Summary of the invention
The problems referred to above that exist technically for existing Martensite Stainless Steel, the invention provides a kind of high-strong toughness high-strength plasticity Martensite Stainless Steel and preparation method thereof, to the independent or alloy element such as compound interpolation Ni, Si, Al in traditional Martensite Stainless Steel, and optionally add the micro alloying elements such as Mo, N, Nb, V, Ti, by thermal treatment process, control to introducing certain volume fractional in martensitic stucture and stable retained austenite is prepared into high-strong toughness high-strength plasticity Martensite Stainless Steel.
The composition of high-strong toughness high-strength plasticity Martensite Stainless Steel of the present invention is by weight percentage containing C 0.15 ~ 0.4%, and N 0 ~ 0.12%, and Si 0.2 ~ 2.5%, Mn 0.4 ~ 3.0%, S≤0.02%, P≤0.02%, Cr 13.0 ~ 17.0%, Ni 0 ~ 5.0%, and Mo 0 ~ 2.0%, and V 0 ~ 0.3%, Nb 0 ~ 0.2%, Ti 0 ~ 0.05%, and Al 0 ~ 0.8%, and surplus is Fe and inevitable impurity.
The yield strength of above-mentioned high-strong toughness high-strength plasticity Martensite Stainless Steel is 650 ~ 1250MPa, and tensile strength is 1300 ~ 1800MPa, unit elongation 16 ~ 25%, the summer than v-notch ballistic work at 20 ~ 105J.
Above-mentioned high-strong toughness high-strength plasticity Martensite Stainless Steel be organized as martensite and austenite, wherein austenitic volume fraction is 20 ~ 40%.
The preparation method of high-strong toughness high-strength plasticity Martensite Stainless Steel of the present invention carries out according to the following steps:
1, press set component melting molten steel, then solidify and make strand by continuous caster or mold; Its composition is by weight percentage containing C 0.15 ~ 0.4%, and N 0 ~ 0.12%, and Si 0.2 ~ 2.5%, Mn 0.4 ~ 3.0%, S≤0.02%, P≤0.02%, Cr 13.0 ~ 17.0%, Ni 0 ~ 5.0%, and Mo 0 ~ 2.0%, and V 0 ~ 0.3%, Nb 0 ~ 0.2%, Ti 0 ~ 0.05%, and Al 0 ~ 0.8%, and surplus is Fe and inevitable impurity;
2, strand hot rolling is made to hot rolling slab; Start rolling temperature during hot rolling is 1150 ± 50 ℃, and finishing temperature is 850 ± 50 ℃, and total reduction is 70 ~ 90%;
3, hot rolling slab is heated to 950 ~ 1100 ℃ of insulation 0.5 ~ 2h, then air cooling or oil cooling to 25 ~ 200 ℃, reheat to 350 ~ 500 ℃ of insulation 10 ~ 60min, and last air cooling, to room temperature, obtains high-strong toughness high-strength plasticity Martensite Stainless Steel.
Above-mentioned oil cooling is to adopting industrial quenching oil to carry out cooling.
Above-mentioned melting molten steel is melting under protective atmosphere condition, and protective atmosphere is argon gas or nitrogen.
In aforesaid method, when C adds weight total content >=0.3% of N in strand, carry out anneal after strand is rolled into slab, during annealing, Heating temperature is 850 ~ 900 ℃, is incubated 1 ~ 2h, cools to 400 ~ 500 ℃ with the furnace, then air cooling is to room temperature, then carry out step 3.
In tradition Martensite Stainless Steel, in the quenching structure of middle Low Carbon Martensite Stainless Steel, only contain≤5% retained austenite, only have the quenching structure of medium high carbon Martensite Stainless Steel just to contain >=10% retained austenite, but these austenitic less stable just can change martensite into when temperature reduces; Martensite Stainless Steel prepared by method of the present invention is introduced disperse and stable retained austenite in microstructure, has increased substantially the strong plasticity level of obdurability of Martensite Stainless Steel.
