For structural parts subject to high loads (especially tension, compression, and shear forces), it is advisable to choose steel with good hardenability. For shaft parts subjected to bending and torsional stresses, as the surface bears more stress and the core less, and considering the price and manufacturer of ductile iron pipes - GB ductile iron pipes - K9 ductile iron pipes - ductile iron pipes price - Honghui Casting Co., Ltd., steel with low hardenability can be used. Weldments generally do not use high-hardenability steel, as it can easily lead to quenching structures in the weld and heat-affected zones, causing workpiece deformation and cracking. The hardenability of steel is crucial for enhancing the mechanical properties of parts and realizing the potential of the steel. The hardenability of steel refers to its ability to achieve the highest hardness during quenching under ideal conditions, primarily dependent on the carbon content in the steel. The higher the carbon content, the better the hardenability. Hardenability and hardenability are two distinct concepts. A steel with good hardenability does not necessarily have good hardenability; conversely, a steel with good hardenability does not necessarily have good hardenability. For instance, although carbon tool steel has a high hardness after quenching (good hardenability), its hardenability is low; while certain low-alloy steels have low hardness after quenching but good hardenability. Tempering is performed at temperatures above 500°C. Its purpose is to give the workpiece a comprehensive mechanical property with good strength, plasticity, and toughness. The structure after tempering is sorbite, with a hardness of 200~350HBW. It is mainly suitable for various important load-bearing structural components, such as connecting rods, bolts, gears, and shaft parts. The composite heat treatment process of quenching and high-temperature tempering after quenching the workpiece is called tempering treatment. The treatment of ductile iron pipes price not only serves as the final heat treatment for certain important parts, such as shafts, gears, connecting rods, and bolts, but also as a preliminary heat treatment for some precision parts, such as lead screws, gauges, and molds, to achieve a uniform and fine structure, reducing deformation during the final heat treatment process. In cases where tensile strength and hardness are roughly the same, the plasticity and toughness after tempering are significantly higher than after normalizing. This is because the structure of the steel after tempering treatment is sorbite, with carbides in granular form, whereas the structure obtained by normalizing is lamellar sorbite.