螺丝的强度等级（Strength grade of a screw）

1、螺丝的强度等级（Strength grade of a screw）Strength grade of boltsSteel structure connecting bolts 3.6, 4.6, performance grade 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9 and more than 10 levels, of which 8.8 or more bolt material for low carbon alloy steel or carbon steel by heat treatment (quenching and tempering)

2、, known as the high strength bolts, known as the rest ordinary bolt. There are two parts in the performance grade of bolts. They are the nominal tensile strength of the bolt material and the ratio of the tensile strength. For example, a performance grade 4.6 bolt means yes:1. Nominal tensile strengt

3、h of bolt material reaches 400MPa grade;2, the bolt strength ratio is 0.6;3. The nominal yield strength of bolt material is 400 * 0.6=240MPa class, and the performance grade 10.9 is high strength bolt. The material can be reached after heat treatment:1. Nominal tensile strength of bolt material reac

4、hes 1000MPa grade;2, the bolt strength ratio is 0.9;3. The nominal yield strength of bolt material is 1000 * 0.9=900MPa classThe meaning of the performance grade of a bolt is an international standard. The performance of the bolt of the same performance grade is the same regardless of the material a

5、nd the place of origin. The performance grade can only be used in the design.Strength class, class 8.8 and 10.9The shear stress grades of bolts are 8.8GPa and 10.9Gpa8.8 nominal tensile strength 800N/MM2 nominal yield strength 640N/MM2The general bolt is expressed with the strength of X.Y,X*100= ten

6、sile strength of this bolt,X*100* (Y/10) = yield strength of this bolt(as specified by the mark: yield strength / tensile strength =Y/10)=Class 4.8Of this boltTensile strength: 400MPaThe yield strength is 400*8/10=320MPaDesolateAnother: stainless steel bolts are usually labeled A4-70, A2-70 look, me

7、aning otherwise explainedmeasureThere are two main types of one of the worlds length measuring unit, a metric unit of measure for the meter (m), cm (CM), mm (mm), is widely used in Europe, China and Japan in Southeast Asia, the other one is British, mainly for units of measurement (inch), a. In our

8、country the old rural, is widely used in the United States, Britain and other European countries.1, metric measurement: (10 hexadecimal)1m =100 cm=1000 mm2, imperial measurement: (8 hexadecimal)1 inch =8 1 inch =25.4 mm 3/8 British Phi Phi * 25.4 =9.523, 1/4 of the following products of designation

9、for its name for size, such as:4#, 5#, 6#, 7#, 8#, 10#, 12#ThreadA thread is a solid outer surface or inner surface of the cross section, there is a uniform spiral line convex shape. According to its structure, characteristics and uses can be divided into three categories:(1) ordinary threads: the t

10、eeth are triangular in shape and are used for connecting or fastening parts. The ordinary thread is divided into two kinds of coarse and fine thread according to the pitch, and the connection strength of the fine thread is higher.(two) driving thread: tooth shape has ladder, rectangle, saw shape and

11、 triangle etc.(three) sealing threads: used for sealing connections, mainly for threads, taper threads and taper pipe threads.Two, thread matching level:The thread matching is the loose or tight size between the screw threads, and the grade of fit is the combination of the deviation and the toleranc

12、e on the inside and outside threads.(1) for unified inch threads, there are three kinds of thread: 1A, 2A and 3A, and there are three grades of internal thread:The 1B, 2B, and 3B levels are all gap fit. The higher the grade, the tighter the tie. In British threads, deviations are only specified for

13、grades 1A and 2A, deviations from class 3A are zero, and class deviations for 1A and 2A are equal.The larger the grade, the less the tolerance.1, 1A and 1B class, very loose tolerance level, which is suitable for internal and external thread tolerance match.2, 2A and 2B class, is the British family

14、of mechanical fasteners, the most common thread tolerance class.3, 3A and 3B grade, spin forming the most tight fit, suitable for tight fasteners, for security critical design.4, the external thread, 1A and 2A class has a matching tolerance, 3A class no. The 1A tolerance is 50% larger than the 2A to

15、lerance, 75% larger than the 3A grade, and the 2B tolerance is 30% greater than the 2A tolerance for internal threads. 1B is 50% larger than 2B, 75% larger than 3B.(two) metric thread, the external thread has three kinds of thread grades: 4h, 6h and 6G, the internal thread has three kinds of thread

16、grades: 5H, 6, H, 7H. (Japan standard thread accuracy grade is divided into I, II and III three, usually under the II class) in metric thread, the basic deviation of H and H is zero. The basic deviation of G is positive, and the basic deviation of E, F and G is negative. As shown:1 and H are common

