YIDE DUCTILE IRON CASTING

Yide Casting is a professional iron cast manufacturer & supplier, specialized in manufacturing quality ductile iron casting parts.

Ductile iron casting is spherical graphite casting, doesn’t hurt the structure of the substrate, so the stress concentration effect of ductile iron castor to the substrate is the smallest.

Thus, the ductile iron casting part has high strength feature similar to the medium carbon steel castor, with good plasticity and toughness, fully exert the performance of the substrate (casting performance is better than steel but worse than gray cast iron).

So ductile iron casting is mainly applied to manufacture some workpieces with high toughness requirements and complex shapes, such as internal combustion engine crankshafts, connecting rods, and other parts.

If you are interested in ductile iron cast, please don’t hesitate to contact us for more details.

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CASTING FAQ GUIDE

What is ductile cast iron

Invented in 1943, ductile cast iron is a modern iteration of cast iron. Ductile cast iron—also referred to as spheroidal or nodular iron—is actually a group of irons that exhibit high strength, flexibility, durability, and elasticity due to their unique microstructure. Ductile cast iron normally contains over 3 percent carbon; it can be bent, twisted, or deformed without fracturing. Its mechanical properties are similar to steel, and far exceed those of standard cast irons.

The graphite within ductile iron occurs as spheroids, so it is sometimes referred to as spheroidal graphite. Similarly, the term nodular iron stems from the fact that the carbon contained in ductile iron is held in the form of nodules. This unique microstructure causes ductile cast iron to withstand bending and shock loading far better than traditional cast iron.

Ductile iron castings are solid metal objects that result from molten ductile iron being poured into voids in a mold. The ductile iron subsequently cools and solidifies in the shape of the void it occupies.

What is Ductile Iron Used For?

Ductile iron is great for use where you need strong metal with wear resistance.

Here is a sample list of things made from or contain ductile iron:

Pipe and pipe fittings (almost 50% of ductile iron sold in the US is for pipe and fittings)

Axles iron casting

Connecting rods ductile cast (like in engines)

Crankshafts cast iron

Cylinders iron ductile iron

Disc brake calipers iron casting

Iron casting gears and gear boxes

Housings and manifolds casting

Hydrostatic Barrels iron ductile iron

Idler arms iron cast

Large Machines cast iron

Iron Cast Machine Tooling

Military uses

Piano Harps (the part that holds the strings of a piano)

Spindle Supports Casting

Steering knuckles iron ductile casts

Suspension system iron asting parts

Casting Truck axles

Valves iron casting ductile (especially high-pressure valves)

Wheel hubs Casting

Yokes for power transmission casting parts

What is the difference between ductile and cast iron?

Ductile iron is an alloy of iron, rich with graphite whereas cast iron is an alloy of iron that we can readily cast in a mould.

When considering the composition of each iron alloy, the ductile iron contains iron, carbon, silicon, manganese, magnesium, etc. along with copper or tin while the cast iron contains iron, carbon, silicon, manganese along with trace amounts of sulfur and phosphorous as well.

Furthermore, their carbon and silicon contents also differ from each other; ductile iron contains about 3.2 to 3.6% carbon, and cast iron contains about 2 to 4% carbon while the silicon contents are 2.5% and 1-3% respectively. Moreover, a significant difference between ductile iron and cast iron is their ductility.

Ductile iron is highly ductile whereas cast iron is less ductile.  We can say the key difference between ductile iron and cast iron as their respective uses due this property.

Ductile iron is a form of cast iron having improved properties.

The difference between ductile iron and cast iron is that we use ductile iron for water pipes due to its durability while we use cast iron usually for engineering and construction structures because of its stability.

Why is ductile cast iron in general ductile than gray cast iron?

Compared with gray cast iron, ductile cast iron has absolute advantages in terms of strength.

The tensile strength of ductile iron is 60k, while gray cast iron is only 31k. Ductile cast iron has a yield strength of 40k, while cast iron does not show yield strength and eventually breaks.

The ratio of strength to cost of ductile cast iron is far superior to gray cast iron.

Ductile cast iron refers to cast iron with graphite in spherical form.

Since graphite is distributed on the substrate in a spherical shape, the cutting effect on the substrate is minimized, and the properties of the substrate can be fully exerted.

Therefore, the mechanical properties of ductile cast iron are higher than those of gray cast iron. Ductile cast iron’s tensile strength, plasticity, and toughness are similar to the cast steel of the corresponding matrix structure, and are generally used for diesel engine crankshaft, gearbox gears and rolling mill rolls.

Is ductile cast iron stronger than steel?

The strength of ductile iron and cast steel are comparable.

Ductile iron has a higher yield strength, the lowest yield strength is 40k, while the yield strength of cast steel is only 36k. In most municipal applications, such as water, brine, steam, etc., the corrosion resistance and oxidation resistance of ductile cast iron exceed that of cast steel.

Due to the nodular graphite microstructure, ductile cast iron is superior to cast steel in terms of weakening vibration ability, so it is more conducive to relaxing stress.

Is ductile cast iron magnetic?

Yes, ductile cast iron is magnetic.

With the increasing application range of ductile cast iron, especially in the occasions with magnetic field requirements, it is often required to have better magnetic properties as functional materials.

