Effect Of Welding Heat Input On HAZ Microstructure And Properties Of 22Cr-1.3Ni-2.0Mn-0.52N High Nitrogen Nickel-saving Duplex Stainless Stee

The N element can stabilize the austenite phase and expand the austenite phase region.In the nickel-saving duplex stainless steel,part or even all of the N element is used to replace the Ni element to stabilize the austenite phase.While reducing costs,it can also improve the duplex phase.Corrosion resistance and mechanical strength of stainless steel.Welding is a very important process in mechanical steel.It is of practical significance to study the corrosion resistance and mechanical properties of high-nitrogen-nickel duplex steel HAZ under different welding heat inputs.Compared with2205 commercial steel,this project researches the welding heat simulation experiment of 22Cr-1.3Ni-2.0Mn-0.52N duplex stainless steel with Gleeble-3800 thermal simulation experiment machine under the condition of heat input of 0.848k J/mm-5.991k J/mm,explore its HAZ structure change and its influence on corrosion resistance and mechanical properties,and analyze the structure and performance changes at different solution temperatures.By observing the microstructure and microstructure of welded HAZ,and analyzing the change law and mechanism of mechanical and corrosion properties,the results show that:（1）As the solution temperature increases,the proportion of austenite structure in22Cr-1.3Ni-2.0Mn-0.52N duplex stainless steel gradually increases,and the corrosion resistance gradually decreases,which is attributed to the expansion of the difference between the two phases PREN.The tensile strength of 22Cr-1.3Ni-2.0Mn-0.52N duplex steel is above 800MPa,the tensile strength,yield strength and elongation after fracture decrease with the increase of solid solution temperature,and the impact energy gradually increases.Tensile strength and plasticity.When the solution temperature is 1050℃,22Cr-1.3Ni-2.0Mn-0.52N duplex steel has better corrosion resistance and the highest plastic strength.（2）With the increase of welding heat input,the two-phase grains of 22Cr-1.3Ni-2.0Mn-0.52N duplex steel are gradually refined,and there are some transformed austenites,and the proportion of austenite gradually increases,and the proportion of both are more than 50%,which is because the high nitrogen content makes the nitrogen element solid solution in the austenite,which has a strong ability to stabilize the austenite.Compared with 2205 steel,as the heat input value increases,the cooling rate slows down,the proportion of austenite gradually increases,the ferrite grains are first refined and then grow and coarsen,and the intragranular austenite（IGA）and intergranular austenite The size of asterite（GBA）gradually increases,and Widmanstatten austenite（WA）appears,and the ratio of two-phase structure is close to 1:1.（3）Under high heat input,the Eb value and E_b-E_corr value of 22Cr-1.3Ni-2.0Mn-0.52N duplex steel are higher than the experimental steel of 2205 duplex steel.Under medium and high heat input,the Cr₂O₃ content and Fe oxide content in the 22Cr-1.3Ni-2.0Mn-0.52N duplex steel HAZ passivation film are relatively high,and the Mn O content is low.The formation of chromium-containing oxides forms NH₄⁺during dissolution,and the consumption of H⁺is beneficial to improve the pitting corrosion environment.Under high heat input,the austenite PREN value of 2205 duplex steel is lower than that of ferrite,and the pitting pits are distributed in austenite in the bulk and at grain boundaries.（4）With the increase of low heat input,the sensitivity value R_a of 2205 duplex steel HAZ intergranular corrosion increases gradually.The R_a value of 22Cr-1.3Ni-2.0Mn-0.52N duplex steel decreases with the increase of high heat input,and is smaller than that of 2205 duplex steel,which is related to the refinement of austenite phase grains by high N content.The intergranular sensitivity value R_a under low heat input is generally lower than that under high heat input,which may be due to the long cooling time under high heat input conditions,which will precipitate chromium-rich nitrides on the grain boundaries,resulting in an increase in the intergranular sensitivity value.（5）The tensile strength,yield strength and elongation after fracture of 22Cr-1.3Ni-2.0Mn-0.52N duplex steel HAZ under different heat inputs are higher than those of 2205duplex stainless steel,which is due to high nitrogen through solid solution strengthening.Increased strength.With the increase of heat input,the tensile strength,yield strength and elongation after fracture of 22Cr-1.3Ni-2.0Mn-0.52N duplex steel HAZ gradually decrease,which is attributed to the gradual increase in the number and size of the second phase particles.The impact energy of 2205 duplex steel HAZ is much higher than that of high-nitrogen nickel duplex steel.Since 22Cr-1.3Ni-2.0Mn-0.52N duplex steel increases with heat input,the ferrite content is lower and contains inclusions.The impact toughness is caused,and the obvious river pattern and large area of cleavage steps can be seen from the fracture morphology,which is a typical brittle fracture.