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| Question | Answer |
| Why is shielded metal-arc welding a commonly used process? | Welding Shielded metal-arc welding (SMAW) is one of the oldest, simplest, and most versatile joining processes |
| fungsi elektroda pada SMAW | sbg filler dan ujung busur listrik |
| the functions of electrodes | 1. deliver required power to circuit for welding 2. electrode melts and provide the filler material for welding 3. |
| the functions of electrodes coating | used as a flux and provide shielding gas |
| the functions of shielding gas | used to protect the molten-weld pool and the weld area against oxidation |
| What properties are useful for a shielding gas? | Inert, so the shielding gas will not react with metal |
| What are the advantages to thermit welding | 1. No external power source is required (heat of chemical reaction is utilized) 2. Very large heavy section parts may be joined |
| What electron-beam and are the advantages of laserbeam welding compared with arc welding? | 1. Electron-beam and laser beam are used for very accurate cutting a wide variety of metals and the surface finish is better than that of other arc welding 2. Narrow weld they can lay down. 3. Localizing the heat zone minimizes the total heat that gets dissipated. Many failures occur in the HAZ(heat affected zone). By localizing the heat input and weld metal deposited, the HAZ narrow considerably compared to joint width. Making the likelihood of residual stresses and microstucture change less |
| Weld failures always occur in the fusion zone of the weld joint, since this is the part of the joint that has been melted: (a) true, (b) false? | (b). Failures also occur in the heat-affected zone because metallurgical damage often occurs in this region |
| Perbedaan electrogas welding dan electroslag welding | Electroslag : Resistance heating is used for melting the filler metal Electrogas : Continous arc is used to melt the filler metal and workpiece Electrogas : The arc and the weld puddle is shielded by a gas such CO2 Electroslag : shielded by slag |
| Metals that are easiest to weld in resistance welding are ones that have low resistivities since low resistivity assists in the flow of electrical current: (a) true, or (b) false? | Metals with low resistivities, such as aluminum and copper, are difficult to weld in RW. Higher resistance is required in the conversion of electrical power to heat energy; hence, metals with high resistivity are generally preferable. |
| The Highest labor skill required | Oxyfuel and shield metal arc |
| DC current | GMAW and FCAW |
| The most expensive cost | Electro beam and Lase beam |
| The cheapest cost and lowest quality | oxfuel |
| If the materials to be welded are preheated, is the likelihood for porosity increased or decreased | Generally porosity will decrease with preheating. Weld pieces will cool slower allowing trapped gases to have time to do stuff. Cracks and bridging created when the weld is cooled to quickly will be dissipated by preheating the metal. It is still possible to end up with porosity in the weld if the molten pool is given too much time to cool. |
| What is weld spatter? How can spatter be controlled? Explain. | A very common occurrence in gas metal arc welding (GMAW) is the creation of what welders call "spatter," which is essentially droplets of molten material that are generated at or near the welding arc. In SAW, the thick layer of flux prevents spatter |
| Jelaskan apa itu oxyfuel-gas Welding | Oxyfuel-gas welding (OFW) is a general term to describe any welding process that uses a fuel gas combined with oxygen to produce a flame, which is the source of the heat required to melt the metals at the joint |
| 3 tipe flames | neutral, oxidizing and carburizing(reducing) flames |
| Fungsi flux pada Oxyfuel Welding | memperlambat terjadinya oksidasi serta melarutkan dan menghilangkan oksidasi dengan perisai gas |
| Fungsi slag pada oxyfuel welding | Merupakan gabungan dari oxides, flux, electrode-coating material. The slag developed protects the molten puddle of metal against oxidation as it cools. |
| Oxyfuel dapat digunakan pada banyak jenis besi dan non besi (T/F) | T |
| flames yang tidak menyebabkan perubahan kimia pada metal | neutral flames |
| flames yang menyebabkan perubahan kimia pada baja dan besi | carburizing flames |
| flames yang tidak boleh diaplikasikan pada jenis logam yang dapat menyerap karbon | carburizing flames |
| flames yang paling panas | oxidizing flames |
| Jelaskan apa itu oxyfuel welding | this processutilizes the heat generated by the combustion of acetylene gas (C2H2) in a mixture with oxygen. |
| jenis jenis flames dipisahkan berdasarkan | ratio acetlyne dengan oksigen |
| oxidizing flames cocok dan tidak cocok kepada jenis logam | This flame is harmful, especially for steels, because it oxidizes the steel. Only in copper and copper-base alloys is an oxidizing flame desirable because a thin protective layer of slag forms over the molten metal. |
| prosedur pada oxyfuel welding serta nama-nama komponennya | Pertama kali katup acetylene dibuka; gasdinyalakan dengan korek api atau penyala;kemudian katup oksigen dibuka dan nyala diatur. |
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