Repair welding with the process
parameters used for this study has no detrimental effects on tensile or fatigue properties of E357-T6 sand castings. Te study appears to support the principle that proper welding is appropriate for repairing or joining sand cast components to one another, though additional research is necessary for other alloys.
Tis article is based on a paper (13-1210) published in AFS Transactions 2013.
Fig. 7. Fatigue data for three types of weld repair specimens of E357-T6 sand castings shows the effect of the type of weld repair on fatigue life.
weld repair specimens was interden- dritic (Figure 10). Te smaller radii of curvature in these shapes gener- ally have a greater negative effect on fatigue life. As seen in Figures 11-12, the pores in the weld metal are smaller
and rounder compared to the larger interdendritic shrink porosity seen in the as-cast regions of the weld repaired specimens. Te available data does not explain the apparent increased fatigue life for the half-weld specimens.
Fig. 10. This micrograph shows the typical shape of porosity in E357-T6 sand castings.
Fig. 8. This micrograph shows the typical microstructure in E357-T6 cast (original) metal in weld repair specimens.
Fig. 9. The micrograph shows the typical microstructures of weld metal in E357-T6 weld repair specimens.
Table 2. Comparison of Tensile Test Statistics Showing Effect of Type of Weld Repair Specimen
Data Set No Weld Statistic Mean
Std. Dev High Low
Half Weld Mean
Std. Dev High Low
Full Weld Mean
Std. Dev High Low
Ultimate
Strength MPa 340.2
5.0
350.3 329.6 340.3 4.3
346.1 326.1 340.2 7.1
348.2 315.1
0.2% Yield Strength MPa
306.9 4.0
317.2 299.9 307.1 3.7
313.0 299.2 308.4 3.3
313.7 302.0
Elongation %
1.94 0.62 3.62 1.16 2.00 0.52 3.47 0.98 1.92 0.55 2.94 0.69
Fig. 11. This micrograph shows the compar- ison of pore size and shape in weld metal and cast metal in partial weld specimen.
Fig. 12. This micrograph shows a compari- son of pore size and shape in weld metal and cast metal in the full-weld specimen.
December 2013 MODERN CASTING | 45
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