Q345R Alloy for Pressure Vessels

　　Q345R steel is akind of alloy pressure vessel special plate with a yield strength of 345 MPa, which has good comprehensive mechanical properties and process properties. The phosphorus and sulfur content is slightly lower than that of low-alloy high-strength steel plate Q345(16Mn) steel. In addition to the increase of tensile strength and elongation requirement than Q345 steel, it is also required to ensure impact toughness. Q345Ralloyis currently the most widely used and most used pressure vessel special steel plate in China.

　　Q345R steel is a large class in steel plates - container plate

　　Q345R. Q—“Qu” the first letter of Chinese Pinyin. 345 - yield strength value. R: The first letter of the Chinese pinyin.

　　Standard: GB 713-2014 standard

　　Category: alloy pressure vessel steel

　　According to the new classification of GB 713-2014Steel Plate for Boiler and Pressure Vessel, which was implemented on September 1, 2008, 16Mng and 16MnR, 19Mng were combined into Q345R. Q345Rmaterialis a common low-alloy steel, which is commonly used in boiler pressure vessels. The delivery status is: hot-rolled or normalized, and it is a low-alloy steel. The performance is similar to that of Q345 (16Mn) (the yield strength of 16mm steel plate is more than 345Mpa), the tensile strength is between (510-640), the elongation is greater than 21%, and the zero-degree V-type impact energy is greater than 34J. Q345R process reference standard GB713-2014.

　　Attention problems

　　First, the operating conditions of the equipment (such as design pressure, design temperature, characteristics of the medium), the welding properties of the material, the hot and cold processing properties, the heat treatment, and the structure of the container must be considered.

　　Second, on the premise of satisfying the first article, consider economic rationality:

　　1. When the required steel plate thickness is less than 8mm, carbon steel plate (except for multi-layer containers) should be used between carbon steel and low-alloy high-strength steel.

　　2. In the case of stiffness or structural design, ordinary carbon steel should be used as much as possible. In the case of strength design, steel plates such as Q235B, 20R (20G) and Q345R (16MnR) should be used in turn according to the restrictions on pressure, temperature and medium.

　　3. When the thickness of the required stainless steel is greater than 12mm, the structural forms such as lining, composite and surfacing should be used.

　　4. Stainless steel should not be used as heat-resistant steel with a design temperature of 500 degrees Celsius or less.

　　5. Pearlitic heat-resistant steel should not be used as heat-resistant steel with a design temperature of 350 ° C or less. When pearlitic heat-resistant steel must be used as heat-resistant steel or hydrogen-resistant, the variety and specifications of steel should be minimized and combined.

　　Third, Q345R steel plate with thickness greater than 60mm, the upper limit of carbon content can be increased to 0.22%.

　　4. Q545R steel plate can be added with yttrium, vanadium and titanium elements. The content should be filled in the quality certificate. The sum of the above three elements should be no more than 0.050%, 0.10% and 0.12% respectively.

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