AWS weld filler metal allowable

By eng6112 Date 02-07-2013 22:22

Does anyone know how the 0.3 factor was arrived at, that is used in table 2.3 of the AWS D1.1 Structural welding code for steel?
This is for fillet weld allowable connection stress and is applied to the nominal tensile strength of the filler metal. Is this an experimentally obtained number? Does it reflect the probable lower strength in the Heat Affected Zone? a fatigue consideration?, or some other reasoning? I am familiar with the 0.6 factor usually applied to a parent material tensile strength to obtain shear strength, but not this 0.3 factor. Thanks for any insight

By 803056

Date 02-08-2013 17:16

Not that I have any special insight or sit on the committee responsible for determining the allowable stresses, but the 0.3 factor is probably used to take into account the "crack initiator" present in the root of the fillet weld and partial joint penetration groove welds.

The incomplete fusion present in the root of the fillet weld, where the butting and nonbutting members are joined, acts as a notched stress riser. The reduced allowable stress is the accepted manner used to accommodate the stress riser.

Where did it come from, your guess is as good as mine.

Best regards - Al