Abstract: Provided is a flux for submerged arc welding that has good welding workability and can reduce the diffusion hydrogen content in a weld metal using either an AC or a DC welding power source. The flux includes Al2O3: 15 to 35% by mass; SiO2: 10 to 30% by mass; MgO: 10 to 25% by mass; F expressed in terms of CaF2: 10 to 25% by mass; Mn expressed in terms of MnO: 3 to 20% by mass; Na expressed in terms of Na2O and/or K expressed in terms of K2O: 0.5 to 4.5% by mass in total; Fe expressed in terms of FeO: 0.5 to 8% by mass; and CaO: 6% by mass or less. A water-soluble SiO2 in the flux is less than 1% by mass. In addition, the flux has a composition that satisfies the following formula: 0.2?[Mg/O]/([Al2O3]+[MnO])?0.8.

Abstract: Provided is a flux for submerged arc welding that has good welding workability and can reduce the diffusion hydrogen content in a weld metal in the use of either an AC or a DC welding power source. The flux for submerged arc welding includes: MgO: 25 to 35% by mass; F (in terms of CaF2): 15 to 30% by mass; Al2O3: 10 to 25% by mass; SiO2: 10 to 20% by mass; at least one of Na (in terms of Na2O) and K (in terms of K2O): 0.5 to 5.5% by mass in total; Fe (in terms of FeO): 0.5 to 5% by mass; TiO2: 1 to 5% by mass; CaO: 6% by mass or less; and Mn (in terms of MnO): less than 2.0% by mass; and further includes: water-soluble SiO2: less than 1% by mass; wherein the flux satisfies the following numerical expression (I): 0.5 ? [ MgO ] [ Al 2 ? O 3 ] + [ CaF 2 ] + [ TiO 2 ] ? 1.

Abstract: Provided is a flux for submerged arc welding that has good welding workability and can reduce the diffusion hydrogen content in a weld metal in the use of either an AC or a DC welding power source. The flux for submerged arc welding includes Al2O3: 15 to 35% by mass; SiO2: 10 to 30% by mass; MgO: 10 to 25% by mass; F (in terms of CaF2): 10 to 25% by mass; Mn (in terms of MnO): to 20% by mass; Na (in terms of Na2O) and/or K (in terms of K2O): 0.5 to 4.5% by mass in total; and Fe (in terms of FeO): 0.5 to 8% by mass, in which a CaO content is restricted to 6% by mass or less, a water-soluble SiO2 is restricted to less than 1% by mass, and the flux has a composition that satisfies the following formula (I): 0.2?[MgO]/([Al2O3]+[MnO])?0.8??(I).

Abstract: A multi-quantum well structure with a large second order optical nonlinearity and transparent at short wavelengths of up to 350 nm. is described. Alternating insulator and semiconductor layers are grown on a substrate to form a multi-quantum well structure, such that the potential function for electrons in the semiconductor layers is asymmetric in a direction normal to the substrate. Sub-bands of electrons in the conduction band lead to a large optical nonlinearity with efficient second harmonics generation, and is obtained by an appropriate selection of the width and shape of the well. The structure, preferably packaged on the same substrate of a laser diode, is used as an on-chip source of blue light.