Material Degradation in Heavy Steel Plates Caused by Bending with a Laser

摘要

A new process for bending heavy steel plates, using a laser to supply line heat, is described. A set of samples bent by this methods was examined for metallurgical damage. Metallographic examination revealed problems of grain growth and carbide segregation. Hardness measurements led to the conclusion that the heat affected zone is being transformed into untempered martensite. Microprobe analysis indicated a loss of nickel to carbide segregation. Charpy V-notch tests indicated a loss of ductility in the heat affected zone. The extent of damage was found to be a function of the surface temperature produced by the laser. A multiple-pass procedure was found to do much less damage than a single-pass procedure for an equivalent degree of bend.