91 Magnesium Alloy ◽

Az91 Magnesium

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X-ray Determination of Compressive Residual Stresses in Spring Steel Generated by High-Speed Water Quenching

Materials ◽

10.3390/ma12071154 ◽

2019 ◽

Vol 12 (7) ◽

pp. 1154

Author(s):

Diego E. Lozano ◽

George E. Totten ◽

Yaneth Bedolla-Gil ◽

Martha Guerrero-Mata ◽

Marcel Carpio ◽

...

Keyword(s):

Heat Treatment ◽

Residual Stresses ◽

High Speed ◽

Spring Steel ◽

X Ray Diffraction ◽

Laboratory Equipment ◽

X Ray ◽

Water Chamber ◽

Hardened Case ◽

Compressive Residual Stresses

Automotive components manufacturers use the 5160 steel in leaf and coil springs. The industrial heat treatment process consists in austenitizing followed by the oil quenching and tempering process. Typically, compressive residual stresses are induced by shot peening on the surface of automotive springs to bestow compressive residual stresses that improve the fatigue resistance and increase the service life of the parts after heat treatment. In this work, a high-speed quenching was used to achieve compressive residual stresses on the surface of AISI/SAE 5160 steel samples by producing high thermal gradients and interrupting the cooling in order to generate a case-core microstructure. A special laboratory equipment was designed and built, which uses water as the quenching media in a high-speed water chamber. The severity of the cooling was characterized with embedded thermocouples to obtain the cooling curves at different depths from the surface. Samples were cooled for various times to produce different hardened case depths. The microstructure of specimens was observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) was used to estimate the magnitude of residual stresses on the surface of the specimens. Compressive residual stresses at the surface and sub-surface of about −700 MPa were obtained.

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