In the present study, an AZ31B magnesium alloy was welded using a low-power pulsed Nd:YAG laser attached to a six-axis welding robot. The welding metallurgical characteristics, including microstructure, porosity formation, texture evolution and microhardness distribution were systematically investigated using a scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and a microhardness tester. The transverse cross-sectional microstructure of the AZ31B-alloy joint was composed of the base metal (BM), columnar-grain zone (CGZ) and equiaxed-grain zone (EGZ) in the center of the fusion zone (FZ). Some pores were observed in the FZ and believed to be related to the pre-existing pores in the BM. Especially, it was noted that many columnar grains observed in the transverse cross-section of the FZ were almost perpendicular to the solid-fusion boundary. Nevertheless, a large number of fine equiaxed grains formed on the top surface of the FZ and exhibited obvious random orientations. Different grain-growth mechanisms found on the transverse cross-section and the top surface of the weld bead were empirically investigated. Owing to apparent grain coarsening, the lowest microhardness value (~43 HV) was detected in the center of the FZ, which was evidently lower than that of the BM (~68 HV). Keywords: AZ31B magnesium alloy, Nd:YAG laser welding, microstructure, pores, texture, electron backscatter diffraction Avtorji {tudije so magnezijevo zlitino AZ31B varili s pulznim Nd:YAG laserjem nizke mo~i, name{~enem na {estosnem varilnem robotu. Sistemati~no so izvedli metalur{ko karakterizacijo varjenja, vklju~no z analizo mikrostrukture, analizo tvorbe poroznosti in razvoja teksture s pomo~jo vrsti~ne elektronske mikroskopije (SEM) v kombinaciji s sipanjem povratnih elektronov (EBSD). Porazdelitev mikrotrdote po preseku zvara so dolo~ili z merilnikom mikrotrdote. Posnetki mikrostrukture v pre~nem preseku zvarnega spoja zlitine AZ31B so pokazali, da je le ta sestavljen iz osnovne kovine (BM; angl.: base metal), cone stebri~astih kristalnih zrn (CGZ; angl.: columnar grains zone), cone enakoosnih zrn (EGZ; angl.: equiaxed grains zone) in centralne staljene cone (FZ, angl.: fusion zone). V FZ so opazili tudi nekaj por in avtorji verjamejo, da je to posledica predhodno obstoje~ih por v BM. [e posebej poudarjajo opa`anje, da se mnoga stebri~asta zrna nahajajo v pre~nem preseku FZ , ki so skoraj pravokotna na fazno mejo trdno-talina. Kakorkoli, na vrhu povr{ine FZ se nahaja veliko {tevilo tvorjenih drobnih enakoosnih kristalnih zrn z o~itno naklju~no orientacijo. Avtorji prispevka empiri~no razpravljajo v~lanku tudi o razli~nih mehanizmih rasti zrn med pre~nim presekom in vrhom povr{ine varilne posteljice (bazen~ka staljene kovine). Zaradi jasne rasti zrn so najmanj{o mikrotrdoto (~43 HV) izmerili v centru FZ, kar je o~itno precej manj kot v BM (~68 HV). Klju~ne besede: magnezijeva zlitina AZ31B, varjenje z Nd:YAG (Neodim:Itrij-Aluminijev granat) laserjem, mikrostrukture, pore, teksture, sipanje povratnih elektronov