‹#›,,,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,单击此处编辑母版标题样式,第七,章,章,建筑,钢,钢材,基本,要,要求,7.1,概述,7.2,基本,知,知识,7.3,技术,性,性质,7.4,冷加,工,工和,时,时效,7.5,技术,标,标准,及,及选,用,用,目,录,录,基,本,本,要,要,求,求,本章,学,学时,讲课,3,实验,0.5,主要,内,内容,建筑,钢,钢材,的,的特,点,点、,分,分类,及,及应,用,用,建筑,钢,钢材,的,的拉,伸,伸性,能,能、,冲,冲击,韧,韧性,及,及冷,弯,弯性,能,能,建筑,钢,钢材,的,的冷,加,加工,及,及时,效,效强,化,化,常用,建,建筑,钢,钢材,的,的标,准,准及,选,选用,重点,建筑,钢,钢材,的,的拉,伸,伸性,能,能、,冲,冲击,韧,韧性,及,及冷,弯,弯性,能,能,常用,建,建筑,钢,钢材,的,的标,准,准及,选,选用,Back,基,本,本,要,要,求,求,§7.1,概,述,述,定义,分类,特点,应用,意义,,,,,,,,,,,,,Back,指用,于,于工,程,程建,设,设的,各,各种,钢,钢材,，,，包,括,括：,型钢,钢板,钢丝,钢筋,定义,,钢筋,型钢,,钢板,钢丝,Back,概,述,述,分类,金属,材,材料,有色,金,金属,黑色,金,金属,铜、,铝,铝及,合,合金,钢,结,结,构,构,钢,筋,筋,生铁,(c>2.06%),按化,学,学成,分,分可,分,分为,:,黑色,金,金属,和,和有,色,色金,属,属,Back,优点,比强,度,度高,塑性,好,好、,韧,韧性,好,好,能承,受,受冲,击,击和,振,振动,荷,荷载,加工,性,性好,特点,缺点,易锈,蚀,蚀,维护,费,费用,大,大,Back,建筑,钢,钢材,可,可用,于,于,:,大跨,度,度结,构,构,多层,及,及高,层,层结,构,构,受动,荷,荷载,作,作用,的,的工,业,业厂,房,房,应用,钢桥,Back,建筑,钢,钢材,是,是建,筑,筑中常用,的,的材,料,料,钢材,的,的品,种,种多,，,，性,质,质差,别,别大,，,，为,了,了掌,握,握钢,材,材的,合,合理,使,使用,，,，应,对,对钢,材,材的,生,生产,、,、组,成,成、,性,性质,和,和用,途,途等,知,知识,有,有一,定,定的,了,了解,。
本章,的,的重,点,点是,钢,钢材,的,的技术,性,性质（主,要,要是,抗,抗拉,性,性能,）,）、技术,标,标准和选用意义,Back,§7.2,基本,知,知识,钢材,的,的冶,炼,炼过,程,程及,其,其对,钢,钢材,质,质量,的,的影,响,响,冶炼,原,原理,炉种,的,的影,响,响,分类,按化,学,学成,份,份分,按质,量,量分,按结,构,构用,途,途分,Back,将熔,融,融的,生,生铁,水,水或,焦,焦炭,及,及铁,矿,矿石,加,加入,炼,炼钢,炉,炉中,精,精炼,，,，使,炭,炭及,其,其它,杂,杂质,氧,氧化,而,而挥,发,发或,变,变成,氧,氧化,物,物进,入,入渣,内,内，,降,降低,炭,炭及,其,其它,杂,杂质,的,的含,量,量冶炼,原,原理,钢材,的,的冶,炼,炼过,程,程,及其,对,对钢,材,材质,量,量的,影,影响,Back,过程,焦炭,铁矿,石,石,生铁,,高炉,熔融,生铁,,精炼,氧化,还原,钢,,铸锭,钢锭,建筑,钢,钢材,,图,7.2.1,钢材,的,的冶,炼,炼过,程,程,炉种,的,的影,响,响及,氧,氧化,程,程度,炉种,的,的影,响,响及,氧,氧化,程,程度,见,见表,7.2.1,和表,7.2.2,。
