The seamless steel pipe of the present embodiment consists of in mass %, C: 0.21 to 0.35%, Si: 0.10 to 0.50%, Mn: 0.05 to 1.00%, P: 0.025% or less, S: 0.010% or less, Al: 0.005 to 0.100%, N: 0.010% or less, Cr: 0.05 to 1.50%, Mo: 0.10 to 1.50%, Nb: 0.010 to 0.050%, B: 0.0003 to 0.0050%, and Ti: 0.002 to 0.050%, the balance being Fe and impurities. In a main body region of the seamless steel pipe, a grain size number of prior-austenite grain conforming to ASTM E112 is 7.0 or more, a difference between a maximum value and a minimum value of the grain size number is 1.0 or less, yield strength is 655 to less than 862 MPa, and a difference between a maximum value and a minimum value of tensile strength is 27.6 MPa or less.

The invention discloses a method for preparing a stainless steel seamless tube with ultra-high cleanliness for an integrated circuit and an IC industry preparation device, and a stainless steel seamless tube with ultra-high cleanliness. The stainless steel seamless tube which comprises, by mass, C≤0.010%, P≤0.020%, S≤0.010%, Mn≤0.10%, Si≤0.30%, Se≤0.010%, Al≤0.010%, Cu≤0.20%, Cr16.50-17.00%, Ni14.50-15.00%, Mo2.20-2.50%, N≤0.010%, Ni≤0.010%, Ti≤0.010% and the balance Fe and impurities is prepared through a: a stainless steel refining process; b: a vacuum induction melting and vacuum consumable remelting process; c: a stainless steel forging process; d: a hot piercing process; e: a cold working process; f: an inner bore electrolytic polishing, pickling and passivation process; and g: a cleaning process. The stainless steel seamless tube with ultra-high cleanliness prepared through these processes meet the requirements for ultra-high cleanliness and high performance of 316L stainless steel tubes for a semiconductor preparation device.

The invention discloses a method for preparing a stainless steel seamless tube with ultra-high cleanliness for an integrated circuit and an IC industry preparation device, and a stainless steel seamless tube with ultra-high cleanliness. The stainless steel seamless tube which comprises, by mass, C≤0.010%, P≤0.020%, S≤0.010%, Mn≤0.10%, Si≤0.30%, Se≤0.010%, Al≤0.010%, Cu≤0.20%, Cr16.50-17.00%, Ni14.50-15.00%, Mo2.20-2.50%, N≤0.010%, Ni≤0.010%, Ti≤0.010% and the balance Fe and impurities is prepared through a: a stainless steel refining process; b: a vacuum induction melting and vacuum consumable remelting process; c: a stainless steel forging process; d: a hot piercing process; e: a cold working process; f: an inner bore electrolytic polishing, pickling and passivation process; and g: a cleaning process. The stainless steel seamless tube with ultra-high cleanliness prepared through these processes meet the requirements for ultra-high cleanliness and high performance of 316L stainless steel tubes for a semiconductor preparation device.

A method for piercing a titanium alloy solid billet, the method including: 1) providing a Mannesmann rotary piercer including two rollers, a feed channel, a plurality of centering devices, and a mandril including a plug; fixing the mandril using the plurality of centering devices, where the Mannesmann rotary piercer has a feeding angle of 6-18°, a cross angle of 15°, and a roll speed of 30-90 rpm; 2) heating a titanium alloy solid billet to 930-990° C.; 3) transferring the titanium alloy solid billet to the feed channel of the Mannesmann rotary piercer; and 4) aligning the titanium alloy solid billet with the plug of the mandril, and driving the titanium alloy solid billet to pass through the plug of the mandril, thereby piercing the titanium alloy solid billet and yielding a titanium alloy tube.

