Abstract: A process for surface treatment which comprises mechanically polishing the surface of a stainless steel component with abrasive grains having particle diameters of 1-10 .mu.m to such an extent that the surface has a work-strained layer formed therein which is characterized by that X-ray diffraction by the (111) plane of austenitic iron gives the diffraction beams whose half-value width (2.theta.) is greater than 0.5 degree, and subsequently performing heat treatment in an atmosphere in which the partial pressure of oxygen is low, thereby forming an oxide film composed mainly of chromium oxide which has a thickness greater than 200 .ANG. and a surface roughness R.sub.max smaller than 1 .mu.m.The surface-treated stainless steel exhibits outstanding corrosion resistance to halogen gases such as Cl.sub.2, HCl, and F.sub.2. It has such a smooth surface that it hardly adsorbs moisture vapor and gases. Therefore, it is suitable for use as components of semiconductor manufacturing apparatus.

Abstract: A nitrogen-containing dual phase stainless steel with high hot workability, containing in percentage by weight:less than 0.03% of C;0.3-2.0% of Si;0.4-4.0% of Mn;16-22% of Cr;4-7% of Ni;2-4% of Mo;0.06-0.20% of N;less than 0.005% of S;0.001-0.01% of Ca in a Ca/S ratio of greater than 1.5;andthe balance of iron and inevitable impurities.

Abstract: Disclosed herein is a dual phase stainless steel suitable for use in sour wells. It comprises 0.06-0.20% C, .ltoreq.1.0% Si, 2.5-4% Mn, 20-27% Cr, 5-8% Ni, 2.5-4% Mo, 0.3-2% Cu, 0.1-0.25% N, 40-60% ferrite and the balance Fe and inevitable impurities. It may further contain one or more metals selected from Ti, Nb and V in a total amount of 0.1% to 0.5%. The dual phase stainless steel is excellent in proof strength, tensile strength and elongation and is capable of exhibiting good corrosion resistance in Cl.sup.- --CO.sub.2 --H.sub.2 S environments.

Abstract: This invention relates to a novel chemical apparatus, the inner surfaces of which are constituted by titanium material. The invention solves the problems of crevice corrosion and embrittlement of the material by taking in hydrogen, and discloses a method of solving such problems.The prior art methods of preventing crevice corrosion in apparatus prepared from titanium metal and also preventing the titanium of such apparatus from becoming fragile due to absorption of hydrogen include a method , in which an element of the platinum group is deposited on the surface of the titanium material and diffused thereinto. Alternatively, a Ti-Pd alloy is used as the material of the apparatus. Such methods, however, complicate the manufacture of the apparatus and are also disadvantageous in view of the cost of the great quantity of the platinum group element such as palladium which is consumed.

Abstract: The invention relates to a novel chemical apparatus, the inner surfaces of which are constituted by titanium material. The invention solves the problems of crevice corrosion and embrittlement of the material by taking in hydrogen, and discloses a method of solving such problems.The prior-art methods of preventing crevice corrosion in apparatus prepared from titanium metal and also preventing the titanium of such apparatus from becoming fragile due to absorption of hydrogen include a method in which an element of the platinum group is deposited on the surface of the titanium material and difffused thereinto. Alternatively, a Ti-Pd alloy is used as the material of the apparatus. Such methods, however, complicate the manufacture of the apparatus and are also disadvantageous in view of the cost of the great quantity of the platinum group element such as palladium which is consumed.