Papers by Keyword: TP304H

Abstract: 12Cr2MoV steel pipe and T91 steel pipe were joined by transient liquid phase diffusion bonding process (TLP) in argon atmosphere using FeNiCrSiB amorphous filler. TP304H steel pipe and 12Cr2MoV steel pipe were joined by the same method using Fe₇₈Si₉B₁₃ and BNi₂ amorphous filler. The qualified welding joint can be achieved by suitable adjustment of process parameters. The diffusion asymmetry in TLP of different metals has been analyzed. The research shows that there exists a diffusion asymmetry in TLP of different metals. The main reason is the difference of isothermal solidification rate in different materials, which results in a deviation of the bonding interface from the original centerline to T91 and TP304H side.

Abstract: Exposed to 650°C air, TP304H stainless steel with two different grain size was oxidized at this temperature. At the meantime, comparison of their oxidation was through the oxidation kinetics curves and analysis of the morphology and composition of oxide scale which conducted by SEM and X-ray. The results showed that the oxidation rate of TP304H stainless steel was slowed down by grain refinement and oxide scale of fine-grained TP304H steel was thinner than that of coarse-grained steel. The nucleation and the growth of nuclei of coarse-grained oxide scale were more rapid. In addition, the grain refinement of austenitic stainless steel accelerated the diffusivity of Cr and made for the formation of dense and continuous oxide scale, so that the oxidation of stainless steel can be effectively inhabited.

Abstract: The oxide scale of TP304H austenitic stainless steel was analyzed with SEM, X-ray, and ESA after being oxidized at 650 °C, 750 °C and 850 °C for different time. The results show that: the initial oxide film consists of needle-like cores. With the heating proceeding, the needle-like cores grow up gathering into granular cores, and then new needle-like cores grow up on former granular cores, and gradually grow into flakes which continue to gather into more granular cores then. As the oxide film becomes thicker, this process is in continuous cycle. The subsequent needle-like or flakey cores form on the basis of previous granular cores. The content of metallic elements is analyzed to find the law of diffusion and oxidation. As the figure shows the Fe of the matrix diffuses outward and the oxidation takes place at the oxide film-gas interface, which means a series of reactions does not occur inside the matrix. Below the temperature of 650 °C, the growth of oxide film is relatively slow, while above this temperature diffusion and displacement of metallic elements and oxide film growth rate accelerates. The oxide film is easy to fall off when reaching to a certain thickness, which means that TP304H stainless steel is not suitable in high-temperature and oxidative environment for long service.