3.1 hot-dip pure zinc coating hot-dip zinc coating (Z) Hot-dip galvanizing line, the pretreated strip immersed in molten zinc solution obtained by plating. Zinc content in molten zinc solution should be not less than 99%. 3.2 Galvanized iron alloy coating hot-dip zinc-iron alloy coating (ZF) Hot-dip galvanizing line, the pretreated strip immersed in molten zinc solution obtained by plating. Zinc content in molten zinc solution should be not less than 99%. Then, by alloying process for forming zinc-iron alloy layer on the entire coating alloy coating iron content is usually 7 to 15%. 3.3 interstitial free steel interstitial free steels Interstitial free steel is adding an appropriate amount of titanium or niobium in ultra-low carbon steel, the steel carbon, nitrogen interstitials completely fixed into carbon, nitride, steel no interstitial atoms present in a type of steel. 3.4 Interstitial high strength steel high strength interstitial free steels (Y) By controlling the chemical composition of the steel to improve steel plastic strain ratio (r value) and strain hardening exponent (n value). Since the solid solution strengthening elements in steel and the microstructure of interstitial free, which has both high strength steel, but also has a very good cold-forming properties, usually used to make complex parts require deep drawing. 3.5 bake-hardening steel bake hardening steels (B) To retain a certain amount of low-carbon steel or ultralow-carbon steel in the dissolved carbon, nitrogen atoms, while strengthening elements to increase the strength by adding phosphorus, manganese and other solid solution. After the forming process, after baking at a certain temperature, age hardening due to make a further increase the yield strength of steel. High-strength low-alloy steel 3.6 high strength low alloy steels (LA) In the low-carbon steel or ultralow-carbon steel, single or composite niobium, titanium, vanadium micro-alloying elements, the formation of carbonitride precipitation particles to strengthen, while the grain refinement effect by micro-alloying elements to obtain higher strength. 3.7 duplex steel dual phase steels (DP) The main steel microstructure of ferrite and martensite, martensite dispersed to the island on a ferrite substrate. Duplex steel non-aging, has a low yield ratio and a higher work hardening and bake-hardening exponent value, is one of the preferred material structure type parts. 3.8 transformation induced plasticity steel transformation induced plasticity steels (TR) The microstructure of the steel is ferrite, bainite and retained austenite, wherein the content of residual austenite at least not less than 5%. During the forming process, the residual austenite into martensite relative, has a high work hardening rate, uniform elongation and tensile strength. Compared with the same tensile strength dual-phase steel has higher elongation. 3.9 multiphase steel complex phase steels (CP) The main steel microstructure of ferrite and (or) bainite. In and (or) bainitic ferrite substrate, usually distributed small amounts of martensite, retained austenite and pearlite structure. By adding micro-alloying elements Ti or Nb, forming grain refinement or precipitation hardening effect. This steel has a very high tensile strength. Compared with the same tensile strength dual-phase steel, which is obviously much higher yield strength. This steel has high energy absorption capability and higher residual resilience. 3.10 tensile strain mark stretcher strain marks Cold forming process, since the aging of the reason, uneven deformation of the steel sheet or strip, plate or strip resulting in local plastic deformation occurs, eventually rendering the stretching at an angle of a series of parallel lines in the surface of the steel sheet or strip shaped folds or irregular polyline, irregular surface distortions detrimental to the surface appearance quality defects. 3.11 Coating weight coating mass That is the weight of the coating and double-sided, in order to form the coating weight on each side, respectively, in units of grams / square meter (g / m2).