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AWS A5.35/A5.35M:2015 pdf free download
AWS A5.35/A5.35M:2015 pdf free download.Specification for Covered Electrodes for Underwater Wet Shielded Metal Arc Welding.
A4. Welding Considerations
Due to the much higher cooling rate of wet welds, as compared to welding in the dry. weldment hardness is increased and weidment ductility is reduced. The degree of this weldment degradation is dependent on the metallurgy of the particular filler metal and base metal being used. ‘Weld discontinuities are also more prevalent in wet welds than welds made in the dry, with the discontinuities becoming more prevalent as the depth increases. In general. the austenitic stainless steel and high nickel filler metals tend to be more depth sensitive than the ferritic steel tiller metals.
Weld metal porosity is the most significant discontinuity occurring in wet welds. The increased porosity is a result of the weld metal solidifying before gases can escape, due to the increased cooling rate in the wet; it is also a result of increased hydrogen produced in the welding arc. The degree of porosity will depend on the welding electrode used, water depth. position of welding. and welding technique.
Hydrogen induced underbead cracking can be a problem when using t’erritic steel filler metals to weld carbon steel base metals with a high carbon equivalent. This can generally be expected when the base metal carbon equivalent is above 0.40 when calculated in accordance with AWS D3.6M. The use of austenitic stainless steel and high nickel tiller metals tend to eliminate the underbead cracking problem in the higher carbon equivalent steels, due to the higher affinity for hydrogen of the tiller metals, resulting in less hydrogen in the base metal heat aftected zone. However, it should be noted that austenitic stainless steel (3(X) series) groove weld size, and fillet weld throat dimensions, should be limited to a maximum of approximately 3/8 inch 110 mrnl to avoid diffusion ZOflC cracking at the weld fusion line when welding higher carbon equivalent ferritic steels. When using austenitic stainless steel filler metal, there is the potential for knife-edge CorrosiOfl at the toe of the weld due to dissimilar metal galvanic action. This will depend on the relative surface area size of the dissimilar metals.
Care should be exercised when welding on base metals less than 1/4 inch 16 mmj in thickness. Burn-through can be a problem due to the increased amperage required for wet welding, and due to increased welding current density from arc constriction caused by pressures at depth.
Electrodes procured to this specification, when used with properly qualified procedures by properly trained and qualified personnel, should result in weldments in which the limitations addressed above are minimized. This specification covers three sub-classes of electrodes (see &2) Levels I. 2, and 3. Level 3 is the least stringent: most currently available welding electrodes should meet the requirements of this level. Level 2 requirements will be met by higher quality electrodes currently available.AWS A5.35/A5.35M:2015 pdf free download.
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