| 摘要 |
PURPOSE:To develop a steel product having stable nonmagnetism and an excellent yield strength, toughness, corrosion resistance, and drilling workability by using an Mn-Cr-V-N austenitic stainless steel having a specific compsn. as a steel for a nonmagnetic drill collar for excavation of oil wells. CONSTITUTION:The high-Mn nonmagnetic steel having the following compsn. is used as the steel material for the nonmagnetic drill collar for excavation of the oil wells and gas wells: The steel material having the compsn. contg., by wt%, 0.1-0.50% C, <2.0% Si, 12-20% Mn, 0.01-6.00% Ni, 12-20% Cr, 0.1-1.5% V, 0.1-0.5% N, <0.15% S, and >=1 kinds among 0.005-0.30% Se, 0.005-0.30% Te, and 0.03-0.20% Pb or further contg. <1.5% Cu or >=1 kinds of 0.01-2.00 Mo and 0.01-1.00% Nb alone or in combination and satisfying the formula 20XC%+20XN%+0.5XMn%+Ni%>=18.5% is used. |