Method of the present invention by elements such as independent in traditional Martensite Stainless Steel or compound interpolation Ni, Si, Al to regulate martensitic transformation to start end (Mf) temperature improve stabilization of austenite of (Ms) temperature and martensitic transformation, and optionally add Mo, the element such as N, Nb, V, Ti is with raising intensity and corrosion resistance nature; When the weight content <0.3% of C and N, after controlling hot rolling slab heating, there is complete austenitizing, when weight content >=0.3% of C and N, after hot-work, carry out anneal, and heat and roll heating of plate blank incomplete austenitizing occurs in final thermal treatment time control; Heating austenitizing is controlled cooling termination temperature between Ms and Mf temperature later, obtains martensite and adds the tissue that residual austenite two-phase is master; Subsequently again heat up and insulating process in suppress the Carbide Precipitation in martensite, promote the carbon (nitrogen) in martensite to spread enrichment in austenite, the increase of carbon in austenite (nitrogen) content impels its stability to strengthen, and martensitic transformation does not occur in process of cooling again; Through normalizing-tempering (or being called quenching-partition), process the last microstructure that martensite adds retained austenite that obtains, give the combination of strength and toughness of this steel excellence and good corrosion resistance nature.
Embodiment
In the embodiment of the present invention, austenitic martensitic transformation starts the method for calculation of (Ms) temperature and is: Ms(℃)=539-430 * [C]-30 * [Mn]-12 * [Cr]-15 * [Ni]-7 * [Mo]-5.0 * [Si]; Wherein [C], [Mn], [Cr], [Ni], [Mo] and [Si] are respectively C, Mn, Cr, Ni, Mo and the Si weight content in Martensite Stainless Steel; The method of calculation that martensitic transformation finishes (Mf) temperature are: Mf(℃)=Ms-250; It should be noted that: at incomplete austenitizing state, austenitic composition is different from the original composition of steel, its Ms temperature can not be calculated by the original composition of steel, take and surveys as main.
In the embodiment of the present invention, by the method for GB GB/T 228-2002, test yield strength, tensile strength and unit elongation; The equipment adopting is the CMT5105 electronic universal tester that SANS company produces.
In the embodiment of the present invention, by the method for GB GB/T 229-1994, test the summer than v-notch ballistic work.
Embodiment 1
Press set component melting molten steel under protective atmosphere, protective atmosphere is nitrogen; By mold, solidify and make strand again; Its composition is by weight percentage containing C 0.15%, and Si 0.2%, and Mn 0.4%, and S 0.012%, and P 0.016%, and Cr 13.0%, and Ni 5.0%, and Mo 2.0%, and Nb 0.2%, and V 0.3%, and N 0.12%,, surplus is Fe and inevitable impurity;
Strand hot rolling is made to the hot rolling slab that 15mm is thick, and start rolling temperature is 1150 ± 50 ℃, and finishing temperature is 850 ± 50 ℃, and total reduction is 80%;
Hot rolling slab is heated to 950 ℃ of insulation 2h, then air cooling to 150 ℃,, reheat to 450 ℃ of insulation 10min, air cooling is to room temperature, obtain high-strong toughness high-strength plasticity Martensite Stainless Steel, yield strength is 873MPa, and tensile strength is 1445MPa, unit elongation 22.0%, summer at 70J, is organized as martensite and austenite than v-notch ballistic work, and austenitic volume fraction is 27%; As shown in Figure 1, as shown in Figure 2, as shown in Figure 3, in Fig. 3, shinny part is austenite to transmission electron microscope microstructure (details in a play not acted out on stage, but told through dialogues) to transmission electron microscope microstructure (light field) in optical microstructure, and dark part is martensite.
Embodiment 2
Press set component melting molten steel under protective atmosphere, protective atmosphere is argon gas; By mold, solidify and make strand again; Its composition is by weight percentage containing C 0.28%, and Si 2.5%, and Mn 3.0%, and S 0.008%, and P 0.019%, and Cr 13.0%, and Al 0.8%, and Mo 1.0%, and Nb 0.2%, and Ti 0.05%, and surplus is Fe and inevitable impurity;
Strand hot rolling is made to the hot rolling slab that 20mm is thick, and start rolling temperature is 1150 ± 50 ℃, and finishing temperature is 850 ± 50 ℃, and total reduction is 80%;
Hot rolling slab is heated to 1050 ℃ of insulation 2h, then air cooling to 25 ℃, reheats to 500 ℃ of insulation 60min, and air cooling is to room temperature, obtain high-strong toughness high-strength plasticity Martensite Stainless Steel, yield strength is 650MPa, and tensile strength is 1695MPa, unit elongation 25.0%, summer than v-notch ballistic work at 56J, be organized as martensite and austenite, austenitic volume fraction Wei40%, optical microstructure as shown in Figure 4.
