Bases axiomáticas para un proyecto de análisis antihomofóbico

There are many nickel base alloys used in the Oil Patch. We'll examine a few of the more important ones in this section. The compositions given are typical for

commercial grades and do not necessarily reflect the limits in our material

specifications. I am identifying these alloys by their most widely recognized trade

names just as a matter of convenience. Most of them are available from more than one supplier under various alloy names.

Monel® 400 (UNS N04400) - 63.0% min. Ni, 28.0 - 34.0% Cu, 2.5% max. Fe, 2.0% max. Mn, 0.3% max. C, 0.5% max. Si

The Monels® are essentially nickel-copper alloys containing

approximately D copper and E nickel. They have excellent corrosion resistance in sea water, in many acids, alkalies, and wellhead

environments. Monel® 400 was the first to be developed. It has the good corrosion resistance typical of the family and is frequently specified for heat exchangers, pumps, shafts, valves, and piping in the chemical and marine industries where corrosion is a primary concern. NACE MR0175 allows Monel® 400 to be used in sour service up to 35 HRC. Monel® 400

condition. A typical anneal is done at 1600-1800(F and is followed by an air quench. The yield strength of annealed Monel® 400 is around 25-50 ksi. This relatively low value frequently limits its use in wellhead

equipment to low stress applications such as seals.

Monel® K-500 (UNS N05500) - 63.0% min. Ni, 27.0-33.0% Cu, 2.30- 3.15% Al, 0.35-0.85% Ti, 2.0% max. Fe, 0.25% max. C, 1.5% max. Mn, 0.5% max. Si

This alloy is the age hardenable version of Monel® 400. In the solution annealed and aged condition the yield strength is around 110 ksi: a considerable improvement over Monel® 400. A typical heat treatment for the Oil Patch would be to solution anneal at 1700-1800(F, water quench, and then age around 1100(F. NACE MR0175 allows the use of Monel® K-500 in sour service in the hot worked and age hardened condition, the solution annealed condition, and the solution annealed and age hardened condition up to a maximum of 35 HRC. The high strength and good

corrosion resistance of Monel® K-500 make it a popular choice for valve trim, propeller and pump shafts, fasteners, etc. Monel® K-500 should not be used for cathodically protected parts because it is subject to hydrogen embrittlement.

Inconel® 600 (UNS N06600) - 72.0% min. Ni, 14.0-17.0% Cr, 6.0-10.0% Fe, 0.15% max. C, 1.0% max. Mn, 0.5% max. Si, 0.5% max. Cu

The Inconel® family consists of nickel-chromium-iron alloys. Inconel® 600 has outstanding corrosion and heat resistance which make it a commonly used material in the chemical, power, and aerospace industries. Its high nickel content gives it excellent toughness even down to cryogenic temperatures. NACE MR0175 allows the use of Inconel® 600 up to 35 HRC maximum in sour service. Inconel® 600 cannot be hardened through heat treatment. It can be strengthened, of course, through cold working. Inconel® 600 is typically annealed at 1700-1800(F and then air cooled. Yield strength is around 30-35 ksi in the annealed condition. The low strength level relegates the use of Inconel® 600 in the Oil Patch to low stress parts such as seals, trim, etc.

Inconel® X-750 (UNS N07750) - 70.0% min. Ni, 14.0-17.0% Cr, 5.0-9.0% Fe, 2.25-2.75% Ti, 0.40-1.00% Al, 0.70-1.20% Cb, 0.08% max. C, 1.00% max. Mn, 0.50% max. Si, 0.50% max. Cu, 1.00% max. Co

Inconel® X-750 is the age hardenable version of Inconel® 600.

Depending on the amount of work and specific heat treatment, X-750 in the solution annealed and aged condition can have a yield strength over 100 ksi. NACE MR0175 allows X-750 to be used up to 35 HRC in the solution annealed and aged condition, solution annealed condition, hot worked condition, hot worked and aged condition. We've already

X-750 has been used for stems, springs, and other highly stressed parts in the Oil Patch. It is subject to hydrogen embrittlement under cathodic protection.

