SEDL / STP / STP1042-EB / STP24585S

A Method for Developing Postweld Heat Treatments and Evaluating Effects of Residual Elements on Heat-Affected Zone Tempering Resistance

Biron, RH
Welding engineer and manager of Materials and Processes Engineering, General Electric Company, Lynn, MA

Kreischer, CH
Welding engineer, General Electric Company, Schenectady, NY

Melilli, AS
Welding engineer and manager of Materials and Processes Engineering, General Electric Company, Lynn, MA

Pages: 5    Published: Jan 1989

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Abstract

A method was developed to define a postweld subcritical heat treatment to provide optimum ductility of the heat-affected zone. The results have been used to define the post-weld heat treatment included as part of welding procedure qualification tests. By themselves, required qualification tests, which involve tensile, bend, and sometimes impact, can be misleading because they are not primarily designed to evaluate heat-affected zone ductility. The test method involved generating a heat-affected zone (HAZ), extracting a series of as-welded cross sections, heat treating each section at varying times and temperatures, measuring the peak heat-affected zone hardness, and defining the heat-affected zone ductility by correlating the peak HAZ hardness with the Hollomon-Jaffe parameter associated with each time and temperature. Several heats of CrMo and CrMoV turbine alloys were studied in this manner to define their weld HAZ tempering response and to evaluate specific tempering effects of residual alloy element content.