Welding process and characteristics of fine K-type thermocouple: non-contact discharge welding for fine metal wires

Welding of very high strength quenched and tempered steel, Rp0.2≥ 900 MPa, put high demands on choice of welding process, consumables and also on the heat input. Such steels commonly have a quite narrow tolerance box for a suitable weld heat input to control the cooling time, Δt8/5, pertaining to minimize the risk for generating weld defects such as undercut, a too soft weld heat affected zone, delayed cracking etc. When welding very high strength steel is the risk for cold cracking in the weld metal not negligible due to the high alloy content of such high strength filler wires used. Furthermore, filler metal wires having equal strength levels to very high strength steel are hard to find which, together with the above described drawbacks, favour use of under-matching filler wires.

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Advances in ultramicrotomy for physical sciences applications

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100149386 ◽

1993 ◽

Vol 51 ◽

pp. 710-711

Author(s):

G. McMahon ◽

T. Malis

Keyword(s):

Particle Surface ◽

Zeolite Catalysts ◽

Physical Sciences ◽

Pull Out ◽

Large Particles ◽

Novel Applications ◽

Metal Wires ◽

Frequent Problem ◽

Specific Orientation ◽

Diamond Knife

As with all techniques which are relatively new and therefore underutilized, diamond knife sectioning in the physical sciences continues to see both developments of the technique and novel applications.Technique Developments Development of specific orientation/embedding procedures for small pieces of awkward shape is exemplified by the work of Bradley et al on large, rather fragile particles of nuclear waste glass. At the same time, the frequent problem of pullout with large particles can be reduced by roughening of the particle surface, and a proven methodology using a commercial coupling agent developed for glasses has been utilized with good results on large zeolite catalysts. The same principle (using acid etches) should work for ceramic fibres or metal wires which may only partially pull out but result in unacceptably thick sections. Researchers from the life sciences continue to develop aspects of embedding media which may be applicable to certain cases in the physical sciences.

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Effects of bottom plate in friction stir welding of AA6061-T6

Metallurgical Research & Technology ◽

10.1051/metal/2020087 ◽

2020 ◽

Vol 118 (1) ◽

pp. 108

Author(s):

M.A. Vinayagamoorthi ◽

M. Prince ◽

S. Balasubramanian

Keyword(s):

Mechanical Properties ◽

Axial Load ◽

Weld Zone ◽

Welding Process ◽

Bottom Plate ◽

Welding Parameters ◽

Nugget Zone ◽

Friction Stir ◽

Weld Joints ◽

Fine Grain

The effects of 40 mm width bottom plates on the microstructural modifications and the mechanical properties of a 6 mm thick FSW AA6061-T6 joint have been investigated. The bottom plates are placed partially at the weld zone to absorb and dissipate heat during the welding process. An axial load of 5 to 7 kN, a rotational speed of 500 rpm, and a welding speed of 50 mm/min are employed as welding parameters. The size of the nugget zone (NZ) and heat-affected zone (HAZ) in the weld joints obtained from AISI 1040 steel bottom plate is more significant than that of weld joints obtained using copper bottom plate due to lower thermal conductivity of steel. Also, the weld joints obtained using copper bottom plate have fine grain microstructure due to the dynamic recrystallization. The friction stir welded joints obtained with copper bottom plate have exhibited higher ductility of 8.9% and higher tensile strength of 172 MPa as compared to the joints obtained using a steel bottom plate.

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