TESTING 1-2-3
THE IMPACT OF WELD REPAIR ON ALUMINUM SAND CASTINGS
S 1
2 3
Researchers investigate the accepted belief that weld repair does not affect the mechanical properties of an E357 sand casting. AN MCDP STAFF REPORT
tructurally sound castings may contain minor surface de- fects such as blow holes, misruns, mold-wash holes, fl ash holes, sand holes, isolated porosity and cosmetic mechani- cal damage. Purchase orders or similar documents often permit repair welding of these minor defects. In addition, other governing specifi cations may permit repair welding. Metalcasters have thought properly accomplished weld
repair has little or no eff ect on a casting’s fi nal mechani- cal properties. However, some end users and government agencies do not accept this axiom and either don’t accept weld repair or require that design properties be “knocked
down” to permit their use with a consequent increase in the cost of using castings. A research team investigated this widely accepted assumption in a study designed to either validate or refute the claim. T e fi ndings were published in the paper,
ADDING IT ALL UP
“Effect of Weld Repair on Static and Dynamic Tensile Properties of E357-T6 Sand Castings” Gerald Gegel, Material & Process Consultancy, Morton, Ill.; Dan Hoefert, Eck Industries Inc., Manitowoc, Wis.; Joseph Hirvela, Consolidated Precision Products Corp., Minneapolis; Randy Oehrlein, Carley Foundry, Blaine, Minn.
Background—Proper weld repair is thought to have little or no effect on a casting’s fi nal mechanical and physical properties. This study was designed to consolidate industry best practices for the in-process weld repair of aluminum-silicon hypoeutectic alloys, develop me- chanical properties to demonstrate the effi cacy of the practice, and develop statistical data that facilitates acceptance of weld practice.
Procedure—Artifi cial “defects” were machined into standardized E357- T6 test plates and then repair welded using a standardized procedure. Test specimens containing full and partial penetration welds then were tested to determine tensile and fatigue properties. Results and Conclusions—Repair welding with the process param- eters used for this study had no detrimental effects on either tensile or fatigue properties of E357-T6 sand castings. The study appears to support the conjecture that, properly accomplished, TIG welding is appropriate for weld repair of cosmetic surface defects and does not affect static and dynamic tensile properties of the casting. Ad- ditional research is needed to determine if this is true for other cast aluminum alloys.
“Eff ect of Weld Repair on Static and Dynamic Tensile Properties of E357-T6 Sand Castings,” by Gerald Gegel, Material & Process Consul- tancy, Morton, Ill.; Dan Hoefert, Eck Industries Inc., Manitowoc, Wis.; Joseph Hirvela, Consolidated Precision Products Corp., Minne- apolis; and Randy Oehrlein, Carley Foundry, Blaine, Minn., which was presented at the 2013 AFS Met- alcasting Congress. While the study focused solely
on E357 castings, its conclusions suggest similar results would be ex- pected for other weldable aluminum casting alloys. Additional testing would be necessary to validate any assumptions for performance other than that covered in this research.
1
Background In-process repair welding
is an economical means to repair localized cosmetic or processing damage. Individu-
al studies show proper heat treatment and inspection do not compromise the structural integrity of cast alumi- num. Defi ning the best practices for in-process welding provides a tool that may result in quality castings that can save time and cost, especially dur- ing short production runs. As part of a larger program to establish statistically validated mechanical properties for E357- T6 sand castings, this weld repair study was designed to consolidate industry best practices to establish an AFS Recommended Practice for the in-process weld repair of
Nov/Dec 2013 | METAL CASTING DESIGN & PURCHASING | 43
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