A current supplier is requesting they substitute an 8620 investment casting instead of the specified 1020(A732 Grade 1A). The part is welded to low carbon steel tubing having .125 wall thickness. The part is not highly stressed. My concern is with weld cracking. I do not want to pre or post heat the weld. Should I be concerned? The reason they want to substitute is that they are having porosity issues with the 1A grade. Is this common?

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