Abstract: A thermoelectric power generation system 20 includes a heat exchanger 1 having double tubes which are an inner tube 1a and an outer tube 1b, and a thermoelectric power generation module 2 mounted between the inner tube and the outer tube. The thermoelectric power generation module generates thermoelectric power using a temperature difference between a medium inside the inner tube and a medium outside the outer tube, and a highly thermal conductive elastic sheet 3a, 3b is mounted between the thermoelectric power generation module and the inner tube and/or the outer tube in close contact therewith.

Abstract: In austenitic free-cutting stainless steel containing lead, decrease of hot workability caused by the addition of lead can be dissolved by adding a specific amount of boron. Thus, there is obtained an austenitic free-cutting stainless steel with improved machinability, corrosion resistance and hot workability of which are maintained at the level of conventional austenitic stainless steel.

Abstract: A free cutting steel for construction of machines, characterized in that the deoxidation product remaining in the steel has a composition of 40-60% of SiO.sub.2, 10-30% of MnO and 5-25% of Al.sub.2 O.sub.3, the balance being other oxides such as CaO and the sum of contents of SiO.sub.2, MnO and Al.sub.2 O.sub.3 being so adjusted as to be at least 85% of the whole oxides in the deoxidation products, the steel being further incorporated with 0.02 - 0.10% of Pb, and that the non-metallic composite inclusions comprising sulfides and finely divided Pb particles are uniformly dispersed.