CN114959447A - Economical duplex stainless steel and high-performance welding heat affected zone hot working method thereof - Google Patents

Abstract

The invention discloses a high-N and low-Ni saving duplex stainless steel and a high-performance welding heat-affected zone thermal processing method, belonging to the technical field of duplex stainless steel. The invention adopts vacuum furnace smelting, and then performs forging and rolling treatment on the stainless steel billet, and obtains the plate through water quenching; the plate is subjected to solid solution treatment, and then water-cooled; , 1.10KJ/mm～2.15KJ/mm, 2.85KJ/mm～2.95KJ/mm three-stage heat input parameter range and 1325℃ peak temperature for welding thermal cycle treatment to obtain corresponding welding heat affected zone samples; The samples in the area have been tested for mechanical properties, intergranular corrosion resistance and pitting corrosion resistance, and have high mechanical properties, excellent comprehensive properties, and high corrosion resistance. The processing method in this area can promote the application of this low-cost stainless steel in special fields such as chemical pipelines, petrochemical industries, and marine engineering.

Description

Economical duplex stainless steel and its high-performance welding heat-affected zone thermal processing method

technical field

The invention belongs to the technical field of duplex stainless steel, and in particular relates to a high-N and low-Ni saving duplex stainless steel and a high-performance welding heat-affected zone thermal processing method.

Background technique

High-N and low-Ni-saving duplex stainless steel is a material with good corrosion resistance to various media and excellent mechanical properties, which is widely used in petrochemical, paper and construction industries and other fields. To a certain extent, it has become one of the ideal materials to replace traditional stainless steel. The ability of N to stabilize austenite is 30 times that of Ni, and the resistance to pitting corrosion is 16 times that of Cr, so N can be used as one of the most beneficial elements to replace Ni. Adding a higher content of N to the steel can effectively stabilize the austenite to obtain a duplex structure, and can significantly improve the yield strength, creep resistance, toughness and corrosion resistance of duplex stainless steel. In addition, N can also adjust the distribution of alloying elements such as Cr and Mo between the two phases. At the same time, the addition of a certain amount of Mn can improve the solid solubility of N in stainless steel, and has the effect of stabilizing the austenite phase and improving the strength. Ni is a metal with small reserves and high price, and the price is rising year by year, which greatly increases the cost of stainless steel manufacturing. Compared with high-Ni series stainless steel, Ni-type duplex stainless steel reduces a series of allergic symptoms caused by Ni to the human body due to low Ni or no Ni, and has the characteristics of low toxicity and environmental protection. Therefore, the patent of the present invention discloses a high-N and low-Ni saving duplex stainless steel with high performance welding heat effect, which can not only greatly reduce the cost but also reduce the harm to human beings, and has great application prospects in the future.

With the increasing application of duplex stainless steel, N-generation Ni-saving duplex stainless steel has gradually become a research hotspot, but it is difficult to improve its corrosion resistance and mechanical properties in the heat-affected zone. ; At present, there is a lack of reasonable processing technology for obtaining high-N and low-Ni-saving duplex stainless steel with high corrosion resistance and mechanical properties in the welding heat-affected zone. For example, the proportion of the two phases in the welding heat-affected zone is seriously unbalanced, and more precipitations are formed, resulting in a serious decrease in mechanical and corrosion resistance. As a result, the material production cost is high, which cannot meet large-scale production. The high-N and low-Ni-saving duplex stainless steel and the thermal processing method for the welding heat-affected zone in the present invention can obtain excellent corrosion resistance of the welding heat-affected zone, and at the same time have higher impact performance and tensile mechanical properties, which can not only solve the problem of The above problems exist, and the application of the economical duplex stainless steel in the high-strength and high-toughness environment is effectively improved.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention provides a high-N, low-Ni-saving duplex stainless steel and a high-performance welding heat-affected zone thermal processing method. The zone has excellent corrosion and mechanical properties.

