Teknologi Las Kapal Elementary Concept SAW Submerged arc

Teknologi Las Kapal Elementary Concept SAW (Submerged arc welding)

Submerged arc welding v Submerged arc welding (SAW) is a rocess that melts and joins metals by heating them with an arc established between a consumable wire electrode and the metals, with the arc being shielded by a molten stag and granular flux. Teknologi dan Rekayasa

Submerged arc welding • The arc is submerged and invisible. • The flux is supplied from a hopper, which travel with the torch. • The shielding gas may not be required because the molten metal is separated from the air by the molten slag and granular flux. Teknologi dan Rekayasa

Principles of operation v SAW utilizes the heat of an arc between a continiously fed electrodeand the work. v The heat of the arc melts the surface of the base metal and the end of the electrode. v Shielding is obtained from a blanket of granular flux, which is laid directly over the weld area. v The flux close to the arc melts and intermixes withthe molten weld metal and helps purify and fortify it. v The flux forms a glasslike slagthat is lighter in weight than the deposited weld metal and floats on the surface as a protective cover. v The electrode is fed into the arc automaticallyand travel can be manual or by machine. v The metal transfer mode is less important in SAW. Teknologi dan Rekayasa

SAW Equipment Teknologi dan Rekayasa

SAW Process Teknologi dan Rekayasa

SAW machine Teknologi dan Rekayasa

SAW Flux and Filler Teknologi dan Rekayasa

SAW Flux and Filler F 7 A 2 -EM 12 K v F indicates flux § 70 -95 ksi UTS, 58 ksi minimum yield strength, 22% elongation § A - as welded; P - postweld heat treated § 2 - minimum impact properties of 20 ft-lbs @ 20°F Teknologi dan Rekayasa

SAW Flux and Filler F 7 A 2 -EM 12 K v E indicates electrode (EC - composite electrode) § M - medium manganese per AWS Specifications § 12 - 0. 12% nominal carbon content in electrode § K - produced from a heat of aluminum killed steel Teknologi dan Rekayasa

Advantages High deposition rates No arc flash or glare Minimal smoke and fumes Flux and wire added separately - extra dimension of control v Easily automated v Joints can be prepared with narrow grooves v Can be used to weld carbon steels, low alloy steels, stainless steels, chromium-molybdenum steels, nickel base alloys v v Teknologi dan Rekayasa

Disadvantages • Cannot weld in a flat-position and circumferential (pipe). • High heat input can reduce the weld quality and increase distortions. Teknologi dan Rekayasa

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