We investigated the addition of water to molten nitrate-nitrite salt and its effect on the cooling power of the salt when used as a quenching medium in austempering. We also investigated and compared the quenching distortion and mechanical properties of carbon steel, austempered using water-added salt, with those of conventionally quenched-and-tempered steel. The cooling power was evaluated using the heat-transfer coefficient obtained from a cooling curve measured using a silver probe. The results showed that the heat-transfer coefficient of molten salt saturated with water was approximately 2.0 to 4.1 times higher than that without water because of the vaporisation heat of the added water and the agitation effect of the vapour bubbles. The variation in distortion after austempered quenching decreased when using water-added salt. The results also showed that carbon steel austempered using water-added salt had a higher toughness than conventional quenched-and-tempered steel.

The experimental study was carried out to evaluate the influence of chemical composition of substrates, grid blasting materials, surface roughness and brazing temperature on the spreadability of Ni base brazing filler metal BNi-2. Ratio of braze spreading is subject to Ni and Fe content of substrates. More Ni content tends to have higher ratio of braze spreading and more Fe content tends to have lower ratio of braze spreading. This is attributed to the fact that eutectic temperature of Ni, B and Si is lower than eutectic temperature of Fe, B and Si. Grid blasting materials affect ratio of braze spreading. It is also ascertained that sequence in ratio of braze spreading is SiC>GB>Al₂O₃. Regarding Ni base alloy, larger surface roughness have higher ratio of braze spreading. On the other hand, surface roughness of stainless steel in not related to ratio of braze spreading. Ratio of braze spreading is influenced by brazing temperature. Higher ratio of braze spreading tends to be smaller wetting angle and shallower melt depth.