Nickel is the main alloying element in austenitic JISG4304 SUS 201 stainless steel. Its main function is one million and stabilizes austenite, which gives the steel a complete austenite structure, so that the steel has good strength and plasticity, and toughness. Cooperating, and has excellent cold, hot workability and cold formability as well as welding, low temperature and non-magnetic properties, while improving the thermodynamic stability of austenite JISG4304 SUS 201 stainless steel, making it not only the same chromium, molybdenum content Ferrite, martensite, etc. JISG4304 SUS 201 stainless steel has better properties of rust and oxidation resistant medium, and the stability of the surface film is improved, so that the steel has more excellent resistance to some reduction. The performance of the medium. Nickel is an element that is strongly one million and stabilizes austenite and enlarges the austenite phase. To obtain a single austenitic structure, the minimum nickel content required for steel containing 0.1% carbon and 18% chromium is approximately 8%, this is the basic score of the most famous 18-8 chromium nickel austenite JISG4304 SUS 201 stainless steel. In the austenitic JISG4304 SUS 201 stainless steel, the residual ferrite can be completely eliminated with the increase of nickel content. And significantly reduce the tendency of σ phase formation; at the same time, the martensite transalkylation temperature is reduced, and even λ→M phase transition may not occur, but the increase of nickel content will reduce the solubility of carbon in austenite JISG4304 SUS 201 stainless steel, thereby The tendency to precipitate carbides is enhanced.
The effect of nickel on the mechanical properties of austenitic JISG4304 SUS 201 stainless steel, especially for chrome-nickel negative JISG4304 SUS 201 stainless steel, is mainly determined by the influence of nickel on austenite stability, and martensite may occur in steel. Within the range of the converted nickel content, as the nickel content increases, the strength of the steel decreases, the sheet plasticity increases, and the chromium-nickel austenite JISG4304 SUS 201 stainless steel having a stable austenitic structure is excellent in toughness (including extremely low temperature toughness). It can be used as a low-temperature steel. It is well known that for chromium-manganese austenite JISG4304 SUS 201 stainless steel with a stable austenitic structure, the addition of nickel can further improve its toughness. Nickel can also significantly reduce austenite JISG4304 SUS 201 The cold work hardening tendency of stainless steel, mainly due to the increased austenite stability, reducing or eliminating the martensite transformation during cold working, and the cold work hardening effect on austenite itself is not obvious, JISG4304 SUS 201 stainless Effect of cold working hardening tendency of steel, nickel reduced austenite JISG4304 SUS 201 stainless steel cold working hard The rate, the effect of lowering the room temperature and low temperature strength of steel and increasing the plasticity, determines that the increase of nickel content is beneficial to the cold forming properties of austenitic stainless steel, and the increase of nickel content can also reduce or even eliminate 18-8 and 17-14- Type 2 Chromium Nickel 9 Clamp) Austenitic JISG4304 SUS 201 stainless steel δ ferrite, thereby improving its hot workability, but the reduction of δ ferrite is unfavorable for the weldability of these steels. The tendency of hot cracked filaments, in addition, nickel can also significantly improve the hot workability of chromium manganese nitrogen (chromium manganese nickel nitrogen) austenite JISG4304 SUS 201 stainless steel, thereby significantly increasing the steel yield.
In austenitic JISG4304 SUS 201 stainless steel, the addition of nickel and the increase in nickel content lead to an increase in the thermodynamic stability of steel, so austenitic JISG4304 SUS 201 stainless steel has better rust and oxidation resistance. The performance of the medium, and with the increase of nickel content, the performance of the reducing medium is further improved. It is worth noting that nickel is the only important element to improve the austenitic stainless resistance to the transgranular stress corrosion of many media. The effect of nickel on the corrosion resistance of austenite JISG4304 SUS 201 stainless steel in various acid media, it should be pointed out that under some conditions of high temperature and high pressure water, the increase of nickel content leads to the intergranular stress corrosion sensitivity of steel and alloy. Increase, but this adverse effect can be alleviated or suppressed due to the increase of chromium content in steel and alloy. With the increase of nickel content in magnetic austenitic JISG4304 SUS 201 stainless steel, the critical carbon content of intergranular corrosion is reduced. That is, the intergranular corrosion sensitivity of steel is increased. As for the resistance to pitting corrosion and crevice corrosion of austenitic JISG4304 SUS 201 stainless steel, the effect of nickel is not significant. In addition, nickel also improves austenite JISG4304 SUS 201 stainless steel High temperature oxidation resistance, which mainly improves the composition, structure and performance of chromium oxide film with nickel, and the higher the nickel content, the more harmful, mainly due to one million low melting point nickel sulfide in the grain boundary of steel .