Abstract
The carbide characteristics of 2.25Cr1Mo0.25V steel have an extremely important influence on the mechanical properties of welding joints. In addition, hydrogen resistance behavior is crucial for steel applied in hydrogenation reactors. The carbide morphology was observed by scanning electron microscopy (SEM) and the carbide microstructure was characterized by transmission electron microscopy (TEM). Tensile and impact tests were carried out and the influence of carbides on properties was studied. A hydrogen diffusion test was carried out, and the hydrogen brittleness resistance of welding metal and base metal was studied by tensile testing of hydrogenated samples to evaluate the influence of hydrogen on the mechanical properties. The research results show that the strength of the welding metal was slightly higher and the Charpy impact value was significantly lower compared to the base metal. The hydrogen embrittlement resistance of the welding metal was stronger than that of the base metal. The presence of more carbides and inclusions was the main cause of the decreased impact property and hydrogen brittleness resistance of the welding metal. These conclusions have certain reference value for designing and manufacturing hydrogenation reactors.
Highlights
Hydrogen reactors are necessary and very important equipment in the petrochemical and coal chemical industries
WMamount under selected welding carbides and heat in treatment destroys the continuity of the matrix
The yield strength and tensile strength of the welding metal (WM) phase were interfaces are prone to increased crack initiation andafter decreased impact performance
Summary
Hydrogen reactors are necessary and very important equipment in the petrochemical and coal chemical industries. Material damage or failure can occur when the reactor operates under high temperature and high pressure and is in contact with hydrogen for a long period. Two typical materials for hydrogenation reactors are 2.25Cr1Mo and 2.25Cr1Mo0.25V steel. In the past few decades, a large amount of literature has become available on 2.25Cr1Mo steel, including its mechanical properties [1,2], microscopic properties [3,4], reheat cracking properties [5,6], and hydrogen environmental properties [7,8,9,10]. 2.25Cr1Mo0.25V steel has been widely used in hydrogen reactors instead of the traditionally used 2.25Cr1Mo steel, due to its excellent hydrogen resistance, high-temperature strength, and other mechanical properties. The influence of welding and post-weld heat treatment (PWHT) on its impact properties and carbides is less studied
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