Performance Analysis and Improvement of 20MnTiB Seamless Steel Tube for Hydraulic Cylinder Body

The mechanical performance of Φ426 mm×38 mm 20MnTiB quenched and tempered seamless steel tube for cylinder casing service are studied, in order to assess the feasibility of using 20MnTiB steel in tubes thicker than 30 mm or in low temperature environment.The testing results indicate that the quenching depth of 20MnTiB steel is about 15 mm and it is not suitable for producing steel tubes thicker than 30 mm when it is cooled on both the inner and outer surfaces.Furthermore, since the ductile-brittle transition temperature of 20MnTiB steel is around 13℃, it is not applicable in low temperature environment.In place of 20MnTiB steel, it is suggested to use a steel type with higher hardenability and lower ductile-brittle transition temperature for thick wall high strength hydraulic cylinder pipe.The replacement has higher strength and excellent low temperature toughness and its comprehensive properties are better than 20MnTiB steel, which makes it more suitable for producing high strength hydraulic cylinder pipe with WT more than 30 mm or to be used in low temperature environment.