Abstract: An object of the present invention is to provide a Ni base alloy solid wire for welding, which has excellent cracking resistance to ductility dip cracking in weld metal, can increase the tensile strength of the weld metal to not less than the tensile strength of the base material, and has excellent weldability. The present invention provides a solid wire which has a composition containing Cr: 27.0 to 31.5 mass %, Ti: 0.50 to 0.90 mass %, Nb: 0.40 to 0.70 mass %, Ta: 0.10 to 0.30 mass %, C: 0.010 to 0.030 mass %, and Fe: 5.0 to 11.0 mass %, and is regulated to Al: 0.10 mass % or less, N: 0.020 mass % or less, Zr 0.005 mass % or less, P:0.010 mass % or less, S: 0.0050 mass % or less, Si: 0.50 mass % or less, and Mn: 1.00 mass % or less, with the balance including Ni and inevitable impurities.

Abstract: Provided is a steel for machine structural use which has excellent machinability (particularly, with respect to tool life) for both intermittent cutting with a high-speed steel tool and continuous cutting with a cemented carbide tool while maintaining strength properties required of the steel for machine structural use. Specifically, the steel for machine structural use contains C: 0.05-0.9 mass %, Si: 0.03-2 mass %, Mn: 0.2-1.8 mass %, P: 0.03 mass % or less, S: 0.03 mass % or less, Al: 0.1-0.5 mass %, N: 0.002-0.017 mass %, and O: 0.003 mass % or less, and contains one or more selected from a group consisting of Ti: 0.05 mass % or less (excluding 0 mass %) and B: 0.008 mass % or less (excluding 0 mass %), with the remainder being iron and unavoidable impurities, and satisfies all of the following inequalities (1)-(3) below: (1): [N]?0.3[Ti]?1.4[B]<(0.0004/[Al])?0.002; (2): [Ti]?[N]/0.3<0.005; and (3): [B]?([N]?0.3[Ti])/1.4<0.003 when [Ti]?[N]/0.3<0 and [B]<0.003 when [Ti]?[N]/0.3?0.

Abstract: The present invention provides a steel for machine and structural use which is capable of maintaining mechanical characteristics such as strength by reducing a S content as well as of exhibiting excellent machinability (particularly tool life) in intermittent cutting (such as hobbing) with the high speed tool, and a method useful for producing the steel for machine and structural use. The steel for machine and structural use according to the invention secures 0.002% or more of solute N in the steel and has a chemical composition which is appropriately adjusted and satisfies a relationship of the following expression (1): (0.1×[Cr]+[Al])/[O]?150 . . . (1), in which [Cr], [Al], and [0] represent a Cr content (mass %), an Al content (mass %), and an O content (mass %), respectively.