Comparison table of commonly used precision casting materials for water pump impellers

Water PumpimpellerCommonly usedPrecision castingMaterial Grade Comparison Table

This table highlights the correspondence between American Standard (ASTM) and Chinese Standard (GB), and includes the corresponding rolled stock (i.e., bar/plate) grades for your reference during procurement and design.

Comparison table of commonly used materials for precision casting of water pump impellers

Material Category	Common Name	American Standard Casting Grades (ASTM)	National standard casting grades (GB/T 12230, etc.)	Corresponding rolled materials/forgings (for reference only)	Key features in summary
Austenitic stainless steel	304	CF8	ZG08Cr18Ni9	304 (S30400)	The most common type of corrosion-resistant stainless steel is used for clean water and food.
	316	CF8M	ZG08Cr18Ni12Mo2	316 (S31600)	Contains molybdenum, has better corrosion resistance than 304, and is used in seawater and chemical industries.
	304L	CF3	ZG03Cr18Ni10	304L (S30403)	The low-carbon version of 304 has better welding performance and is resistant to intergranular corrosion.
	316L	CF3M	ZG03Cr18Ni12Mo2	316L (S31603)	Low-carbon version of 316, the first choice for high-end pumps and valves, resistant to strong corrosion.
duplex stainless steel	2205	4A (CD3MN)	ZG022Cr22Ni5Mo3N	2205 (S31803/S32205)	High strength and resistant to chloride ion corrosion, standard equipment for seawater desalination pumps.
	2507	5A (CE3MN)	ZG022Cr25Ni7Mo4N	2507 (S32750)	Super duplex steel for extremely harsh marine environments.
	CD4MCu	CD4MCu	ZG05Cr26Ni6Cu3Mo2	–	Early duplex steel, with its high hardness and wear resistance, was often used in mud pumps.
carbon steel	WCB	WCB	WCB / ZG250-485	A105 / 25# steel	Ordinary carbon steel, used for non-corrosive water, oil, and gas.
Precipitation hardening steel	17-4PH	CB7Cu-1	ZG05Cr17Ni4Cu4Nb	630 (17-4PH)	Extremely high strength and hardness, suitable for high-pressure and wear-prone applications.

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💡 Expert Tips (Technical Notes):

1. Regarding the naming rules for characters starting with "C":
   • In the US standard, C The beginning usually indicates casting.
   • The first letter C = Corrosion resistant (corrosion resistant series).
   • The second letter (e.g.) FThe number () indicates the position of the nickel (Ni) content in the iron-chromium-nickel ternary diagram, roughly representing the level of alloy content.
   • Numbers (such as) 8 或 3() represents the maximum carbon content:8 This indicates a carbon content of ≤0.08% (similar to 304).3 This represents a carbon content of ≤0.03% (similar to 304L).
   • Common Misconceptions: When purchasing castings, please be sure to write CF8 Instead of 304. Although the chemical composition is similar, the requirements for mechanical properties differ between casting and rolling standards.
2. Regarding the selection of duplex steel:
   • If your water pump is usedseawater或High chloride ionEnvironment, strongly recommended to use 2205 (4A) 或 2507 (5A) It replaces 316L. Although it is slightly more expensive, its lifespan is usually more than twice that of 316L, and it is stronger, allowing for a thinner and lighter impeller design.
3. Material testing:
   • During the acceptance of precision castings, in addition to checking the chemical composition (spectral analysis), it is usually also required to perform...Mechanical performance testing(Stretch bar) andIntergranular corrosion testTo ensure that the materials are up to standard.