Sus441(022cr18nbti) ferritic stainless steel has extremely low carbon and nitrogen content, and a small amount of beneficial alloying elements Nb and Ti are added. The lattice structure of sus441(022cr18nbti) ferritic stainless steel is body-centered cubic, and its octahedral gap radius is only 0. 15 times that of Fe atom (face-centered cubic is 0.4 14 times), so its ability to contain interstitial compound particles is poor. Therefore, the carbonitride particles of Nb and Ti are easily dispersed in the matrix metal, which improves the comprehensive properties of stainless steel.
The affinity of Ti and N in stainless steel is greater than that of Nb, and the affinity of Nb and C is greater than that of C. Therefore, there are a large number of dispersed second phase particles of TiN and NbC in 022Cr 18NbTi ferritic stainless steel, which not only strengthens the second phase, but also inhibits excessive grain coarsening at high temperature during welding thermal cycle, thus improving the weldability of the material (3). With proper welding process parameters, the grain size of weld and heat affected zone can be controlled above grade 4, and it has good mechanical properties and meets the application requirements.
1, C and N with very low profile, and Ti and Nb are added to improve the high temperature strength, corrosion resistance, weldability and machinability of the material. Steel grades specially developed by TISCO. 2. Features 1) High temperature corrosion resistance; 2) solderability; 3) High high temperature strength; 4) magnetism; 5) Excellent processability. 3. Scope of application Exhaust manifold, front pipe, converter, etc. Automobile exhaust system.
1. The performance of ferritic stainless steel for high-temperature end of automobile exhaust system requires that the ambient temperature of manifold and front pipe of automobile exhaust system can reach 750~ 900, and the local temperature may reach 950. The high-temperature properties of materials, such as high-temperature strength and high-temperature fatigue, are higher. However, with the improvement of emission level and engine performance, the exhaust temperature rises, and because of the need to reduce the weight of parts, especially for three-way catalytic devices, the use of ferritic stainless steel manifold can quickly improve the catalytic efficiency. ?
2. At present, ferritic stainless steels used in high-temperature end (exhaust manifold) of automobile exhaust system are mainly 429, 44 1 and 444, of which 429 and 444 are mainly used in Japanese cars and 44 1 are used in European and American systems.