SEAMLESS STEEL PIPE ROLLING PLUG, MANUFACTURING METHOD FOR SEAMLESS STEEL PIPE ROLLING PLUG, SEAMLESS STEEL PIPE ROLLING PLUG MILL, ROLLING METHOD FOR SEAMLESS STEEL PIPE ROLLING PLUG, AND MANUFACTURING METHOD FOR SEAMLESS STEEL PIPE

To provide techniques for a seamless steel pipe rolling plug that improves a wear resistance property and suppresses deformation with no need of performing a plurality of times when performing heat treatment.SOLUTION: A seamless steel pipe rolling plug comprises: a plug material; and an oxide layer formed on a surface of the plug material. The plug material has a component composition containing, by mass%: 1.0 to 2.0% of C; 0.3 to 1.5% of Si; 0.3-1.5% of Mn; 0.01-0.1% of Al; 0.01-5.0% of Ni; 12-20% of Cr; 0.1-3.0% of one or two types of Mo and W (Mo+W); 0.01-0.1% of V, with a balance consisting of Fe and unavoidable impurities. The oxide layer has a spinel-type oxide of 50% or more in terms of body integration rate and a layer thickness of 0.4 mm or more. The plug material should have Vickers hardness of 500 to 700 Hv at a position 10 mm from an outer surface of the plug in a thickness direction.SELECTED DRAWING: None 【課題】複数回の熱処理を施さなくとも、耐摩耗性を向上させ、変形抑制を実現した継目無鋼管圧延用プラグの技術を提供すること。【解決手段】プラグ素材と、該プラグ素材表面に形成された酸化物層と、を有する継目無鋼管圧延用プラグであって、プラグ素材は、質量％で、Ｃ：１．０〜２．０％、Ｓｉ：０．３〜１．５％、Ｍｎ：０．３〜１．５％、Ａｌ：０．０１〜０．１％、Ｎｉ：０．０１〜５．０％、Ｃｒ：１２〜２０％、ＭｏとＷの１種または２種を（Ｍｏ＋Ｗ）：０．１〜３．０％、Ｖ：０．０１〜０．１％を含有し、残部がＦｅおよび不可避不純物からなる成分組成を有し、酸化物層は、スピネル型酸化物を体積分率で５０％以上有すると共に、層の厚みが０．４ｍｍ以上であり、プラグ外表面から厚み方向に１０ｍｍの位置がビッカース硬度で５００〜７００ＨＶを満たすようにする。【選択図】なし