Performance, Characteristics, and Applications of 07Cr25Ni21 Seamless Stainless Steel Pipe

As a high-performance specialty steel, 07Cr25Ni21 stainless steel pipe plays a vital role in various industrial sectors. Its unique material properties and wide range of applications make it an indispensable material in numerous engineering projects. 07Cr25Ni21 seamless stainless steel pipes are produced using the following methods: cold-rolled seamless steel pipes, cold-drawn seamless steel pipes, and heat-treated and rinsed for delivery.

The chemical composition of 07Cr25Ni21 seamless stainless steel pipes is as follows: Nickel: 19.00-22.00, Chromium: 24.00-26.00, Silicon: ≤0.75, Manganese: ≤2.00, Carbon: 0.040-0.10, Sulfur: ≤0.015, Phosphorus: ≤0.030.

First, the chemical composition and physical properties of 07Cr25Ni21 seamless stainless steel pipes.

Based on its chemical composition, 07Cr25Ni21 stainless steel primarily contains approximately 25% chromium and 21% nickel, and may also contain smaller amounts of carbon, silicon, manganese, phosphorus, and sulfur. The high chromium and nickel content imparts this stainless steel with excellent corrosion resistance and high-temperature strength. Chromium forms a dense oxide film on the steel surface, effectively preventing corrosion from oxygen and other corrosive media. Nickel, on the other hand, enhances the steel's structural stability and improves its creep resistance in high-temperature environments.

In terms of physical properties, 07Cr25Ni21 stainless steel features high density, good thermal conductivity, and a low coefficient of linear expansion. Its density is approximately 8.0 g/cm³, which means it is heavier than some other stainless steel grades for the same volume, but this also results in better wear resistance. Its good thermal conductivity makes it excellent for use in heat exchange equipment, while its low coefficient of linear expansion ensures dimensional stability in both high and low-temperature environments.

Second, the corrosion resistance and weldability of 07Cr25Ni21 stainless steel seamless pipes.

07Cr25Ni21 stainless steel is renowned for its exceptional corrosion resistance, particularly in both oxidizing and reducing media. While its corrosion resistance in chloride-containing environments is slightly lower than that of some super stainless steels, it is more than adequate for most common chemical media. This material also exhibits excellent corrosion resistance to organic acids such as nitric acid and acetic acid, making it suitable for chemical containers and pipelines. Regarding weldability, 07Cr25Ni21 stainless steel is an austenitic stainless steel with excellent weldability. However, due to its high nickel and chromium content, it is prone to thermal cracking during welding, especially when welding thick-walled materials. Therefore, in practice, measures such as preheating, interpass temperature control, and slow cooling after welding are necessary to minimize cracking. Furthermore, selecting the right welding consumables is crucial for ensuring welding quality. It is generally recommended to use welding wire or electrodes with a composition similar to that of the base material.

Third, Applications of 07Cr25Ni21 Seamless Stainless Steel Pipe.

1. Chemical Industry: Due to its excellent corrosion resistance, it is particularly suitable for manufacturing components such as piping, reactors, and heat exchangers in chemical equipment.

2. Power Industry: In nuclear and thermal power plants, 07Cr25Ni21 seamless stainless steel pipe is used in critical areas such as high-temperature and high-pressure steam pipelines, condensers, and feedwater heaters.

3. Oil and Gas Industry: Due to its excellent corrosion resistance and high-temperature strength, it is suitable for corrosive media pipelines used in oil and gas extraction and transportation.

4. Food Processing Industry: Stainless steel seamless pipes that meet food-grade standards can be used in the production of pipelines, storage tanks, and other equipment used in food production, ensuring food safety.

5. Environmental Protection and Water Treatment: 07Cr25Ni21 stainless steel seamless pipes are highly favored in environmental protection projects such as wastewater treatment and seawater desalination due to their corrosion resistance.

Fourth, Production Process and Quality Control of 07Cr25Ni21 Stainless Steel Seamless Pipes

The production of 07Cr25Ni21 stainless steel seamless pipes primarily involves the following steps: raw material preparation, heat piercing, rolling and elongation, heat treatment, pickling and passivation, inspection and testing, and finished product packaging.

- Raw Material Preparation: High-quality 07Cr25Ni21 stainless steel billets are selected to ensure uniform chemical composition and the absence of inclusions.

- Heat Piercing: After heating the billet to the appropriate temperature, it is pierced through a piercing machine to form the initial tube billet. - Rolling and Elongation: The pierced tube billet undergoes multiple rolling passes, gradually reducing its diameter and increasing its wall thickness until the desired specifications are achieved.

- Heat Treatment: The rolled steel tube undergoes solution treatment and aging treatment to eliminate internal stresses, improve structural uniformity, and enhance performance stability.

- Pickling and Passivation: Pickling removes scale and impurities from the steel tube surface, followed by passivation treatment to enhance surface corrosion resistance.

- Inspection and Testing: Finished steel tubes undergo visual inspection, dimensional measurement, mechanical property testing, and hydrostatic testing to ensure product quality meets standards.

- Finished Product Packaging: Qualified steel tubes undergo rust-proofing treatment and are packaged with appropriate packaging materials for transportation and storage.

In addition to the rigorous monitoring of the aforementioned production processes, quality control also requires rigorous chemical composition analysis of raw materials, regular sampling inspection of finished products, and the establishment of a comprehensive quality traceability system to ensure the traceability and quality stability of each batch.

In summary, 07Cr25Ni21 stainless steel seamless pipe has become an indispensable material in the industrial field due to its excellent performance, wide application fields, and strict production quality control. With the continuous advancement of science and technology and the acceleration of industrialization, the demand for 07Cr25Ni21 stainless steel seamless pipe will continue to grow, and its development prospects are worth looking forward to.