Abstract: A three-dimensional object made of a bulk nitride, carbide, or boride-containing material may be manufactured using a powder bed fusion additive manufacturing technique. A layer of powder feed material may be distributed over a solid substrate and scanned with a high-energy laser beam to locally melt selective regions of the layer and form a pool of molten feed material. The pool of molten feed material may be exposed to gaseous nitrogen, carbon, or boron to respectively dissolve nitride, carbide, or boride ions into the pool of molten feed material to produce a molten nitrogen, carbon, or boron-containing solution. The molten nitrogen, carbon, or boron-containing solution may cool and solidify into a solid layer of fused nitride, carbide, or boride-containing material. In one form, the three-dimensional object may comprise a permanent magnet made up of a plurality of solid layers of fused iron nitride material having a magnetic Fe16N2 phase.

Abstract: A process for treating a piece of tantalum or of a tantalum alloy, which consists in: placing the piece in a furnace and heating the furnace under vacuum at least at 1 400° C.

Abstract: Fracture-resistant and self-lubricating wear surfaces are provided. In an implementation, a machine surface that is subject to wear is coated with or is constructed of a metallic nanostructure to resist the wear and to provide fracture-resistant hardness, built-in lubrication, and thermal conductivity for heat-sinking friction. The metallic nanostructured surface may be used, for example, on a face seal, bushing, bearing, thrust member, or hydraulic flow passage of an electric submersible pump. In an implementation, the metallic nanostructured surface is a nanocrystalline alloy including nanograin twins of a body-centered cubic (BCC), face-centered cubic (FCC), or hexagonal closest packed (HCP) metal. The nanostructured alloy may include atoms of copper, silver, gold, iron, nickel, palladium, platinum, rhodium, beryllium, magnesium, titanium, zirconium, or cobalt, and may provide more hardness and lubricity than diamond-like carbon coatings or carbides.

Abstract: A method for improving corrosion resistance in FNC cast iron substrates without the need for additional coating or painting. The exemplary methods remove a portion of the FNC coating applied to a cast iron substrate, preferably through polishing, to expose the epsilon phase portion of the compound area. The epsilon phase portion is thought to provide improved corrosion protection as compared to non-polished FNC cast iron substrates. One exemplary product that may be provided with improved corrosion protection according to the above method is a brake rotor having a FNC treatment.

Abstract: This invention relates to a partially carbonitriding heat treated stainless steel ferrule, having a first region with a first hardness and a second region with a second hardness, wherein the first region includes a nitrogen layer having a nitrogen concentration higher than a carbon concentration, and a carbon layer formed under the nitrogen layer and having a carbon concentration higher than a nitrogen concentration, so that the first hardness is greater than the second hardness. Thereby, partial heat treatment is effective at preventing rotational torque of the region, except for the portion to be heat treated, from increasing due to the total hardening.

Abstract: Disclosed herein is a partial heat treatment method using a double metal layer, in which a surface of a workpiece is hardened by heat treatment, including the steps of: primarily plating the surface of the workpiece with a first metal layer; secondarily plating the surface of the first metal layer with a second metal layer; partially stripping the first metal layer and the second metal layer to expose a part of the surface of the workpiece; heat-treating the workpiece to harden the exposed surface of the workpiece; and removing the first metal layer and the second metal layer remaining on the surface of the workpiece.

Abstract: A coated piston ring having a base body of chromium steel with more than 10 wt.-% chromium and having an inner circumferential surface, a first flank surface, a second flank surface and an outer circumferential surface. The first flank surface comprises a nitride diffusion layer with a layer thickness of from 5-300 ?m, a nitride connecting layer with a layer thickness of from 0.5-15 ?m on the nitride diffusion layer, and an oxide layer with a layer thickness of from 0.05-3 ?m on the nitride connecting layer. The second flank surface comprises the nitride diffusion layer, and the outer circumferential surface comprises the nitride diffusion layer and a chromium solid particle layer with 0.1-30 vol.-% solid particles, relative to the total volume of the chromium solid particle layer on the nitride diffusion layer.