In order to achieve the above-mentioned technical effect, the present invention is achieved through the following technical solutions: a high-N, low-Ni-saving duplex stainless steel and a high-performance welding heat-affected zone thermal processing method, characterized in that, comprising the following steps:

S1: C: 0.012-0.018%, Si: 0.09-0.12%, Mn: 7.95-8.05%, Cr: 22.45-22.65%, Ni: 1.30-1.40%, Mo: 2.65-2.74%, Cu : 0.10～0.16%, N: 0.420～0.450%, P: ≤0.01%, S: ≤0.01%, the balance is Fe and inevitable impurities, smelted in a 50 kg vacuum melting furnace to obtain stainless steel billets;

S2: perform pre-forging treatment on the stainless steel billet; obtain a pre-forged plate;

S3: pre-rolling the pre-forged sheet;

S4: put the pre-rolled sheet into a box-type resistance furnace for solution treatment;

S5: Use the S4 solution-treated plate on the thermal simulation test machine according to the three-stage heat input parameters of 0.45KJ/mm～0.95KJ/mm, 1.10KJ/mm～2.15KJ/mm, 2.85KJ/mm～2.95KJ/mm The welding heat cycle treatment was carried out according to the range and the peak temperature of 1325℃, and the thermal simulation samples of the corresponding welding heat input and peak temperature were obtained;

S6: The thermal simulation sample obtained in S5 was prepared into an electrochemical sample, and the pitting corrosion resistance and crystal resistance of the sample were tested by the cyclic voltammetry potentiodynamic polarization curve and the double loop potentiodynamic reactivation method (DL-EPR). Intergranular corrosion sensitivity (DOS), in which pitting corrosion resistance test uses pitting corrosion solution, and intergranular corrosion resistance sensitivity test uses intergranular corrosion solution;

S7: The thermal simulation sample obtained in S5 is processed into a standard V-notch impact sample and a standard tensile sample, and an impact test and a tensile test are used to test the mechanical properties of the sample.

Preferably, the pre-forging conditions are starting forging at a temperature of 1120-1190 °C, a final forging temperature > 970 °C, a forging ratio of 4-5, and water cooling at room temperature;

Preferably, the pre-rolling conditions are starting rolling at a temperature of 1100-1180°C, finishing rolling at a temperature of >955°C, and water quenching at room temperature;

Preferably, the solution treatment conditions are a temperature of 1030-1070° C., a solution time of 0.3-1 h, and water cooling at room temperature;

Preferably, the pitting corrosion solution is 3.5 wt.% NaCl, and the intergranular corrosion solution has a ratio of 1.2 mol/l H ₂ SO ₄ +1.1 mol/l NaCl + 0.01 mol/l KSCN.

The beneficial effects of the present invention are:

The optimized heat input parameters proposed by the present invention are used for welding thermal cycle treatment at 1.10KJ/mm～2.15KJ/mm. The tensile strength of the welding heat affected zone is Rm≥780MPa, the yield strength Rp0.2≥547MPa, and the elongation is tested by mechanical properties. A≥31.76%, the impact energy of the welding heat-affected zone is greater than or equal to 48J, the pitting corrosion potential Eb≥0.94, and the intergranular sensitivity value Ra≤2.22%. The obtained welding heat affected zone has excellent comprehensive performance;

The welding heat cycle treatment is carried out in the heat input range of 0.45KJ/mm~0.95KJ/mm, the tensile strength of the welding heat affected zone is Rm≥796MPa, the yield strength Rp0.2≥561MPa, the elongation A≥32%, the welding heat affected zone The impact energy is greater than or equal to 57J, and the obtained welding heat-affected zone has high mechanical properties;

The welding heat cycle treatment is carried out in the heat input range of 2.85KJ/mm～2.95KJ/mm. The pitting corrosion potential Eb of the welding heat affected zone is greater than or equal to 0.93, and the intergranular sensitivity value Ra is less than or equal to 0.31%. The obtained welding heat affected zone has high resistance to Corrosive properties.

