Sumitomo Metal Industries, Inc.

Tadashi Douhara

Tomio Yamakawa

Masayuki Sagara

Hiroaki Murakami

A starting material to be extruded made of a high alloy comprising, in mass %, Cr: 20 to 30% and Ni: more than 22% and 60% or less is heated to a temperature predetermined according to the contents of Mo and W and is subjected to a hot-extrusion process, the heating temperature T (&#xb0; C.) satisfying a relationship of Formula (1), (2), or (3), which is expressed in terms of the average cross-sectional area A (mm) of the starting material to be extruded, the extrusion ratio EL (&#x2212;), and the extrusion speed V (mm/s). As a result, a high-alloy seamless tube can be produced without generating cracking and/or seam flaws.When 0%&#x2266;Mo+0.5W&#x3c;4%:&#x2266;1343&#x2212;0.001322&#xd7;&#x2212;1.059&#xd7;&#x2212;0.129&#xd7;&#x2003;&#x2003;(1)When 4%&#x2266;Mo+0.5W&#x3c;7%:&#x2266;1316&#x2212;0.001322&#xd7;&#x2212;1.059&#xd7;&#x2212;0.129&#xd7;&#x2003;&#x2003;(2)When 7%&#x2266;Mo+0.5W:&#x2266;1289&#x2212;0.001322&#xd7;&#x2212;1.059&#xd7;&#x2212;0.129&#xd7;&#x2003;&#x2003;(3)

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Osaka, Japan

Tadashi Douhara