Abstract: A steel which is excellent in delayed fracture resistance containing, by mass %, C: 0.10 to 0.55%, Si: 0.01 to 3%, and Mn: 0.1 to 2%, further containing one or more of Cr: 0.05 to 1.5%, V: 0.05 to 0.2%, Mo: 0.05 to 0.4%, Nb: 0.001 to 0.05%, Cu: 0.01 to 4%, Ni: 0.01 to 4%, and B: 0.0001 to 0.005%, and having a balance of Fe and unavoidable impurities, the structure being a mainly tempered martensite structure, the surface of the steel being formed with (a) a nitrided layer having a certain thickness range and a nitrogen concentration higher than the nitrogen concentration of the steel by 0.02 mass % or more and (b) a low carbon region having a certain depth range from the surface of the steel and having a carbon concentration of 0.9 time or less the carbon concentration of the steel.

Abstract: The present invention provides spring use heat treated steel which is cold coiled, can achieve both sufficient atmospheric strength and coilability, has a tensile strength of 2000 MPa or more, and can improve the performance as a spring by heat treatment after spring fabrication, that is, high strength spring-use heat treated steel characterized by containing, by mass %, C: 0.45 to 0.9%, Si: 1.7 to 3.0%, and Mn: 0.1 to 2.0%, restricting N: to 0.007% or less, having a balance of Fe and unavoidable impurities, and satisfying, in terms of the analyzed value of the extracted residue after heat treatment, [amount of Fe in residue on 0.2 ?m filter/[steel electrolysis amount]×100?1.1.

Abstract: In a method of manufacturing a photomask pattern, a light-shielding layer pattern and an anti-reflective layer pattern are formed sequentially on a transparent substrate. Oxidation and nitridation processes are performed on a sidewall of the light-shielding layer pattern to form a protection layer pattern on a lateral portion of the light-shielding layer pattern.

Abstract: Forming a 3D topology by forming a monolayer of nano-particles on a stainless steel surface, masking the stainless steel surface forming at least one unmasked regions, the unmasked region having an average density of nano-particles less than a critical average density, and introducing a plurality of exogenous atoms into the stainless steel surface only in the unmasked regions, the exogenous atoms causing the associated metal lattice to expand and harden and have an increase corrosion resistance, thereby selectively forming a 3D topology on the stainless steel surface.

Abstract: A method is disclosed for forming a brake rotor including a desired custom marking having a predetermined size and shape. The method includes applying a chemical treatment to a marking portion of a surface of the rotor. The marking portion has a size and shape corresponding to the predetermined size and shape of the desired custom marking. The chemical treatment is configured to affect, in a predetermined manner, an ability of a stimulus, to which the rotor is to be exposed, to alter properties of the rotor. The method also includes exposing the rotor, having the chemical treatment applied thereto, to the stimulus. The stimulus alters properties of the rotor at the marking portion differently than the stimulus alters properties of the rotor at other portions of the rotor adjacent the marking portion, thereby forming physical differences in the rotor, which, being visually perceptible, form the custom marking.

Abstract: A forged composite gear and a method of making a forged composite powder metal gear. The forged composite gear includes a plurality of teeth extending from a core, a first section having a first powder metal material, a second section having a second powder metal material and a variable boundary profile. The variable boundary profile is formed between the first section and the second section, whereby said variable boundary profile exhibits greater tooth wear resistance on the teeth and greater impact resistance in the core.

Abstract: The disclosure provides a device and method used to produce a tubular structure made of a refractory metal compound. In particular, the disclosure provides a device and method used to produce a tubular structure made of a refractory metal compound by reacting a green tubular structure made of a refractory metal with at least one reactive gas.

Abstract: A nitrided metal includes a metal core with a first microstructure and a nitrogen-containing solid solution region on the metal core. The nitrogen-containing solid solution region is free of nitride compounds and includes a second microstructure which is equivalent to the first microstructure. The first microstructure and the second microstructure are a tetragonal crystal structure.

Abstract: A method for diffusing titanium and nitride into a sports equipment component. The method generally includes the steps of providing a sports equipment component providing a salt bath which includes sodium dioxide and a salt selected from the group consisting of sodium cyanate and potassium cyanate; dispersing metallic titanium formed by electrolysis of a titanium compound in the bath, heating the salt bath to a temperature ranging from about 430° C. to about 670° C.; and soaking the sports equipment component in the salt bath for a time of from about 10 minutes to about 24 hours. In accordance with another aspect of the present invention, the sports equipment component may further be treated with conventional surface treatments or coatings.

