In the GB heavy rail manufacturing process, quality control runs through the whole process, and several key links are particularly important. The steelmaking process is the foundation, and accurate control of the composition of molten steel is the core point. Through advanced testing technology, the content of carbon, manganese, phosphorus, sulfur and other elements is monitored in real time. Accurate control of carbon content can ensure that the strength and hardness of heavy rails meet the standards, and the appropriate addition of manganese can improve toughness. At the same time, strict restrictions on impurities such as phosphorus and sulfur can reduce the risk of brittleness and lay a solid foundation for quality in subsequent processes.
During the billet heating stage, accurate control of temperature and time is extremely critical. In the heating furnace, the billet needs to be evenly heated to 1100-1300 degrees Celsius. If the temperature is too low, the billet plasticity is insufficient and defects are easy to occur during rolling; if the temperature is too high, it may cause overheating and overburning problems, seriously affecting the performance of heavy rails. The heating time must also strictly match the billet size and material characteristics to ensure that the internal structure is fully homogenized and create good conditions for rolling.
The rolling process is the top priority. When using a universal rolling mill, the spacing, speed and rolling force of the rollers need to be precisely adjusted according to the specifications of the heavy rails. Taking a 60kg/m heavy rail as an example, it is necessary to ensure that the dimensional accuracy of the head, waist and bottom is within the extremely small tolerance range, the head width tolerance is within ±0.5mm, and the waist thickness tolerance is within ±0.3mm. Through the automated control system, the rolling data is monitored in real time, and the parameters are adjusted in time to ensure that the cross-sectional shape of the heavy rail is accurate and meets the high standard use requirements.
The subsequent processing links should not be underestimated either. The cooling process adopts a slow cooling process to prevent internal stress and cracks caused by excessive cooling. The straightening process uses high-precision straightening equipment to control the straightness deviation of the heavy rail within the specified range. Flaw detection is even more critical. Ultrasonic, electromagnetic flaw detection and other technologies are used to conduct a full-scale scan of the heavy rail to check for minor internal defects. Only heavy rails that have passed rigorous flaw detection are qualified to enter the market and ensure the safety of railway operation.