Vacuum Annealing of Welded Joints of Titanium Alloys OT4 – VT6, VT20 – VT6 and VT23 – VT6

Koemets

Гриб

2021

DDF

The structure, the phase composition and microhardness over the section of welded joints aged at 500 and 550 °C have been studied by means of structural and microdurometric analyzes. The welded joints of OT4-VT23, VT6-VT23 and VT19-VT23 titanium alloys pairs were obtained by the argon-arc welding with a nonconsumable tungsten electrode. It has been established that the aging at 500 °C for 8 hours promotes the decomposition of metastable phases (b, a”) which formed after welding in the welded joint of VT19-VT23 titanium alloys pair. The decomposition process leads to strengthening of the main zones of the welded joint (except for the parent metal of VT23 alloy) and provides a favorable smooth change of microhardness in the joint during the transition from one alloy to another. The aging at 500 and 550 °C during 8 hours of the welded joints of OT4-VT23, VT6-VT23 titanium alloys pairs also led to the development of the decomposition of metastable phases (b, a”, a’) in the weld and heat affected zones of the alloys being joined, but did not provide the required monotonic change in microhardness over the cross section of the joint.

Section: Resultsmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Aging of the OT4-VT23, VT6-VT23, VT19-VT23 Titanium Welded Pairs

Koemets

Гриб

2021

DDF

“…%) refers to deformable, thermally hardened, moderately alloyed α+β-titanium alloys of martensitic class possessing good technological plasticity [1,2]. Complex alloying with both isomorphic (V, Mo) and eutectoid-forming (Cr, Fe) β-stabilizers provides a favorable combination of strength, ductility and impact toughness, [3], weldability [4] with the opportunity of obtaining welded joints with other titanium alloys [5] and steel [6]. The processing and operational characteristics of VT23 alloy are greatly influenced by chemical composition as well as phase composition and structure formed during heat treatment, deformation, and thermomechanical processing [7][8].…”

Section: Introductionmentioning

confidence: 99%

Evolution of Phase Composition and Thermal Expansion during Heating of VT23 Titanium Alloy

Vodolazskiy

Рыжков

2022

MSF

Changes in thermal expansion during heating of hot-extruded tube made of VT23 titanium alloy (Ti-5.45 Al-4.7 V-2.45 Mo-1.1 Cr-0.7 Fe, wt. %) were analyzed. The volume effect of α→β-transformation, β-transus temperature as well as the volume fraction of α-and β-phase formed during heating were calculated based on the received data of dilatometric analysis. Results obtained were compared to thermodynamic calculations and published data. The change in the CTE value of VT23 alloy upon heating to 975 °C was estimated, and the explanation of different CTE values obtained in the present study and published data was proposed.

“…A two-phase martensitic α+β-alloy VT23 belongs to the Ti-Al-Mo-V-Cr-Fe system. The alloy was developed to obtain high-strength extruded semi-finished products with good weldability [1,2], including welding with various titanium alloys and steel [3][4][5]. The best combination of strength, plastic and toughness properties in this alloy is achieved through the use of complex alloying with several β stabilizers -isomorphic (Mo, V) and eutectoid-forming (Cr, Fe).…”

Section: Introductionmentioning

confidence: 99%

Microstructure, Phase Composition, Physical and Mechanical Properties of Titanium Alloy VT23 Hot-Extruded Tube

Vodolazskiy

Shirinkina

2021

DDF

Macro-, microstructural, fine structure, phase composition, texture and complex of physical and mechanical properties in titanium alloy VT23 (Ti-5.5Al-4.7V-2.5Mo-1.1Cr-0.7Fe, wt. %) tube were studded by the macroanalysis, optical and transmission microscopy, X-ray phase analysis, durometry and microindentation methods. A close relationship between the structural-textural-phase state formed during the extrusion and the obtained level of strength, plastic, durometric properties and the contact modulus of elasticity in a hot-extruded tube has been established.