High Temperature Mechanical Properties Of2205Duple Stainless Steel Billet

Duplex stainless steel contains ferrite and austenite two-phase, and thus has boththe excellent performance of between the ferritic stainless steel and austenitic stainlesssteel, after decades of research and development, has been widely used in petroleum,chemical, natural gas, paper and many other fields. Duplex stainless steel casts byvertical continuous casting machine. In order to avoid cracks defects in continuouscasting process, to improve the finished product rate in continuous casting and rolling,need to understand the high temperature mechanical properties of2205duplexstainless steel billet, that is to understand the capacity of plastic deformation whensolidification cooling to each temperature range, to identify the brittle temperaturerange, thus avoiding the subject to greater stress in the corresponding temperature orthe occurrence of large deformation.Taking high temperature tensile test to2205duplex stainless steel by usingGleeble-1500D thermal simulation testing machine, and scanning electron microscope,metallurgical microscope and spectroscopy methods to observe and analyze thefracture morphology organization.2205duplex stainless steel contains a higher content of alloying element Cr、Ni、Mo, and due to the alloying elements have different diffusion capacity in ferrite andaustenite phase, making the duplex stainless steel often gets along with the formationof brittle organization in the ferrite phase, caused the stress increase, accelerated crackgrowth. Study found that the lower cooling rate can effectively avoid the precipitationof the brittle phase. 2205duplex stainless steel specimens’ reasons of embrittlement in the I brittletemperature is the interdendritic enriching low-melting-point inclusions (Cu, As, P, etc.)in high temperature, so that the liquid film freezing point depression, leading to themelting of the grain boundary. The embrittlement in II brittle zone is mainly due tostrain rate too high to re-crystallization, coarsening the austenite grain in the rapidcooling rate, forming widmanstatten structure, the coarse widmanstatten structure isshaped with reticular or needle distribution in the matrix, destroying the continuity ofthe matrix. The reason of embrittlement in Ⅲ brittle temperature was mainly due to theprecipitation of nonmetallic inclusions in/γ phase boundary, pine precipitates in thegrain boundary nailed to prevent the migration of grain boundaries, reduced thecapacity of plastic deformation.Verse plastic is less compared to vertical, with more inclusion-Al, S and Mg, Cain the fracture. and occurred widmanstatten transformation in III brittle zone,precipitating coarse the σ+γ2organization by ferrite, the plastic is very low. Thethermoplastics of2205duplex stainless steel can be improved by reducing thecomponents of segregation.