表,7.2.1,炉种,的,的影,响,响,炉型,原料,吹入,气体,冶炼时间,钢材,质量,成本,应用,氧气转炉,熔融铁水,氧气,15-30,分钟,好,低,优质碳素钢及合金钢,平炉,生铁、铁矿石等,空气,5-12,小时,好,高,同上及特殊用途的钢,,电炉,废钢、,生铁,空气,短,最好,高,同上,冶炼,中,中为,除,除去,杂,杂质,而,而进,行,行的,氧,氧化,部分,铁,铁不,可,可避,免,免的,被,被氧,化,化,使,钢,钢,锭,锭,内,内,生,生,成,成,许,许,多,多,气,气,泡,泡,降,低,低,了,了,钢,钢,的,的,质,质,量,量,为,了,了,使,使,FeO,和,Fe,2,O,3,还,原,原,为,为,Fe,,在,炼,炼,钢,钢,的,的,后,后,阶,阶,段,段,必,必,须,须,脱,脱,氧,氧,脱,氧,氧,程,程,度,度,的,的,影,影,响,响,表,7.2.2,脱,氧,氧,程,程,度,度,及,及,钢,钢,材,材,质,质,量,量,钢种,脱氧程度,冷却情况,钢材质量,沸腾钢,不充分,浇筑时有大量,CO,逸出,差,半镇静钢,介于二者之间,,好,镇静钢,充分,平静冷却，无,CO,逸出,组织致密、成分均匀、机械性能好,特殊镇静钢,最充分,,最好,Back,碳,素,素,钢,钢,低,碳,碳,钢,钢,C<0.25%√,中,碳,碳,钢,钢,C=0.3,～,0.55%,高,碳,碳,钢,钢,C>0.6%,合,金,金,钢,钢,低,合,合,金,金,钢,钢,<5%√,中,合,合,金,金,钢,钢,=5,～,10%,钢,合,合,金,金,钢,钢,>10%,按,化,化,学,学,成,成,分,分,分,分,类,类,分,类,类,表,7.2.3,碳,素,素,结,结,构,构,钢,钢,的,的,化,化,学,学,成,成,分,分,（,（,GB700,—,—88,）,牌号,,等级,化学成分,%,,,,,,脱氧方法,,,,C,Mn,Si,S,P,,,,,,,≤,,,,,,Q195,,0.06~0.12,,0.30,0.050,,0.045,F,、,b,、,Z,Q215,A,0.09~0.15,0.25~0.55,0.30,0.050,0.045,,0.045,F,、,b,、,Z,,B,,,,,,,,Q235,A,0.14~0.22,0.30~0.65,0.30,0.050,,0.045,F,、,b,、,Z,,B,0.12~0.20,0.30~0.70,,0.045,,,,,C,≤0.18,0.35-0.80,,0.040,,0.040,Z,,D,≤,0.17,,,0.035,,0.035,TZ,Q255,A,0.18~0.28,0.40~0.70,0.30,0.050,,0.045,Z,,B,,,,0.045,,,,Q275,,0.20~0.38,0.50~0.80,0.35,0.050,,0.045,Z,按,质,质,量,量,分,分,普,通,通,钢,钢,P,≯,0.045%,S,≯,0.055%,优,质,质,钢,钢,P,≯,0.035-0.04%,S,≯,0.04%,高,级,级,优,优,质,质,钢,钢,P,≯,0.025%,S,≯,0.025%,分,类,类,按,结,结,构,构,用,用,途,途,分,分,结,构,构,钢,钢,各,种,种,工,工,程,程,构,构,件,件,及,及,机,机,械,械,零,零,件,件,,,属,低,低,碳,碳,钢,钢,或,或,中,中,碳,碳,钢,钢,工,具,具,钢,钢,刀,具,具,、,、,模,模,具,具,特,殊,殊,钢,钢,不,锈,锈,钢,钢,、,、,耐,耐,热,热,钢,钢,、,、,耐,耐,磨,磨,钢,钢,Back,§7.3,建,筑,筑,钢,钢,材,材,的,的,技,技,术,术,性,性,质,质,拉,伸,伸,性,性,能,能,低,碳,碳,钢,钢,的,的,应,应,力,力,－,－,应,应,变,变,图,图,强,度,度,塑,性,性,冲,击,击,韧,韧,性,性,冷,弯,弯,性,性,能,能,Back,工程中,的,的钢结,构,构和钢,筋,筋混凝,土,土结构,中,中的钢,材,材的基,本,本性能,有,有：,机械性,能,能,拉伸性,能,能,冲击韧,性,性,疲劳强,度,度,工艺性,能,能,冷弯性,能,能,焊接性,能,能,Back,拉伸性,能,能录像,拉伸性,能,能是建,筑,筑钢材,的,的主要,性,性能,钢材受,拉,拉后的技术性,能,能指标可以用,低,低碳钢,的,的应力,—,应变图,来,来反映,。
