During the heat treatment of 904L stainless steel coil, overheating is most likely to lead to the coarseness of austenite grains. To eliminate the heredity of coarse structure, intermediate annealing or multiple high-temperature tempering can be used.
Overburning phenomenon when the heating temperature is too high, it not only causes coarse austenite grains, but also local oxidation or melting at the grain boundary, resulting in weakening of the grain boundary, which is called overburning. The performance of the waste steel bar straightener for seamless pipe is seriously deteriorated after overburning, and cracks are formed during quenching. The burned tissue cannot be recovered and can only be scrapped.
Therefore, over burning should be avoided in work. When decarburized and oxidized stainless steel pipe is heated, the carbon on the surface reacts with oxygen, hydrogen, carbon dioxide and water vapor in the medium (or atmosphere), reducing the carbon concentration on the surface, which is called decarburization. After decarburized stainless seamless pipe is quenched, the surface hardness, fatigue strength and wear resistance are reduced, and residual tensile stress is formed on the surface, which is easy to form surface network cracks.
When heated, the iron and alloy on the surface of stainless steel pipe react with elements and oxygen, carbon dioxide and water vapor in the medium (or atmosphere) to form oxide film, which is called oxidation. The dimensional accuracy and surface brightness of high temperature (generally above 570 ℃) workpiece deteriorate after oxidation, and the stainless steel pipe fittings with poor hardenability of oxide film are prone to quenching soft spots.
Measures to prevent oxidation and reduce decarburization include: workpiece surface coating, 904L stainless steel coil sealed and heated with stainless steel solenoid valve steel pipe foil, heated in salt bath furnace, heated in protective atmosphere (such as purified inert gas, controlling carbon potential in furnace) Hydrogen embrittlement in flame combustion furnace (reducing the furnace gas) the phenomenon that the plasticity and toughness of high-strength stainless NSK bearing decrease when heated in hydrogen rich atmosphere is called hydrogen embrittlement. The workpiece with hydrogen embrittlement can also eliminate hydrogen embrittlement through hydrogen removal treatment (such as tempering and aging). Hydrogen embrittlement can be avoided by heating in vacuum, low hydrogen atmosphere or inert atmosphere.
904L stainless steel coil is a kind of hollow long steel, which is widely used as pipelines for conveying fluids, such as oil, natural gas, water, gas, steam, etc. in addition, when the bending and torsional strength are the same, the weight is lighter, so it is also widely used in the manufacture of mechanical parts and engineering structures. It is also commonly used to produce various conventional.
Surface micro arc oxidation grinding and polishing method of 904L Stainless Steel Coil for sale: the treatment method of 904L stainless steel coil includes the following steps: firstly, the surface of stainless steel products is mechanically polished, and then degreased; Clean the stainless steel products after degreasing treatment; Place the stainless steel product in the electrolyte solution, turn on the sine wave commutation power supply, and use the sine wave micro arc generated by the sine wave commutation power supply to enhance and activate the reaction on the anode at the temperature of 20 ~ 35 ℃, so as to form a strengthened oxide film on the surface of the stainless steel product; Then, the stainless steel products with enhanced oxide film can be cleaned and dried; The invention solves the problem that micro arc oxidation cannot be carried out on the surface of stainless steel (austenite and martensite) in the past, and greatly improves the protective performance and application field of stainless steel.