SEM

RESUME

C. Kendall Clarke
Ph.D., P.E.

President and Principal Engineer

Don Halimunanda
M.S., P.E.

Mechanical Engineer

WELDING

This large welded truss required careful control over the welding.

Metallurgical principles have been applied to welding problems in production and repair applications. Repair welding in paper and chemical industries sometimes requires special considerations to address contamination problems or deteriorated structures. Use of preheat and post weld stress relief procedures may need to be imposed when not normally required. Production welding problems can benefit from a metallurgical evaluation of cracking problems.

Several in-depth investigations of spot welds in automobiles have involved evaluations of weld quality and failure analysis of welds broken in accidents. Many welds have been broken open or sectioned for metallurgical analysis. Investigations of broken welds in accidents have involved the determination of the strength of the welds at the time of the accident. Expert testimony has been provided in these cases.

Cross section through slag from plasma cut on stainless steel.

• A metallurgical review of steels and welding procedures prior to construction was requested for a large auditorium project that utilized jumbo section wide flange structural shapes for tension members. There are published warnings on the use of jumbo sections for tension applications. Special cutting, welding and fabrication procedures were specified to assure safe usage of these heavy sections. An overall welding quality control program was established for the project.

• Poor welding with excessive porosity had been identified as the cause of a weld failure based upon the condition of a plasma cut through the welded connection. Tests were performed on wrought stainless to demonstrate that porosity in the plasma slag was not related to underlying weld porosity.

Unusual base plate cracking away from weld.

• Welds in a lethal process line were being rejected during fabrication inspection. Examination of areas outside the weld revealed unusual areas of intergranular cracking. This was a rare case where the metal being welded had cracking problems which were opened up by the welding.