Abstract: A hot work tool steel having a chemical composition in wt %: C: 0.10 to 0.35%, Si: less than 0.80%, Mn: 3.0% or less, Cr: 2.0% or more and less than 7.0%, N: more than 0.05% and 0.50% or less, O: 0.0100% or less, P: 0.050% or less, Al: 0.050% or less, with the proviso that ½W+Mo: 0.3 to 5.0%, C+N: 0.20 to 0.60% and C/N: 6 or less, and the balance: substantially Fe, and optionally V: 0.01 to 0.5%. The hot work tool steel exhibits excellent resistance to melting, while retaining good toughness and good resistance to heat checking.

Abstract: Cold work tool steel of the present invention comprises 0.4?K value?2.6 (K value Cr(wt %)?6.8C (wt %)), 15.5?L value?21.0 (L value=Cr(wt %)+15.5C (wt %), 0.60 wt %?Si?2.0 wt %, 0.10 wt %?Mn?1.0 wt %, 0.03 wt %<S?0.2 wt %, 1.25 wt %<Mo+0.5 W<3.0 wt %, 0.05 wt %?V?1.0 wt %, and the balance Fe and inevitable impurities, in which the highest hardness obtained by tempering at 450° C. or higher after quenching is HRC 61 or more.

Abstract: A free-cutting tool steel is provided containing Fe and C in an amount of 0.1 to 2.5 wt %, Ti and or Zr where WTi+0.52WZr constitutes 0.03 to 3.5 wt %, and WTi represents Ti content and WZr represents Zr content, at least any one of S, Se and Te where WS+0.4WSe+0.25WTe constitutes 0.01 to 1.0 wt %, and (WTi+0.52WZr)/(WS+0.4WSe+0.25WTe) constitutes 1 to 4, and WS represents S content, WSe represents Se content and WTe represents Te content; and dispersed therein a texture thereof from 0.1 to 10% in terms of area ratio in a section of a machinability improving compound phase of a metallic element component of Ti and/or Zr as major components, and a binding component for the metallic element component containing C and any one of S, Se and Te.

Abstract: A free-cutting tool steel is provided containing Fe and C in an amount of 0.1 to 2.5 wt %, Ti and or Zr where WTi+0.52WZr constitutes 0.03 to 3.5 wt %, and WTi represents Ti content and WZr represents Zr content, at least any one of S, Se and Te where WS+0.4WSe+0.25WTe constitutes 0.01 to 1.0 wt %, and (WTi+0.52WZr)/(WS+0.4WSe+0.25WTe) constitutes 1 to 4, and WS represents S content, WSe represents Se content and WTe represents Te content; and dispersed therein a texture thereof from 0.1 to 10% in terms of area ratio in a section of a machinability improving compound phase of a metallic element component of Ti and/or Zr as major components, and a binding component for the metallic element component containing C and any one of S, Se and Te.

Abstract: A steel shaft material having desirable cuttability and induction hardenability even in the form of milled stock without being subjected to any heat treatment, such as annealing, and a method for manufacturing the same. A steel ingot is prepared containing 0.38 to 0.45 wt. % of carbon, 0.15 wt % or less of silicon, 0.3 to 1.0 wt % of manganese, 0.0005 to 0.0030 wt % of boron, 0.01 to 0.05 wt % of titanium, 0.01 to 0.06 wt % of aluminum, 0.010 wt % or less of nitrogen, optionally at least one of chromium in an amount of 0.3 wt % or less and molybdenum in an amount of 0.10 wt % or less, and optionally at least one of 0.005 to 0.30 wt % of sulfur, 0.0002 to 0.005 wt % of calcium, 0.005 to 0.30 wt % of lead and 0.005 to 0.10 wt % of tellurium, and the remainder being iron and unavoidable impurities. After the ingot is heated to 1,100.degree. C. or less, the ingot is milled at a finishing temperature of 950.degree. C. or below and an area reduction rate of 70% or higher, and then cooled in the atmosphere.

Abstract: A fixture capable of a brittle pre-crack introduction of prescribed shape and size in a ceramic specimen with high reproducibility comprises an anvil provided on the upper side thereof with a central groove perpendicularly intersecting a specimen to be mounted thereon for pre-crack introduction and a groove for positioning the specimen and a platelike pusher possessing a smooth and flat lower surface. To ensure stability of the brittle pre-crack introduction, the positioning groove in the anvil is so formed as to rise rectangularly in an equal length on either side of the central groove and the overall length of the positioning groove, i.e. the sum of the lengths of the raised portions plus the width of the central groove, is kept from exceeding the length of the specimen. To enhance the results of the introduction, the lower surface of the pusher is finished with roughness of not more than 0.8S and flatness of not more than 0.01 mm.