With the booming oil industry, more and more sour oil and gas fields containing HSCO have been developed. The harsh environment of the oilfield puts forward higher requirements for the corrosion resistance of materials used in oil and gas wells, and nickel-based alloys have been widely used in oil and gas industrial production due to their excellent resistance to acid oil and gas corrosion. Among them, Alloy 28, as a high-chromium-iron-nickel-based alloy, has the characteristics of ultra-low carbon, high chromium content and appropriate amount of molybdenum and copper, has good resistance to oxidation medium corrosion, and has excellent resistance to stress corrosion, pitting corrosion and crevice corrosion, so it has become a high-quality OCTG material.
Other commonly used grades of Sanicro 28 include Alloy 28, NO4563。This alloy belongs to fe-Ni-based austenitic alloys, also known as fe-Cr-Ni-based alloys, in which the CR (chromium) content is higher.
In terms of application fields, Sanicro 28 is widely used in the development of sour oil and gas fields because it is rich in CR, NI, MO and other elements, and has good corrosion resistance.
Unlike other nickel-based alloys, Sanicro 28 has higher Cr and Mo content in the precipitated phase than the matrix, while Fe and Ni content is lower than that of the matrix. This alloy construction helps to improve its corrosion resistance.
Regarding processing and heat treatment, Sanicro 28 alloy can be subjected to conventional hot and cold working, and proper heat treatment is carried out after processing to guarantee the performance of the material. During high-temperature heat treatment, attention needs to be paid to how the material is cooled to ensure optimal performance and corrosion resistance.
The results show that the structure of Alloy 28 alloy with a cold deformation of about 60% is basically equiaxed after holding at 900 1200 for 20 minutes, and the grain shows a trend of first refining and then growing. When the heat treatment temperature approaches 1100, the grains begin to grow rapidly. In addition, the strength and hardness of alloy 28 gradually decrease with the increase of heat treatment temperature, while the elongation tends to be stable when the temperature is close to 1100, and the mechanical properties are optimalWith the increase of heat treatment temperature, the corrosion rate first decreases significantly and then tends to be stable. Therefore, the mechanical properties and corrosion resistance of Alloy 28 alloy are optimal when the heat treatment temperature is close to 1100, which can be regarded as the optimal heat treatment temperature.
The alloy is available in a variety of formats, including plates, tubes, rods, wires, etc., with a choice of cold-drawn or hot-rolled products, in a wide range of sizes and sizes.