Forging on metal organization, performance, and the influence of forging defects

Forging defects including surface defects and internal defects. Some forging defects affect the subsequent process of processing quality, some are serious impact on the performance of forgings, reduce the service life of the manufactured parts, and even endanger the safety. Therefore, in order to improve the quality of forgings, avoid the generation of forging defects, corresponding countermeasures should be taken at the same time also should strengthen the whole production process quality control. This chapter briefly introduce three problems: forging effect on the properties of metal organization, and forging defects; Contents and methods of the forgings quality inspection; General process of forging quality analysis. ( A) The effects of forging on the microstructure and mechanical properties of metal forging production, besides must ensure that the forgings to the required shape and size, also must satisfy the performance requirements of the parts in the process of using the proposed, in which mainly includes: pointer, plastic pointer strength, impact toughness, fatigue strength, fracture toughness and stress corrosion resistance, etc. , for the work of high temperature parts, and high temperature tensile properties of instantaneous and durable properties, creep resistance and thermal fatigue properties, etc. Raw materials are ingot casting, rolling, forging and forging billet. And rolling, bar and forging billet are respectively ingot are formed after rolling, extrusion and forging processing semi-finished products. Forging production, using reasonable technology and process parameters, can through the following several aspects to improve the organization and performance of raw materials: 1) Break the columnar crystal, improve macro segregation, the as-cast organization into forging state organization, and under the appropriate conditions of temperature and stress welded internal pore, improve the density of material; 2) Ingot after forging formation of fibrous tissue, further through the rolling, extrusion, die forging, forging get reasonable distribution of fiber direction; 3) Control of grain size and uniformity; 4) To improve the second phase ( For example: the alloy carbide in ledeburite steel) The distribution; 5) Make the organization get deformation strengthening or deformation - — Phase transformation strengthening, etc. Due to the improvement of the organization, forgings plasticity, impact toughness, fatigue strength and the durable performance has been improved, and then the final heat treatment of the parts can get parts required hardness, strength and good comprehensive properties such as plastic. However, if the poor quality of raw materials or forging process is not reasonable, may produce forging defects, including surface defects, internal defects or performance is unqualified, etc. ( 2) Raw material impact on the quality of forgings raw materials of good quality is a prerequisite to ensure the quality of forgings, such as raw material defect, will affect the quality of forgings and forging forming process of the final. Such as raw materials of chemical elements beyond the prescribed scope, or impurity element content is too high, the quality of forgings forming and will bring great influence, for example: S, B, Cu, Sn elements such as formation of low melting point phase, forging heat brittle is seen. 04% ( The mass fraction) 。 Content is too little, don't control the effect of grain growth, often easy to make the essence of the forgings unqualified grain size; Aluminum content too much, the pressure process under the condition of the formation of fibrous tissue formation of wood grain fracture, tear mark fracture, etc. As another example, in 1 cr18ni9ti austenitic stainless steel, Ti,