The effects of cold deformation (0% - 80% ) and 1000 ~ 1090 °C solid sulution treatment on the microstructure and magnetic properties of 0Crl8Nil2 and 0Crl6Nil4 austenitic stainless steels are discussed based on composition and structure stability. The results show that the austenite stability of stainless steel 0Crl8Nil2 and 0Crl6Nil4 is better than that of SUS304, and 0Crl6Nil4 is the best. Deformed martensite is formed during cold rolling deformation of stainless steel 0Crl8Nil2 and 0Crl6Nil4. The relative permeability of 0Crl6Nil4 during cold rolling is always below 1.010, the proportion of deformed martensite of 0Crl8Nil2 is up to 3.5% , and the relative permeability is increased to 1.353. After solution heat treatment, the relative permeability can be controlled below 1.010. Combined with the field production conditions, the heat treatment process of two kinds of austenitic stainless steels is solid solution treatment at 1060 °C for 80 s per mm.

The effects of boron contents on the solution time and temperature of precipitated phase in steel S31254 are studied by solution treatment. The time and temperature required for the complete solution of steel S31254 second phase under different boron contents are obtained. The results show that as the boron content increases, the required solid solution temperature and time decrease. When the boron content in the steel is 0.002% ,a relatively pure austenite structure can be obtained by solid solution treatment at 1200℃ for 4 hours, that is to say, the second phases precipitated in the grains and grain boundary have been re-dissolved into the matrix during the hot working process. In addition, during the solid solution treatment, the second phases in the grains preferentially dissolve, and as passage of time, the second phases at the grain boundary gradually dissolve.

Compare with the three-step method, through the study of smelting and continuous casting of High-Nitrogen stainless steel 10Cr21 Mnl6NiN, the two-step smelting and continuous casting technology has been optimized, the adding nitrogen rate is raised from 5 x 10 ^-6 ~ 10 x 10 ^-6/min to 20 x 10 ^-6~ 30 x 10 ^-6/min in later stages of LF, the LF refining time is shortened from 390 min to 240 min, the CCM steel waiting time is reduced from 4 h to 2 h ； it solves the problem of slag spilling during the nitrogen adding；it also avoids the billet buckling during continuous casting,the breakage rate of No. 1 & No. 2 casting strand reduces from 100% to O,the equipment accident rate decreases from 66. 7% to 0,to achieve 100% 2- heats sequence casting. The practice shows that the billet casting without closely spaced rolls can produced High-Nitrogen stainless steel even though with only one five-high withdrawing and straightening machine.

The production process of steel 10Cr21Mnl6NiN wire rod, including composition design, principle of increasing nitrogen, smelting process, rolling and solution process, precipitation of Cr ₂ N phase is introduced. A 30 t AOD furnace is used for refining, blown nitrogen to increase nitrogen in steel water, and added manganese nitride at the later stage of refining. The surface quality of wire rod is ensured and the problem of central shrinkage is solved by adopting 1 240℃ heating and controlled rolling and cooling in the process. The solution temperature should be controlled at 1 100℃ and cooled quickly after holding for 30 min to prevent the precipitation of Cr ₂ N phase. The 10Cr21Mnl6NiN stainless steel wire rod with excellent surface quality and performance has been successfully produced.

The influence of structure evolution and defects of 304H stainless steel wire during the cold drawing process from Φ2.6 mm to Φ0.89 mm on torsion performance of stainless steel wire are studied. The results show that when the true cold drawing strain of the steel wire is between 0 and 1.39 ,the torsion performance decreases sharply and the number o£ torsion decreases ； when the true cold drawing strain is between 1.39 and 2. 14, the torsion performance gradually rises and the number of torsion increases. With the application of strain,work hardening leads to the deterioration of plastic toughness by dislocation plugging, which is the main factor for the decrease of torsional performance, and the increase in the content of {111} //ND texture at this stage is also not conducible to the torsional performance；as the strain is further increased,and the internal grains of steel wire are refined into ultra-fine grains,leading to further increase in strength and recovery of plastic toughness,which are the main factors for the rebound of torsion performance,and the decrease of {111}//ND texture content is also available to torsion performance. However,when the true cold drawing strain exceeds 1.39,the average areal density of inclusions also increases,which hinders the further recovery of the torsional performance of the steel wire.

