Patent ID: 6843866

Claim:
A process for producing wear-resistant surface layers using laser beam treatment on inductively heatable workpieces, wherein the process satisfies the following conditions: inductive preheating occurs in at least one of two preheating cycles V 1 and V 2 which directly follow one another; temperature fields produced by the two preheating cycles V 1 and V 2 are inhomogeneous and unsteady; effective heat flow density p 1 of first preheating cycle V 1 is lower than a heat flow density p 2 of second preheating cycle V 2 ; the first preheating cycle V 1 utilizes a maximum temperature T 1max in relation to a melting temperature T S of a base material of the workpiece, satisfying the expression: 0.2 ≤ T 1 ⁢ max ⁡ [ °C ] T S ⁡ [ °C ] ≤ 0.6 ; a maximum temperature T 2max of the second preheating cycle V 2 lies within the following temperature interval: 0.3 ≤ T 2 ⁢ max ⁡ [ °C ] T S ⁡ [ °C ] ≤ T S ⁡ [ °C ] - 50 ⁢ K T S ⁡ [ °C ] ; a ratio T 3max >T S applies for maximum temperature T 3max of a laser process cycle L; and the following ratios apply for relations between the two preheating cycles V 1 and V 2 : T 2max ≧T 1max +50 K ; ( Δ ⁢ ⁢ T 1 ⁢ max Δ ⁢ ⁢ t 1 ) < ( Δ ⁢ ⁢ T 2 ⁢ max Δ ⁢ ⁢ t 2 ) ; Δt 1 ≧m*Δt 2 with 1.5 ≦m≦ 30; z 1 ≧1.5 *z 2 whereby ΔT 1max and ΔT 2max correspond to temperature increases, Δt 1 and Δt 2 correspond to heat reaction times, and z 1 and z 2 correspond to heat penetration depths during the preheating cycles V 1 and V 2 .