Stainless steel seamless pipes are widely used in piping systems for high-pressure, low-temperature and corrosion-resistant environments. Mechanical properties, process performance and corrosion resistance are three important indicators to measure the quality of steel pipes, which are also important to ensure the safe navigation of ships. So how to ensure the quality of stainless steel seamless steel pipe? According to the flow chart of stainless steel seamless steel pipe production, round steel billets are made into stainless steel through the main processes of piercing, cold drawing/cold rolling, solutioning, straightening and pickling. Seamless steel tubes are complementary to each other, especially the quality control of raw materials and intermediate products. It is important to ensure that the chemical composition, surface quality, mechanical properties, process properties and corrosion resistance of the finished tubes meet the specifications and standards.
To ensure the accuracy and uniformity of the hot furnace temperature control, perform the following operations.
Heating furnaces used to manufacture seamless stainless steel tubes include billet heating furnaces and tube heat treatment furnaces. The accuracy and uniformity of temperature control are two important indicators to judge the quality of the heating equipment and an important guarantee of the heating process. Therefore, the manufacturer should strictly comply with the thermocouple life and calibration period regulations and furnace temperature uniformity testing.
The heating process should be developed taking into account the inherent properties of the furnace equipment, the type and quantity of billets or seamless stainless steel tubes, and strict control of the heating rate, holding time and cooling rate to avoid cracking, overheating or over-burning. In the case of heating billets in the piercing stage, for example, the preheating time in the furnace should be long, and the heating rate in the initial heating stage should be slow, considering the low thermal conductivity of stainless steel and the expansion coefficient at room temperature. When the billet temperature exceeds a certain temperature (usually about 850°C), the thermal conductivity and plasticity of stainless steel will increase rapidly. At the same time, if the stainless steel stays in the high temperature zone for too long, it will produce alpha phase, namely ferrite, alpha when the phase exceeds a certain percentage, the thermoplasticity of the metal will drop sharply. In serious cases, will not be perforated, and high temperature and long-term insulation will also make the internal grain coarsening. Therefore, the homogenization phase of the manufacturing process of stainless steel seamless steel pipe should be heated rapidly, and the homogenization should be completed in a short time.