Abstract: A method for producing a magnetic powder comprised chiefly of Fe16N2 comprising providing a starting powder comprising an oxy-hydroxide or oxide of iron and an amount of noble metal. The starting powder is reduced into an iron powder by a dry method using a hydrogen gas; and the iron powder is nitrided into a magnetic powder comprised chiefly of Fe16N2 particles using a nitrogen-containing gas at a temperature not higher than 200° C. The amount of noble metal is such that an amount that the atomic percent ratio of the noble metal content to Fe in the magnetic powder is 0.01-10.

Abstract: A treated austenitic steel and method for treating same includes an austenitic steel and a non-metal chemical element incorporated into a surface of the steel. The surface has a bi-layered structure of a compound layer at a top and an underlying diffusion layer, which protects said surface against hydrogen embrittlement.

Abstract: A method for increasing the fretting fatigue resistance of an alloy by prehardened a surface of the alloy followed by laser shock peening the prehardened surface. In one exemplary embodiment, an orthopedic prosthesis is formed from a titanium alloy and subjected to surface nitriding followed by laser shock peening. By nitriding the titanium alloy, the hardness of the alloy's surface is increased. Then, by subjecting the nitrided surface of the alloy to laser shock peening, the fretting fatigue of the nitrided surface may be increased by more than 100%.

Abstract: A raw steel is coated with or surrounded by a boron compound (step S1). A coating film of h-BN is formed on the surface of the raw steel. Then, the raw steel is nitrided by a nitriding gas while being heated (step S2). B from the boron compound and N from the nitriding gas are diffused into the raw steel, turning the raw steel into a steel material containing B and N. Most of B and N are present as an Fe (B, N) solid solution or an Fe (C, B, N) solid solution in the structure of the steel material. The raw steel is heated and nitrided under conditions such that B and N are contained ranging from 7 to 30 ppm by weight and ranging from 10 to 70 ppm by weight, respectively.

Abstract: A body of iron, steel or other such ferrous material is protected from thermochemical erosion by a layer of an iron nitride having a relatively low nitrogen content. The atomic percentage of nitrogen in the iron nitride layer is no greater than 20%, and in specific embodiments is in the range of 10-15%. The nitride layer may have a layer of a refractory material deposited thereatop. Some refractory materials include metals such as chromium. The invention has specific utility for protecting gun barrels, turbines, internal combustion engines, drilling equipment, machine tools, aerospace systems and chemical reactors which are exposed to extreme conditions of temperature and pressure. Specifically disclosed is a gun barrel which incorporates the invention.

Abstract: A method for surface treating a titanium gas turbine engine component. The method includes providing a gas turbine engine component having a titanium-containing surface. The component is heated to a temperature sufficient to diffuse carbon into the titanium and below 1000° F. The surface is contacted with a carbon-containing gas to diffuse carbon into the surface to form carbides. Thereafter, the carbide-containing surface is coated with a lubricant comprising a binder and a friction modifier. The binder preferably including titanium oxide and the friction modifier preferably including tungsten disulfide. The coefficient of friction between the surface and another titanium-containing surface is less than about 0.6 in high altitude atmospheres.

Abstract: Hydrogen embrittlement is prevented in Sm2Co17-based magnets and R2Fe14B-based magnets by metal plating the magnet, then carrying out heat treatment, or by forming a metal oxide or metal nitride layer on the metal plating layer or directly on the magnet itself.

Abstract: A method for diffusing titanium and nitride into a base material having a coating thereon using conventional surface treatments or coatings. The method generally includes the steps of providing a base material having a coating thereon; providing a salt bath which includes sodium dioxide and a salt selected from the group consisting of sodium cyanate and potassium cyanate; dispersing metallic titanium formed by electrolysis of a titanium compound in the bath; heating the salt bath to a temperature ranging from about 430° C. to about 670° C.; and soaking the base material in the salt bath for a time of from about 10 minutes to about 24 hours. In accordance with another aspect of the present invention, titanium and nitride may be diffused into a base material without a coating. The treated base material may further be treated with conventional surface treatments or coatings.

Abstract: The invention relates to components made of steel, more particularly outer joint parts and inner joint parts of constant velocity joints, and to a process of heat treating such components made of steel. The heat treatment operation includes the process stages of nitriding, induction surface layer hardening and tempering, which processes follow one another. As a result of the nitriding operation, the joint parts are provided with a surface layer (15) including nitrides and a diffusion layer (18) positioned thereunderneath. The subsequent induction hardening process causes the diffusion layer (18) to be hardened, so that it comprises good supporting characteristics for supporting the surface layer (15) positioned above same.

