In　Part　of　this　series,　it　can　be　found　that　the　corrosion　resistance　of　metals　in　the　welded　seam　zone　(WSZ)　was　far　higher　than　that　of　the　base　metal　(BM)　of　MBLS10A-200　Mg-Li　alloy.　Therefore,　the　feasibility　of　improving　the　corrosion　resistance　of　MBLS10A-200　Mg-Li　alloy　through　laser　surface　melting　(LSM)　was　further　explored.　Meanwhile,　laser　shock　peening　(LSP)　treatment　was　also　used　for　contrast.　The　results　showed　that　the　surface　melted　zone　with　the　corrosion　resistance　through　LSM　superior　to　that　of　metals　in　WSZ　of　MBLS10A-200　alloy　through　laser　welding　can　be　prepared　by　controlling　heat　input　through　increasing　the　scanning　speed　of　laser　beam,　while　LSP　has　limited　impact　on　the　electrochemical　corrosion　resistance　of　MBLS10A-200　alloy.　The　corrosion　current　density　(Jcorr)　of　the　samples　subjected　LSM　declined　by　two　orders　of　magnitude　compared　with　the　base　metal　(BM)　while　the　charge　transfer　resistance　increased　by　17　times　compared　with　BM.　An　analysis　indicated　that　owing　to　the　fast　cooling　rate　during　laser　processing,　the　multi-phase　microstructures　(i.e.　α　phase,　β　phase　and　Li2MgAl)　of　BM　were　transformed　into　β　single-phase　microstructure　in　WSZ　and　surface　melted　zone.　In　this　way,　not　only　solid　solution　strengthening　of　the　metals　in　WSZ　was　realized　but　also　the　micro-galvanic　coupling　generated　due　to　the　difference　of　electric　potentials　of　multi-phase　microstructures　were　reduced,　thus　improving　the　corrosion　resistance　of　surface　melted　zone.　©　2020　The　Society　of　Manufacturing　Engineers