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LECTURE EIGHT

Welds

Terms Soldering:

Bonding by melting a soft metal to the surface of pieces to be joined. Lowtemperature. Good for joining dis-similar materials. Most common solders are lead-tinalloys.

Tinning:A soldering process, where the surface of a metal is coated with solder.

Leading

A form of soldering, solder is used to fill in the surface of metal. Brazing:

Similar to soldering, but uses a higher temperature to fuse the filler metal to the workpieces. Stronger bond. (Includes "Silver Soldering") Work heated to pre-melttemperatures.

Welding:Joining 2 similar work pieces by melting them together, usually with an additional fillerrod of some sort to take up space. Materials must be similar.

Cutting:Work is heated to melting point and beyond, and "cut" by oxidizing metal. (Literallyburning it away).

Shield:A barrier to keep oxygen away from heated work to prevent oxidation. Includeschemical coatings called flux (liquids, pastes, solids, which may be vaporized into abarrier gas when heated), and inert gasses. Oxidation of the surfaces will preventproper bonding of the metals.

http://www.team.net/www/shop-talk/weldintro.html

Welding

Welding is a very efficient way ofjoining metals

Welding is labour intensive

In a welded structure subject tofluctuating loads, the strength of thewelds determine the strength of thestructure

It is important to select the rightweld type for the right job

Common Weld Types

Partial Penetration Welds

One-sided Butt Weld

Plate preparation

Full Penetration Welds

One-sided Butt Weld

Plate preparation

Backing Bar

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Double-Sided Butt Weld

Double-sided full-penetration Butt Weld

Plate preparation

Fillet Weld

Dry Joint

Basic Weld Design Objectives Will perform its intended function

Will have the desired reliability & safety

Is capable of being constructed fabricated

inspected

transported

assembled

Has minimum cost

Material Strength

Select common steels Grade250 and Grade350

Weld fatigue strength does notincrease with yield strength of steel Do not use high-strength steels with

cyclical loads

Carbon Content

Use steel grades with lowest carbon-equivalent

Carbon Equivalent (CE) = C% + Mn%/6 Steels with CE < 0.35 can be welded

with any electrode type and with anyprocess

Steels with CE > 0.5 need special care preheating post-weld heat treatment

Welding Symbols

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Welding Symbols in Solid Edge Welding Symbols

AS1101.2 is the reference for welding symbols

Welding Symbols

A

ASECTION A-A

Arrow Side V-Butt Symbol

Welding Symbols

Welding Symbols Welding Symbols

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Welding Symbols Welding Symbols

Welding Symbols

50 100

66

6 50-100

Position of the Weld

Welding ProceduresNormally undertaken to a relevant standard bya CERTIFIED WELDER

Processes includes various items as

pre/post heatweld preparationsFiller specificationsPost weld inspection x-ray, NDTEtc.

WPS-FC-6 All position Flux-core on A36 plate using E71T-8 without gas coverage.WPS-GTAW-2 All position Tig on A240(304L) plate using ER308L with 100% Argon.WPS-GTAW-2F All position dual process (Tig root/flux-core fill) on A240(304L) plate.WPS-GTAW-2S All position dual process (Tig root/stick fill) on A240(304L) plate.WPS-GTAW-3 All position Tig on A240(316L) plate using ER316L with 100% Argon.WPS-GTAW-3F All position dual process (Tig root/flux-core fill) on A240(316L) plate.

Think of Fabrication

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Think of Fabrication Who is going to do it?