Description of drawings

Fig. 1 is the cyclic voltammetry polarization test curves of five different heat inputs and solid solution samples of the welding heat affected zone in the range of thermal cycle parameters of 0.84 to 2.95 KJ/mm in Examples 1 and 2;

Fig. 2 is the test curve of double-ring electrochemical potentiodynamic reactivation method of five different heat inputs and solid solution samples in the welding heat-affected zone within the thermal cycle parameter of Example 1 and 2;

Figure 3 is a comparison diagram of the intergranular corrosion susceptibility of five different heat inputs in the welding heat affected zone in the thermal cycle parameters of Examples 1 and 2 in the range of 0.84 to 2.95 KJ/mm;

Figure 4 is a comparison of the yield strength and tensile strength of three different heat input samples in the welding heat affected zone in the thermal cycle parameters of Examples 3 and 4 in the range of 0.84 to 2.95 KJ/mm;

Figure 5 is a comparison of the elongation of three different heat input samples in the welding heat affected zone in the thermal cycle parameters of Examples 3 and 4 in the range of 0.84 to 2.95 KJ/mm;

Figure 6 is a comparison of the impact energy of five different heat input specimens welded to the heat affected zone in the thermal cycle parameters of Examples 3 and 4 in the range of 0.84 to 2.95 KJ/mm.

Detailed ways

In order to make a clear and complete description of the scheme and effect of the present invention, the following examples are used to describe in detail;

The invention provides a high-performance welding heat-affected zone thermal processing method for high-N and low-Ni type duplex stainless steel. %, Mn: 7.95-8.05%, Cr: 22.45-22.65%, Ni: 1.30-1.40%, Mo: 2.65-2.74%, Cu: 0.10-0.16%, N: 0.420-0.450%, P: ≤0.01%, S: ≤0.01%, and the balance is Fe.

In the present invention, the chemical composition of the high-N and low-Ni duplex stainless steel slab preferably includes: C: 0.016%, Si: 0.1%, Mn: 8.01%, Cr: 22.52%, Ni: 1.37%, Mo : 2.69%, Cu: 0.14%, N: 0.446%, P: ≤ 0.01%, S: ≤ 0.01%, and the balance is Fe.

The invention provides a high-N and low-Ni-saving duplex stainless steel and a preparation method for the high-performance welding heat-affected zone, so that the corrosion resistance and mechanical properties of the welding heat-affected zone are improved, and the specific steps include the following steps:

S1: The stainless steel billet made by 50kg vacuum melting furnace is used for pre-forging treatment. The forging starts at 1160°C, the forging ratio is 4, the final forging temperature is 980°C, and the forging is rapidly cooled; then pre-rolling is performed. Treatment, the starting rolling temperature is set to 1150 ° C, the final rolling temperature is 960 ° C, and the plate is obtained by water quenching;

S2: The plate obtained in S1 is subjected to solution treatment, and the conditions are: 1050 ° C, 30 min, and then water-cooled at room temperature;

S3: Process the S2 water-cooled sheet, and perform welding thermal cycle treatment on a thermal simulation test machine with different thermal cycle parameters ranging from 0.84KJ/mm to 2.95KJ/mm to obtain high N and low Ni with high performance welding heat affected zone. Type duplex stainless steel.

Example 1

According to C: 0.016%, Si: 0.1%, Mn: 8.01%, Cr: 22.52%, Ni: 1.37%, Mo: 2.69%, Cu: 0.14%, N: 0.446%, P: ≤ 0.01%, S: ≤ 0.01%, the balance is Fe.

Specifically include the following steps:

S1: The stainless steel billet made by 50kg vacuum melting furnace is used for pre-forging treatment. The forging starts at 1160°C, the forging ratio is 4, the final forging temperature is 980°C, and the forging is rapidly cooled; then pre-rolling is performed. Treatment, the starting rolling temperature is set to 1150 ° C, the final rolling temperature is 960 ° C, and the plate is obtained by water quenching;

S2: The plate obtained in S1 is subjected to solution treatment, and the conditions are: 1050 ° C, 30 min, and then water-cooled at room temperature;

S3: Process the S2 water-cooled plate into a size of 10.5mm×10.5mm×60mm, and use the Gleeble-3800 thermal simulation test machine for welding. The heat input parameter is 1.895KJ/mm for welding thermal cycle treatment, at 200℃/s The heating rate was heated to 1345 °C, and the temperature was kept for 1 s to obtain a high-N and low-Ni-saving duplex stainless steel sample. The sample was cut, rusted on the back, welded with copper wires, ground, polished, cleaned, sealed and insulated on the non-working surface with a mixture of rosin and paraffin. Nickel-saving stainless steel in the heat affected zone.

