Final answer:
The Charpy impact test requires a notched specimen to measure the absorbed energy during impact, rather than a notch-free specimen, pre-heating, or water submersion.
Step-by-step explanation:
If Charpy impact properties are a requirement of a welding procedure, then the specimen must not be notch-free; rather, it should have a notch pre-made in it. This is because the Charpy impact test is designed to measure how well a material can absorb energy during a rapid impact at a precise location. Therefore, the correct answer is that the specimen must be notched before testing. None of the other options provided (decreasing the specimen size, heating the specimen before testing, or submerging the specimen in water during testing) are standard practice for conducting a Charpy impact test according to the question provided.