ASTM A897 Austempered Ductile Iron Isothermal Quenching Process Foundry

ASTM A897 Austempered Ductile Iron Isothermal Quenching Process Foundry

 

 

Product Description and Process

ADI Austempered Ductile Iron Castings Isothermal Quenching Process ASTM A897 Grade 1200/850/04

 

Production process: green sand molding

Machining process: CNC machining, drill, mill, etc.

Heat treatment process: isothermal quenching process

Surface treatment process: paint coating

 

Product Material and Uses

Normally produce with

ASTM A897/897M

Grade 750/500/11,

Grade 900/650/09,

Grade 1050/750/07,

Grade 1200/850/04,

Grade 1400/1100/02,

Grade 1600/1300/01.

 

The austempered ductile iron casting products are widely used for auto-car components, trailer suspension system, truck parts, crankshafts, railcar wheels, cylinder lock cases, tow hooks, cylinder liner, agricultural machinery components, etc.

 

What is Austempered Ductile Iron (ADI)?

Austempered ductile iron castings, or more commonly ADI castings, is a ductile iron casting which is processed by a special heat treatment. The austempering process, with ductile iron’s superior castability, results in a material which can be used to cast complex shapes, with a greater consistency of quality, and often at less cost. The heat treatment requires an interrupted quench, usually into a salt bath, to cool the cast part at a planned rate and long enough to achieve the desired austempered result. The resulting material has a combination of exceptional strength and toughness, meeting and often exceeding those of alloy steels.

 

What are some Benefits of Austempered Ductile Iron Castings?

Up to 40% less cost than hardened steel forgings.

Lower operating noise levels.

10% less weight than steel.

Better wear than case hardened steel.

Excellent resistance to crack propagation.

Good impact strength to -120ºF.

Work hardening.

 

Austempered Ductile Iron Castings Properties

ADI is a group of materials whose mechanical properties can be varied over a wide range by a suitable choice of heat treatment. A high austempering temperature, 750F (400°C), produces ADI with high ductility, a yield strength in the range of 500 MPa with good fatigue and impact strength. These grades of ADI also respond well to a surface strain transformation which greatly increases their bending fatigue strength. A lower transformation temperature, 500F (260°C), results in ADI with very high yield strength (1400 MPa (200 MPa)), high hardness, excellent wear resistance and contact fatigue strength. This high strength ADI has lower fatigue strength as-austempered but it can be greatly improved with the proper rolling or grinding process. Thus, through relatively simple control of the austempering conditions, ADI can be given a range of properties unequaled by any other material. Small amounts of alloying elements such as nickel, copper and molybdenum are used to produce the desired heat treated result.

 

 

What are typical ADI Applications?

Abrasive Protection Liners

Bearing Sleeves

Brake Shoes

Bushing Sleeves

Cable Drums

Camshafts

Chain Sprockets

Connecting Rods

Crankshafts

Cultivating Tools

Differential Spiders

Drive Shafts

Engine Mounting Brackets

Friction Blocks

Ground Engaging Tools

Guide Rollers

Hydraulic Pump Bodies

Piston Sleeves

Pulleys

Pump Impellers

Rack and Pinion Gearing

Rocker Arms

Railroad Car Wheels

Rollers and Sprockets

Shredder Knives

Steering Knuckles

Trolley Wheels

Track shoes

Wear Plates and Guides

Wire Guides

 

Is Machining of Austempered Ductile Iron Difficult?

Machining of A.D.I. is generally speaking, possible, using normal machining techniques. Only the tapping of small diameter holes (especially dead end) and scraping of the softest type is very difficult due to work hardening. It is however common practice to machine to near final size and then heat treat. This is possible because the heat treatment is considered “soft”, and the consequent volume changes are small, and predictable with volume expansion of between only 0.2% – 0.4%.

 

British Standards Specification for ADI EN 1564:1997

 

Mechanical Properties measured on test pieces from separately cast samples
Material Symbol	Number	Tensile Strength N/mm2 (min)	0.2% Proof Stress N/mm2 (min)	Elongation % (min)
EN-GJS-800-8	EN-JS1100	800	500	8
EN-GJS-1000-5	EN-JS1110	1000	700	5
EN-GJS-1200-2	EN-JS1120	1200	850	2
EN-GJS-1400-1	EN-JS1130	1400	1100	1
Refer to relevant Standard for full details

 

 

Standard ADI Grades (USA) ASTM 897-90 (ASTM 897M-90)

Grade	Tensile Strength (min)		Yield Strength (min)		Elongation%	Impact Energy *		Typical Hardness BHN
	Ksi	Nmm2	Ksi	Nmm2		Ft-lbs	Joules
1	125	850	80	550	10	75	100	269-321
2	150	1050	100	700	7	60	80	302-363
3	175	1200	125	850	4	45	60	341-444
4	200	1400	155	1100	1	25	35	388-477
5	230	1600	185	1300	-	-	-	444-555
* Un-notched charpy bars tested @ 22'C (+/-4'C) Refer to relevant Standard for full details

 

 

Grade	Tensile* Strength (KSI)	Yield* Strength (KSI)	Elongation*	Typical Impact Energy (FT-LBS)	Typical Brinell Hardness
0	110	70	11	80	241-302
1	130	90	9	75	269-341
2	150	110	7	60	302-375
3	175	125	4	45	341-444
4	200	155	2	25	388-477
5	230	185	1	15	402-512