Steel Casting Grades – Chemical Composition, Mechanical Properties & Applications

Boro Foundry manufactures high-quality steel castings in a range of carbon and stainless steel grades, tailored to customer specifications. Our foundry produces castings up to 1.7 tonnes and works to recognised British and European standards, including BS 3100 and EN equivalents. Whether you’re sourcing durable stainless components or high-strength carbon steel parts, we offer precision, repeatability, and reliability for demanding industrial applications.

We specialise in producing high-performance steel castings engineered to resist corrosion, withstand extreme temperatures, and deliver exceptional strength and longevity. Our range includes a variety of corrosion-resisting, heat-resisting, and high alloy steels — ideal for use in demanding environments such as chemical processing, marine, food production, and power generation. With decades of metallurgical expertise, we provide not just raw materials but engineered solutions tailored to your application.

The table below details the chemical composition limits for our most commonly supplied steel grades. These specifications ensure consistent metallurgical performance, corrosion resistance, and mechanical integrity across a wide range of industrial uses.

The mechanical performance of our steel grades is optimised through precise heat treatment processes. This table outlines the minimum yield strength, tensile strength, elongation, impact resistance, and associated thermal treatments for each grade — helping engineers and specifiers select the right material for demanding service conditions.

1. Heat treatment designations are as follows:
   • OQ – for quench into oil from a temperature above AC3.
   • AH – for air harden by heating to a temperature above AC3 and cool in air at a rate fast enough to produce a hardened microstructure.
   • T – for temper by heating to a temperature below AC1
   • ST – for solution treat by heating to a temperature high enough to dissolve carbides and intermetallic phases follows by a rapid cool.
2. For steel 309C32, test pieces are heat treated for 24 h at ºC ± 15ºC and cooled in air.

We supply a comprehensive range of carbon, carbon manganese, and low alloy steel castings that combine strength, toughness and versatility. These steels are widely used across structural, automotive, heavy engineering, and general industrial applications where high mechanical performance and cost-efficiency are key. Our castings are made to tight chemical and mechanical standards, ensuring reliable performance in both standard and high-stress environments.

This table outlines the chemical composition ranges for our carbon and low alloy steels, based on the cast analysis. These limits are carefully controlled to deliver the required balance of strength, ductility, and weldability for each application.

1. Composition in percentage mass by mass maximum unless shown as a range or a minimum.
2. For each reduction of 0.01% C below the maximum specified an increase of 0.04% Mn above the maximum specified shall be permitted up to a maximum of 1.1% Mn
3. Residual elements.
4. Manganese/carbon ratio shall exceed 3:1.
5. For each reduction of 0.01% C below the maximum specified, an increase of 0.04% Mn above the maximum specified shall be permitted up to a maximum of 1.4 % Mn.
6. The composition range for these steels shall be such as to give adequate hardenability through the maximum section thickness of the casting.

Mechanical performance is critical to the integrity and durability of steel components. The table below details the minimum mechanical properties for each grade, including yield strength, tensile strength, elongation and impact resistance, ensuring suitability for load-bearing and safety-critical applications.