The edge crack cause of 309L austenitic stainless steel plate in the hot rolling is analyzed by means of metallographic structure observation and thermodynamic calculation. Results test show that the hot rolling temperature of steel plate 309L (0.012% C ,0.034% N) is at 1 260℃：and large area of continuous reticular δ ferrite exists in the triangle area of slab edge. In the subsequent heating process, the ferrite content increased continuously to up 24% , which lead to the decrease of plasticity and formation o£ edge crack in rolling process. By controlling 0.015% ~ 0.025% C, and 0.04% ~ 0.05% N in steel, and slab heating at 1 150 ℃ ,the ferrite content in steel decreases to 10.7% to be available to avoid the edge crack of 309L steel plate and coil qualified rate up to 100%.

The tested steel 0. 05C-14Mn-19Cr-0. 7N is melted by 1 t non vacuum induction furnace and remelted to ESR ingot. By sampling at center of ESR ingot and using Gleeble 3800 thermo-simulation testing machine the thenno tensile examination of tested steel at 800 ~ 1250 °C with strain rate 0. 005 ~ 10 s^-1 has been carried out to get the effect of temper ature and strain rate on reduction of area of tested steel, and the structure of steel tensile-tested at each temperature is ob served. Examination results show that with temperature increasing from 800 ℃ to 1 250 ℃ the tensile strength of tested steel decreases from 327 MPa to 68 MPa and the reduction of area of steel increases from 22% to 55% ；at 1200℃, with strain rate increasing from 0. 01 s^-1 to 10 s-1 the tensile strength of tested steel increases from 43 MPa to 109 MPa and the reduction of area of steel increases from 38% to 71%. Integrating the experimental results it is obtained that the optimized deformation parameters for high nitrogen austenite stainless steel 0. 05C-14Mn-19Cr-0.7N are rolling at 1200 ~ 1250°C with stain rate 1 ~ 10s^-1.

The effect of grain size on 550 ~650 °C 360 〜165 MPa stress rupture property of 316H austenitic stainlees steel 28 mm plate is studued and its rupture mode is analyzed. At 550 °C and by 360 MPa or 335 MPa stress, the stress rupture life of the fine grain (44. 5 μm ) plate only reaches 48. 92% or 51.98% of the coarse grain (89. 6 μm) plate. Wedge crack on the grain boundaries led to the rupture. Tlie grain size has more influence on the stress rupture property, and higher stress makes the effect increase furtherly. However, at 650 °C and by 165 MPa, the stress rupture life of the fine grain (44.5 μm ) plate reaches 91.35% of the coarse grain (89.6 μm)plate. In this case, the grain size has a less influence on the stress rupture property, and microscopic damage occurring during stress-rupture is caused by the growth and coalescence of cavities on grain boundaries.

The process of ultra - pure 316H steel for nuclear power produced by 20 t EAF-AOD-LF-VD-Φ430 mm elecrode-Φ590 mm ESR ingot-homogenizing treating-Φ310 mm forged bar flowsheet is studied by means of composition calculation ,smelting process and electroslag slag analysis, homogenization annealing process test and other methods. When the composition satisfies 0. 042% ~ 0. 047% C, ≤ 0. 55% Si, 1. 60% ~ 1. 80% Mn, 17. 00% ~ 17. 30% Cr, 12. 20% ~ 12. 40%Ni,2. 50% ~2. 60% Mo, ≤ 5 x10 ^-6H, ≤ 30x 10 ^-6 O,0. 055% ~0.070%N, the Φ430 mm electrode is remelted with CaF ₂： Al ₂O ₃: CaO =60%: 30%: 10% slag system electroslag into Φ590 mm ESR ingot, then homogenization treated at 1 200 ~ 1 250 °C for 30 h, it can produce products to meet the standards, that is inclusion rating units- A and C being 0, B _thin 0.5,B _thick being 0,D _thin 1. 0,D _thick 0 -0. 5 and Ds being (0 ~0.5) ；ferrite content ≤ 0. 5% .

The tested super austenitic stainless steel 022Cr24Ni17Mo5Mn6NbN (/% : 0. 028C, 0. 33Si, 6. 21Mn, 24. 93Cr, 17. 03Ni, 4. 24Mo, 0. 45N) is melted by 1 t non vacuum induction furnace and electroslag remelting process, and rolled into Φ 40 mm bar after Φ360 mm electroslage ingot forging. The microstructure, pitting corrosion resistance and mechanical properties of the steel as hot-rolled (end rolling at 1 000 °C , WC) and after solution at 1 070 ~ 1 180 °C are studied. The tested results show that with the increases of solution temperature, the grain size of steel gradually grows, the strength of steel decrease and the plasticity increases, and the pitting corrosion resistance improves. Uniform structure, better pitting corrosion resistance and good mechanical properties of steel are obtained by solid solution at 1 120 °C.

