Shang Hejun,Niu Yubing,Zhang Xin,et al.Effect of Forging and Heat Treatment Processes on Properties of 40CrNi2Mo Subsea Valve Stem Forgings[J].Special Steel,
Shang Hejun,Niu Yubing,Zhang Xin,et al.Effect of Forging and Heat Treatment Processes on Properties of 40CrNi2Mo Subsea Valve Stem Forgings[J].Special Steel,DOI:.
The requirements for mechanical properties and reliability of subsea oil and gas equipment are extremely stringent. This research focuses on 40CrNi2Mo subsea valve stem forgings, systematically analyzes the roles of major alloying elements, and investigates the effects of chemical composition, forging ratio, and heat treatment processes on mechanical properties. Through the preparation and testing of qualification test coupons (QTCs), it was ultimately determined that under a drawing forging ratio of 4.5∶1, the subsea valve stem forgings exhibit excellent performance after 910 ℃ full annealing + (890-900) ℃ dual-medium quenching +(620-630 ) ℃ high temperature tempering. For batch-produced valve stem forgings, the mechanical properties obtained from specimens taken from the body itself are as follows: yield strength of 950 MPa, tensile strength of 1 080 MPa, elongation of 19.5%, reduction of area of 62.0%, average impact absorbed energy of 71.8 J at -29 ℃, and a product surface hardness of 331 HBW, fully meeting the technical requirements.