A method for piercing a titanium alloy solid billet, the method including: 1) providing a Mannesmann rotary piercer including two rollers, a feed channel, a plurality of centering devices, and a mandril including a plug; fixing the mandril using the plurality of centering devices, where the Mannesmann rotary piercer has a feeding angle of 6-18°, a cross angle of 15°, and a roll speed of 30-90 rpm; 2) heating a titanium alloy solid billet to 930-990° C.; 3) transferring the titanium alloy solid billet to the feed channel of the Mannesmann rotary piercer; and 4) aligning the titanium alloy solid billet with the plug of the mandril, and driving the titanium alloy solid billet to pass through the plug of the mandril, thereby piercing the titanium alloy solid billet and yielding a titanium alloy tube.

A method for producing a seamless metal pipe includes the steps of: preparing a billet having a diameter (B); heating the billet; forming, in a center part of a rear end of the heated billet, a hole including four grooves extending in an axial direction of the billet, the grooves each having a groove width (D) satisfying Formula (1), a groove height (H) satisfying Formula (2), and a groove depth (L1) satisfying Formula (3); and subjecting the billet provided with the hole to piercing-rolling from a front end thereof by means of a piercing machine. By this means, the generation of burrs and internal defects at the rear end of a hollow shell after piercing-rolling can be suppressed.
0.12≤D/B≤0.25  (1)
0.10≤H/B≤0.20  (2)
0.05≤L1/B≤0.10  (3)

A method for producing a seamless metal pipe includes the steps of: preparing a billet having a diameter (B); heating the billet; forming, in a center part of a rear end of the heated billet, a hole including four grooves extending in an axial direction of the billet, the grooves each having a groove width (D) satisfying Formula (1), a groove height (H) satisfying Formula (2), and a groove depth (L1) satisfying Formula (3); and subjecting the billet provided with the hole to piercing-rolling from a front end thereof by means of a piercing machine. By this means, the generation of burrs and internal defects at the rear end of a hollow shell after piercing-rolling can be suppressed.
0.12≤D/B≤0.25  (1)
0.10≤H/B≤0.20  (2)
0.05≤L1/B≤0.10  (3)

A piercer plug with increased recyclability is provided. A piercer plug (1) has a chemical composition of, in mass %: 0.15 to 0.30% C; 0.4 to 1.2% Si; 0.2 to 1.5% Mn; 0.1 to 2.0% Ni; 0 to 4.0% Mo and 0 to 4.0% W, where the total content of Mo and W is 1.0 to 6.0%; higher than 1.0% and not higher than 4.0% Cr; 0 to 0.2% B; 0 to 1.0% Nb; 0 to 1.0% V; 0 to 1.0% Ti; and balance Fe and impurities, the plug including a tip portion (2) and a trunk portion (3) made of the same material as the tip portion (2) and contiguous to the tip portion (2). The trunk portion (3) includes a cylindrical portion (5) having a hole used to mount a bar. The tip portion (2) is harder than the cylindrical portion (5).

A method for piercing a titanium alloy solid billet, the method including: 1) providing a Mannesmann rotary piercer including two rollers, a feed channel, a plurality of centering devices, and a mandril including a plug; fixing the mandril using the plurality of centering devices, where the Mannesmann rotary piercer has a feeding angle of 6-18°, a cross angle of 15°, and a roll speed of 30-90 rpm; 2) heating a titanium alloy solid billet to 930-990° C.; 3) transferring the titanium alloy solid billet to the feed channel of the Mannesmann rotary piercer; and 4) aligning the titanium alloy solid billet with the plug of the mandril, and driving the titanium alloy solid billet to pass through the plug of the mandril, thereby piercing the titanium alloy solid billet and yielding a titanium alloy tube.

A method for piercing a titanium alloy solid billet, the method including: 1) providing a Mannesmann rotary piercer including two rollers, a feed channel, a plurality of centering devices, and a mandril including a plug; fixing the mandril using the plurality of centering devices, where the Mannesmann rotary piercer has a feeding angle of 6-18°, a cross angle of 15°, and a roll speed of 30-90 rpm; 2) heating a titanium alloy solid billet to 930-990° C.; 3) transferring the titanium alloy solid billet to the feed channel of the Mannesmann rotary piercer; and 4) aligning the titanium alloy solid billet with the plug of the mandril, and driving the titanium alloy solid billet to pass through the plug of the mandril, thereby piercing the titanium alloy solid billet and yielding a titanium alloy tube.