High Performance Stainless Steels
NASS 45® – (450 Stainless mod.) High Strength, Non-Galling,
Pump Shaft Stainless
TIRED OF GIVING-UP STRENGTH FOR CORROSION RESISTANCE?
Quit using stainless grades like 304L and 316L.
TIRED OF GIVING-UP CORROSION RESISTANCE FOR STRENGTH?
Quit using stainless grades like 410, 416 and 17-4PH.
TIRED OF PARTS THAT GALL AND WILL NOT COME APART?
Get rid of stainless that seizes and tears.
TIRED OF STRAIGHTNESS PROBLEMS?
Get rid of stainless that "moves and walks" during machining.
Benefits and Advantages
High Strength - Nass 45 is a thermally hardened martensitic stainless alloy. It has similar strength levels to 4340 Q&T alloy bar product with approx. 140KSI tensile strength. Austenitic grades, such as 304 and 316 stainless, require strain hardening or cold reduction to obtain their hardness. As the shaft size increases, the hardness, strength, and wear resistance, drop off substantially. Nass 45 is thermally treated, the hardness and strength properties remain virtually constant, from the smallest to the largest bars.
Corrosion Resistance - Similar to that of 316L stainless, Nass 45 is engineered for use in severe service applications. Most commercial stainless grades fight corrosion but lack strength. Alloy grades and hardenable stainless grades have strength but lack corrosion resistance. Nass 45 does both.
Non-Galling - Nass 45 is non-galling. It is compatible with almost every other stainless grade, as well as carbon and alloy grades of steel. Maintenance people will find that hex nuts, caps, and collars come apart easily for inspection, replacement and repair.
Pump Shaft Straightness - Nass 45 has been specifically designed as a maintenance material suitable for pump shaft applications in highly corrosive environments. It is strong, machines easily, and stays straight during machining and in service. Nass 45 is also available with a semi-finished, oversized, surface finish, so that the size will make the size. Specify semi-finished pump shaft stock when you do not require TG&P stock.
Double Stress Relieved - Nass 45 shafts are shipped virtually free of retained stress. This material will be a welcomed change from the warp and bend, common to other stainless grades. Because Nass 45 has "low memory" properties, these shafts will not exhibit the "movement" and "walking" commonly experienced when machining 304, 316, and other stainless grades.
• NACE MR-01-75-97 revision
Typical Straightness Standard
Pump Shaft Straightness = .005" in the first 5 feet, plus .0015" for each additional foot. We take extra precautions to protect small diameter bars with longer lengths but straightness is perishable.
To maintain the unusually high degree of toughness, service temperature should be limited to approx. 800°F, although Nass 45 exhibits excellent oxidation resistance to 1200°F.
* Diameters smaller than 7/8" round may be modified due to production restrictions. Inquire on available lengths.
Typical Diameter Tolerances
- Agitator Shafts
- Pump Shafts
- Fan Shafts
- Line Shafts
- Valve Stems
General Machining Data
Use high speed tools.
Turning Single Point, and box 70/90SFPM IPR .015/.007. Turning and cut-off, 70SFPM IPR .0015
Drilling: (1/4" Diameter SFPM50, IPR.004); (3/4" Diameter SFPM70, IPR.0015)
Milling: Cut-depth .050" SFPM85 IPR.001 to .004. TAP SFPM 12 to 2
General Welding Information
Nass 45 has a grain structure of tempered martensite, and a blended alloy composition that is favorable for welding without preheating. In most instances this alloy may be used "as welded", requiring no post weld heat treatment (PWHT).
The solidification mechanisms of Nass 45 are the same as those of standard austenitic stainless steels, such as 304 and 316. Therefore the welding characteristics and approach should follow that typical to standard austenitic stainless steels. The use of certified welders, and adherence to the sound welding practices and precautions, recommended for the welding of standard austenitic grades, should always be observed.
Nass 45 welds superior to austenitic grades because the carbon content is generally lower than the standard austenitic grades. Ductility at the weld, however, is somewhat less than austenitic grades. A root pass with a highly ductile rod, such as a 308L, should be considered to minimize fracture potential where stress raisers, such as the undercut on a partial penetration weld, might present a potential crack initiation site. The weld may then be completed by use of a higher strength heat treatable filler metal. Type 630 filler wires and covered electrodes closely match the Nass 45 base metal composition. (AMS-5763)
Where high strength is not a requirement, welds may be completed using only the 308L type rod. Use of this rod offers the most forgiving approach in maintenance field weld conditions. This type of weld is less susceptible to hydrogen embrittlement. Items in this category may be used in the as-welded condition. (If welding to dissimilar materials, consideration should be given to use of a more highly alloyed rod, such as a 309 stainless, or Inconel type rod. Arc welding, gas-tungsten arc, gas-metal arc, and shielded metal arc welding processes, have all been used successfully for joining Nass 45, although gas-tungsten arc welds appear to be the most favored for greater weld metal cleanliness, highest ductility and toughness, especially following any post weld heat treatment. Maintain shortest arc. Where maintaining strength properties closest to the original properties of Nass45 is important, a post weld heat treatment (PWHT) of 1150°F for 4 hours should be employed.
Mill Treatment: (as produced 30RC typical)
Solution annealed at 1900°F for 7 hours. Aged at 1150°F for 4 hours. Double stress relieved. Note: Thermal treatment of Nass 45 is different than 17-4 on the length of time for the soak. 17-4 type of material requires only 1 hour. Nass 45 requires 4 hours.
To re-harden Nass 45 from H1150 (30RC) to H900 (36 to 47RC):
Nass 45 is a modified 17-4/15-5 type of PH (precipitation hardening) stainless steel. The modifications consist of elements such as Moly, Silicon, Copper, Columbium, etc., combined with unique processing techniques. Thermal treatment of this product, however, remains similar to the standard solution treatment of a non-modified 17-4PH type base metal. Furnace heat the bar to 1,875°F to 1,925°F, hold 1 hour at temperature. Rapidly air- cool to room temperature. (May be oil quenched to room temperature if preferred). Re-heat to 900°F. Hold at temperature for 4 hours. Let material cool to room temperature. Note: Time at temperature is the same regardless of whether it is a 1-1/2"Diameter or at 4"Diameter.
NASS 45® vs. 300 Series Commercial Grade Stainless
NASS 45® vs. 400 Series Commercial Grade Stainless