Abstract: A method and device for removing particulate matter from a liquid medium, especially a molten salt bath. The structure includes a device for capturing and removing particulate matter from a liquid medium. In operation, the device is inserted into the liquid having the particulate matter, with a particulate matter collector in the particle collecting position. An agitator circulates the liquid having the particulate matter therein. A portion of the particulate matter is collected in the particulate matter collector during the circulation. Thereafter, the circulation is ceased and the device is removed from the liquid with the particulate matter in the particulate matter collector. The device is moved to a discharge position, and the particulate matter collector is moved to a particle discharge position to discharge the particulate matter.

Abstract: A nanostructured tungsten carbide bulk material, sintered from tungsten carbide and metal such as cobalt nano-powders, comprises a tungsten carbide and a metallic binder such as cobalt phases. The tungsten carbide phase has nanostructures comprising a plurality of dislocations, twins, stacking faults, dislocation cells, nano-subgrains with preferred orientation or texture, or a combination thereof.

Abstract: A continuously variable, conical disk transmission including a torque-transmitting member in the form of a plate-link chain or a thrust link band. The chain includes plate links that are interconnected by pairs of rocker members that extend transversely relative to the chain movement direction. The thrust link band includes a number of thrust links that are in face-to-back contact and that extend transversely relative to the band movement direction. Each of the rocker members and the thrust links have ends that contact surfaces of the conical disks of the transmission for transmitting torque between the sets of disks. The ends of the rocker members and of the thrust links have a carbon-nitrided outer layer having a thickness of at least about 50 &mgr;m for increased durability. The surfaces of the conical disks that are contacted by the chain or the thrust link band can also be similarly treated.

Abstract: Hard metal particles having hardness which is lower than the hardness of a nitrided outermost layer of a spring and in the range of Hv 500 to 800 and a diameter of 500 to 900 &mgr;m are protected against the nitrided surface of the spring at a velocity of 40 to 90 m/sec to prevent generation of a microcrack in the surface layer and provide a compression residual stress comparatively deep inside the spring. Against the resultant spring surface, a number of fine metal particles having a mean diameter of all particles of 80 &mgr;m or less, a mean diameter of each particle in the range between 10 &mgr;m inclusive and less than 100 &mgr;m, a spherical or near spherical shape with no square portions, a specific gravity of 7.0 to 9.0, and hardness which falls in the range between Hv 600 and Hv 1100 inclusive and is equal to or less than the hardness of the outermost surface layer of the spring after nitriding, at a velocity of 50 to 190 m/sec.

Abstract: A method for producing a formed member made of a steel sheet according to the present invention is characterized by preparing a steel sheet material having tensile strength of 500 MPa or less and containing a nitriding element; forming a formed member having a predetermined shape by performing a plastic forming on the steel sheet material; and performing a nitriding treatment on the formed member so that an average hardness in the sheet thickness direction of the resultant steel sheet member is Hv 300 or more by Vickers hardness, and further characterized in that the difference in hardness between the surface part and the inside center part in the thickness direction of the steel sheet member of the formed member is Hv 200 or less by Vickers hardness, thereby it is possible to reliably obtain a formed member having a sufficiently high strength after a nitriding treatment while ensuring a plastic formability of a steel sheet in obtaining a formed member made of a steel sheet member of high strength by performi

Abstract: A method of coating a metal substrate, the method comprising the steps of forming the metal substrate, nitriding the substrate to form an oxide layer, and subsequently applying a metal compound coating comprising a titanium, zirconium, or aluminum compound using a vacuum chamber process such as physical vapor deposition (PVD) or chemical vapor deposition (CVD). Optionally, the process may include additional coating steps and/or a heat treatment step following the coating step(s). A polytetrafluoroethylene coating may also be added after the metal compound coating(s) and before any final heat treating.

Abstract: A method for producing a formed member made of a steel sheet according to the present invention is characterized by preparing a steel sheet material having tensile strength of 500 MPa or less and containing a nitriding element; forming a formed member having a predetermined shape by performing a plastic forming on the steel sheet material; and performing a nitriding treatment on the formed member so that an average hardness in the sheet thickness direction of the resultant steel sheet member is Hv 300 or more by Vickers hardness, and further characterized in that the difference in hardness between the surface part and the inside center part in the thickness direction of the steel sheet member of the formed member is Hv 200 or less by Vickers hardness, thereby it is possible to reliably obtain a formed member having a sufficiently high strength after a nitriding treatment while ensuring a plastic formability of a steel sheet in obtaining a formed member made of a steel sheet member of high strength by performi

Abstract: A method for nitriding a metallic base material at low temperatures in a salt bath containing electrolyzed titanium metal. A nitride coating of exceptional depth and hardness is obtained in a very short operating time due to the rapid nitriding process. The method is applicable to steel, titanium, aluminum and alloys thereof.