17、tolerances for internal threads. They are generally not used as surface coating or with extremely thin phosphating layers. The basic deviation of G position is used for special occasions, such as thicker coating, which is seldom used.2 and G are often used for 6-9um plating of thin coating, such as

18、product drawings require 6h bolt, its plating thread before using 6G tolerance zone.3, screw with the best combination of H/g, H/h or G/h, for bolts, nuts and other refined fasteners thread, the standard recommended by the use of 6H/6g coordination(three) thread markFour 、 the main geometric paramet

19、ers of self drilling and self drilling thread:(1) big diameter / tooth outer diameter (D1), the diameter of the imaginary cylinder that coincides with the top of the thread. The large diameter of a screw, basically representing the size of the threadNominal diameter.(two) path / tooth bottom diamete

20、r (D2): the imaginary cylinder diameter of the bottom of the screw thread.(three) the distance between teeth (P): the axial distance between adjacent teeth on the middle meridian corresponds to the two points. Inch (25.4 inches) in EnglishThe number of teeth in the MM indicates the distance between

21、teeth.The following table lists the tooth distance (Metric) teeth (English) of the commonly used specifications1, metric self tapping teeth:Specifications S T 1.5 S T1.9 S T2.2 S T2.6 S T2.9 S T3.3 S T3.5 S T3.9 S T4.2 S T4.8 S T5.5 S T6.3 S T8 S TNine point fiveThe range of teeth was 0.5, 0.6, 0.8,

22、 0.9, 1.1, 1.3, 1.3, 1.3, 1.4, 1.6, 1.8, 1.8, 2.1, 2.12, British self tapping teeth:Specifications 4#, 5#, 6#, 7#, 8#, 10#, 12#, 14#toothNumber AB teeth 2420201918161414A teeth 2420181615121110Material ScienceFirst, the current market standard parts are mainly carbon steel, stainless steel, copper t

23、hree kinds of materials.(I) carbon steel. We distinguish between low carbon steel, medium carbon steel, high carbon steel and alloy steel by the content of carbon in carbon steel.1, low carbon steel C% is less than or equal to 0.25% domestic commonly known as A3 steel. Foreign countries are basicall

24、y called 1008101510181022. Mainly used for 4.8 bolts and 4 nuts, small screws and other products without hardness requirements. (Note: the drill pin is mainly made of 1022 material.)In 2, 0.25%0.45%. At present, the market is basically no use4, alloy steel: alloy elements in general carbon steel, in

25、crease some of the special properties of steel: such as 35, 40 chromium, molybdenum, SCM435, 10B38. Fang screws mainly use SCM435 chrome molybdenum alloy steel, the main components are C, Si, Mn, P, S, Cr, Mo.(two) stainless steel. Performance rating: 45, 50, 60, 70, 80Mainly divided into austenite

26、(18%Cr and 8%Ni), good heat resistance, good corrosion resistance, good weldability. A1, A2, A4Martensite and 13%Cr have poor corrosion resistance, high strength and good wear resistance. C1, C2, C4 ferritic stainless steel. 18%Cr has better upsetting and better corrosion resistance than martensite.

27、 At present, the market is mainly imported Japanese products. According to the level of the main sub SUS302, SUS304, SUS316.(three) copper. Commonly used material is brass. Zinc copper alloy. The market mainly uses H62, H65 and H68 copper as standard parts.Disk elements used in carbon steel products

28、:Serial number, type, optional material14.8 stage six angle bolt 1008K 1010 1015K26.8级六角螺栓 1032 (ch38f 1039 10403 8.8级六角螺栓 1035acr (m10以下) 1040acr (m12以上) ch38f 1045acr 1039 10b21 10b33 10b384 8.8级内六角螺栓 ch38f 1039 10b21 (mac-10 (m12) 10b33 (m14) 10b38 (m12 - m24) 10b215 10.9级六角螺栓 1045acr 10b386 8级螺帽

29、 1008k 10107 8级螺帽 1015 (m 16) ch38f (m16)8 10级螺帽 ch38f 1039 10b21 10b339 12级螺帽 1039 10b21 10b33 10b3810 马车螺丝 1008 1010 101511 六角缘凸螺栓 ch38f 1039 10b21 10b33 10b3812 六角木螺丝 1008k 101013 自攻钉、墙板钉钻尾钉、夹板钉 1018 1022 ch22a14 机螺钉家俱螺丝 1008 1010三、材料中各类元素对钢的性质的影响:1、碳 (c): 提高钢件强度, 尤其是其热处理性能, 但随着含碳量的增加, 塑性和韧性下降, 并