屈服强,度,度,抗拉强,度,度,伸长率,拉伸性,能,能,低碳钢,的,的应力,应,应变图,见,见 图,7.3.1,σ,,,,,,,,,,,,,,,,,,,,,,,,,,,B,C,D,A,δ,σ,b,σ,SU,σ,P,σ,SL,ε,,,弹性阶,段,段,σ/ε=E,σ,σ,p,--,弹性极,限,限,屈服阶,段,段,△,△,ε,＞△,σ,产生塑,性,性变形,B—,上屈服,点,点,B′—,下屈服,点,点,σ,s,—,屈服强,度,度,强化阶,段,段：内,部,部组织,变,变化，,恢,恢复部,分,分强度,σ,b,--,抗拉强,度,度,颈缩阶,段,段：过,C,点后，,试,试件抵,抗,抗变形,的,的能力,下,下降，,变,变形集,中,中在某,局,局部进,行,行，产,生,生颈缩,破,破坏,0,图,7.3.1,低碳钢,的,的应力,应,应变图,Back,定义,屈服强,度,度是指钢,材,材开始,丧,丧失随,变,变形的,抵,抵抗能,力,力,,,并开始,产,产生大,量,量变形,的,的能力,意义,是弹性,变,变形转,变,变为塑,性,性的转,折,折点,当外力,超,超过屈,服,服点时,，,，产生,不,不可恢,复,复的变,形,形，钢,材,材内部,的,的应力,自,自动分,配,配至低,应,应力部,位,位,所以说,，,，屈服,点,点是确,定,定钢结,构,构容许,应,应力值,的,的依据,屈服强,度,度,公式,屈服强,度,度,σ,s,－屈服,强,强度,Fs,－屈服,应,应力,Ao,－试件,截,截面积,对屈服,不,不明显,的,的钢,,,规定以,产,产生,0.2%,残余变,形,形时的,应,应力,f,02,作为屈,服,服强度,σ,02,，见,图,7.2.3,,,,,,,,,,σ,ε,0.2%,O,图,7.3.2,低碳钢,的,的应力,应,应变图,定义,σ,b,是指,钢材能,承,承受的,最,最大拉,应,应力,.,意义,当外力,大,大于抗,拉,拉强度,时,时，钢,材,材完全,丧,丧失对,变,变形的,抵,抵抗能,力,力而断,裂,裂,因此，,在,在结构,设,设计中,不,不能应,用,用,拉伸强,度,度,定义,σ,s,/,σ,b,反映了,钢,钢材的,可,可利用,率,率和安,全,全性的,大,大小,意义,屈强比,对,对钢材,的,的可利,用,用率和,安,安全性,来,来说是,重,重要的,。
表,7.3.1,,图,7.3.3),合理屈,强,强比：,碳素钢,0.58—0.63,低碳合,金,金结构,钢,钢,0.65—0.75,屈强比,（,（,σ,s,/σ,b,）,,,,,,,,,,,,σ,b,σ,s2,σ,s1,σ,ε,图,7.3.3,屈强比,的,的意义,Back,,σ,s,/,σ,b,低,σ,s,/,σ,b,高,可利用率,小,大,安全性,大,小,表,7.3.1,钢材的,屈,屈强比,、,、可利,用,用率及,安,安全性,之,之间的,关,关系,指钢材,在,在外力,作,作用下,发,发生塑,性,性变形,而,而不破,坏,坏的能,力,力定义,塑 性,伸长率,指标和,公,公式,δ,n,—,伸长率,L,0,—the,原标点,间,间距,L,1,—,拉断后,标,标点间,距,距,n=5d or 10d,d—,钢筋直,径,径,δ,5,＞,δ,10,,,,,,,,,d,0,,,,L,0,,,,,,,L,1,,,,,,,,,图,7.3.4,伸长率,的,的测定,断面收,缩,缩率,Ψ,—,断面收,缩,缩率,A,0,—,原断面,面,面积,A,1,—,拉断后断面,面,面积,指标和公式,指标和公式,说明,伸长率是表,示,示钢材塑性,变,变形能力的,重,重要指标,钢结构一般,在,在弹性范围,内,内工作,但在应力集,中,中处，应力,可,可能超过屈,服,服点,,,有一定的塑,性,性变形,因此,可以保持应,力,力重新分布,，,，从而避免,结,结构破坏,Back,冲击韧性是,指,指钢材抵抗,冲,冲击荷载的,能,能力,定义,试验方法,用摆锤打击,有,有槽口的标,准,准试件，直,到,到试件破坏,单位面积所,消,消耗的功,Back,冲击韧性,A,k,—,试件破坏时,的,的冲击功,A—,试件槽口处,截,截面积,公 式,Flash-,冲击韧性试,验,验,冲击韧性,α,k,与温度有关,(,图,7.3.5),温度较低时,，,，发生脆性,断,断裂的现象,发生脆性断,裂,裂时的温度,为,为脆性断裂,温,温度,温度较低时,，,，冷脆性好,冷 脆 性,冲击韧性,,,,,,,,,韧性断裂,脆性断裂,T,ep,：,脆性临界温度范围,T,A,k,,图,7.3.5,脆性断裂、,韧,韧性断裂及,脆,脆性临界温,度,度范围,指钢材在常,温,温下承受弯,曲,曲变形的能,力,力,如果钢材承,受,受弯曲变形,的,的程度大，,那,那么钢材的,冷,冷弯性好,定义,指标,弯曲角度,α,及弯心直径,/,（钢板厚度,或,或直 径,）,）,(d/a),冷 弯 性,能,能,Back,试验,以规定的,α,和,d/a,进行弯曲,检查受弯部,位,位,如不裂纹、,不,不起层或断,裂,裂，则为合,格,格,,冷弯性能录,像,像,冷 弯 性,能,能,冷弯是通过,弯,弯曲处的塑,性,性变形来实,现,现的，因此,它,它也是反映,钢,钢材在静荷,载,载下塑性的,一,一个指标。