S4: Prepare pitting solution and intergranular corrosion solution. The pitting solution is a 3.5wt% NaCl solution (prepared with 1000mL H ₂ O and 35g NaCl). The intergranular corrosion solution is H ₂ SO ₄ , NaCl and KSCN according to 1.2:1.1: A mixed solution prepared with a molar ratio of 0.01 (1000 mL H ₂ O, 54.35 mL H ₂ SO ₄ , 29.25 g NaCl, 0.97 g KSCN). The pitting corrosion properties and intergranular corrosion properties were tested by cyclic voltammetry potentiodynamic polarization curves and double loop potentiodynamic reactivation (DLEPR). The electrochemical parameters for potential polarization curve fitting are summarized in Table 1.

S5: Figure 1 shows five heat input samples and solid solution cyclic voltammetry polarization test curves in the welding heat affected zone within the range of thermal cycle parameters of 0.84KJ/mm to 2.95KJ/mm. Table 1 shows the potentiodynamic polarization The electrochemical parameters of curve fitting can be seen from the table. When the heat input value is 1.895KJ/mm, the pitting point Eb of the sample in the welding heat-affected zone is greater than or equal to 0.94, and the obtained welding heat-affected zone has high resistance. Pitting performance. Figure 2 shows the test curves of five heat input samples in the welding heat affected zone in the range of 0.84KJ/mm~2.95KJ/mm and the solid solution double-ring electrochemical potentiodynamic reactivation method. Figure 3 shows the five heat input samples. The comparison chart of the intergranular sensitivity value of the heat input sample and the solid solution state. It can be seen from Figure 3 that the intergranular sensitivity value decreases first, then increases and then decreases with the increase of heat input. When the heat input value is 1.895 KJ/mm, the sensitivity value of intergranular corrosion of the welding heat affected zone Ra≤2.22%, the obtained welding heat affected zone has high resistance to intergranular corrosion.

Table 1 Electrochemical parameters for potential polarization curve fitting

S6: The specific data are: welding thermal cycle treatment in the heat input range of 1.10KJ/mm ~ 2.15KJ/mm, pitting corrosion potential Eb≥0.94V, intergranular corrosion sensitivity value Ra≤2.22%, the obtained welding heat affected zone has High corrosion resistance.

Example 2

According to C: 0.016%, Si: 0.1%, Mn: 8.01%, Cr: 22.52%, Ni: 1.37%, Mo: 2.69%, Cu: 0.14%, N: 0.446%, P: ≤ 0.01%, S: ≤ 0.01%, the balance is Fe.

Specifically include the following steps:

S1: The stainless steel billet made by 50kg vacuum melting furnace is used for pre-forging treatment. The forging starts at 1160°C, the forging ratio is 4, the final forging temperature is 980°C, and the forging is rapidly cooled; then pre-rolling is performed. Treatment, the starting rolling temperature is set to 1150 ° C, the final rolling temperature is 960 ° C, and the plate is obtained by water quenching;

S2: The plate obtained in S1 is subjected to solution treatment, and the conditions are: 1050 ° C, 30 min, and then water-cooled at room temperature;

S3: Process the S2 water-cooled sheet into a size of 10.5mm×10.5mm×60mm, and use the Gleeble-3800 thermal simulation test machine for welding. The heat input parameter is 2.935KJ/mm for welding thermal cycle treatment. The heating rate was heated to 1345 °C, and the temperature was kept for 1 s to obtain a high-N and low-Ni-saving duplex stainless steel sample. The sample was cut, rusted on the back, welded with copper wires, ground, polished, cleaned, sealed and insulated on the non-working surface with a mixture of rosin and paraffin. High N low Ni saving duplex stainless steel in the heat affected zone.

