Den påvirkning af nikkel

Den effekt af nikkel på væv
Nikkel er et element der stærkt stabiliserer austenit og udvider den austenit fase zone. I rækkefølge til opnå en enkelt austenit struktur, minimum nikkel indhold krævet når stål indeholder 0.1 procent kulstof og 18 procent krom er om 8 procent , som er den grundlæggende komponent af den mest berømte 18-8 krom nikkel austenitisk rustfri stål. In austenitisk rustfrit stål, as den nikkel indhold stiger, resterende ferrit kan være helt elimineret og signifikant reduceret σ Den tendens mod fase dannelse; At den samme tid, den temperatur af Martensite carbonhydrid overførsel falder, lige uden λ → M fase overgang, men en stigning i nikkel indhold vil reducere den opløselighed af kulstof i austenitisk rustfri stål, derved forbedre den den tendens for hårdmetal nedbør.
Den effekt af nikkel på ydeevne
The impact of nickel on the mechanical properties of austenitic stainless steel, especially chromium nickel austenitic stainless steel, is mainly determined by the impact of nickel on the stability of austenite. Within the range of nickel content in steel that may undergo Martensite transformation, with the increase of nickel content, the strength of steel decreases and plasticity increases. Chromium nickel austenitic stainless steel with stable austenite structure has excellent toughness (including extreme low temperature toughness), so it can be used as low temperature steel, It is well known that for chromium manganese austenitic stainless steel with stable austenite structure, the addition of nickel can further improve its toughness. Nickel can also significantly reduce the cold work hardening tendency of austenitic stainless steel, which is mainly due to the increased stability of austenite, reduced or even eliminated the Martensite transformation in the cold work process. At the same time, the cold work hardening effect of austenite itself is not obvious, and the influence of cold work hardening tendency of stainless steel. Nickel reduces the cold work hardening rate of austenitic stainless steel, reduces the room temperature and low temperature strength of steel, and improves plasticity, The increase in nickel content is beneficial for the cold working formability of austenitic stainless steel, and increasing nickel content can also reduce or even eliminate the corrosion of 18-8 and 17-14-2 types of chromium nickel austenitic stainless steel δ Ferrite, thereby improving its Hot working properties, but, δ The decrease of ferrite is unfavorable to the weldability of these steels, which will increase the tendency of welding hot crack wires. In addition, nickel can also significantly improve the Hot working performance of chromium manganese nitrogen (chromium manganese nickel nitrogen) austenitic stainless steel, thus significantly improving the yield of steel. In austenitic stainless steel, the addition of nickel and the increase of nickel content lead to the increase of the thermodynamic stability of steel, Therefore, austenitic stainless steel has better rust resistance and resistance to oxidizing media, and as the nickel content increases, the performance of reducing media is further improved. It is worth pointing out that nickel is still the only important element to improve the resistance of austenitic stainless steel to transgranular stress corrosion in many media. The impact of nickel on the corrosion resistance of austenitic stainless steel in various acid media needs to be pointed out that under certain conditions in high-temperature and high-pressure water, The increase of nickel content will increase the susceptibility of steel and alloy to intergranular stress corrosion, but this adverse effect will be alleviated or restrained due to the increase of chromium content in steel and alloy. With the increase of nickel content in magnetic card austenitic stainless steel, the critical carbon content for intergranular corrosion will decrease, that is, the susceptibility of steel to intergranular corrosion will increase. As for the resistance to pitting corrosion and Crevice corrosion of austenitic stainless steel, The effect of nickel is not significant, and in addition, nickel also improves the high-temperature oxidation resistance of austenitic stainless steel