珠光体
珠光体是奥氏体(奥氏体是碳溶解在γ－Fe中的间隙固溶体)发生共析转变所形成的铁素体与渗碳体的共析体。得名自其珍珠般（pearl-like）的光泽。 Pearlite
Pearlite is austenite (austenite is interstitial carbon dissolved in γ - Fe solid solution) eutectoid a eutectoid transformation of ferrite and cementite. Named after the pearly luster (pearl-like) 概述： 珠光体 pearlite
其形态为铁素体薄层和渗碳体薄层交替重叠的层状复相物，也称片状珠光体。用符号P表示，含碳量为ωc=0.77%。在珠光体中铁素体占88%,渗碳体占12%,由于铁素体的数量大大多于渗碳体,所以铁素体层片要比渗碳体厚得多.在球化退火条件下,珠光体中的渗碳体也可呈粒状,这样的珠光体称为粒状珠光体。
珠光体的性能介于铁素体和渗碳体之间,强韧性较好.其抗拉强度为750 ~900MPa,180 ~280HBS,伸长率为20 ~25%,冲击功为24 ~32J.力学性能介于铁素体与渗碳体之间,强度较高,硬度适中,塑性和韧性较好σb=770MPa,180HBS,δ=20%~35%,AKU=24~32J)。
经2-4%硝酸酒精溶液浸蚀后,在不同放大倍数的显微镜下可以观察到不同特征的珠光体组织.当放大倍数较高时可以清晰地看到珠光体中平行排列分布的宽条铁素体和窄条渗碳体;当放大倍数较低时,珠光体中的渗碳体只能看到一条黑线;而当放大倍数继续降低或珠光体变细时,珠光体的层片状结构就不能分辨了,此时珠光体呈黑色的一团。
图为光学显微镜200倍下薄壁铸件基体.经3%硝酸酒精溶液浸蚀.可见磷共晶体,片状石墨,珠光体及少量铁素体。 Summary： Pearlite pearlite
The morphology of thin ferrite and cementite layer overlapping layered composite material, also known as lamellar pearlite. Is represented by the symbol P, carbon ω c=0.77%. In the pearlite ferrite and cementite accounted for 88%, accounted for 12%, due to the number of ferrite than cementite, so the ferrite layer is much thicker than cementite. Under the condition of the ball
annealing, cementite in pearlite can also be grainy, it is called granular pearlite pearlite
Performance between iron pearlite ferrite and cementite, good strength and toughness. The tensile strength is 750 ~900MPa, 180 ~280HBS, the elongation is 20 ~25%, the impact energy of 24 ~32J. mechanical performance between ferrite and cementite, high strength, hardness, plasticity and toughness are good σ b=770MPa, 180HBS, the δ =20%~35%, AKU=24~32J
The 2-4% nital etch, at different magnification microscope can observe the different characteristics of pearlite. When a higher magnification can clearly see the pearlite parallel distribution width of ferrite and cementite strips; when the magnification is low, the cementite in pearlite see only a black line; and when the magnification to reduce or pearlite thin lamellar pearlite, the structure cannot be resolved, the pearlite with a black regiment.
Fig. 200 times under optical microscope thin wall casting matrix. With 3% nital etch. Visible phosphorus eutectic, flake graphite, pearlite and a small amount of ferrite. 分类：
奥氏体化温度、转变前奥氏体晶粒大小，只影响珠光体团的大小，对片层间距无影响。片状珠光体依片间距不同，可以分成珠光体、索氏体、托氏体三种。在光学显微镜下能够明显分辨出片层的珠光体，其片间距约为150～450nm。片间距为80～150nm时，称为索氏体，其片层在光学显微镜下难以分辨。在更低的温度下形成片间距为30～80nm的珠光体称为托氏体，只有在电子显微镜下才能观察到片层结构。当渗碳体以颗粒状存在于铁素体基体上时称为粒状珠光体。粒状珠光体可以通过不均匀的奥氏体缓慢冷却时分解而得，也可以通过其他热处理方法获得。 Classification:
The austenitizing temperature, transformation of austenite grain size, only the effect of pearlite colony size, had no effect on the lamellar spacing. Lamellar pearlite interlamellar spacing according to different, can be divided into pearlite, sorbite, troostite three. Can clearly distinguish the pearlite interlamellar under optical microscope, the plate spacing is about 150 ~ 450nm. Plate spacing is 80 ~ 150nm, called the sorbite, the sheet under optical microscope, it is difficult to distinguish. Plate spacing of 30 ~ 80nm pearlite called troostite formed at lower temperature, can be observed only lamellar structure in the electron microscope. When the cementite in granular in ferrite matrix called granular pearlite. Granular pearlite through inhomogeneous austenite decomposition and slow cooling, can also be obtained through other heat treatment method.
屈氏体和索氏体区别
其形态为铁素体薄层和渗碳体薄层交替重叠的层状复相物，根据片层间距分为屈氏体和索氏体。在400倍光学显微镜下可以分辨的（片层间距为0.25~1.9μm），称为珠光体。在600