在拉伸试验,中,中，钢材试,件,件的塑性变,形,形则是局部,不,不均匀变形,.,冷弯试验常,常,常能反映钢,材,材内部组织,的,的均匀程度,，,，存在内应,力,力和夹杂物,等,等缺陷,因此可以用,冷,冷弯性来检,查,查钢材的质,量,量，如焊接,质,质量,说明,Back,冷 弯 性,能,能,将热轧钢筋,用,用拉伸设备,在,在常温下拉,长,长，使之产,生,生一定的塑,性,性变形称之,为,为冷拉,钢材用拉伸,设,设备拉伸后,能,能提高强度,冷拉,,,,,,,,,,,,,,,,,,,,,,,,F,图,7.3.6,冷拉示意图,Back,冷 弯 性,能,能,将钢筋通过,硬,硬质合金拔,丝,丝模孔强行,拉,拉拔，使之,不,不仅受拉、,而,而且受挤压,以,以提高强度,每次冷拔,断,断面缩小应,为,为,10%,以下，可多,次,次冷拔,在这个过程,中,中，强度可,提,提高,40-60%,，效果好与,冷,冷拉,冷拔,Back,冷 弯 性,能,能,§7.4,建筑钢材的,冷,冷加工与时,效,效,冷加工与时,效,效的定义,冷加工与时,效,效强化原理,冷加工与时,效,效强化的意,义,义,Back,冷加工,指在常温下,对,对钢材进行,冷,冷拉、冷拔,和,和冷轧处理,冷加工强化,钢材经冷加,工,工后强度和,硬,硬度提高，,塑,塑性和韧性,降,降低的现象,时效,经冷拉钢材,随,随时间延长,强,强度提高,,,塑性、韧性,下,下降的现象,叫,叫做时效,可分为两类,：,：分为自然时,效,效和人工时,效,效,Back,定义,时效,自然时效处,理,理,经冷拉的钢,材,材在常温下,存,存放,15-20,天,其强度和,硬,硬度提高,，,，塑性和,韧,韧性降低,的,的现象,人工时效,处,处理,经冷拉的,钢,钢材在加,热,热至,100-200℃,，并保持,一,一段时间,这将使时,效,效加速,定义,时效敏感,性,性,因时效而,导,导致性能,改,改变的程,度,度大，导,致,致塑性、,韧,韧性降低,。
故动荷载,重,重要结构,，,，敏感性,好,好说明,有些钢材,即,即使没有,经,经过冷加,工,工处理，,长,长时间过,后,后也会出,现,现时效，,但,但不如冷,加,加工后表,现,现明显Back,定义,冷加工时,效,效强化的,原,原理,由于钢材,在,在加工时,产,产生塑性,变,变形所至,，,，当晶体,在,在外力作,用,用下，在,弹,弹性阶段,金,金属原子,偏,偏离平衡,位,位置产生,的,的变形，,在,在外里去,除,除后可以,恢,恢复,---,弹性变形,；,；,当外力继,续,续增大，,使,使晶格的,歪,歪曲程度,超,超过弹性,变,变形之后,，,，晶格产,生,生滑移，,造,造成永久,性,性变形由,由于晶粒,表,表面的畸,变,变及滑动,平,平面的细,小,小碎屑，,使,使晶体在,该,该平面上,继,继续滑动,产,产生困难,，,，抵抗变,形,形的能力,增,增大，因,而,而屈服极,限,限及硬度,提,提高由于塑性,变,变形后钢,材,材可能产,生,生滑移的,区,区域几乎,均,均已滑动,，,，因此塑,性,性降低原 理,Back,时效强化,的,的原理,在高温下,固,固溶在,α-Fe,中的氮和,氧,氧的原子,，,，在温度,降,降低后溶,解,解度下降,，,，但未完,全,全析出，,在,在存放过,程,程中逐渐,析,析出并扩,散,散到晶粒,缺,缺陷处，,形,形成固体,微,微粒，阻,碍,碍晶粒发,生,生滑移，,而,而提高了,对,对塑性变,形,形的抵抗,能,能力。
