The spring is to make full use of the physical characteristics of the material to realize its storage and release of energy through a certain conversion method. The characteristics of the material determine the physical and mechanical characteristics of the spring to a certain extent, and affect the design, development and particularity of the spring Increased requirements. The most commonly used materials are metal materials and non-metal materials.
The development of modern new material varieties is changing with each passing day, especially the continuous emergence and improvement of new high-strength metal alloys, which makes mechanical springs more efficient; at the same time, the subsequent processing methods of raw materials are continuously optimized, such as structural shape, heat treatment and surface quality. Etc., so that the application and development of springs can better meet its functional requirements, and further improve the safety, economy and environmental protection characteristics of spring products.
In recent years, with the rapid development of the chemical rubber industry, polyurethane materials are also widely used in spring products, widely used in the field of shock absorption and noise reduction mechanical structures; air springs with nitrogen or gas-liquid media are also widely used in stamping dies, Main engine dynamic shock absorption, constant force appliances, ultra-high temperature elastic structure and other fields
The application of spring materials initially used wood and bamboo materials, and after entering the industrial age, metal alloys began to be widely used. With the continuous improvement of mechanical spring characteristics, the characteristics of spring materials requiring high strength and high yield ratio have gradually formed special Special, special metal alloy spring steel. The general development trend of metal alloy spring steel is higher tensile strength and yield ratio, and more toughness. At the same time, special stainless steel spring steel can meet the application in severe corrosive environment; special resistance The high temperature constant elastic material can meet the application in higher temperature environment.
Spring steel is the main material specially used to manufacture various springs and elastic elements or structural parts with similar performance requirements.
A. Performance requirements ①High elastic limit σe and yield ratio σs/σb to ensure excellent elastic performance, that is, absorb a large amount of elastic energy without plastic deformation; ②High fatigue limit, fatigue is the main damage of the spring In one form, the fatigue performance is not only related to the composition structure of the steel, but also mainly affected by the metallurgical quality of the steel (such as non-metallic inclusions) and the surface quality of the spring (such as decarburization); ③Sufficient plasticity and toughness Prevent impact fracture; ④ other properties, such as good heat treatment and plastic processing properties, heat resistance or corrosion resistance requirements for working under special conditions, etc.
B. Composition characteristics The content and function of carbon and alloying elements in steel are:
(1) Medium and high carbon In general, carbon spring steel wc=0.6%~0.9%, alloy spring steel wc=0.45%~0.70%, after quenching and tempering at medium temperature, the tempered troostite structure is obtained, which can be compared Well ensure the performance requirements of the spring.
(2) Alloy spring steels for general use of alloying elements are generally low alloy steels. The main elements are Si, Mn, Cr, etc., and their main functions are to improve hardenability, solid solution strengthen the matrix and improve tempering stability; auxiliary addition The elements are strong carbide forming elements such as Mo, W, and V. The main functions are to prevent decarburization defects caused by Si, overheating defects caused by Mn, and improve tempering stability and heat resistance.