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  𝐓𝐲𝐩𝐞𝐬 𝐨𝐟 𝐰𝐞𝐥𝐝𝐢𝐧𝐠 𝐞𝐥𝐞𝐜𝐭𝐫𝐨𝐝𝐞 𝐜𝐨𝐚𝐭𝐢𝐧𝐠𝐬 𝐟𝐨𝐫 𝐜𝐚𝐫𝐛𝐨𝐧 𝐬𝐭𝐞𝐞𝐥 SMAW: 𝟭- 𝗖𝗲𝗹𝗹𝘂𝗹𝗼𝘀𝗲-𝘀𝗼𝗱𝗶𝘂𝗺 (𝗘𝗫𝗫𝟭𝟬):   With cellulosic material in the form of wood flour or reprocessed low alloy electrodes have up to 30 percent paper.  The gas shield contains carbon dioxide and hydrogen, which are reducing agents.  These gases tend to produce a digging arc that provides deep penetration. (used often for pipelines) 𝟮- 𝗖𝗲𝗹𝗹𝘂𝗹𝗼𝘀𝗲-𝗽𝗼𝘁𝗮𝘀𝘀𝗶𝘂𝗺 (𝗘𝗫𝗫𝟭𝟭): This electrode is very similar to the -cellulose-sodium electrode, except more potassium is used than sodium. 𝟯- 𝗥𝘂𝘁𝗶𝗹𝗲-𝘀𝗼𝗱𝗶𝘂𝗺 (𝗘𝗫𝗫𝟭𝟮):   With rutile or titanium dioxide content is relatively high with respect to the other components. Provides a fairly high rate of deposition. 𝟰- 𝗥𝘂𝘁𝗶𝗹𝗲-𝗽𝗼𝘁𝗮𝘀𝘀𝗶𝘂𝗺 (𝗘𝗫𝗫𝟭𝟯): This electrode coating is very similar to the rutile-sodium type, except that potassium is used to provide ...

  what is 𝗛𝗲𝗮𝘁 𝗔𝗳𝗳𝗲𝗰𝘁𝗲𝗱 𝗭𝗼𝗻𝗲 𝗖𝗿𝗮𝗰𝗸 heat affected zone (#HAZ) of a weld is not limited to the weld itself but to the immediate area of parent material surrounding the weld. A HAZ crack can originate at the toes of the weld or a few millimeters from the weld altogether. The most common causes for this type of crack are: excess hydrogen, high residual stress levels on the weld, and high carbon content on the base material. To minimize the susceptibility or prevent HAZ cracks consider: 1. using low hydrogen electrodes 2. pre-heating the base material 3. slow cooling the base material after welding

  𝐆𝐞𝐧𝐞𝐫𝐚𝐥 𝐌𝐚𝐭𝐞𝐫𝐢𝐚𝐥 𝐂𝐥𝐚𝐬𝐬𝐢𝐟𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬 1- 𝘔𝘦𝘵𝘢𝘭𝘴 2- 𝘊𝘦𝘳𝘢𝘮𝘪𝘤𝘴 3- 𝘗𝘰𝘭𝘺𝘮𝘦𝘳𝘴 4- 𝘊𝘰𝘮𝘱𝘰𝘴𝘪𝘵𝘦𝘴 𝟏- 𝐌𝐞𝐭𝐚𝐥𝐬 ★ Ferrous Metals  (irons, carbon steels, alloy steels, stainless steels,etc) ★ Non Ferrous Metals (aluminum, copper, magnesium, nickel, titanium, precious metals, refractory metals, super alloys) 𝟐- 𝐂𝐞𝐫𝐚𝐦𝐢𝐜𝐬 ★ Defined as “an inorganic, nonmetallic solid that is prepared from powdered materials, is fabricated into products through the application of heat, and displays such characteristic properties as hardness strength, low electrical conductivity and brittleness. ★ Such as aluminum and oxygen (alumina-Al2O3), calcium and oxygen (calcia - CaO), and silicon and nitrogen (silicon nitride-Si3N4). ★ Ceramics' Properties: - Brittle in nature. Ceramics can also be formed to serve as electrically conductive materials or insulators. - Some ceramics, like superconductors, also display magnetic properties. They are also...

 𝐖𝐡𝐚𝐭 𝐢𝐬 𝐏𝐫𝐞𝐡𝐞𝐚𝐭𝐢𝐧𝐠 𝐢𝐧 𝐖𝐞𝐥𝐝𝐢𝐧𝐠? Heating the base metal surrounding the weld joint, to a specific  minimum temperature (Preheat Temperature) prior to welding or performing tack welds. Preheating can be either just before the welding or continuous preheat maintenance till the welding is completed. 𝗣𝘂𝗿𝗽𝗼𝘀𝗲 𝗼𝗳 𝗣𝗿𝗲𝗵𝗲𝗮𝘁𝗶𝗻𝗴: Prevention of Hydrogen Cracking (Cold Cracking/ Delayed Cracking). Reduce residual stresses and control distortion. Reduce propensity of hard micro-structure formation. Eliminate stress-oriented weld cracking & minimize welding porosity. 𝗪𝗵𝗶𝗰𝗵 𝗺𝗮𝘁𝗲𝗿𝗶𝗮𝗹𝘀 𝘀𝗵𝗮𝗹𝗹 𝗯𝗲 𝗽𝗿𝗲𝗵𝗲𝗮𝘁𝗲𝗱? 1- Depending on the thickness of base metals. 2- Base metal chemical composition & CE (Carbon Equivalent) value. 3- According to applied Code or SPECs. 4- Presence of hard micro-structures in the base metal or weld metal. 5-Type of welding electrodes & level of hydrogen in the welding rod. 6-Base material type...

  𝑯𝒂𝒓𝒅𝒏𝒆𝒔𝒔 𝑻𝒆𝒔𝒕: The hardness test is a mechanical test for material properties which are used in engineering design, analysis of structures, and materials development. The principal purpose of the hardness test is to determine the suitability of a material for a given application, or the particular treatment to which the material has been subjected. The ease with which the hardness test can be made has made it the most common method of inspection for metals and alloys. Hardness is defined as the resistance of a material to permanent deformation such as indentation, wear, abrassion, scratch. Principally, the importance of hardness testing has to do with the relationship between hardness and other properties of material. For example, both the hardness test and the tensile test measure the resistance of a metal to plastic flow, and results of these tests may closely parallel each other. The hardness test is preferred because it is simple, easy, and relatively nondestructi...