原 理,,,,,,,,σ,ε,O,O,1,B,D,1,C,D,C,1,K,1,K,,未冷拉,屈服点,B,冷拉,屈服点,: σ,s,变大,塑性和韧,性,性降低,时效,σ,s,, σ,ν,变大,塑性和韧,性,性降低,图,7.4.1,冷加工和,时,时效强化,示,示意图,建筑钢材,的,的冷加工,与,与时效,可提高强,度,度，冷拉,后,后屈服强,度,度可提高,20-30%,，时效处,理,理后还可,使,使抗拉强,度,度提高可节约钢,材,材,20-30%,对于受动,荷,荷载或经,常,常处于中,温,温条件工,作,作的钢结,构,构，如桥,梁,梁、钢轨,、,、锅炉等,，,，为避免,过,过大脆性,，,，出现突,然,然断裂，,要,要求采用,时,时效敏感,小,小的钢材,意义,Back,§7.5,建筑钢材,的,的技术标,准,准与选用,钢结构用,钢,钢材,碳素结构,钢,钢,低合金高,强,强度结构,钢,钢,钢筋混凝,土,土结构用,钢,钢材,热轧钢筋,冷轧带肋,钢,钢筋,冷拔低碳,钢,钢丝,Back,建筑钢材,的,的技术标,准,准与选用,建筑钢材,包,包括：,型钢,钢管,钢板,钢丝,钢筋,常用的钢,材,材品种为,：,：,碳素钢与,低,低合金钢,二,二大类。
Back,钢结构用,钢,钢材,我国钢结,构,构用的钢,材,材主要有,碳素结构,钢,钢,低合金钢,碳素结构,钢,钢,指各种钢,结,结构中采,用,用的结构,钢,钢和工程,用,用热轧钢,板,板、型钢,等,等现行国家,标,标准为,《,碳素结构,钢,钢,》,（,GB700-88,）,Back,牌号及其,表,表示方法,如,如,flash,中所示,Q235-AF:,屈服强度,是,是,235MPa,A,级,,,沸腾钢,钢结构用,钢,钢材,请点击右,键,键选择“,播,播放”观,看,看,Flash,动画,碳素结构,钢,钢的技术,要,要求,技术要求,包,包括：,化学成分,力学性质,冶炼方法,交货状态,表面质量,下面重点,介,介绍前两,个,个性质化学成分,各种不同,牌,牌号的碳,素,素结构钢,的,的化学成,分,分应符合,GB700-88,的要求表,7.5.1,碳素结构,钢,钢的化学,成,成分（,GB700-88,）,牌号,质量等级,化学成分（,%,）,,,,,,,,C,Mn,Si,,S,,,,,,不大于,,,,Q195,—,0.06,～,0.12,0.25,～,0.50,0.30,0.050,,0.045,Q215,A,B,0.09,～,0.15,0.25,～,0.55,0.30,0.050,0.045,,0.045,Q235,A,B,C,D,0.14,～,0.22,0.12,～,0.20,≤0.18,≤0.17,0.35,～,0.80,0.30,0.050,0.045,0.040,0.035,,0.045,0.045,0.040,0.035,Q255,A,B,0.18,～,0.28,0.40,～,0.70,0.30,0.050,0.045,,0.045,Q275,—,0.28,～,0.38,0.50,～,0.80,0.35,0.050,,0.045,碳素结构,钢,钢的拉伸,和,和冲击试,验,验指标应,符,符合下表,规,规定：,碳素结构,钢,钢的力学,性,性能指标,（,（,GB700-88,）,力学性能,冷弯试验,碳素结构,钢,钢的冷弯,试,试验指标,（,（,GB700-88,）,表,7.5.2,碳素结构,钢,钢的力学,性,性能（,GB700—88,）,牌号,等级,拉伸试验,,,,,冲击试验,,,,屈服点,(N/mm),,抗拉强度,σb,(N/mm),伸长率（,%,）,,温度 （℃）,V,型冲击功 （纵向）,J,,,钢材厚度 （直径）,mm,,,钢材厚度 （直径）,mm,,,,,,≤16,＞,16~40,,≤16,＞,16~40,,,,,≥,,,≥,,,≥,Q195,—,(195),(185),315~390,33,32,—,—,Q215,A,B,215,205,335~410,31,30,—,20,—,27,Q235,A,B,C,D,235,225,375~460,26,25,—,20,—,-20,—,27,27,27,Q255,A,B,255,245,410~510,24,23,—,20,—,27,Q275,—,275,265,490~610,20,19,—,—,Tab.7.5.3,碳素结构,钢,钢抗弯试,验,验指标,(GB700-88),牌号,试样方向,冷弯试验,B=2a180°,,,,,