30、会影响到钢件的冷镦性能及焊接性能.2、锰 (mn): 提高钢件强度, 并在一定程度上提高可淬性.即在淬火时增加了淬硬渗入的强度, 锰还能改进表面质量, 但是太多的锰对延展性和可焊性不利.并会影响电镀时镀层的控制.3、镍 (ni): 提高钢件强度, 改善低温下的韧性, 提高耐大气腐蚀能力, 并可保证稳定的热处理效果, 减小氢脆的作用.4、铬 (cr): 能提高可淬性, 改善耐磨性, 提高耐腐蚀能力, 并有利于高温下保持强度.5、钼 (mo): 能帮助控制可淬性, 降低钢对回火脆性的敏感性, 对提高高温下的抗拉强度有很大影响.6、硼 (b): 能提高可淬性, 并且有助于使低碳钢对热处理产生预期的反

31、应.7、矾 (v): 细化奥氏体晶粒, 改善韧性.8、硅 (): 保证钢件的强度, 适当的含量可以改善钢件塑性和韧性.四、关于不锈钢材质之特性简介 (304、316)(一) 该三种材质均为300系列的奥氏体不锈钢, 其化学成分如下:名称 c p s ni cr mo cu mn304m 0.03 0.06 1.0 2.0 0.045 8.91 - 10.0 18.0 - 20.0 0 0316 0.03-0.06 1.0 2.0 0.045 0.03 10.0 - 14.0 10.4 16.0 - 2.0 - 3.0 0 18.0304hc 0.03 0.08 1.0 2.0 0.045 8.

32、0 - 10.5 17.0 - 19.0 0 1.0 - 3.0(二) 主要化学成分与不锈钢性能之关系.1、碳c 可增加硬度和强度, 含量过高会降低其延展性和耐蚀性2、铬cr 可增加耐蚀性、抗氧化性, 使品粒细化, 增加强度, 硬度和耐磨性3、镍ni 可增加高温强度、耐蚀性, 降低冷加工硬化之速率4、钼mo增加强度, 对氧化物和海水的耐蚀性优良5、铜cu利于冷加工成型, 降低磁性(三) 材质之其它性能1、以上材质正常状态无磁性.304m冷加工后略有磁性 (1.6u - 2.0u左右); 304hc磁性为 (1.01u - 1.6u左右); 316材质冷加工后磁性小于 1.01u.2、各材质均有

33、良好的延展性, 易冷加工成型, 抗拉强度、屈服强度、均可达到要求. (ts抗拉强度min700n / mm, ys屈服强度 min 450n / mm)(四) 结论1、304m、304hc、316三种材质是目前300系列奥氏体不锈钢使用最广的材质之一.各材质明显差异为: 冷加工后材质磁性为316 304hc 304m.316材质抗化学品腐蚀, 抗孔蚀性及抗海水耐蚀性能相对于304m及304hc要优良.2、总之.Stainless steel standard parts characteristics of corrosion resistance, beautiful appearance

34、and sanitation, but its strength and hardness under normal circumstances is equivalent to the carbon steel (6.8) of the stainless steel products should not be hit, beat, pay attention to the maintenance of the surface roughness, accuracy, and can not use carbon steel products and as readily applied

35、force, not force at the same time because of too large, stainless steel has good ductility, easy to produce steel chips stuck on the nut teeth at the level of use, increase the friction force, easy to cause the lock, and the use of carbon steel even if iron filings produced will drop, compared with

36、stainless steel is not easy to lock.Major categories of products(1) six angle bolts (HEXAGON, HEAD, BOLTS);1, inch bolt reference standard is ANSI/ASME B18.2.1, Japanese standard refers to JIS B1180 (Wei Shiya). British reference BSW916 (Wei Shiya).(1) HEX, MACHINE, BOLT: no division, with tail, hal

37、f teeth, six angle bolts,(2) HEX, TAP, BOLT: no division, no tail, all teeth, six angle bolts,(3), HEX, CAP, SCREWS: there are Chinese company, with tail, half teeth, six angle bolts,2. The metric bolt standard is as follows. The difference between them is shown in the table:Old GB, new national sta

38、ndard, ISO standard, DIN (German standard)GB30GB5780 (half teeth)GB5781 (all teeth)GB5782 (half teeth)GB5783 (all teeth) ISO4016ISO4018ISO4014ISO4017 DIN601DIN558DIN931DIN933(two) carriage screw / round head square neck bolt (Carriage, Bolts):ANSI/ASME B18.5; DIN603; ISO 8677; GB12; GB14(three) inner angle bolts (Hexagon, Socket-Head, cap, screws,):DIN912; GB70; ISO4762; ANSI, /ASME, B18.3(four) six angle wood screws (Hexagon, Head, Lag, Screws):ANSI/ASME B18.2.1 DIN 571(five) furniture screw (Furniture, screws): according to customer standard(six) and