The Short Version
This claim is false as commonly understood. While stomach acid (pH ~1–2) is highly corrosive and can slowly corrode metal in laboratory settings — one study showed ~37% mass loss after 24 hours in simulated gastric juice — food and foreign objects typically remain in the stomach for only 30–120 minutes. Medical case reports consistently show ingested razor blades passing through or being surgically removed intact, not dissolved. The claim conflates a lab demonstration of slow corrosion with actual digestive capability.