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The Welding Handbook for Maritime Welders.pdf

October 23, 2009 · Filed Under Mechanical & Industrial Engineering · 1 Comment  · Tags: , , , ,

Taken from Solutions: Problem Steel: Among the low alloy steels, there is also a large group of special steels with complicated chemical composition. These include spring steel, vanadium steel, high speed steel, tool steel, etc. All these steel types are difficult to weld. In many cases the steel has been hardened by annealing, and welding can destroy the hardening.
In principle, all these steels can be welded with matching ferritic consumables with the aid of preheating and postweld heat treatment to avoid hydrogen cracking in the heat affected zone (HAZ).
In the case of repair welding, it is, however, often not possible to preheat or to perform any postweld heat treatment.
So, in this case, welding with austenitic stainless or nickel-based consumables is considered to be one of the best methods. The risk of cracking is reduced by the higher solubility of hydrogen and the greater ductility of the weld metal.
There are so many types of low alloy steel on the market today that even specialists have difficulty in keeping track of the entire range. Numerous types of special alloys not classified under existing standards, are marketed by the steel works. Most types can be welded satisfactorily with Unitor Tensile having a tensile strength of 850 N/mm2. This electrode may be used both for joining and for building-up work

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Miller - Plasma Cutting Guide.pdf

September 4, 2009 · Filed Under Mechanical & Industrial Engineering · Comment  · Tags: ,

Taken from Plasma Advantages: Plasma provides numerous advantages over other cutting processes. While there are many common methods of cutting metal, the plasma process offers the following advantages:
Cuts any type of electrically conductive metals including aluminum, copper, brass and stainless steel
Cuts faster — up to 130 in. per minute on 1/4 in. steel
Does not require a pre-heat cycle which saves time and is more convenient
Produces a small and more precise kerf (width of the cut)—great when precision matters
Has a smaller heat affected zone which prevents the area around the cut from warping and minimizes paint damage
Provides gouging and piercing capabilities
Sawing or chopping can take a long time and will typically leave a rough edge — plasma cutting is fast, clean, and leaves a nice straight edge. It is also a less expensive and more convenient method for cutting than many other processes because compressed air is typically available in most applications via shop or portable compressors.