2019 年 54 巻 6 号 p. 452-458
High nitrogen austenitic stainless steel forgings with heavy thickness and complex configuration are used for the ITER TF coil case. In the forging process for high nitrogen austenitic stainless steel, it is generally difficult to simultaneously obtain good ultrasonic attenuation, the required mechanical properties and the desired near-net shape. Accordingly, JCFC undertook development of an innovative forging method to form the near-net shape of the product, through consideration of possible methods and laboratory testing. By applying JCFC’s innovative method in trial manufacturing commissioned by QST, it was confirmed that the resulting forgings had material properties that satisfy ITER requirements and were also formed into a near-net shape. Subsequently, JCFC manufactured the actual forgings.