钢材厚度（直径）（,mm,）,,,,,60,＞,60~100,＞,100~200,,,弯心直径,d,,,Q195,纵,横,0,0.5a,—,,—,,Q215,纵,横,0.5a,a,1.5a,2a,2a,2.5a,Q235,纵,横,a,1.5a,2a,2.5a,2.5a,a,Q255,2a,3a,3.5a,－,Q275,3a,2a,4.5a,－,各类牌号,钢,钢材的性,能,能,牌号与性,能,能的关系,根据国家,标,标准,GB700-88,的规定，,碳,碳素结构,钢,钢按屈服,点,点分为五,个,个牌号,如表,7.5.1,和表,7.5.2,所示，,当牌号增,大,大时，钢,材,材的含碳,量,量提高，,伸,伸长率降,低,低，冷弯,性,性能也降,低,低。
质量等级,：,：取决于,钢,钢材内有,害,害杂质,S,、,P,的含量，,钢,钢材的质,量,量与好，,其,其焊接性,能,能和低温,抗,抗冲击性,能,能也提高,各类牌号,钢,钢材的性,能,能,碳素结构,钢,钢的选用,建筑钢结,构,构中最常,用,用的牌号,为,为,Q235(,综合性能,符,符合建筑,工,工程的要,求,求,),因为,Q235,钢既有较,高,高的强度,，,，又有良,好,好的塑性,和,和韧型，,如,如：,B,、,C,、,D,等，可焊,接,接性也很,好,好，能满,足,足一般钢,结,结构用钢,的,的要求Q235,的,C,级,和,和,D,级,钢,钢,，,，,其,其,S,和,P,的,含,含,量,量,低,低,，,，,所,所,以,以,主,主,要,要,作,作,重,重,要,要,的,的,焊,焊,接,接,结,结,构,构,尤,其,其,适,适,用,用,于,于,低,低,温,温,条,条,件,件,下,下,，,，,受,受,冲,冲,击,击,荷,荷,载,载,作,作,用,用,的,的,焊,焊,接,接,钢,钢,结,结,构,构,各,类,类,牌,牌,号,号,钢,钢,材,材,的,的,性,性,能,能,碳,素,素,结,结,构,构,钢,钢,的,的,选,选,用,用,Q195,及,Q215,：,强,强,度,度,低,低,，,，,但,但,塑,塑,性,性,和,和,韧,韧,性,性,好,好,，,，,易,易,冷,冷,加,加,工,工,，,，,在,在,轧,轧,制,制,、,、,焊,焊,接,接,加,加,工,工,成,成,受,受,冲,冲,击,击,、,、,偶,偶,然,然,荷,荷,载,载,等,等,情,情,况,况,下,下,，,，,能,能,保,保,证,证,安,安,全,全,使,使,用,用,。
Q255,及,Q275,：,强,强,度,度,高,高,，,，,但,但,塑,塑,性,性,和,和,韧,韧,性,性,差,差,，,，,可,可,焊,焊,接,接,差,差,，,，,不,不,易,易,冷,冷,加,加,工,工,；,；,可,可,用,用,作,作,砼,砼,配,配,筋,筋,和,和,钢,钢,结,结,构,构,中,中,的,的,构,构,件,件,及,及,螺,螺,栓,栓,（,（,在,在,机,机,械,械,零,零,件,件,及,及,工,工,具,具,中,中,常,常,用,用,之,之,）,）,选用钢材，,主,主要根据工,程,程结构的重,要,要性、荷载,类,类型、焊接,要,要求及使用,环,环境温度等,条,条件选择Back,定义,在碳素结构,钢,钢的基础上,，,，添加少量,的,的一种或几,种,种合金元素,，,，合金元素,的,的总含量小,于,于,5%,的结构钢常用的合金,元,元素有：,Si,、,Mn,、,Ti,、,Nb,、,V,和,C,等牌号及其表,示,示方法,现行国家标,准,准,《,低合金结构,钢,钢,》,（,GB1591-94,）共有,5,个牌号：,Q295,、,Q345,、,Q390,、,Q420,、,Q460,低合金高强,度,度结构钢,Back,牌号由以下,四,四部分组成,(,如,flash,所示,),低合金高强,度,度结构钢,请点击右键,选,选择“播放,”,”观看,Flash,动画,低合金高强,度,度结构钢,低合金高强,度,度结构钢的,化,化学组成,(GB1591-94),如表,7.5.4,所示。
