Metal Casting

AQL Acceptable Quality Level. A quality level established on a prearranged system of inspection using samples selected at random.

As-cast condition Casting without subsequent heat treatment.

Backing sand The bulk of the sand in the flask. The sand compacted on top of the facing sand that covers the pattern.

Binder The bonding agent used as an additive to mold or core sand to impart strength or plasticity in a “green” or dry state. Read more

Mechanical Properties of Cast Carbon and Low Alloy Steels

For the purpose of this article, carbon steels are considered to be those steels in which carbon is the principal alloying element. Other elements that are present and that, in general, are required to be reported are manganese, silicon, phosphorous and sulfur. In a sense, all of these elements are residuals from the raw materials used in the manufacture of the steel, although the addition of manganese is often made during the steel making process to counter the deleterious effect of sulfur and silicon is added to aid in deoxidation. Read more

White and High Alloy Irons

An important group of alloyed irons that fall outside of the ordinary types of Alloy Die castings have been designated the white and high alloy irons, or the special irons. The high alloy irons are considered separately because their alloy content exceeds 3% and they cannot be produced by ladle additions to irons of otherwise standard compositions.

The high alloy irons are usually produced in foundries that are specially equipped to produce the highly alloyed compositions. These irons are often melted in electric arc or induction furnaces, which provide for precise control of composition and temperature. The high alloy irons are sold at premium prices and are expected to outperform ordinary compositions in applications that involve severe service conditions. The foundries that produce these irons may be equipped with heat treating furnaces and quenching equipment or cooling facilities to provide for the most economical use of alloys. Read more

Cast Copper Alloys

A Primer on Selecting Cast Copper Alloys

Traditionally, cast copper alloys were classified by a variety of systems including the ASTM letter-number designation based on nominal composition, by trade names, and by descriptive terms such as “ounce metal,” “Navy M” and so forth. However, with technological developments, new alloys were produced and existing alloys modified, making the old designation systems inadequate and misleading.

A new system was developed based on a precise description of the composition range for each alloy, which is now the accepted alloy designation system used in North America for cast copper and copper alloy products. Originally developed as a three digit system by the copper and brass industry, the designations have now been expanded to five digits that follow a prefix letter “C,” and have been made part of the Unified Numbering System (UNS) for Metals and Alloys. The UNS is managed jointly by the American Society for Testing and Materials, and the Society of Automotive Engineers. Read more

Aluminium Casting

A Basic Guide to Choosing Aluminum Casting Alloys Part 2

Alloys 319.0, A319.0, B319.0 & 320.0
Alloys 319.0 and A319.0 exhibit very good castability, weldability, pressure tightness and moderate strength. They are very stable alloys (i.e., their good casting and mechanical properties are not affected seriously by fluctuations in the impurity content). Alloys B319.0 and 320.0 show higher strength and hardness than 319.0 and A319.0 and are generally used with the permanent mold casting process. Characteristics other than strength and hardness are similar to those of 319.0 and A319.0. Read more

Aluminum Casting Alloys

The mechanical properties of alumi- num casting alloys are obtainable only if the chemical and heat treating specifications are followed carefully. It should be noted that the properties obtained from one particular combination of casting alloy, foundry practice and thermal treatment may not necessarily be identical to those achieved with the same alloy in a different foundry or with a different thermal treating source. In all aluminum casting alloys, the percentages of alloying elements and impurities must be controlled carefully. If they are not, characteristics such as soundness, machinability, corrosion resistance and conductivity are affected adversely. Read more

Mechanical Properties of Cast Iron

Ductile iron is characterized by having all of its graphite occur in microscopic spheroids. Although this graphite constitutes about 10% by volume of ductile iron, its compact spherical shape minimizes the effect on mechanical properties. The graphite in commercially produced ductile iron is not always in perfect spheres. It can occur in a somewhat irregular form, but if it is still chunky as Type II in ASTM Standard A247, the properties of the iron will be similar to cast iron with spheroidal graphite. Of course, further degradation can influence mechanical properties. The shape of the graphite is established when the metal solidifies, and it cannot be changed in any way except by remelting the metal.  Read more