Sumitomo Metal Industries, Inc.

Kazuyo Kushida, Legal Representative

Takahiro Kushida

Kunio Kondo

Tomohiko Omura

Keiichi Nakamura

Hisashi Amaya

Masakatsu Ueda

Mitsuhiro Numata

A martensitic stainless steel comprising C: 0.01-0.10%, Si: 0.05-1.0%, Mn: 0.05-1.5%, P: not more than 0.03%, S: not more than 0.01%, Cr: 9-15%, Ni: 0.1-4.5%, Al: not more than 0.05% and N: not more than 0.1% in mass %, and further comprising at least one of Cu: 0.05-5% and Mo: 0.05-5%, the residual being Fe and impurities, is provided, wherein the contents of Cu and Mo satisfy the following formula (a) or (b),0.2%&#x2266;Mo+Cu/4&#x2266;5%&#x2003;&#x2003;(a)0.55%&#x2266;Mo+Cu/4&#x2266;5%&#x2003;&#x2003;(b)and wherein the hardness is 30-45 in HRC and the carbide amount in grain boundaries of the prior austenite is not more than 0.5 volume %. The marensitic stainless steel has excellent properties regarding the sulfide stress cracking resistance, the resistance to corrosive wear and the localized corrosion.

Martensitic stainless steel

A steel product for a line pipe according to the invention has a composition containing, in mass %, C : 0.03% to 0.15%, Si: 0.05% to 1.0%, Mn: 0.5% to 1.8%, P: 0.015% or less, S: 0.004% or less, O: 0.01% or less, N: 0.007% or less, sol. Al: 0.01% to 0.1%, Ti: 0.024% or less, Ca: 0.0003% to 0.02%, and the balance consisting of Fe and impurities. The size of TiN in the steel product for a line pipe is at most 30 &#x3bc;m. The steel product has high HIC resistance and its crack area ratio can be reduced to 3% or less.

Steel product for use as line pipe having high HIC resistance and line pipe produced using such steel product

Growing community of inventors

Amagasaki, Japan

Kazuyo Kushida, Legal Representative