A method of laser hardening a surface area of a workpiece, such as a surface of a journal of a crankshaft, includes the step of: 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. The method also includes the step of repetitively scanning the laser beam so as to produce a two-dimensional equivalent effective laser spot on said surface area, during the relative movement. The scanning pattern can include at least three substantially parallel lines which the laser spot follows in a certain order. When the workpiece includes several journals having different widths, two laser sources may be used to harden the surface area of the wider journals.

Steel for a crankshaft includes 0.37 to 0.42 wt % of carbon (C), 0.55 to 0.70 wt % of silicon (Si), 1.45 to 1.65 wt % of manganese (Mn), 0.025 wt % or less (excluding 0 wt %) of phosphorus (P), 0.020 to 0.035 wt % of sulfur (S), 0.15 to 0.30 wt % of chromium (Cr), 0.035 to 0.055% of vanadium (V), and the remainder of Fe and other inevitable impurities. The steel for a crankshaft has strength that is maintained high even when reducing the amount of vanadium.

Steel for a crankshaft includes 0.37 to 0.42 wt % of carbon (C), 0.55 to 0.70 wt % of silicon (Si), 1.45 to 1.65 wt % of manganese (Mn), 0.025 wt % or less (excluding 0 wt %) of phosphorus (P), 0.020 to 0.035 wt % of sulfur (S), 0.15 to 0.30 wt % of chromium (Cr), 0.035 to 0.055% of vanadium (V), and the remainder of Fe and other inevitable impurities. The steel for a crankshaft has strength that is maintained high even when reducing the amount of vanadium.

Metal components subject to wear or contact fatigue in a first area, and subject to bending, axial and/or torsional stress loading in a second area comprise a surface hardened, first surface layer in the first area; and a surface compressive-stress treated, second surface layer in the second area. The second surface layer has a material hardness different from, and typically lower than the first surface layer, and induced residual compressive stress to improve fatigue strength. Example components described include a gear, a cog, a pinion, a rack, a splined shaft, a splined coupling, a torquing tool and a nut driving tool. A hybrid manufacturing process is described, including area-selective surface hardening combined with a process to add compressive stress to fatigue failure prone areas.

Metal components subject to wear or contact fatigue in a first area, and subject to bending, axial and/or torsional stress loading in a second area comprise a surface hardened, first surface layer in the first area; and a surface compressive-stress treated, second surface layer in the second area. The second surface layer has a material hardness different from, and typically lower than the first surface layer, and induced residual compressive stress to improve fatigue strength. Example components described include a gear, a cog, a pinion, a rack, a splined shaft, a splined coupling, a torquing tool and a nut driving tool. A hybrid manufacturing process is described, including area-selective surface hardening combined with a process to add compressive stress to fatigue failure prone areas.

The invention relates to a method for the impact treatment of transition radii (8) of a crankshaft (4, 4), in particular transition radii (8) between connecting rod bearing journals (5, 5) and crank webs (7, 7) and/or transition radii (8) between main bearing journals (6, 6) and the crank webs (7, 7) of the crankshaft (4, 4). The crankshaft (4, 4) is then rotated along a rotational direction into an impact position by means of a drive device (3, 3). A locking device (12) is provided in order to lock the crankshaft (4, 4) in the impact position, and an impact force is then introduced into at least one transition radius (8) by at least one impact tool (16, 16).

A method for manufacturing a crankshaft for an internal combustion engine with a plurality of journals having a hardened case with a first microstructure. The crankshaft is comprised of a steel comprising between about 0.3 wt % and 0.77 wt % Carbon. The first microstructure of the hardened case of the journals comprises between about 15% and 30% ferrite and a balance of martensite and the resultant subsurface residual stress between 310 MPa and 620 MPa.

A method for manufacturing a crankshaft for an internal combustion engine with a plurality of journals having a hardened case with a first microstructure. The crankshaft is comprised of a steel comprising between about 0.3 wt % and 0.77 wt % Carbon. The first microstructure of the hardened case of the journals comprises between about 15% and 30% ferrite and a balance of martensite and the resultant subsurface residual stress between 310 MPa and 620 MPa.

A nitrided part excellent in contact fatigue strength plus rotating bending fatigue strength, the nitrided part having a steel material having a predetermined chemical composition as a material, wherein the nitrided part comprises a compound layer formed on the surface of the steel material, the compound layer containing iron, nitrogen, and carbon, a thickness of the compound layer being 3 m to less than 20 m; a phase structure in the compound layer in a range from the surface down to a depth of 5 m contains phases in an area ratio of 50% or more; a pore area ratio in a range from the surface down to a depth of 3 m is less than 10%; and a compressive residual stress of the compound layer surface is 500 MPa or more.

The invention relates to a hammering device for influencing the subsurfaces of workpieces comprising a beating tool for acting on the workpiece, a beating mechanism which has a first beater for producing a beating pulse on the beating tool, and a drive for driving the beating mechanism, wherein the beating mechanism has at least a second beater for producing a beating pulse on the beating tool. According to the invention, it is intended for the beating mechanism to comprise a drive shaft that extends along a drive axis and a wobble ring for transforming a rotational movement of the drive shaft into a translational movement, and the first beater and the second beater to be driven by the wobble ring.