Stainless steel and method of manufacturing the same
AssigneeToyota Jidosha Kabushiki Kaisha
InventorsYu Takanezawa, Izuru Yamamoto, Keisuke Kadota, Hironori Aoyama, Toshiya Yamaguchi
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Abstract
A stainless steel that includes chromium and other alloying element as a plurality of alloying elements including: a base material layer including chromium of a specified chromium content necessary for forming a passive film or more; and a superficial layer including chromium at a lower chromium content than the chromium content contained in the base material layer, and the superficial layer including the other alloying elements at a same content of the other alloying element as the content of the other alloying element contained in the base material layer.
Claims12
A stainless steel that contains chromium and other alloying element as a plurality of alloying elements, the stainless steel comprising:
- a base material layer including 11% or more of the chromium and the other alloying element;
- and
- a superficial layer including chromium at a chromium content greater than zero and less than a chromium content contained in the base material layer, and the superficial layer including the other alloying element at a same content of the other alloying element as the content of the other alloying element contained in the base material layer,
- wherein the stainless steel forms a part of an inner wall surface of an exhaust path of an internal combustion engine, and the superficial layer contacts exhaust gas in the exhaust path, and
- wherein the chromium content of the superficial layer increases corresponding to a depth from an outermost surface layer of the superficial layer toward the base material layer.
A stainless steel comprising:
- a base material layer including chromium and other alloying element as a plurality of alloying elements;
- and
- a superficial layer that includes chromium and the other alloying element as a plurality of alloying elements, a chromium content contained in the superficial layer being greater than zero and less than 11%, the base material layer including chromium at a higher chromium content than the chromium content contained in the superficial layer, a difference between the chromium content contained in the base material layer and the chromium content contained in the superficial layer being larger than a difference between a content of the other alloying element contained in the base material layer and a content of the other alloying element contained in the superficial layer,
- wherein the stainless steel forms a part of an inner wall surface of an exhaust path of an internal combustion engine, and the superficial layer contacts exhaust gas in the exhaust path, and
- wherein the chromium content of the superficial layer increases corresponding to a depth from an outermost surface layer of the superficial layer toward the base material layer.
Dependencies are inferred from the claim text.