Austenitic stainless steel
AssigneeUpl Ltd
InventorCecil Vernon Roscoe
Life of this patent
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Abstract
Austenitic stainless steel is disclosed herein. In the described embodiments, the austenitic stainless steel comprises 16.00 wt % of Chromium to 30.00 wt % of Chromium; 8.00 wt % of Nickel to 27.00 wt % of Nickel; no more than 7.00 wt % of Molybdenum; 0.40 wt % of Nitrogen to 0.70 wt % of Nitrogen, 1.0 wt % of Manganese to 4.00 wt % of Manganese, and less than 0.10 wt % of Carbon, wherein the ratio of the Manganese to the Nitrogen is controlled to less than or equal to 10.0. Austenitic stainless steel based on specified minimum PREN (Pitting Resistance Equivalent Number) values is also disclosed. (1) PRE=wt % Cr+3.3×wt % (Mo)+16 wt % N>=25 for N in range of 0.40-0.70. (2) PRE=wt % Cr+3.3×wt % (Mo+W)+16 wt % N>=27 for N in range of 0.40-0.70 with W present.
Claims47
Austenitic stainless steel base metal having a non-magnetic austenitic base metal microstructure comprising 16.00 wt % of Chromium to 30.00 wt % of Chromium (Cr);
- 8.00 wt % of Nickel to 27.00 wt % of Nickel (Ni);
- no more than 7.00 wt % of Molybdenum (Mo);
- 0.40 wt % of Nitrogen to 0.70 wt % of Nitrogen (N), 1.0 wt % of Manganese to less than 4.00 wt % of Manganese (Mn), no more than 1.0 wt % of Niobium (Nb), less than 0.10 wt % of Carbon (C), ≦0.070 wt % Oxygen, no more than 2.00 wt % of Silicon (Si), ≧0.03 wt % of Cerium and ≦0.08 wt % of Cerium, and a balance of iron and inevitable impurity,
- wherein ratio of the Manganese (Mn) to the Nitrogen (N) is controlled to less than 10.0;
- and
- wherein ratio of Chromium Equivalent [Cr] to Nickel Equivalent [Ni] is determined and controlled to more than 0.40 and less than 1.05;
- and
- wherein the Chromium Equivalent is determined and controlled according to a first formula:
- [Cr]=(wt % Cr)+(1.5×wt % Si)+(1.4×wt % Mo)+(wt % Nb)−4.99;
- and
- wherein the Nickel Equivalent is determined and controlled according to a second formula:
- [Ni]=(wt % Ni)+(30×wt % C)+(0.5×wt % Mn)+((26×wt % (N−0.02))+2.77;
- and wherein
- the ratio of the [Cr] equivalent divided by the [Ni] equivalent is optimized at a melting stage in order to primarily obtain an austenitic microstructure in the base stainless steel after solution heat treatment performed in the range 1100 deg C. to 1250 deg C. followed by water quenching.
Austenitic stainless steel base metal having a non-magnetic austenitic base metal microstructure comprising 0.40 to 0.70 wt % of Nitrogen and an alloy composition having a specified Pitting Resistance Equivalent (PREN) of ≧25;
- wherein
- PREN=wt % of Chromium+(3.3×wt % of Molybdenum)+(16×wt % of Nitrogen), and wherein the alloy composition further includes 16.00 wt % of Chromium to 30.00 wt % of Chromium (Cr);
- 8.00 wt % of Nickel to 27.00 wt % of Nickel (Ni);
- no more than 7.00 wt % of Molybdenum (Mo);
- 1.0 wt % of Manganese to less than 4.00 wt % of Manganese (Mn), no more than 1.0 wt % of Niobium (Nb), less than 0.10 wt % of Carbon (C), ≦0.070 wt % Oxygen, no more than 2.00 wt % of Silicon (Si), ≧0.03 wt % of Cerium and ≦0.08 wt % of Cerium, and a balance of iron and inevitable impurity,
- wherein ratio of the Manganese (Mn) to the Nitrogen (N) is controlled to less than 10.0;
- and
- wherein ratio of Chromium Equivalent [Cr] to Nickel Equivalent [Ni] is determined and controlled to more than 0.40 and less than 1.05;
- and
- wherein the Chromium Equivalent is determined and controlled according to a first formula:
- [Cr]=(wt % Cr)+(1.5×wt % Si)+(1.4×wt % Mo)+(wt % Nb)−4.99;
- and
- wherein the Nickel Equivalent is determined and controlled according to a second formula:
- [Ni]=(wt % Ni)+(30×wt % C)+(0.5×wt % Mn)+((26×wt % (N−0.02))+2.77;
- and wherein
- the ratio of the [Cr] equivalent divided by the [Ni] equivalent is optimized at a melting stage in order to primarily obtain an austenitic microstructure in the base stainless steel after solution heat treatment performed in the range 1100 deg C. to 1250 deg C. followed by water quenching.
