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1、金属材料的加工工艺性能（Processing properties of metal materials）Processing properties of metal materialsThe information collection to add this information to print: anonymous source: unknown-Blanking (blank) - heat treatment - rough processing - heat treatment (quenching and tempering) - finishing (surface tre
2、atment) (heat treatment) blank manufacturing methods, casting, welding, forming. This chapter deals with casting, forging, welding, heat treatment and machinability. The casting properties of 14.1. metal materials usually refer to fluidity, shrinkage, casting stress, segregation, suction tendency an
3、d crack sensitivity. The alloy is commonly used in casting, and the alloy grain is small. Influence factors of 14.1.1. on alloy fluidity factors: alloy chemical composition, casting temperature and mold filling conditions. Alloy chemical composition: carbon content: pure iron liquidity is good, the
4、greater the carbon content, the worse the liquidity. About 2% of the fluidity is the worst, and eutectic cast iron has the best fluidity in cast iron. The fluidity of the alloy can be reduced by forming elements with high melting point inclusions in the alloy composition. The iron in the melting poi
5、nt of MnS is 1620, is not conducive to flow. P can form Fe-Fe3P-Fe3C and the melting point is 950, which is favorable to flow. The 14.1.2. casting shrinkage shrinkage and shrinkage of 14.1.2.1. cast iron with carbon content increasing, graphite is conducive to eliminate this kind of phenomenon crack
6、 14.1.2.2. casting cold crack and hot cracking, the increase of P and S alloy strength, the cracking tendency increases. Forging properties of 14.2. metal materials: plasticity and deformation resistance 14.2.1. the forging of high alloy tool steel is aimed at breaking the coarse eutectic carbides i
7、n steel. Slow cooling after forging (furnace cooling) to prevent cracks. 14.2.2. stainless steel forged stainless steel because of its special organization, pay attention to the process of forging and heat treatment on intergranular corrosion of 475 DEG C brittleness: high Cr steel containing Cr was
8、 more than 15% in the temperature range of 400-525 long time to pause or slow cooling, Cr atomic ordering, phase and the parent lattice distortion caused by crystal figure large internal stress caused by large the. Martensitic stainless steel: slow cooling to about 600 degrees of air cooling, so as
9、to avoid martensitic transformation. Ferritic and austenitic stainless steels: rapid cooling (air cooling) in intergranular corrosion and brittleness temperature range of 475. High temperature deformation resistance and lower plasticity of 14.2.3. superalloy forging alloy at high temperature are obs
10、erved. The mould is firm and the power is large. It is sensitive to forging temperature and air cooled after forging. 14.2.4. nonferrous metal forging aluminum: forging temperature narrow. Magnesium: forging temperature is narrow, heat transfer is fast, easy to cool, mold needs preheating. Copper: t
11、he forging temperature is narrow, the mold needs preheating, forging should be protected, avoid oxidation. Titanium: deformation resistance, chemical properties of active, pay attention to protection. The performance of electric arc welding of metal materials 14.3., electroslag welding, friction wel
12、ding, brazing, welding and brazing explosion: non ferrous metal filled in contact with molten solder such as brass and the like (the melting point is lower than that of the base metal to the weld metal melting point). 14.3.1. carbon steel and alloy steel welding low carbon steel, low alloy steel wel
13、dability. For medium and high carbon steel and alloy steel, pre weld preheating and post weld heat treatment are adopted. Improve the microstructure and eliminate the welding stress. Austenitic stainless steel welded with 14.3.2. stainless steel: intergranular corrosion.Martensitic stainless steel:
14、martensite microstructure was obtained in the weld zone under air cooling condition, preheating before welding (200-400), heat treatment after welding, heating to 730-790 degrees, then slowly cooling to 540 DEG C, air cooling. Ferritic stainless steel: pre weld preheating, post welding heat treatmen
15、t (730-840 C) 14.3.3. non-ferrous metal welding copper: poor welding performance, brazing. Aluminum: argon arc welding, high surface requirements of weldment. Titanium: automatic welding, high surface requirements. The machinability of 14.4. metal materials is called machinability of materials.Influ
16、encing factors: machinability is related to the chemical composition, hardness, toughness, thermal conductivity, metallographic structure and working hardening ability of metal materials. The effect of 14.4.1. chemical composition on the strength and hardness of steel reduced by carbon content: S, Al, alloying elements that increase the strength and hardness of steel: graphitization: free graphit
