A multi-track laser beam process for surface hardening a low-carbon and low manganese steel. The process includes providing cold rolled close annealed (CRCA) steel sheets having in weight percentage, C: 0.03-0.07, Mn: 0.15-0.25 or 1.4, S: 0.005-0.009, P: 0.009-0.014, Si: 0.005-0.02, Al: 0.04, V: 0.001, Nb: 0.001, and Ti: 0.002 and heating the surface of the steel sheet to an austenizing temperature using a multi-track laser beam, where, upon cooling, phase transformation of the initial microstructure to a harder dual phase structure occurs. The surface temperature of the steel sheet may be controlled based on a comparison of the on-line surface temperature effect with pre-stored data representing the desired surface temperature effect to eliminate any possibility of melting the sheet. The development of the desired microstructure of the sheet, including measurement of the hardness level and the fraction of different phases, may be periodically reviewed.

Hot rolling stock (1) made of metal which is rolled in at least one roll stand (2) and then cooled in a cooling section (5) arranged downstream of the at least one roll stand (2). Sound generated by means of a sound generator arrangement (8) is coupled into the rolling stock (1) by a coupling device (1) so that a standing sound wave is formed at least in the region of the rolling stock (1) which is located in the vicinity of the coupling device (10).

The invention relates to a surface-hardened, rotationally symmetrical workpiece, to a hardening method and to a hardening apparatus. The proposed hardening apparatus comprises a machine frame on which two coaxially arranged rotary bearings designed to support a rotationally symmetrical workpiece are arranged, at least one rotary bearing being operatively connected to a drive device to generate rotation of the workpiece; and at lease one laser apparatus for generating focussed, high-energy radiation is arranged on said rotary bearing, said laser apparatus being movable in the axial direction, and the radiation being directed toward the workpiece.

The invention relates to a surface-hardened, rotationally symmetrical workpiece, to a hardening method and to a hardening apparatus. The proposed hardening apparatus comprises a machine frame on which two coaxially arranged rotary bearings designed to support a rotationally symmetrical workpiece are arranged, at least one rotary bearing being operatively connected to a drive device to generate rotation of the workpiece; and at lease one laser apparatus for generating focussed, high-energy radiation is arranged on said rotary bearing, said laser apparatus being movable in the axial direction, and the radiation being directed toward the workpiece.

The present invention suppresses leakage of combustion gas from a contact surface. A cylinder head (20) is attached to a cylinder block. The surface (26) of the side of the cylinder head (20) that is attached to the cylinder block includes a first region (AH1) and a second region (AH2) that has higher hardness than the first region (AH1).

The present invention suppresses leakage of combustion gas from a contact surface. A cylinder head (20) is attached to a cylinder block. The surface (26) of the side of the cylinder head (20) that is attached to the cylinder block includes a first region (AH1) and a second region (AH2) that has higher hardness than the first region (AH1).

The present invention relates to a process for cooling a metal component, the process comprising the step of cooling said component in a confined space, said cooling involving cooling by means of a gas, the gas being cooled by heat exchange with a cooling surface of a heat sink inside said confined space, wherein a low frequency sound wave is provided into said confined space in order to improve heat exchange both between the gas and a cooling surface of the at least one heat sink, and between the gas and the metal component, characterised in that the cooling gas comprises at least one protective inert gas. The invention further relates to an apparatus for performing the process.

A method for conditioning a welded vehicle body assembly is provided. The method includes welding the vehicle body member to at least one additional vehicle body member together to form the welded vehicle body assembly, the welded vehicle body assembly includes a weld area; and laser annealing a weld heat affected zone adjacent to the weld area to soften material in the weld heat affected zone.

A method for conditioning a welded vehicle body assembly is provided. The method includes welding the vehicle body member to at least one additional vehicle body member together to form the welded vehicle body assembly, the welded vehicle body assembly includes a weld area; and laser annealing a weld heat affected zone adjacent to the weld area to soften material in the weld heat affected zone.

A non-heat treated steel for induction hardening contains, in mass %, C: 0.35 to 0.44%, Si: 0.01 to less than 0.30%, Mn: 0.80 to 1.50%, P: 0.030% or less, S: more than 0.010 to 0.095%, Cr: more than 0.10 to 0.30%, V: 0.050 to 0.200%, N: 0.0040 to 0.0200%, O: 0.0024% or less, Cu: 0.05% or less and Ni: 0.05% or less, and for which fn1≤50.0, fn2: 0.70 to 1.00, and fn3≥1.30. In the steel, a ratio of a number of Mn oxides containing oxygen in an amount of 20.0 mass % or more and Mn in an amount of 10.0 mass % or more to the number of oxides is 10.0% or less
fn1=80C.sup.2+55C+13Si+4.8Mn+30P+30S+1.5Cr
fn2=C+(Si/10)+(Mn/5)−(5S/7)+(5Cr/22)+1.65V
fn3=−2C—Si+2.33Mn+0.26Cr+V−1.5Cu−1.5Ni.