Austenitic stainless steel base metal having a non-magnetic austenitic base metal microstructure comprising 0.40 to 0.60 wt % of Nitrogen and an alloy composition having a specified Pitting Resistance Equivalent (PREM) of ≧25;
- wherein
- PREN=wt % of Chromium+(3.3×wt % of Molybdenum)+(16×wt % of Nitrogen) and wherein the alloy composition further includes 16.00 wt % of Chromium to 30.00 wt % of Chromium (Cr);
- 8.00 wt % of Nickel to 27.00 wt % of Nickel (Ni);
- no more than 7.00 wt % of Molybdenum (Mo);
- 1.0 wt % of Manganese to less than 4.00 wt % of Manganese (Mn), no more than 1.0 wt % of Niobium (Nb), less than 0.10 wt % of Carbon (C), ≦0.070 wt % Oxygen, no more than 2.00 wt % of Silicon (Si), ≧0.03 wt % of Cerium and ≦0.08 wt % of Cerium, and a balance of iron and inevitable impurity,
- wherein ratio of the Manganese (Mn) to the Nitrogen (N) is controlled to less than 10.0;
- and
- wherein ratio of Chromium Equivalent [Cr] to Nickel Equivalent [Ni] is determined and controlled to more than 0.40 and less than 1.05;
- and
- wherein the Chromium Equivalent is determined and controlled according to a first formula:
- [Cr]=(wt % Cr)+(1.5×wt % Si)+(1.4×wt % Mo)+(wt % Nb)−4.99;
- and
- wherein the Nickel Equivalent is determined and controlled according to a second formula:
- [Ni]=(wt % Ni)+(30×wt % C)+(0.5×wt % Mn)+((26×wt % (N−0.02))+2.77;
- and wherein
- the ratio of the [Cr] equivalent divided by the [Ni] equivalent is optimized at a melting stage in order to primarily obtain an austenitic microstructure in the base stainless steel after solution heat treatment performed in the range 1100 deg C. to 1250 deg C. followed by water quenching.
Austenitic stainless steel base metal having a non-magnetic austenitic base metal microstructure comprising 0.50 wt % to 1.00 wt % of Tungsten, 0.40 to 0.70 wt % of Nitrogen, and an alloy composition having a specified Pitting Resistance Equivalent (PRENW)≧27;
- wherein
- PRENW=wt % of Chromium+[(3.3×wt % (Molybdenum+Tungsten)]+(16×wt % Nitrogen)
- and wherein the alloy composition further includes 16.00 wt % of Chromium to 30.00 wt % of Chromium (Cr);
- 8.00 wt % of Nickel to 27.00 wt % of Nickel (Ni);
- no more than 7.00 wt % of Molybdenum (Mo);
- 1.0 wt % of Manganese to less than 4.00 wt % of Manganese (Mn), no more than 1.0 wt % of Niobium (Nb), less than 0.10 wt % of Carbon (C), ≦0.070 wt % Oxygen, no more than 2.00 wt % of Silicon (Si), >0.03 wt % of Cerium and ≦0.08 wt % of Cerium, and a balance of iron and inevitable impurity,
- wherein ratio of the Manganese (Mn) to the Nitrogen (N) is controlled to less than 10.0;
- and
- wherein ratio of Chromium Equivalent [Cr] to Nickel Equivalent [Ni] is determined and controlled to more than 0.40 and less than 1.05;
- and
- wherein the Chromium Equivalent is determined and controlled according to a first formula:
- [Cr]=(wt % Cr)+(1.5×wt % Si)+(1.4×wt % Mo)+(wt % Nb)−4.99;
- and
- wherein the Nickel Equivalent is determined and controlled according to a second formula:
- [Ni]=(wt % Ni)+(30×wt % C)+(0.5×wt % Mn)+((26×wt % (N−0.02))+2.77;
- and wherein
- the ratio of the [Cr] equivalent divided by the [Ni] equivalent is optimized at a melting stage in order to primarily obtain an austenitic microstructure in the base stainless steel after solution heat treatment performed in the range 1100 deg C. to 1250 deg C. followed by water quenching.