S4: Prepare pitting solution and intergranular corrosion solution. The pitting solution is a 3.5wt% NaCl solution (prepared with 1000mL H ₂ O and 35g NaCl). The intergranular corrosion solution is H ₂ SO ₄ , NaCl and KSCN according to 1.2:1.1: A mixed solution prepared with a molar ratio of 0.01 (1000 mL H ₂ O, 54.35 mL H ₂ SO ₄ , 29.25 g NaCl, 0.97 g KSCN). The pitting corrosion properties and intergranular corrosion properties were tested by cyclic voltammetry potentiodynamic polarization curves and double loop potentiodynamic reactivation (DLEPR).

S5: Figure 1 shows five heat input samples and solid solution cyclic voltammetry polarization test curves in the welding heat affected zone within the range of thermal cycle parameters of 0.84KJ/mm to 2.95KJ/mm. Table 1 shows the potentiodynamic polarization The electrochemical parameters of curve fitting can be seen from the table, when the heat input value is 2.935KJ/mm, the pitting point Eb of the sample in the welding heat affected zone is ≥ 0.93, which has high pitting corrosion resistance, Figure 2 That is, the thermal cycle parameters are in the range of 0.84KJ/mm ~ 2.95KJ/mm for the five heat input samples in the welding heat affected zone and the test curves of the solid solution double-ring electrochemical potentiodynamic reactivation method. Figure 3 shows the five heat inputs The comparison chart of the intergranular sensitivity value of the sample and the solid solution state, it can be seen from Figure 3 that the intergranular sensitivity value first decreases, then increases and then decreases with the increase of heat input. When the heat input value is 2.935KJ/ mm, the intergranular corrosion sensitivity value of the welding heat-affected zone Ra≤0.31%, and the obtained welding heat-affected zone has high resistance to intergranular corrosion.

S6: The specific data are: welding thermal cycle treatment in the heat input range of 2.850KJ/mm ~ 2.95KJ/mm, pitting corrosion potential Eb ≥ 0.93, intergranular corrosion sensitivity value Ra ≤ 0.31%, the obtained welding heat affected zone has high Corrosion resistance.

Example 3

According to C: 0.016%, Si: 0.1%, Mn: 8.01%, Cr: 22.52%, Ni: 1.37%, Mo: 2.69%, Cu: 0.14%, N: 0.446%, P: ≤ 0.01%, S: ≤ 0.01%, the balance is Fe.

Specifically include the following steps:

S1: The stainless steel billet made by 50kg vacuum melting furnace is used for pre-forging treatment. The forging starts at 1160°C, the forging ratio is 4, the final forging temperature is 980°C, and the forging is rapidly cooled; then pre-rolling is performed. Treatment, the starting rolling temperature is set to 1150 ° C, the final rolling temperature is 960 ° C, and the plate is obtained by water quenching;

S2: The plate obtained in S1 is subjected to solution treatment, and the conditions are: 1050 ° C, 30 min, and then water-cooled at room temperature;

S3: Process the S2 water-cooled plate into a size of 10.5mm×10.5mm×60mm, and use the Gleeble-3800 thermal simulation test machine for welding. The heat input parameter is 1.895KJ/mm for welding thermal cycle treatment, at 200℃/s The heating rate was heated to 1345 °C, and the temperature was kept for 1 s to obtain a high-N and low-Ni-saving duplex stainless steel sample.

S4: Use tensile test and impact test on the sample to test the tensile and impact properties of the sample.

S5: Figures 4, 5 and 6 are the yield strength and tensile strength curves, elongation curves and impact curves of the thermal simulation samples under three different heat input conditions. It can be seen from the figure that the welding heat cycle treatment is carried out in the heat input range of 1.10KJ/mm ~ 2.15KJ/mm, the tensile strength of the welding heat affected zone is Rm≥780MPa, the yield strength Rp _0.2≥547MPa , and the elongation A≥31.76% , the impact energy of the welding heat-affected zone is greater than 48J.

