What is required for testing fillet welded joints?

Testing fillet welded joints requires careful consideration of various factors to ensure the integrity and quality of the welds. Each of the listed requirements plays a critical role in the testing process.

Preparing at least four specimens is essential because having multiple samples allows for a more reliable assessment of the welding process. This helps to account for variability and ensures that the results reflect the quality of the welding method used, rather than relying on a single specimen which may not accurately represent the overall quality.

The specification that the specimens may be machine cut or oxygen cut provides flexibility in how the samples are prepared. Machine cutting ensures precision and consistency in specimen dimensions, which is crucial for valid test results, while oxygen cutting can be employed for rough cutting of larger jobs where ultimate precision is less critical, but still acceptable for initial sample preparation.

Cooling the specimens to ambient temperature before testing is important as it ensures that potential residual stresses caused by rapid cooling or heating are minimized. Performing tests on specimens that are at a uniform temperature helps in obtaining accurate and consistent results, preventing anomalies that could arise from thermal influences.

Given that all these criteria are integral to the validation of the welding process and the testing of fillet welded joints, it is clear why the correct answer encompasses all aspects mentioned.