Method of laser hardening of a surface area of a workpiece, such as a surface of a journal of a crankshaft, comprising: generating a relative movement between the surface of the workpiece and a laser source to allow a laser spot to subsequently be projected onto different portions of said surface area, and during said relative movement, repetitively scanning the laser beam (2) so as to produce a two-dimensional equivalent effective laser spot (5) on said surface area. The energy distribution of the effective laser spot is adapted so that it is different in a more heat sensitive subarea, such as in an area adjacent to an oil lubrication opening, than in a less heat sensitive subarea, so as to prevent overheating of said more heat sensitive subarea.

Method of laser hardening of a surface area of a workpiece, such as a surface of a journal of a crankshaft, comprising: generating a relative movement between the surface of the workpiece and a laser source to allow a laser spot to subsequently be projected onto different portions of said surface area, and during said relative movement, repetitively scanning the laser beam (2) so as to produce a two-dimensional equivalent effective laser spot (5) on said surface area. The energy distribution of the effective laser spot is adapted so that it is different in a more heat sensitive subarea, such as in an area adjacent to an oil lubrication opening, than in a less heat sensitive subarea, so as to prevent overheating of said more heat sensitive subarea.

There is provided a hot forging steel including, by mass %, C: more than 0.30% and less than 0.60%, Si: 0.10% to 0.90%, Mn: 0.50% to 2.00%, S: 0.010% to 0.100%, Cr: 0.01% to 1.00%, Al: more than 0.005% and 0.100% or less, N: 0.0030% to 0.0200%, Bi: more than 0.0001% and 0.0050% or less, Ti: 0% or more and less than 0.040%, V: 0% to 0.30%, Ca: 0% to 0.0040%, Pb: 0% to 0.40%, and a remainder including Fe and impurities, in which P and O in the impurities are respectively P: 0.050% or less and O: 0.0050% or less, an expression d+3<20 is satisfied, and a presence density of MnS having an equivalent circle diameter of smaller than 2.0 m is 300 pieces/mm.sup.2 or more in a cross section parallel to a rolling direction of a steel.

A nitrided steel part excellent in bending straightening ability and bending fatigue characteristic enabling reduction of size and decrease of weight of parts or enabling demand for high load capacities to be met, using as a material a steel material containing, by mass %, C: 0.2 to 0.6%, Si: 0.05 to 1.5%, Mn: 0.2 to 2.5%, P: 0.025% or less, S: 0.003 to 0.05%, Cr: 0.05 to 0.5%, Al: 0.01 to 0.05%, and N: 0.003 to 0.025%, and having a balance of Fe and impurities, having formed on the steel surface a compound layer of a thickness 3 m or less comprising iron, nitrogen, and carbon and a hardened layer formed below the compound layer, and having an effective hardened layer depth of 160 to 410 m.

A steel material which is excellent in machinability, in which occurrence of cracks during hot working and melting cracks during induction hardening can be suppressed, and which has excellent fatigue strength when formed into a component for machine structural use is provided. A steel material of the present embodiment contains, in percent by mass, C: 0.05 to 0.30%, Si: 0.05 to 0.45%, Mn: 0.30 to 2.00%, P: 0.030% or less, S: 0.010 to 0.095%, Cr: 0.01 to 2.00%, Bi: 0.0051 to 0.1500%, and N: 0.0030 to 0.0250%, and satisfies the following Formula (1). In the steel material, a number density of fine Bi particles is 80 to 8000 pieces/mm.sup.2 and a number density of coarse Bi particles is 10 pieces/mm.sup.2 or less.

[00001]$\begin{array}{cc}0.25C+\left(\mathrm{Si}/10\right)+\left(\mathrm{Mn}/5\right)-\left(5S/7\right)+\left(5\mathrm{Cr}/22\right)+1.65V1.& \left(1\right)\end{array}$

A connecting rod for a variable compression internal combustion engine, the connecting rod including a crank bearing eye for connecting the connecting rod with a crank shaft; a connecting rod bearing eye configured to connect the connecting rod with a cylinder piston of the internal combustion; an eccentrical element adjustment arrangement configured to adjust an effective connecting rod length, wherein the eccentrical element adjustment arrangement includes an eccentrical element that cooperates with an eccentrical element lever, wherein the eccentrical element is configured to receive a wrist pin of the cylinder piston, wherein the eccentrical element adjustment arrangement includes at least one cylinder with a piston that is displaceably supported in a cylinder bore hole and connected with a support rod, wherein the eccentrical element lever includes two eccentrical element lever segments which are connected by at least one connecting bolt to which the support rod is pivotably connected.

A connecting rod for a variable compression internal combustion engine, the connecting rod including a crank bearing eye for connecting the connecting rod with a crank shaft; a connecting rod bearing eye configured to connect the connecting rod with a cylinder piston of the internal combustion; an eccentrical element adjustment arrangement configured to adjust an effective connecting rod length, wherein the eccentrical element adjustment arrangement includes an eccentrical element that cooperates with an eccentrical element lever, wherein the eccentrical element is configured to receive a wrist pin of the cylinder piston, wherein the eccentrical element adjustment arrangement includes at least one cylinder with a piston that is displaceably supported in a cylinder bore hole and connected with a support rod, wherein the eccentrical element lever includes two eccentrical element lever segments which are connected by at least one connecting bolt to which the support rod is pivotably connected.

A method and apparatus for heat treatment of an object, such as for hardening of objects with complex shapes such as crankshafts, includes the steps of projecting an energy beam such as a laser beam onto a surface of the object, operating a scanner so as to repetitively scan the beam to displace a primary spot in accordance with a first scanning pattern so as to establish an effective spot on the object, and displacing the effective spot in relation to the surface of the object. The beam follows an optical path between the scanner and the surface of the object. A beam deflector device is placed in the optical path to redirect the beam. The beam deflector device can be placed close to the surface of the object.

A method and apparatus for heat treatment of an object, such as for hardening of objects with complex shapes such as crankshafts, includes the steps of projecting an energy beam such as a laser beam onto a surface of the object, operating a scanner so as to repetitively scan the beam to displace a primary spot in accordance with a first scanning pattern so as to establish an effective spot on the object, and displacing the effective spot in relation to the surface of the object. The beam follows an optical path between the scanner and the surface of the object. A beam deflector device is placed in the optical path to redirect the beam. The beam deflector device can be placed close to the surface of the object.

Provided is a non-thermal refined soft-nitrided component including chemical composition of a steel material of a base metal containing: in mass %, C: 0.25 to 0.40%; Si: 0.10 to 0.35%; Mn: more than 2.0% to 2.8% or less; N: 0.0030 to 0.0250%; Cu: 0 to 1.0%; Mo: 0 to 0.3%; Ni: 0 to 0.5%; Ti: 0 to 0.020%; and a balance being Fe and impurities, the impurities including P: 0.08% or less; S: 0.10% or less; Al: 0.05% or less; and Cr: less than 0.20%, wherein a Vickers hardness at a position of 0.05 mm from the surface is 400 to 480, a Vickers hardness at a position of 1.0 mm from the surface is 200 or more, and a compound-layer depth at a stress concentrated region is 5 m or less. This non-thermal refined soft-nitrided component has an excellent bending straightening property and a high fatigue strength.