The production flowsheet of titanium stabilizing austenite stainless steel 321 (/% : 0. 04 ~0, 08C, 0.40 ~ 0.70Si, 0. 80~1.50Mn, ≤  0.035P, ≤ 0.005S, 17. 0 ~ 18. 0Cr, 9.0~9.5Ni, 0,20~0.40Ti, ≤ 0.0200N) is 90t EAF45 t AOD-LF-180 mm x 1 238 mm slab casting. The "floater" in liquid of steel in mold occurs and the nozzle blocking produces in casting process. Based on analysis on TiN precipitation rule it is obtained that in order to decrease of TiN precipitation in liquid it should be controlled [N] ≤ 0.015 0% , [Ti] ≤0.25% and temperature of liquid in tundish 〜 1 500 °C. With process measures including using extra-pure Ar stirring in whole AOD process, controlling ladle slag thickness 150 mm, [O] 15 x 10 ^-6 ~20 x 10 ^-6 and [N] ~ 110 x 10 ^-6, and using shielding slag with basicity 0. 75 and viscosity 0. 165 pa ·s at 1 300 ℃ , the yield of Ti increases from original 40% to 52% , the N content in finished liquid decreases from 0.014 0% to 0.010 5% , the inner diameter of nozzle at finished casting increases from original 42 mm to 50 mm, and the defect of rolled products decreases from original 3. 5% to 1. 2% .

The tested 316 steel (/% : 0.04C, 0.36Si, 2.OOMn, 0.009P, 0.024S, 17.74Cr, 11.74Ni, 2.56Mo) is melted by a 30 kg vacuum induction furnace and the tested adding nitrogen-saving nickel 316 steel (/% : 0. 04C, 0.25Si, 1.86Mn, 0.012P, 0.021S, 16.90Cr, 8.18Ni, 2.64Mo, 0.36N) is melted by nitrogen filled at ambient pressure and adding nitriding alloy, forged and rolled to 4 mm strip and solid-solution treated at 1 100℃ for 1 h. The erosion rate and the morphology of surface of steel erosion-tested are characterized and analyzed by electronic balance, SEM and homemade slurry erosion wear-erosion device. Results show that with increasing erosion impact angle the erosion rate of both tested austenite stainless steel increases and appears to rise-fall-rise, two peaks of erosion rate occur at erosion impact angle 45° and 90° and the max erosion rate occurs at 90°; with increasing velocity and time of erosion impact the erosion rate of both steels increases. At same conditions of erosion, the adding nitrogen-saving nickel 316 austenite stainless steel has better wear-erosion performance and lower erosion rate.

The influence of the status of billet steel, rolling compression ratio, deformation rate per pass on grain of 316 austenitic stainless steel medium plate was done in laboratory. The results explained that the total compression ratio is more than 6, the original structure of steel billet has no influence on grain size of hot rolling plate, when the total compression ratio is more than 6, the homogeneous grain in the whole thickness is obtained in condition of same billet steel heating- up temperature and deformation rate per pass. But when the total compression ratio is more than 6, the 2 grade and 7 grade duplex grain are obtained even though the deformation rate per pass is more than 30% , and when the total compression ratio is less than 10% , the grain is heterogeneous even though the total compression ratio is big enough.

The cold rolling with 10% ~60% deformation and tensile tests of 3 mm hot rolled plate of saving in nickel high nitrogen austenitic stainless steel Mn17Cr19N0.6 produced by induction furnace-electroslag remelting are carried out. The microstructure changes in the cold deformation process of high nitrogen austenitic stainless steel are studied by metallographic observation and XRD phase analysis. It is concluded that in the process of cold rolling, with the increase of the deformation, the shape of the grain in the test steel is from lump to flat elongate, and the slip from single slip to cross slip, and the twinning band will eventually be cut and broken. The microstructure of the test steels with different cold rolling deformation is single austenite phase, and there is no other phase. There is no martensitic transformation in the cold deformation process. Therefore, no phase transformation strengthening occurred during cold rolling of test steel, and the deformation strengthening is main in the cold rolling process, the tensile strength of the test steel increases from 1045 MPa by 10% deformation to 1880 MPa by 60% deformation. Therefore, special materials with different strength levels and single austenite structure can be prepared by cold deformation.