Iron Casting Hardness and Tensile Strength

Foundry industry is an important branch of mechanical industry, due to the existence of graphite, cast iron is endowed with excellent casting properties, cutting performance, antifriction performance, damping performance and low notch sensitivity. And casting equipment is simple; the manufacturing cost is low, which make it widely used in industrial production. In all kinds of machinery products, the proportion of iron castings is up to 50% by mass.

The first indicator of quality in iron castings is the mechanical properties, and there are two main methods to test the mechanical properties, one is the tensile strength test, and the other is the hardness test. Tensile test is to test the tensile strength, yield strength and elongation of metal castings, and hardness test reflects the material elasticity, plasticity, strength, toughness and wear resistance and many other physical overall performance under certain conditions. In the United States casting standards, almost every product is provided with a tensile test and most of the products are provided with a hardness test.

Tensile test equipment is complex and the investment is higher, therefore we need professionals, and to prepare samples. The test is in low efficiency and the cost is high. Hardness test equipment is simple and easy to master, the indentation is small, which can be regarded as non-destructive testing, and finished or semi-finished parts can be tested directly. This test is efficient, and can be used to test bulk castings piece by piece. With the development of hardness manufacturing technology, a variety of portable devices, especially high-precision portable devices appears constantly, making the hardness test simple, fast and accurate, which also making the on-site hardness testing, the hardness control on the production line and the precision hardness testing of large castings possible.

Hardness test and tensile test are basically testing the ability of metal to resist deformation. The results of these two tests in some way are to detect the similar characteristics of metal. Both test results are fully comparable, for most metals, hardness and tensile strength can be converted by looking up the table . Therefore, in testing the mechanical properties of materials, people are more intended to choose the hardness test than tensile test.

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