S6: The specific data are: the welding heat cycle treatment is carried out in the heat input range of 1.10KJ/mm~2.15KJ/mm, the tensile strength of the welding heat affected zone is Rm≥780MPa, the yield strength Rp _0.2≥547MPa , the elongation A≥31.76 %, the impact energy of the welding heat-affected zone is greater than 48J, and the obtained welding heat-affected zone has excellent mechanical properties.

Example 4

According to C: 0.016%, Si: 0.1%, Mn: 8.01%, Cr: 22.52%, Ni: 1.37%, Mo: 2.69%, Cu: 0.14%, N: 0.446%, P: ≤ 0.01%, S: ≤ 0.01%, the balance is Fe.

Specifically include the following steps:

S1: The stainless steel billet made by 50kg vacuum melting furnace is used for pre-forging treatment. The forging starts at 1160°C, the forging ratio is 4, the final forging temperature is 980°C, and the forging is rapidly cooled; then pre-rolling is performed. Treatment, the starting rolling temperature is set to 1150 ° C, the final rolling temperature is 960 ° C, and the plate is obtained by water quenching;

S2: The plate obtained in S1 is subjected to solution treatment, and the conditions are: 1050 ° C, 30 min, and then water-cooled at room temperature;

S3: Process the S2 water-cooled sheet into a size of 10.5mm×10.5mm×60mm, and use the Gleeble-3800 thermal simulation test machine for welding. The heat input parameter is 0.848J/mm for welding thermal cycle treatment. The heating rate was heated to 1345 °C, and the temperature was kept for 1 s to obtain a high-N and low-Ni-saving duplex stainless steel sample.

S4: Tensile test and impact test are used for the sample to test the tensile and impact properties of the sample.

S5: Figures 4, 5 and 6 are the yield strength and tensile strength curves, elongation curves and impact energy curves of the thermal simulation samples under three different heat input conditions. It can be seen from the figure that in the range of 0.45KJ/mm～0.95KJ/mm, the tensile strength of the welding heat affected zone is Rm≥796MPa, the yield strength Rp _0.2≥561MPa , the elongation A≥32%, and the impact of the welding heat affected zone is The work is greater than 57J.

S6: The specific data are: welding heat cycle treatment is carried out in the heat input range of 0.45KJ/mm ~ 0.95KJ/mm, the tensile strength of the welding heat affected zone is Rm≥796MPa, the yield strength Rp _0.2≥561MPa , the elongation A≥32 %, the impact energy of the welding heat-affected zone is greater than 57J. The obtained welding heat affected zone has excellent mechanical properties.

Example 5

On the basis of Example 1, the difference is that the mass percentages of alloy components are: C: 0.015%, S: 0.005%, P: 0.018%, N: 0.25%, Cr: 25.25%, Si: 0.65%, Mn: 1.06%, Ni: 7.08%, Mo: 3.89%, the remaining components are iron and other inevitable impurities, and the welding heat input is 1.12KJ/mm.

The specific data are: it can be seen that the SAF2507 duplex stainless steel is subjected to welding thermal cycle treatment in the heat input range of 1.12KJ/mm, the pitting corrosion potential Eb ≥ 0.870V, and the welding heat affected zone has high corrosion resistance. The stainless steel of the invention is subjected to welding thermal cycle treatment at a heat input of 1.10-2.15 KJ/mm, the pitting corrosion potential Eb is greater than or equal to 0.94 V, and the welding heat-affected zone has high corrosion resistance. In contrast, the welded heat-affected zone obtained by the stainless steel of the present invention has more excellent corrosion properties.

Example 6

On the basis of Example 3, the difference is that the mass percentages of alloy components are: C: 0.019%, S: 0.001%, P: 0.022%, Cr: 22.54%, Si: 0.469%, Mn: 1.175%, Ni: 5.53%, Mo: 3.142%, the remaining components are iron and other inevitable impurities, and the welding heat input is 1.10KJ/mm.