低合金高强,度,度结构钢的,力,力学性能,(GB1591-94),如表,7.5.5,所示如表,7.5.5,所示，,低合金钢的,强,强度大大高,于,于碳素结构,钢,钢，并且具,有,有良好的塑,性,性和韧性、,耐,耐磨性、耐,蚀,蚀性及耐低,温,温性也好于,碳,碳素钢，其,生,生产工艺和,成,成本都与碳,素,素钢相近比采用碳素,结,结构钢节省,钢,钢材，而且,可,可以减轻自,重,重，延长使,用,用寿命，,尤其适用于,大,大跨度结构,和,和桥梁工程,等,等低合金高强,度,度结构钢,表,7.5.4,低合金高强,度,度结构钢的,化,化学成分（,GB1591-94,）,牌号,,质量等级,,化学成分（,%,）,,,,,,,,,,,,,,C,≤,Mn,Si,P,≤,S,≤,V,Nb,Ti,Al,≥,Cr≤,Ni≤,Q295,A,,B,0.16,,0.16,0.80,～,,1.50,0.80,～,,1.50,0.55,,0.55,0.045,,0.040,0.045,,0.040,0.02,～,,0.15,0.02,～,,0.15,0.015,～,0.060,0.015,～,0.060,0.02,～,0.20,0.02,～,0.20,—,,—,,,续表,Q345,A,,B,,C,,D,,E,,0.02,,0.02,,0.20,,0.18,,0.18,1.00,～,1.60,1.00,～,1.60,1.00,～,1.60,1.00,～,1.60,1.00,～,1.60,0.55,,0.55,,0.55,,0.55,,0.55,0.045,,0.040,,0.035,,0.030,,0.025,0.045,,0.040,,0.035,,0.030,,0.025,0.02,～,0.15,0.02,～,0.15,0.02,～,0.15,0.02,～,0.15,0.02,～,0.15,0.015,～,0.060,0.015,～,0.060,0.015,～,0.060,0.015,～,0.060,0.015,～,0.060,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,—,,—,,0.015,,0.015,,0.015,,,续表,Q390,A,,B,,C,,D,,E,0.20,,0.20,,0.20,,0.20,,0.20,1.00,～,1.60,1.00,～,1.60,1.00,～,1.60,1.00,～,1.60,1.00,～,1.60,0.55,,0.55,,0.55,,0.55,,0.55,0.045,,0.040,,0.035,,0.030,,0.025,0.045,,0.040,,0.035,,0.030,,0.025,,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.015,～,0.060,0.015,～,0.060,0.015,～,0.060,0.015,～,0.060,0.015,～,0.060,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,—,,—,,0.015,,0.015,,0.015,0.30,,0.30,,0.30,,0.30,,0.30,0.70,,0.70,,0.70,,0.70,,0.70,续表,Q420,A,,B,,C,,D,,E,0.20,,0.20,,0.20,,0.20,,0.20,1.00,～,1.70,1.00,～,1.70,1.00,～,1.70,1.00,～,1.70,1.00,～,1.70,0.55,,0.55,,0.55,,0.55,,0.55,0.045,,0.040,,0.035,,0.030,,0.025,0.045,,0.040,,0.035,,0.030,,0.025,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.015,～,0.060,0.015,～,0.060,0.015,～,0.060,0.015,～,0.060,0.015,～,0.060,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,—,,—,,0.015,,0.015,,0.015,0.40,,0.40,,0.40,,0.40,,0.40,0.70,,0.70,,0.70,,0.70,,0