Laser-hardened steels

Laser Hardening and Modification. Lasers are used to surface harden ductile steels and improve the toughness to a depth of 0.35 min or more. Lasers can also be used to bond solid or powder coatings to a surface. Typical coalings are nickel or titanium carbide on iron, and nickel, cobalt, manganese, and titanium carbide. TiC. on aluminum. I1 sc of lasers with other specialized coating methods is common. 

Laser/EB harden Carbonitride/caiburize/cyanide Induction-hardened steels Flame-hardened steels... 

Fig. 4. Hardness—depth curve for case hardening of 0.6 wt % C steel by laser heating (7).

For short periods of time, most bodies can be modeled as semi-infinite solids since heat does not have sufficient time to penetrate deep into the body, and the thickness of the body does not enter into the heat transfer analysis. A steel piece of any shape, for example, can be treated as a. semi-infinite solid when it is quenched rapidly to harden its surface. A body whose surface is heated by a laser pulse can be treated the same why. 

The LP process utilizes water-penetrable green light of a frequency-doubled Nd YAG laser delivered with an optical fiber and generates the high pressure plasma of several Gpa on the surface [8.3-8.5], The WJP process relies on the pressure derived from the cavitation collapse at the surface under the high pressure water jet [8.6 - 8.8]. The SP process utilizes spherical Type 304 stainless steel shots (diameter< 2mm) hardened during production process to have Vickers hardness about 500, which are projected by highly pressurized water ( IMPa) on the surface [8.9, 8.10]. 

Local surface hardening, for example, flame, induction, or laser for medium-carbon steels... 

For medium-carbon steel parts, consider the surface treatments listed above for mild steels, plus local surface hardening, for example, flame, induction, or laser for maximum loading, and for large rolling components (e.g., large cylindrical roller bearings and tracks). 

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