Abstract: A metallic drilling member is surface hardened except at an end portion, because the end portion is masked. The masking is achieved by placing on the end portion a lid which forms a slight gap around the surface being heat treated. During the heat treatment a furnace atmosphere enters the gap to cause the depth of the heat treatment to be gradually decreased in a manner producing a relatively elongated transition zone between heat treated and non-heat treated portions of the surface. The gap can be of constant width, or gradually decreasing width.

Abstract: A motor rotary shaft according to the present invention is constructed only at the surface layer of a journal portion with a hard nitride layer, so that the resultant motor rotary shaft is available at a low cost, not so heavy and excellent in durability in comparison with a case employing a hard material for the whole motor rotary shaft. Also, a method of manufacturing a motor rotary shaft according to the present invention employs fluorinating process prior to nitriding process to change a passive coat layer such as oxide layer on the surface of the journal portion to a fluoride layer, which protects the same surface. Therefore, even when there is space of time between formation of fluoride on the surface of the journal portion and nitriding process, the fluoride layer protects and keeps the surface of the journal portion in a favorable condition, resulting in that re-formation of oxide layer on that surface is prevented.

Abstract: A coil spring made of an oil-tempered steel wire with internal hardness of more than Hv 550 in cross-section, the surface hardness of the oil-tempered steel wire being determined in an extent between Hv 420 in a minimum value and hardness defined by subtraction of Hv 50 from the internal hardness in a maximum value.

Abstract: Creping doctor blades useful for making soft tissues are substantially improved by ion nitriding the surface(s) of the doctor blade to produce a hardened surface while retaining the resilient interior of the non-treated blade. The resulting blades have approximately a three-fold increase in blade life.

Abstract: A method for producing cast iron gears includes the steps of heating a blank composed of cast iron and having a teeth forming part to such a temperature that at least the teeth forming part is at least austenitized, and hot rolling the teeth forming part of the blank by pressing projecting teeth of a rolling machine against the teeth forming part which is in a hot state and within an austenitized range, while cooling the blank, thereby generating a teeth part in the teeth forming part of the blank. Hot rolling with a low plastic deformation resistance prevents lowering of strength due to the exposure of graphite particles of cast iron and occurrence of quenching cracks and rolling cracks, and improves gear accuracy.

Abstract: Object: Prevention of generation of press marks as well as increase of wear resistance at a corrugation tip portion and thereby providing a corrugating roll having a much improved life.Construction: A manufacturing method of a corrugating roll useful for forming a wave-shaped core paper of corrugated board, characterized in that the corrugating roll is worked to form tooth-shaped corrugation portions on the outer circumference and applying a nitriding treatment or a carbo-nitriding treatment, and then applying to the corrugation portion of the corrugating roll a quenching and tempering treatment, and further forming a wear resistant coating on the surface of the corrugation portion.

Abstract: The invention relates to the application of molybdenum alloys, which are superficially hardened by means of nitriding, for female dies and comparable construction components for extruding light and nonferrous metals. It is possible through the application of these materials to achieve distinct improvements over the materials used heretofore with respect to the tool life, extrusion rate and surface quality of the extruded material.

Abstract: A substrate material to be coated with either a nitride, carbide, or oxide contains a small percent of a specific reactive element, like titanium, which forms very stable nitrides, carbides, or oxides. The material also contains larger percentages of elements, such as chromium, which form less-stable nitrides, carbides, or oxides. When the substrate material is immersed in a process medium which contains reactants, such as nitrogen, carbon, or oxygen, at a chosen elevated temperature and concentration, the less-stable nitrides, carbides, or oxides are reduced and cannot form a coating on the material surface. Thus, only a very stable nitride, carbide, or oxide can form a strong, adherent coating.

