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Hardened steel gears carburized distortion of 20CrMnTi


And because of its low cost of raw materials, heat treatment process is simple, easy to operate. Market prospect is very wide. Analysis of its mechanism, is due to subcritical quenching. Heating temperature is lower than the Ac, it is heated to et + - ~ two-phase zone. Prior to the formation of austenite,[link widoczny dla zalogowanych], non-equilibrium microstructure by the small and uniform granular carbide and ferrite recrystallization composition, phase interface increases, the position of austenite nucleation time,[link widoczny dla zalogowanych], and even more. Nucleation rate is high, so even relatively small initial grain. Subcritical quenching the same time lower the heating temperature, holding time shorter, are not conducive to atomic diffusion, so austenite grow more difficult. Quenching process in the subsequent acquired martensite and ferrite also small and uniform. In addition. Subcritical quenching is obtained by type of dislocation martensite, the sub-structure of the movable than the big twins, dislocation of the exercise can ease the local area of stress concentration, thus delaying the crack initiation and slow crack development, These are beneficial for improving toughness. At the same time lath martensite within the austenite grains arranged in the original bundle. That martensitic transformation does not occur when the crystal between the impact on each other microcracks. Limited due to atomic diffusion, the carbon content of ferrite ferrite higher than normal. Will cause the carbon in solid solution strengthening. At the same time the pre-hardening of silicon, manganese can be fully spread, and in the sub-temperature quenching of silicon, manganese re-distribution of silicon enriched leaving the ferrite solid solution strengthening of ferrite, manganese enrichment to improve the quenching austenite permeability. In addition,[link widoczny dla zalogowanych], ferrite also contains a high density of dislocations. This will result in dislocation strengthening, so the ferrite phase organization higher than the strength of ferrite ��3]. Impurity elements such as P and the residue dissolved in a small amount of ferrite, reducing the element of P and other impurities in the original austenite grain boundary segregation, reducing the degree of its brittle ��4]. Therefore, temperature quenching the resulting sub-organization than the average two-phase ferrite + martensite strength and toughness and wear better. 3 Conclusions (1) 20MnSi pre-hardened steel using subcritical quenching + tempering in the temperature of the heat treatment process. Receive is lath martensite ferrite asked small and uniform distribution of the organization. The grain was refined than ordinary quenching. (2) 20MnSi steel quenched after subcritical. Changes in the organization of materials, band structure to eliminate grain refinement. Strength and hardness of materials to improve overall performance,[link widoczny dla zalogowanych], wear resistance can be improved. (3) The experimental results show that. Reasonable heat treatment process for the 880 �� x2min water quenching +800 �� �� 1min tempering water quenching +400 �� xlOmin References: [1] Xue Bing. China's cotton processing machinery and the status and development of processing enterprises [J]. China's cotton processing, 2001, (3) :3-5. [2] Party HEAVY MACHINERY. Dual Phase Steel Research and application prospects [J]. Shanxi Machinery, 2002, (4) :14-15. [3] Cui Shihai, Han Jianmin, Li Wei Jing, et al. Enhanced dual-phase steel 20MnSi heat treatment [J]. Iron and Steel Research, 2005, (4): 65.67. [4] Ding Wei, Lin Xiao Ping, Liu opened, and so on. Low-carbon martensitic steel fine-grained microstructure and wear resistance [J]. Heat Treatment of Metals, 2007, (1): 59.62. Tin (Continued from page 7 distortion of carburized steel 20CrMnTi a significant impact. 20CrMnTi steel carburized quenching temperature on the impact of distortion shown in Figure 4. Quenching temperature / 'c Figure 4 quenching temperature on the impact of the carburized distortion Fig. 4Influenceofquenchingtemperatureoncarburizingdistortion3 Conclusions (I) steel carburizing carburizing temperature distortion of 20CrMnTi significant impact, due to lower carburizing carburizing temperature can effectively reduce the generation of distortion. (2) carbon potential of carburizing steel 20CrMnTi deformation of the most significant, with the increase of carbon potential, 20CrMnTi carburized distortion of steel increased significantly, while the formation of undesirable carbides in the surface,[link widoczny dla zalogowanych], and therefore strictly on the carbon potential control. (3) quenching temperature on the deformation of cementite is also very significant, as the quenching temperature increases, due to thermal stress and organizational transformation hardening stress increases. Also will increase the amount of distortion. References: [1] XU Bin-shi, Liu reference. China Materials Engineering Dictionary (16) [M]. Beijing: Chemical Industry Press. 2006.608. [2] Sun Shengyu, Daiya Kang. Crack analysis of ceramic heat spectrum [M]. Dalian: Dalian Press. 2002.92. [3] Chun-Sheng Li. Steel Manual [M]. Nanchang: Jiangxi Science and Technology Press, 2004.208. Tin \
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