Austenitic stainless steel base metal having a non-magnetic austenitic base metal microstructure comprising 0.40 to 0.60 wt % of Nitrogen, 0.50 wt % to 1.00 wt % of Tungsten and an alloy composition having a specified Pitting Resistance Equivalent (PRENW)≧27;
- wherein
- PRENW=wt % of Chromium+[(3.3×wt % (Molybdenum+Tungsten)]+(16×wt % Nitrogen)
- and wherein the alloy composition further includes 16.00 wt % of Chromium to 30.00 wt % of Chromium (Cr);
- 8.00 wt % of Nickel to 27.00 wt % of Nickel (Ni);
- no more than 7.00 wt % of Molybdenum (Mo);
- 1.0 wt % of Manganese to less than 4.00 wt % of Manganese (Mn), no more than 1.0 wt % of Niobium (Nb) and less than 0.10 wt % of Carbon (C), ≦0.070 wt % Oxygen, no more than 2.00 wt % of Silicon (Si), ≧0.03 wt % of Cerium and ≦0.08 wt % of Cerium, a balance of iron and inevitable impurity,
- wherein ratio of the Manganese (Mn) to the Nitrogen (N) is controlled to less than 10.0;
- and
- wherein ratio of Chromium Equivalent [Cr] to Nickel Equivalent [Ni] is determined and controlled to more than 0.40 and less than 1.05;
- and
- wherein the Chromium Equivalent is determined and controlled according to a first formula:
- [Cr]=(wt % Cr)+(1.5×wt % Si)+(1.4×wt % Mo)+(wt % Nb)−4.99;
- and
- wherein the Nickel Equivalent is determined and controlled according to a second formula:
- [Ni]=(wt % Ni)+(30×wt % C)+(0.5×wt % Mn)+((26×wt % (N−0.02))+2.77;
- and wherein
- the ratio of the [Cr] equivalent divided by the [Ni] equivalent is optimized at a melting stage in order to primarily obtain an austenitic microstructure in the base stainless steel after solution heat treatment performed in the range 1100 deg C. to 1250 deg C. followed by water quenching.
A method of manufacturing austenitic stainless steel base metal having a non-magnetic austenitic base metal microstructure comprising 16.00 wt % of Chromium to 30.00 wt % of Chromium (Cr);
- 8.00 wt % of Nickel to 27.00 wt % of Nickel (Ni);
- no more than 7.00 wt % of Molybdenum (Mo);
- 0.40 wt % of Nitrogen to 0.70 wt % of Nitrogen (N), 1.0 wt % of Manganese to less than 4.00 wt % of Manganese (Mn), no more than 1.0 wt % of Niobium (Nb), less than 0.10 wt % of Carbon (C), ≦0.070 wt % Oxygen, no more than 2.00 wt % of silicon, ≧0.03 wt % of Cerium and ≦0.08 wt % of Cerium, and a balance of iron and inevitable impurity,
- the method comprising:
- (i) performing solution heat treatment of a metal alloy composition at a temperature between 1100° C. and 1250° C., wherein a ratio of Chromium equivalent divided by Nickel equivalent is optimized at a melting stage in order to primarily obtain an austenitic microstructure in the base stainless steel after solution heat treatment performed in the range 1100 deg C. to 1250 deg C. followed by water quenching to form the non-magnetic austenitic stainless steel base metal microstructure;
- wherein, ratio of the Manganese (Mn) to the Nitrogen (N) is controlled to less than 10.0;
- and
- ratio of Chromium Equivalent [Cr] to Nickel Equivalent [Ni] is determined and controlled to more than 0.40 and less than 1.05;
- and
- wherein the Chromium Equivalent is determined and controlled according to a first formula:
- [Cr]=(wt % Cr)+(1.5×wt % Si)+(1.4×wt % Mo)+(wt % Nb)−4.99;
- and
- wherein the Nickel Equivalent is determined and controlled according to a second formula:
- [Ni]=(wt % Ni)+(30×wt % C)+(0.5×wt % Mn)+((26×wt % (N−0.02))+2.77.
Dependencies are inferred from the claim text.