| Through to adding different amount of tungsten into super duplex stainless steel00Cr25Ni7Mo3.5WCuN, test the phase proportion, mechanical performance, decay resistance, high temperature tensile, high temperature compression performance, at different solution temperatures. I have calculating the element distribution in the microstructure by using thermodynamic software. I analyzed the experimental results by using scanning electron microscope (SEM), transmission electron microscopy (TEM) and other instruments. I was studied the microstructure, corrosion resistance, mechanical properties, impact thermoplastic from tungsten in super duplex stainless steel00Cr25Ni7Mo3.5WCuN. Simultaneously I have studied super duplex stainless steel00Cr25Ni7Mo3.5WCuN microstructure, corrosion resistance, mechanical properties the effects of different thermoplastic solution treatment temperature. I have got the best performance in which solid solution temperature, of00Cr25Ni7Mo3.5WCuN, and determine the coefficient of tungsten in the resistance to pitting corrosion equivalent formula. Draw the following conclusions:Super duplex stainless steel has poor impact toughness and high tensile strength at low solid solution temperature. The amount of precipitated phase in steel, Sigma phase is the main precipitation phase. As temperatures rise, precipitated phase has decreases and strength decrease. At temperature of1100℃above, super duplex stainless steel has good toughness, absorbing work at about200j, for low strength at the same time. Super duplex stainless steel solid solution, y and a close to1:1. As temperatures rise, a proportion increase, strength to rise. Plastic performance has opposite change rule with the intensity The best pitting corrosion resistance of solid solution temperature for super duplex stainless steel is1100℃.00Cr25Ni7Mo3.5WCuN has the excellent intergranular corrosion resistant ability, it has no tendency of intergranular corrosion in5mol/L H2SO4+0.001mol/L KSCN at50℃. Tungsten’s content makes a proportion of super duplex stainless steel00Cr25Ni7Mo3.5WCuN increased, austenitic proportion to drop, and improve the sigma phase completely solid solution temperature. Tungsten content increased the tensile strength and yield strength of00Cr25Ni7Mo3.5WCuN. Each increment of1%Tungsten can raise30MPa of yield strength and25～30MPa of tensile strength.before the sample solution completely, The dissolution of tungsten by influencing the precipitated phase temperature affects the super duplex stainless steel toughness, Tungsten influence the toughness of super duplex stainless steel, by the precipitated phase solution temperature. When the temperature higher than completed solid solution temperature, tungsten has little influence on impact toughness.With the increase content of tungsten, super duplex stainless steel corrosion resistance on the rise roughly. At1100℃,the corrosion resistance of first increase then decrease. When tungsten content in1%～1.5%, the corrosion resistant performance of SDSS was best. At this point CPT is higher than70℃. With the addition of tungsten, Cr, Mo content in Austenite decreased gradually, and N, Ni content increased. But the content of Cr, Ni, Mo, N are reduced in the ferrite. Accroding to the calculation, coefficient of tungsten in the pitting resistance equivalent formula is1.5366～1.6068.The pitting resistance equivalent formula of Super duplex stainless steel is1.5366。With hot working temperature increase, hot compression for the steady-state flow stress and peak stress are reduced obviously by00Cr25Ni7Mo3.5WCuN.And the tensile strength of high temperature tensile reduce gradually.Its plastic rise before1100℃. When1100℃～1150℃the surface shrinkage rate was more than60%.If the temperature is too high, the super duplex stainless steel will dissolve. The best hot working temperature for00Cr25Ni7Mo3.5WCuN at1100℃～1150℃. The tungsten content has a certain influence on the hot tensile peak stress, within a reasonable hot working temperature range, the tungsten slightly improved the peak stress of the SDSS. It is not obvious that the influence of tungsten content on the SDSS thermoplastic. |
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