Plain Carbon & Low Alloy Steel Castings

Plain Carbon Steel Castings

The main alloying element in Carbon Steel Casting is carbon. Other elements are present in small amounts, including those added for melting and deoxidation. Silicon and manganese in carbon steels generally range from 0.25% to about 0.80%Si and 0.50% to 1.00% Mn.

Carbon steels castings can be classified into three different groups according to their carbon content:
• Low carbon steels: 0.20% Carbon
• Medium carbon steels: 0.20% to 0.50% Carbon
• High carbon steels: 0.50% Carbon

Carbon Steels Structure and Property Relations:
Carbon steel castings can be produced with a wide range of properties. Different compositions and heat treatments can be selected to achieve combinations of specific properties such as hardness, strength, ductility, fatigue resistance and toughness.

Although a wide range of properties can be selected, it is important to recognize the interactive relationships between these properties. For example, higher hardnesses, lower toughness and lower ductility values are linked to higher strength values.

Low Alloy Steel Castings

Low alloy steels form a category of alloy materials that exhibit mechanical properties superior to plain carbon steels through the addition of alloying elements such as chromium, nickel and molybdenum. Total alloy content can range from 2.07 % to levels just below stainless steels containing at least 10 % Cr.

For most low alloy steels, the primary function of alloying elements is to improve hardenability to optimize mechanical properties and toughness after heat treatment. In some cases, however, alloy additions are used to reduce physical deterioration under certain service conditions.

As with steels in general, low alloy steels can be classified as follows:
• Nickel steels, molybdenum steels, nickel-chromium steels, chromium molybdenum steels, etc.
• Heat treatments such as normalized and tempered, quenched and tempered, annealed, etc.

There are four main groups of low alloy steels:
• Low carbon quenched and tempered steels,
• Medium carbon ultra-high strength steels,
• Bearing steels,
• Heat resistant chromium-molybdenum steels.