Abstract: The process serves for the manufacture of an erosion-resistant turbine blade which is preferably used in the low-pressure stage of a steam turbine and is made of a vanadium-containing (.alpha./.beta.)-titanium base alloy. This involves the formation, by remelt alloying of a blade section which is situated in the region of the blade tip and comprises the leading edge of the blade, in a boron-, carbon- and/or nitrogen-containing gas atmosphere, with the aid of a high-power energy source, of an erosion-resistant protective layer made of a titanium boride, titanium carbide and/or titanium nitride. The remelt alloyed blade section is subjected to a heat treatment at a temperature between 600.degree. and 750.degree. C. with the formation of a vanadium-rich .beta.-titanium phase.

Abstract: An interconnection in a semiconductor device is made of a conductive laminate including a Ti film, a TiN film and an aluminium alloy film consecutively formed on a SiO.sub.2 film grown on a Si substrate. A heat treatment of the conductive layer is performed at 450.degree.-600.degree. C. before plasma-etching to introduce nitrogen and oxygen atoms from TiN film and SiO.sub.2 film, respectively, into the Ti film. The nitrogen and oxygen atoms prevent the side-etching of the Ti film during a plasma etching of the laminate using a plasma containing chlorine atoms. An interconnection having a high reliability is obtained with a high productivity.

Abstract: A monolithic metallic drive shaft for a marine propulsion device is disclosed which is resistant to corrosion. The drive shaft comprises proximal and distal end portions, each of which has a predetermined surface hardness. The surface hardness of one of the proximal and distal end portions is greater than the surface hardness of the other of the proximal and distal end portions.

Abstract: This is a highly purified metal comprising one metal selected from the group consisted of titanium, zirconium and hafnium. The highly purified metal has an Al content of not more than 10 ppm. It also has an oxygen content of more than 250 ppm, each of Fe, Ni and Cr contents not more than 10 ppm and each of Na and K contents not more than 0.1 ppm. The highly purified metal is obtained by either purifying crude metal by the iodide process or surface treating crude metal to remove a contaminated layer existing on the surface thereof and then melting The surface treated material with electron bean in a high vacuum.

Abstract: The diffusion bonding of aluminum and aluminum alloys presents problems because, when left exposed to the atmosphere even for a short time, they acquire an extremely tenacious surface oxide layer that inhibits or prevents satisfactory diffusion bonding. Unlike titanium, this oxide layer is not absorbed at diffusion bonding temperatures. The present invention comprises a method of reducing oxidation of a surface of aluminum or aluminum alloy by causing a nitride film to form on the surface. This film is believed to prevent oxidation of the aluminum or aluminum alloy, but to be absorbable into it at diffusion bonding temperatures. In the preferred embodiment shown in FIG. 1, the nitride film is applied to the piece of aluminum or aluminum alloy (10) in a vacuum chamber (4) by sputtering with nitrogen ions, or by heating the piece (10) in a nitrogen gas atmosphere.

Abstract: A process for producing a crack-free, laser nitride-hardened layer on a titanium substrate, the process including preheating the substrate, melting a small area of substrate with a laser, and shrouding the melted area with a gas mixture having a maximum critical amount of nitrogen not greater than 85%. A crack-free pump shaft so hardened to Rockwell 52 C is produced.

Abstract: Objects of titanium or titanium alloys having the surface converted to a hard and wear-resistant nitride layer with good adhesion, which is distributed uniformly and also provides internal capillaries. The objects are produced by being treated in a vacuum furnace with an atmosphere of pure nitrogen gas at a temperature of 650.degree.-1000.degree. C. and at a pressure below atmospheric pressure. The thickness of the nitride layer can be controlled by controlling the treatment time and temperature.

Abstract: The object of the present invention is to provide a piston ring which is free from occurrence of cracks on the nitrided layer and having enhanced abrasion resistance and fatigue strength, and to provide a process for manufacturing the piston ring. In the invention, a surface of the steel body is subjected to a two-stage nitriding treatment consisting of low-temperature nitriding and high-temperature nitriding. A white layer on the slidable surface along the inner periphery surface of a cylinder is removed, and a white layer on each of the upper and lower surfaces and the corner portions each being adjacent to the slidable surface is removed to have a thickness of not more than 5 .mu.m.

Abstract: A process for producing a crack-free, laser nitride-hardened layer on a titanium substrate, the process including preheating the substrate, melting a small area of substrate with a laser, and shrouding the melted area with a gas mixture having a maximum critical amount of nitrogen not greater than 85%. A crack-free pump shaft so hardened to Rockwell 52 C is produced.