US3926685A — Semi-ferritic stainless manganese steel

Claim 1

Independent Claim 245 words

A PROCESS FOR TREATING A SEMI-FERRITIC STAINLESS STEEL HAVING AN IN-USE STRUCTURE OF ALPHA AND DELTA FERRITE AND CARBIDES, CHARACTERIZED BY HIGH STRENGTH PROPERTIES, GOOD BEND CHARACTERISTICS, GOOD MICRO-HARDNESS, GOOD FUSION WELD RESILIENCE AND GOOD CORROSION RESISTANCE, BOTH IN THE PRESENCE AND ABSENCE OF CHLORINE AND ACID MEDIA, COMPRISING: A. PREPARING A STEEL HAVING A COMPOSITION SELECTED FROM THE GROUP CONSISTING OF BY WEIGHT 0.1% MAX. C, 3-6% MN, 1% MAX. SI, 1% MAX. NI, 18-22% CR, 1.5% MAX. MO, 1% MAX. CU, 0.1% MAX. N2 AND THE BALANCE FE AND INCIDENTAL IMPURITIES, .1% MAC. C, 3-6% MN, 1% MAX. SI, 1% MAX. NI, 15-18% CR, 1.5-3.0% MO, 1% MAX. CU, .1% MAX. N2 AND THE BALANCE FE AND OTHER INCIDENTAL IMPURITES AND 0.1% MAX. C, 3-6% MN, 1-2% SI, 1% MAX. NI, 15-18% CR, 0.5-2.0% MO, 1% MAX. CU, 0.1% MAX. N2 AND THE BALANCE FE AND OTHER INCIDENTAL IMPURITIES, SAID STEEL CHARACTERIZED BY CHROMIUM AND NICKEL EQUIVALENTS FALLING WITHIN THE PENTAGON ON THE GRAPH OF THE SOLE FIGURE, SAID PENTAGON HAVING AS ITS ORDINATES, A(15,4.5) B (18.5, 8), C (24,8), D (24,6), E (20,2); B. HOT WORKING SAID STEEL SO AS TO MAINTAIN AN AUSTENITE CONTENT WHILE HOT OF FROM 10 TO 50%, THE BALANCE BEING DELTA FERRITE; C. COOLING SAID STEEL TO RETAIN SAID AUSTENITE AT ROOM TEMPERATURE; D. TREATING SAID STEEL TO TRANSFORM THE AUSTENITE INTO MARTENSITE; AND E. TEMPERING THE MARTENSITE TO TRANSFORM THE MARTENSITE INTO ALPHA FERRITE AND CARBIDES.

Claim 2

Dependent Claim 245 words

A PROCESS FOR TREATING A SEMI-FERRITIC STAINLESS STEEL HAVING AN IN-USE STRUCTURE OF ALPHA AND DELTA FERRITE AND CARBIDES, CHARACTERIZED BY HIGH STRENGTH PROPERTIES, GOOD BEND CHARACTERISTICS, GOOD MICRO-HARDNESS, GOOD FUSION WELD RESILIENCE AND GOOD CORROSION RESISTANCE, BOTH IN THE PRESENCE AND ABSENCE OF CHLORINE AND ACID MEDIA, COMPRISING: A. PREPARING A STEEL HAVING A COMPOSITION SELECTED FROM THE GROUP CONSISTING OF BY WEIGHT 0.1% MAX. C, 3-6% MN, 1% MAX. SI, 1% MAX. NI, 18-22% CR, 1.5% MAX. MO, 1% MAX. CU, 0.1% MAX. N2 AND THE BALANCE FE AND INCIDENTAL IMPURITIES, .1% MAC. C, 3-6% MN, 1% MAX. SI, 1% MAX. NI, 15-18% CR, 1.5-3.0% MO, 1% MAX. CU, .1% MAX. N2 AND THE BALANCE FE AND OTHER INCIDENTAL IMPURITES AND 0.1% MAX. C, 3-6% MN, 1-2% SI, 1% MAX. NI, 15-18% CR, 0.5-2.0% MO, 1% MAX. CU, 0.1% MAX. N2 AND THE BALANCE FE AND OTHER INCIDENTAL IMPURITIES, SAID STEEL CHARACTERIZED BY CHROMIUM AND NICKEL EQUIVALENTS FALLING WITHIN THE PENTAGON ON THE GRAPH OF THE SOLE FIGURE, SAID PENTAGON HAVING AS ITS ORDINATES, A(15,4.5) B (18.5, 8), C (24,8), D (24,6), E (20,2); B. HOT WORKING SAID STEEL SO AS TO MAINTAIN AN AUSTENITE CONTENT WHILE HOT OF FROM 10 TO 50%, THE BALANCE BEING DELTA FERRITE; C. COOLING SAID STEEL TO RETAIN SAID AUSTENITE AT ROOM TEMPERATURE; D. TREATING SAID STEEL TO TRANSFORM THE AUSTENITE INTO MARTENSITE; AND E. TEMPERING THE MARTENSITE TO TRANSFORM THE MARTENSITE INTO ALPHA FERRITE AND CARBIDES.

