April 1, 2019

Stainless Steel CF8M (SS316)

CF8M is a cast austenitic material for pressure containing parts, which covered by and and standard.

CF8M Chemical Requirements in those three standards as bellow, little difference:

Standard Specification for Castings, Austenitic, for Pressure-Containing Parts:
Carbon: 0.08 max
Manganese: 1.50 max
Silicon: 1.50 max
Sulfur: 0.040 max
Phosphorus: 0.040 max
Chromium: 18.0-21.0
Nickel: 9.0-12.0
Molybdenum: 2.0-3.0
Tensile Strength: min 70ksi(485Mpa)
Yield Strength: min 30ksi (205Mpa)
Elongation in 2in. or 50mm: min 30.0%

ASTM 743 Standard Specification for Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application:

Standard Specification for Castings, Iron-Chromium-Nickel, Corrosion Resistant, for Severe Service: same as A743

ASTM A240 Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications

ASTM A182 Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service

ASTM A276 Standard Specification for Stainless Steel Bars and Shapes

Pump Suction Cover by investment casting

Pump Suction Cover by investment casting

 

CF8M Heat treatment process: Heat to 1900°F [1040°C] minimum, hold for sufficient time to heat casting to temperature, quench in water or rapid cool by other means.
CF8M equal to SS316/F316 and Chinese Standard 0Cr17Ni12Mo2

 

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CF8M (SS316) Listed in American Standard:

CF8M/TP316/SS316/F316 Chemical Requirements Composition and Mechanical Properties

StandardASTM A376ASTM A240ASTM A276ASTM A182
GradeCF8MCF8MCF8MTP316SS316SS316F316
UNSJ92900J92900J92900S31600S31600S31600S31600
C % max0.080.080.080.080.080.080.08
Mn % max1.501.501.502.02.02.02.00
Si % max1.502.02.00.750.751.001.00
S % max0.040.040.040.030.0300.0300.030
P % max0.040.040.040.0450.0450.0450.045
Cr % 18.0-21.018.0-21.018.0-21.016.0-18.016.0-18.016.8-18.016.0-18.0
Ni % 9.0-12.09.0-12.09.0-12.011.0-14.010.0-14.010.0-14.010.0-14.0
Mo % 2.0-3.02.0-3.02.0-3.02.0-3.02.0-3.02.0-3.02.0-3.0
Tensile, min,Ksi(MPa)70(485)70(485)70(485)75(515)75(515)75(515)75(515)
Yield, min,  Ksi(MPa)30(205)30(205)30(205)30(205)30(205)30(205)30(205)
Elongation Min, %30303035 L; 25 T404030
Reduction, Min, %5050
Hardness, HB217

CF-8M is a molybdenum bearing modification of CF8 alloy and is the cast equivalent of wrought AISI 316 Stainless steel. The presence of molybdenum increases the general corrosion resistance and the resistance to pitting by chlorides. The alloy is used in mildly acidic and alkaline conditions and for handling citric, oxalic and phosphoric acids.

Stainless Steel CF8M Application:

CF8M is popular stainless steel castings, it’s wided used in most industry, such as Impellors, propellers, pump casings, valve bodies, press plates.

Stainless Steel CF8M weldability: 

CF-8M may be welded by the SMAW, GTAW and GMAW processes.

No need Preheat before welding.

Stainless Steel CF8M Equivalent Grade: 

  •  SS316, F316, TP316
  • EN 1.4408
  • 0Cr17Ni12Mo2
  • 08X17H13M2
  • X5CrNiMo18-10
  • SUS316, S31600

How to produce stainless steel CF8M/SS316 casting?

Stainless steel castings can be made through sand casting or investment casting process in Casting Quality Industrial. Gengerally small will be produced by invetment casting, max to 50kgs; and those big castings will be made by resin sand casting, our capacity can cast 50ton stainless steel parts.

Why choose investment casting for stainless steel CF8M/SS316 casting?

Investment casting can acheive the best dimensions and pretty apperance, the casting dimesnions can meet the requirment of product design, it will save much machining cost. Our investment casting process can meet ISO8062 CT4 – CT6 grade.

Why choose Sand Casting for stainless steel CF8M/SS316 casting?

Since investment casting can get the best quality castings, somebody will ask  why choose sand casting. Yes, investment casting is the best choice, but Investment casting can’t produce big size castings because of the machinery limiataion. Generally the investment casting process only make 800mm length/height castings, otherwise we can’t place the wax pattern for shell.

But sand casting dont have any limitation of size, it can produce any size castings, several tons or several handreds tons castings. The sand casting only follow relax tolerance per ISO8062 CT10-CT12, it means the machining allowance will be big too.

What different between CF8M and CF3M? 

There is only difference: carton content. CF8M contain 0.08% carton but CF3m only have 0.03% carton. but the corrosiion resistance property of CF3M is better much than CF8M. Their machinical property is similar.

Is stainless steel CF8M same as SS316, F316 and TP316?

“Yes, mostly, it’s same.”

But they are defined in different standards, and their chemistry and property are little different too. CF8M is defined in ASMT A351, ASMT A743 and , which are for casting purpose only. SS316 is defined in ASTM A240 and ASTM A276, it’s for plate, sheet, strip or stainless steel bars.

Another grade is named as F316, which is from ASTM A182 for Forged parts only. TP316 will be found in ATSTM A376 for pipe only.

If you want to buy castings, Pls indicate CF8M as material, otherwise you can adopt SS316. VERY IMPORTANT!

How to purchase Stainless Steel Castings?

Drawings are necessary for any casting enqiuries, our software is Solidworks and AutoCAD. IGS/STEP files are acceptable for us, and we also need the CAD/PDF drawings for further machining.

If you don’t have drawings or design, you can send us the pictures with major dimensions and unit weight, we will help our clients to finish the design in software. Of cause, you also can send us the physical sample, we will use 3D Scanning process to get the design, it’s FREE cost in our company.

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What means of CF8M?

As to the designation – www.castingquality.com

C (first letter) means the service it is intended to be used in this case – corrosion resistant service , but we think sometimes it means of CASTING USAGE because you will find F316 in ASTM A 350 ( F = FORGE)

F(second letter) -The second letter indicates the approximate location of the alloy on the iron-chromium-nickel (FeCrNi) ternary diagram. For users familiar with the diagram, the second letter does provide an indication of the nominal iron, nickel, and chromium content, but most people would have to obtain alloying information from a material specification.

8M – the third and fourth digits represent the maximum permitted carbon content in units of 0.01% (e.g., CF8M has a maximum of 0.08% carbon)

Metal Castings

Material, Stainless Steel , , , , ,
10 Comments
  1. In CF8m magenet is fixed or not

    • If good heat treatment, CF8M should be no magnet, because the metallurgical structure will be the most Austenite after solution treatment.

      Bad heat treatment or no heat treatment, structure will have Martensite or Ferrite, those two structure have magnet.

      The heat treatment just improve all structure to Austenite.

  2. equivalent is material SS 316

  3. Hello,

    Does ASTM A351 CF8M, suitable for:

    fluid: water with 20gram/liter sulphuric acid
    Ambient tem: 10 to 40C
    Operation Temp.: 20C
    Fluid pH: 7
    Over altitudeL: 2600m
    Service: Indoor

  4. normally nonmagnetic. Can be made to be magnetic with different heat treatment?

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