Inconel® 625 (UNS N06625) - 58.0% min. Ni, 20.0-30.0% Cr, 8.0-10.0% Mo, 3.15-4.15% Cb, 5.0% max. Fe, 0.10% max. C, 0.50% max. Mn, 0.50% max. Si, 0.40% max. Al, 0.40% max. Ti

Inconel® 625 has outstanding corrosion resistance. It is very resistant to pitting and chloride stress corrosion cracking in chloride solutions. It is frequently the alloy of choice for severe wellhead environments such as found in Mobile Bay and the North Sea. 625 is widely used for main pressure containing parts, hangers, stems, gates, etc. in the Oil Patch. We use 625 to clad low alloy steels by HIP’ing or welding in order to make these steels suitable for highly corrosive environments. NACE MR0175 allows 625 to be used up to 35 HRC. It is usually solution annealed at 2000-2200(F. Yield strength is relatively low in the solution annealed condition (around 40-60 ksi). In wrought products, some strengthening can be obtained by aging the solution annealed material at 1100-1300(F where a sluggish precipitation occurs. Yield strengths can be increased in relatively thin parts up to around 75 ksi by aging. Amazingly, HIP’ed 625 (we'll talk about HIP’ing in detail in the Chapter on Forging, Casting, and Powder Metallurgy) can develop yield strengths well over 100 ksi without exceeding the NACE hardness limit in relatively large parts after aging. Why this occurs is not altogether understood, but is related to the fine grain size of the HIP’ed product, the use of a more restrictive chemistry, as well as other reasons.

Inconel® 718 (UNS NO7718) - 50.0-55.0% Ni, 17.0-21.0% Cr, 4.75-5.50% Cb, 2.80-3.30% Mo, 0.65-1.15% Ti, 0.20-0.80% Al, 1.0% max. Co, 0.08% max. C, 0.35% max. Si, 0.006% B, 0.30% Cu, Balance Fe

718 is one of the workhorses of the Oil Patch. It has excellent corrosion resistance and can attain high strength levels through aging. This makes it useful for main body components, gates, stems, hangers, etc. Wrought 718 can be used in sour service in the following conditions as permitted by NACE MR0175:

1. solution annealed to 35 HRC maximum 2. hot worked to 35 HRC maximum

3. hot worked and aged to 35 HRC maximum

4. solution annealed and aged to 40 HRC maximum

Annealing is generally done at 1700-1950(F. Yield strength may vary from about 45 ksi to 80 ksi depending on annealing temperature and the

amount of working. Like X-750, 718 has many possible aging heat treatments. The one most commonly used in the Oil Patch is a single

double prime. Yield strengths well above 100 ksi can be obtained in the aged condition without exceeding the maximum NACE hardness. Equipment made from 718 is used in many hostile wellhead

environments. At temperatures over roughly 300(F, it can become

susceptible to sulfide stress corrosion cracking in high chloride solutions if free sulfur is present.

625 Plus® (UNS NO7716) - 59.0-63.0% Ni, 19.0-22.0% Cr, 2.75-4.00% Cb, 0.15% max. Cu, 7.00-9.50% Mo, 1.00-1.60% Ti, 0.20% max. Si, 0.20% max. Mn, 0.03% max. C, 0.35% max. Al, Balance Fe

This rising star in the Oil Patch is essentially a 625 alloy that has been modified to have a better aging response. In the solution annealed and aged condition, yield strengths in excess of 120 ksi can be obtained without exceeding the 40 HRC maximum hardness imposed by NACE MR0175 for use in sour service. 625 Plus® is typically solution annealed at 1800-1900(F. A two step aging process is used: age at 1350-1375(F, furnace cool down to 1150-1200(F, and then age again. The high strength and good corrosion resistance of 625 Plus® make it a natural for main body components, hangers, stems, etc.

Inconel® 725 (UNS NO7725) - 55.0-59.0% Ni, 19.0-22.50% Cr, 7.00- 9.50% Mo, 2.75-4.00% Cb, 0.35% max. Al, 1.00-1.70% Ti, 0.20% max. Si, 0.03% max. C, 0.35% max. Mn, Balance Fe

This alloy is INCO's version of 625 Plus®. The two alloys have similar chemistries, heat treatments, and properties. NACE has approved its use in sour service in the solution annealed condition up to a maximum of 40 HRC.

Hastelloy® C-276 (UNS NO10276) - 14.5-16.5% Cr, 0.02% max. C, 4.00- 7.00% Fe, 1.00% max. Mn, 15.0-17.0% Mo, 2.5% Co, 0.08% max. Si, 0.03% max. V, 3.0-4.5% W, Balance Ni

The Hastelloys® are a group of Ni-Mo-Cr alloys with outstanding corrosion resistance that make them widely used in the chemical and petroleum industries. C-276 is not considered to be hardenable through heat treatment, although some minor aging may occur at elevated temperatures. It is typically annealed at 2050(F and then rapidly

quenched. The yield strength is about 50 ksi in the annealed condition. NACE permits its use in sour service in the following conditions:

1. solution annealed or solution annealed plus cold worked up to 35 HRC maximum

2. cold worked and unaged condition at 45 HRC maximum when used at a minimum temperature of 250(F

C-276 is typically used for seals or other low stressed parts that must perform satisfactorily in a highly corrosive environment.