Claim 3

Dependent Claim 243 words

A process for treating a semi-ferritic stainless steel having an in-use structure of alpha and delta ferrite and carbides, characterized by high strength properties, good bending characteristics, good micro-hardness, good fusion weld resilience and good corrosion resistance, both in the presence and absence of chlorine and acid media, comprising: A. Preparing a steel having a composition selected from the group consisting of by weight 0.1% max. C, 3-6% Mn, 1% max. Si, 1% max. Ni, 18-22% Cr, 1.5% max. Mo, 1% max. Cu, .01% max. N2 and the balance Fe and incidental impurities, 0.1% max. C, 3-6% Mn, 1% max. Si, 1% max. Ni, 15-18% Cr, 1.5-3.0% Mo, 1% max. Cu, 0.1% max. N2 and the balance Fe and other incidental impurities and 0.1% max. C, 3-6% Mn, 1-2% Si, 1% max. Ni, 15-18% Cr, 0.5-2.0% Mo, 1% max. Cu, .1% max. N2 and the balance Fe and other incidental impurities, said steel characterized by chromium and nickel equivalents falling within the pentagon on the graph of the sole FIGURE, said pentagon having as its ordinates, A (15, 4.5), B (18.5, 8), C (24, 8), D (24, 6), E (20, 2); B. Hot working said steel so as to maintain an austenite content while hot of from 10 to 50%, the balance being delta ferrite; C. Annealing the steel for a prolonged period at about 800*C so as to transform the austenite to alpha ferrite and carbides; and D. Cold forming the steel.

Claim 4

Dependent Claim 243 words

A process for treating a semi-ferritic stainless steel having an in-use structure of alpha and delta ferrite and carbides, characterized by high strength properties, good bending characteristics, good micro-hardness, good fusion weld resilience and good corrosion resistance, both in the presence and absence of chlorine and acid media, comprising: A. Preparing a steel having a composition selected from the group consisting of by weight 0.1% max. C, 3-6% Mn, 1% max. Si, 1% max. Ni, 18-22% Cr, 1.5% max. Mo, 1% max. Cu, .01% max. N2 and the balance Fe and incidental impurities, 0.1% max. C, 3-6% Mn, 1% max. Si, 1% max. Ni, 15-18% Cr, 1.5-3.0% Mo, 1% max. Cu, 0.1% max. N2 and the balance Fe and other incidental impurities and 0.1% max. C, 3-6% Mn, 1-2% Si, 1% max. Ni, 15-18% Cr, 0.5-2.0% Mo, 1% max. Cu, .1% max. N2 and the balance Fe and other incidental impurities, said steel characterized by chromium and nickel equivalents falling within the pentagon on the graph of the sole FIGURE, said pentagon having as its ordinates, A (15, 4.5), B (18.5, 8), C (24, 8), D (24, 6), E (20, 2); B. Hot working said steel so as to maintain an austenite content while hot of from 10 to 50%, the balance being delta ferrite; C. Annealing the steel for a prolonged period at about 800*C so as to transform the austenite to alpha ferrite and carbides; and D. Cold forming the steel.

Claim 5

Dependent Claim 38 words

The process of claim 1 wherein the treating of step D includes annealing between 700* and 900*C for about 4 hours, slow cooling at a rate of about 25*C per hour down to 650*C, and then air cooling.

Claim 6

Dependent Claim 21 words

The process of claim 1 wherein the treating of step D includes cryogenically treating at about -80*C for about 3 hours.

Claim 7

Dependent Claim 25 words

The process of claim 1 wherein the treating of step D includes cold working at ambient temperature by a cold reduction of at least 30%.

Claim 8

Dependent Claim 35 words

The process of claim 1 wherein the treating of step D includes slow cooling from a last processing hot rolling pass at a rate of about 25*C per hour to 650*C and then air cooling.

Claim 9

Dependent Claim 23 words

The process of claim 1 wherein the tempering of step E includes annealing at a temperature less than 850*C until the martensite disappears.

Claim 10

Dependent Claim 13 words

The process of claim 1 wherein the annealing is between 750* and 800*C.

Claim 11

Dependent Claim 17 words

The process of claim 1 wherein the annealing is for a duration of less than 1 hour.

Claim 12

Dependent Claim 11 words

The product made in accordance with the process of claim 1.

Claim 13

Dependent Claim 11 words

The product made in accordance with the process of claim 10.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1978-12-15	1979-06-16	1979-12-16	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1982-12-15	1983-06-16	1983-12-16	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1986-12-15	1987-06-16	1987-12-16	$7700.00	Window Closed / Lapsed

Semi-ferritic stainless manganese steel

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