For functional materials, magnetic properties are often used as an important basis.

It is necessary to evaluate the magnetic induction, maximum permeability, remanence, etc. of ductile cast iron, and also to ensure that the ductile cast iron has good mechanical properties.

According to the data, among the common graphite forms of cast iron, spherical graphite is the most beneficial to magnetic properties.

Spherical graphite can increase the maximum magnetic permeability, reduce remanence and hysteresis loss.

Besides, other various alloy elements indirectly affect the magnetic properties of ductile cast iron through the influence on the structure.

Yes, it can.

Will ductile iron casting rust, the key is whether the anti-corrosion process of the ductile iron castings is in place. Qualified ductile iron castings are required to be lined with standard thick road cement; the outer wall of the casting is required to be sprayed with zinc and coated with asphalt, and other epoxy paints may be selected.

There are some specific methods to prevent ductile iron castings from rust:

  1. Asphalt paint coating:

The asphalt paint coating is suitable for gas pipelines. Preheating the ductile iron cast pipe before painting can improve the adhesion of asphalt paint and accelerate drying.

  1. Cement mortar lining with special coating:

This internal anti-corrosion measure is applicable to sewage pipelines, which can improve the corrosion resistance of the lining.

  1. Epoxy coal asphalt coating:

Epoxy coal asphalt coating is suitable for both gas pipelines and sewage pipelines. It is a two-component coating, which has high adhesion and a very smooth surface.

  1. Epoxy ceramic lining:

Epoxy ceramic lining is suitable for sewage casting pipes and gas pipelines, but due to difficulties in the manufacturing process and high cost, there are certain limitations in use. The epoxy ceramic lining has high adhesion and smoothness, and is an excellent anti-corrosion coating.

  1. Aluminate cement coating or sulfate cement coating:

These two special cement coatings are suitable for internal anti-corrosion of sewage pipes, which can improve the resistance to acid and alkali components in sewage.

  1. Polyurethane coating

How long does ductile iron pipe last?

The ductile iron pipe is the carrier of the piped water supply business with its excellent mechanical properties and external quality.

Its super pressure bearing capacity, reliable sealing performance, unparalleled anti-corrosion treatment and water quality assurance system make the piped water supply seemingly perfect.

The ductile iron pipe can complete the water supply task, even in complex saline, marshland, high slope, desert and other similar soil.

The tensile strength and pressure resistance of centrifugal ductile iron pipes are comparable to steel pipes. Compared with gray cast iron pipes, ductile iron pipes’ elongation is greatly improved and has good toughness. Not only does it overcome the shortcomings of gray iron pipes that are easy to break, but also avoids steel pipes in undesirable deformation under large pressure.

In this way, the centrifugal ductile iron pipe has a significant effect on the seismic resistance, and the service life is also significantly extended, up to 50-70 years.

Four types of cast iron

There are several different types of cast iron, each of which is unique.

  1. Gray Cast Iron

The most common type, gray cast iron features a graphite microstructure consisting of many small fractures.

  1. White Cast Iron

While not as common as gray cast iron, white cast iron is another type worth mentioning. It receives its namesake from its off-white color, which is the result of iron compounds known as cementite.

  1. Ductile Cast Iron

Also known as nodular cast iron, ductile cast iron is a type of soft, ductile iron alloy with a high carbon content.

  1. Malleable Cast Iron

Malleable cast iron is usually annealed from white cast iron through graphitization, so that the carbon mainly exists in the form of flocculent graphite.

How to identify the quality ductile iron casting

The main organizations that affect the performance of the ductile iron cast are graphite shape and matrix structure.

The quality of ductile iron casting is generally evaluated by the spheroidizing rate.

  • The Shape of Graphite

If the graphites are rounder, finer, and distributed uniformly, which expresses the ductile car iron has better performance, with a smaller cutting effect on the metal matrix and less stress concentration.

  • The Ferrite & pearlite

If the ductile iron casting includes high ferrite content and low pearlite content, then the ductile iron casts will have good toughness and low strength. If not, the ductile iron cast will get a performance of worse toughness and good strength.

Why Poor Quality Ductile Iron Cast

  1. Poor chemical composition control and too many elements that hinder graphitization during the ductile iron casting production, and cause the cementite of the ductile iron to exceed the standard.
  2. Poor control of the incubation and spheroidization process.
  3. Molten iron cooling too fast.
  4. Too long pouring time that will lead to poor graphite spheroidization.

The Way To Improve Ductile Iron Casting

  1. If the ductile iron casting has a poor speroidization or excessive phosphorous eutectics, then no way to remedy at a later stage. So it is required an effective quality control in the production process.
  2. If the pearlite and cementite in the casting exceed the standard, you can solve the quality problem through heat treatment such as low temperature and high temperature.

In a word, to equipped with the best production equipment line is better than a good quality control system, which can reduce the defective rate of ductile cast iron, and ensure good quality casting iron production.

What Are the Excellent Characteristics of Ductile Iron Casting?

Ductile cast iron is widely used in the machinery manufacturing industry, with advantages of good impact resistance and ductility, which sometimes can replace the more expensive forged steel and cast steel.

Here, Yide Casting will introduce some excellent performance of ductile casting.

  1. Ductile cast irons have a good impact