AIS AIS Forensic Testing Laboratory, Inc.    Metallurgical Testing
Introduction to Metallurgy...a Metallurgical Tutorial

Welding - Carbon Steels - Stainless Steels - Cast Iron - Super Alloys - Steel - Heat Treating - Corrosion - Galvanic corrosion - Ceramics - Refractories

Welding of Metals

We general consider welding to be the joining of two-metals by an arc, and we will keep to this principal because this type of welding is common.

Joining two-pieces of metals by a welding arc can only be done if the metals are similar above the melting point of the metals. When the two are not similar then their weldability is difficult and must include transition (buttering) welds.

Weldment on steel plate

There are four-categories of welding steels and these are:

  1. Low Carbon Steels

  2. Medium Carbon Steels

  3. High Carbon Steels

  4. Alloy Steels

Welding is a complex metallurgical process that is likened to a steel mill but on a micro scale joining relatively cool pieces of steel. There is a great temperature swing at great rates at a few mm or fraction of an inches away.

Welding should be done with a qualified weld procedure (WPS) and a qualified weld operator (WQR). these are ASME terms. Essentially, every weld should be weldable with the end result being that the weld joint (weldment) be stronger than the metals being joined. To achieve this requires great skill of the welder with proper settings on the weld machine, joint configuration, and weld rod, which are written instructions in the WPS (weld procedure) to follow, to make a superior weld with the right desirable weld metallurgy.

 

Metallurgy of Arc Welding: Hydrogen Embrittlement

 

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