The specific data are: it can be seen that 2205 duplex stainless steel is subjected to welding thermal cycle treatment in the heat input range of 1.10KJ/mm, tensile strength Rm≥720MPa, yield strength Rp _0.2≥518MPa , elongation A≥27.5%, welding heat affected zone Has excellent mechanical properties. The stainless steel of the present invention is subjected to welding thermal cycle treatment at a heat input of 1.10-2.52KJ/mm, and the tensile strength Rm≥780MPa, the yield strength Rp _0.2≥547MPa , and the elongation A≥31.76%. In contrast, the stainless steel of the present invention obtained The welding heat-affected zone has more excellent mechanical properties.

Claims (5)

1. A high-N low-Ni economical duplex stainless steel and a high-performance welding heat affected zone hot working method thereof are characterized by comprising the following steps:

s1: according to the element mass percentage as C: 0.012-0.018%, Si: 0.09-0.12%, Mn: 7.95-8.05%, Cr: 22.45-22.65%, Ni: 1.30-1.40%, Mo: 2.65-2.74%, Cu: 0.10-0.16%, N: 0.420-0.450%, P: less than or equal to 0.01 percent, S: less than or equal to 0.01 percent, and the balance of Fe and inevitable impurities, and refining in a vacuum smelting furnace of 50 kilograms to obtain a stainless steel casting blank;

s2: pre-forging the stainless steel casting blank; obtaining a pre-forged plate;

s3: pre-rolling the pre-forged plate;

s4: putting the pre-rolled plate into a box-type resistance furnace for solution treatment;

s5: carrying out welding heat cycle treatment on the plate subjected to the solution treatment of S4 on a thermal simulation experiment machine according to three sections of heat input parameter ranges of 0.45 KJ/mm-0.95 KJ/mm, 1.10 KJ/mm-2.15 KJ/mm and 2.85 KJ/mm-2.95 KJ/mm and the peak temperature of 1325 ℃ to obtain thermal simulation samples corresponding to the welding heat input and the peak temperature;

s6: preparing the thermal simulation sample obtained in the S5 into an electrochemical sample, and testing the pitting corrosion resistance and the intergranular corrosion resistance sensitivity (DOS) of the sample by adopting a cyclic voltammetric potentiodynamic polarization curve and a double-potentiodynamic reactivation method (DL-EPR), wherein the pitting corrosion resistance test uses a pitting corrosion solution, and the intergranular corrosion resistance sensitivity test uses an intergranular corrosion solution;

s7: and (4) processing the thermal simulation sample obtained in the step S5 into a standard V-shaped notch impact sample and a standard tensile sample, and testing the mechanical properties of the samples by adopting an impact experiment and a tensile experiment.

2. The high-N low-Ni saving duplex stainless steel and the hot working method of the high-performance weld heat affected zone thereof according to claim 1, wherein the pre-forging condition is that the forging is started at a temperature of 1120-1190 ℃, the finish forging temperature is more than 970 ℃, the forging ratio is 4-5, and the steel is cooled by water at normal temperature.

3. The high-N low-Ni economical duplex stainless steel and the high-performance welding heat affected zone hot working method thereof as claimed in claim 1, wherein the pre-rolling condition is that the rolling is started at a temperature of 1100-1180 ℃, the finish rolling temperature is more than 955 ℃, and the normal temperature water quenching is performed.

4. The high-N low-Ni saving duplex stainless steel and the high-performance welding heat affected zone hot working method thereof as claimed in claim 1, wherein the solution treatment conditions are 1030-1070 ℃, the solution time is 0.3-1 h, and normal temperature water cooling is performed.

5. The high-N low-Ni saving duplex stainless steel and the high-performance weld heat affected zone hot working method thereof according to claim 1, wherein the pitting solution is 3.5 wt.% NaCl, and the intergranular corrosion solution ratio is 1.2mol/lH ₂ SO ₄ +1.1mol/lNaCl+0.01mol/l KSCN。

Images