Basic knowledge of metal materials (1)

Pig iron and steel are collectively referred to as ferrous metals. Iron is its main component and also contains a certain amount of carbon and other trace elements. Alloys with carbon content less than 2.11% (mass) are called steel, and alloys with carbon content greater than or equal to 2.11% (mass) are called pig iron.

Pig iron can be divided into pig iron for steelmaking (also known as white iron) and pig iron for casting.

Cast iron is referred to as cast iron. According to the shape characteristics of graphite, cast iron can be divided into the following categories: gray cast iron, codenamed HT; ductile cast iron, codenamed QT; corrosion-resistant cast iron; other cast irons, such as heat-resistant cast iron and malleable cast iron, Malleable cast iron is code-named KT, also known as malleable iron.

Cast iron pressure pipes and fittings are no longer mass-produced in the United States and other countries, but may be mass-produced in some countries. Ductile iron pressure pipes have replaced cast iron pressure pipes. Relevant standard specifications include: ASME B16.3, ASME B16.4, ASME B16.12, ASME B16.42, ASMEB16.42, ASTM A74, ASTM A126, AWWA C110, AWWA C111, AWWA C150, AWWA C153, etc.

Steel is essentially an alloy. The main component is iron and a small amount of carbon. It also contains trace elements such as silicon, manganese, phosphorus, sulfur, chromium, nickel, molybdenum, tungsten and vanadium. The classification of steel is shown in the figure