Best Known Welding Methods From Experts Around The Globe

Welding.jpg

Welding is a sculptural process of binding and joining metals or thermoplastics by causing fusion. Welding melts the base metal and a filler material is typically added to the joints to form a pool of molten material. This molten metal then cools down to form a joint.

There are different methods for welding and each has its own pros and cons. For example, there are less common methods for welding processes such as friction welding in which the base metal does not melt.

Some mostly used welding methods as revealed by the experts in non-destructive testing are:

  • Oxy-fuel welding – This method is also known as oxyacetylene welding or oxy-welding in short. It uses fuel gas and oxygen to weld and cut metals.

  • Shielded metal arc welding – Better known as ‘stick’ or ‘electric’ welding, this method uses a flux coated electrode. The electrode holder holds the electrode as it slowly melts away.

  • Gas tungsten arc welding – Also known as TIG, this one uses a non-consumable tungsten electrode to produce the weld. The welded area is protected from atmospheric contamination by an inert shielding gas such as argon or helium.

  • Gas metal arc welding – Mostly termed as MIG, it uses a wire feeding gun that feeds wire at an adjustable speed and flows an argon-based shielding gas or a mix of argon and carbon dioxide over the weld puddle to protect it from atmospheric contamination.

  • Flux-cored arc welding – Almost same as MIG except the fact that it uses a special tubular wire filled with flux. It can be used with or without shielding gas, depending on the filler.

  • Submerged arc welding – This method uses an automatically fed consumable electrode and a blanket of granular fusible flux. The molten weld and the arc zone are protected from atmospheric contamination by being “submerged” under the flux blanket.

  • Electroslag welding – This one is a highly productive method using single pass welding process for thicker materials between 1 inch and 12 inches in a close to vertical position.

There are a number of companies providing services for welding inspection, welding supervision and non-destructive testing (NDT). Inspection is readily necessary after the job is done and should not be left out, since it might prove to be dangerous afterwards.

Advertisements

Defining Forensic Engineering And Failure Analysis

magnetic.jpg

Failure analysis on a metal is performed by systematic examining, analyzing and testing the failure or flaw, gathering information about the application, component and history, which is further followed by a detailed visual examination. Failure analysis is a part of nondestructive testing which is scientifically known as magnetic particle testing, dye penetrant testing, low magnification, etc. High magnification examination and destructive testing is also sometimes applied like, sectioning the sample for Metallographic micro analysis, Chemical Analysis, Hardness testing, Mechanical testing.

These tests can only performed by a certified welding inspection team in Melbourne.

Macro Examination

macro1.jpg

Macroetching is the procedure of etching a sample and evaluating it macro structurally at low magnifications. It is a very frequent technique used for evaluating steel products. There are many different procedures for rating a steel sample by graded series of photographs. The images shows the incidence of certain conditions and is applicable to carbon and low alloy steels.

A number of different etching reagents may also be used depending on the type and process of examination to be applied. You should know that steels react differently to etching reagents because of variations and difference in chemical composition, heat treatment, method of manufacturing and many other factors.

Macro examinations are also performed on a polished and etched cross-section of a welded material. During the testing process, a number of features can be determined including the sequence of weld, weld procedure and qualifications tests. Any defect on the sample can be assessed for compliance with relevant specifications. It can be a slag, lack of weld penetration, porosity, lack of sidewall fusion and poor profile of a weld.

Micro Examination

microtesting.JPG

Micro examination is performed on specimen either cut to size or mounted in a resin mold. At first they are polished to a fine finish and then etched in an appropriate chemical solution prior to examination on a metallurgical microscope. Micro examination is performed to assess the structure of the material. It is also very common to examine for metallurgical anomalies such as third phase precipitates, excessive grain growth, and various other reasoMicro Examinationns. Many routine tests such as phase counting or grain size determinations are performed in conjunction with micro-examinations.

Forensic engineering and failure analysis of a metal are all high profile examinations, which are conducted to find out even the simplest flaw in a material component.