Embodiment 3
Press set component melting molten steel under protective atmosphere, protective atmosphere is argon gas; By continuous caster, make strand again; Its composition is by weight percentage containing C 0.4%, and Si 0.6%, and Mn 0.4%, and S 0.015%, and P 0.013%, and Cr 17.0%, and Mo 1.0%, and V 0.3%, and Ni 2.8%, and surplus is Fe and inevitable impurity;
Strand hot rolling is made to the hot rolling slab that 25mm is thick, and start rolling temperature is 1150 ± 50 ℃, and finishing temperature is 850 ± 50 ℃, and total reduction is 70%;
Because C in strand adds weight total content >=0.3% of N, after hot rolling, carry out anneal, during anneal, be heated to 900 ℃ of insulation 2h, then cool to 500 ℃ with the furnace, then air cooling is to room temperature;
Hot rolling slab after anneal is heated to 1050 ℃ of insulation 0.5h, then adopt industrial quenching oil to be cooled to 100 ℃, reheat to air cooling after 350 ℃ of insulation 20min to room temperature, obtain high-strong toughness high-strength plasticity Martensite Stainless Steel, yield strength is 1250MPa, tensile strength is 1800MPa, unit elongation 16.6%, the summer at 20J, is organized as martensite and austenite than v-notch ballistic work, austenitic volume fraction Wei26%, optical microstructure as shown in Figure 5.
Embodiment 4
Press set component melting molten steel under protective atmosphere, protective atmosphere is argon gas; By continuous caster, make strand again; Its composition is by weight percentage containing C 0.22%, and Si 0.9%, and Mn 2.3%, and S 0.015%, and P 0.02%, and Cr 14.1%, and Ni 0.8%, and Mo 0.9%, and Nb 0.14%, and Ti 0.05%, and Al 0.36%, and surplus is Fe and inevitable impurity;
Strand hot rolling is made to the hot rolling slab that 15mm is thick, and start rolling temperature is 1150 ± 50 ℃, and finishing temperature is 850 ± 50 ℃, and total reduction is 90%;
Hot rolling slab is heated to 1000 ℃ of insulation 1.5h, then air cooling to 200 ℃, reheat to 500 ℃ insulation 20min after air cooling to room temperature, obtain high-strong toughness high-strength plasticity Martensite Stainless Steel, yield strength is 750MPa, and tensile strength is 1300MPa, unit elongation 23.5%, summer at 105J, is organized as martensite and austenite than v-notch ballistic work, and austenitic volume fraction is 20%.
Embodiment 5
Press set component melting molten steel under protective atmosphere, protective atmosphere is argon gas; By continuous caster, make strand again; Its composition is by weight percentage containing C 0.34%, and N 0.008%, and Si 1.2%, and Mn 1.5%, and S 0.017%, and P 0.02%, and Cr 14.8%, and Ni 1.8%, and Nb 0.05%, and Ti 0.05%, and surplus is Fe and inevitable impurity;
Strand hot rolling is made to the thick hot rolling slab of 25mm, and start rolling temperature is 1150 ± 50 ℃, and finishing temperature is 850 ± 50 ℃, and total reduction is 80%;
Because C in strand adds weight total content >=0.3% of N, after hot rolling, carry out anneal, 850 ℃ of annealing heating temperature, soaking time is 1h, cools to 400 ℃ after anneal with the furnace, air cooling is to room temperature;
Anneal air cooling to the hot rolling slab of room temperature is heated to 1100 ℃ of insulation 1.5h, then air cooling to 25 ℃, reheat to 450 ℃ of insulation 20min, last air cooling, to room temperature, obtains high-strong toughness high-strength plasticity Martensite Stainless Steel, yield strength is 695MPa, tensile strength is 1695MPa, unit elongation 23%, the summer than v-notch ballistic work at 39J, be organized as martensite and austenite, austenitic volume fraction is 36%.