AWS C7.4/C7.4M PDF

This specification covers the preparation, the process control, and quality control requirements for laser beam welding. Welding equipment includes Gas Lasers (CO2) and Solid-State Lasers (Nd:YAG, Yb:YAG, Nd:Glass, Diode, Ruby, Disk and Fiber) in pulsed, continuous wave (CW), and quasi-continuous wave (QCW) output as defined in AWS A3.0M/A3.0, Standard Welding Terms and Definitions.

Tutorial information regarding techniques of welding or details of equipment setup or operation is beyond the scope of this specification. For more information on this subject and recommended practices, refer to the latest published version of AWS C7.2, Recommended Practices for Laser Welding, Cutting, and Allied Processes.

Materials. This specification covers all major engineering alloys including:

(1) Ferrous Alloys (e.g., Carbon steels, stainless steels, etc.);

(2) Nonferrous Alloys (e.g., Alloys of Al, Ni, Ti, etc. and Super-alloys);

(3) Heat-Resisting and Refractory Metal Alloys (e.g., Alloys of Mo, Ta, W, etc.);

(4) Other Alloys (e.g., Be and Cu alloys, precious metals);

(5) Nonmetals (Plastics, polymers, etc.).

Qualification Categories. There are three categories to which welds may be qualified: Class A, B, or C. Classification levels are intended to delineate inspection level and process control. Examples of acceptance criteria, which may be applied to the classification levels, are presented in Annex D.

Class A—Critical Applications. Critical weldments include those where a failure of any portion of a weldment would cause loss of system, loss of major component, loss of control, unintentional release of critical stores, such as fuel or cargo, or endangerment of personnel.

Class B—Semicritical Applications. Semicritical weldments include those where a failure of any portion of a weldment would reduce the overall efficiency of the system, but loss of the system or endangerment of personnel would not be experienced.

Class C—Noncritical Applications. Noncritical weldments include those where a failure of any portion of a weldment would not affect the efficiency of the system or endanger personnel.