Material of this forged part:
14CrNi3MoV (921D), suitable for steel forgings with a thickness not exceeding 130mm used in ships.
Manufacturing process:
The forged steel should be smelted using electric furnace and electric slag remelting method, or other methods approved by the demand side. The steel should undergo sufficient deoxidation and grain refinement processes. When forging the ingot directly into a forged part, the forging ratio of the main body of the part should be no less than 3.0. The forging ratio of flat parts, flanges, and other extended sections of the forged part should be no less than 1.5. When forging the billet into a forged part, the forging ratio of the main body of the part should be no less than 1.5, and the forging ratio of protruding parts should be no less than 1.3. Forged parts made from ingots or forged billets should undergo sufficient dehydrogenation and annealing treatment. Welding of steel billets used for producing forged parts is not allowed.
Delivery condition:
The forged part should be delivered in a quenched and tempered state after normalizing pre-treatment. The recommended process is (890-910)°C normalizing + (860-880)°C quenching + (620-630)°C tempering. If the thickness of the forged part exceeds 130mm, it should undergo tempering after rough machining. Tempered forged parts should not undergo stress relief annealing without the consent of the demand side.
Mechanical properties:
After tempering treatment, the mechanical properties of the forged part should comply with the relevant specifications. At least impact tests at temperatures of -20°C, -40°C, -60°C, -80°C, and -100°C should be conducted, and complete impact energy-temperature curves should be plotted.
Non-metallic inclusions and grain size:
Forged parts made from ingots should have a grain size rating not coarser than 5.0. The level of A type inclusions in the steel should not exceed 1.5, and the level of R type inclusions should not exceed 2.5, with the sum of both not exceeding 3.5.
Surface quality:
Forged parts should not have visible surface defects such as cracks, folds, shrinkage cavities, scars, or foreign non-metallic inclusions. Surface defects can be rectified using scraping, chiseling, grinding with a grinding wheel, or machining methods, ensuring sufficient allowance for finishing after rectification.
Post time: Nov-24-2023