.70,Q460,C,,D,,E,,,0.20,,0.20,,0.20,1.00,～,1.70,1.00,～,1.70,1.00,～,1.70,0.55,,0.55,,0.55,0.035,,0.030,,0.025,0.035,,0.030,,0.025,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.015,～,0.060,0.015,～,0.060,0.015,～,0.060,0.02,～,0.20,0.02,～,0.20,0.02,～,0.20,0.015,,0.015,,0.015,0.70,,0.70,,0.70,0.70,,0.70,,0.70,表,7.5.5,低合金高强,度,度结构钢的,力,力学性能（,GB1591-94,）,牌号,,质量等级,,拉伸试验,,,,,,,,180°,弯曲试验,,d=,弯心直径,,a=,试验厚度,,（直径）,,,,,屈服点,(MPa),,,,抗拉强度,,σ,b,Mpa,伸长率,,δ,5,%,冲击功,（纵向）,,（,J,）,,,,,,厚度,,（直径、边长）,,mm,,,,,,,,,,,≤,15,＞,16~35,,,,+20,℃,,0,℃,,钢材厚度,,(,直径,),（,mm,）,,,,,≥,,,,,≥,,,,≤,16,＞,16~100,Q295,A,B,295,295,,275,275,390~570,390~570,23,23,34,,d=2a,d=2a,d=3a,d=3a,Q345,A,B,C,D,E,345,345,345,345,345,325,325,325,325,325,470~630,470~630,470~630,470~630,470~630,21,21,22,22,22,34,,,34,d=2a,d=2a,d=2a,d=2a,d=2a,d=3a,d=3a,d=3a,d=3a,d=3a,Q390,A,B,C,D,E,,390,390,390,390,390,370,370,370,370,370,490~650,490~650,490~650,490~650,490~650,19,19,20,20,20,34,,,34,d=2a,d=2a,d=2a,d=2a,d=2a,d=3a,d=3a,d=3a,d=3a,d=3a,续 表,Q420,A,B,C,D,E,420,420,420,420,420,380,380,380,380,380,520~680,520~680,520~680,520~680,520~680,18,18,19,19,19,34,,34,d=2a,d=2a,d=2a,d=2a,d=2a,d=3a,d=3a,d=3a,d=3a,d=3a,Q460,C,D,E,460,460,460,420,420,420,550~720,550~720,550~720,17,17,17,,34,d=2a,d=2a,d=2a,d=3a,d=3a,d=3a,续 表,钢筋混凝土,结,结构用钢材,可以分为：,热轧钢筋,冷拉钢筋,冷拔低碳钢,丝,丝,钢绞线,Back,包括热轧光,圆,圆钢筋,(Tab.7.5.6),及热轧变形,钢,钢筋。
热轧钢筋按,屈,屈服强度及,抗,抗拉强度分,为,为四个等级,其品种、牌,号,号、力学性,能,能及其应用,见,见下表,7.5.7,热 轧 钢,筋,筋,Back,表,7.5.6,建筑用低碳,热,热轧圆盘条,力,力学性能及,工,工艺性能,牌号,力学性能,,,冷弯试验,180℃,d,＝弯心直径,a,＝试样直径,,σ,s,（,MPa,）,σ,b,（,MPa,）,δ,10,（％）,,,≥,,,,Q215,Q235,215,235,375,410,27,23,d,＝,0,d,＝,0.5a,Tab.7.5.7,热轧钢筋力,学,学性能及工,艺,艺性能表,（,（,GB/T701-1997,、,GB1499-1998,）,牌号,公称直径,（,mm,）,屈服强度,σ,s,,（,MPa,）,抗拉强度,σ,b,（,MPa,）,伸长率,δ,5,(%),冷弯试验,180℃,d,＝弯心直径,a,＝试样直径,,,≥,,,,HRB335,6,～,25,28,～,50,335,490,16,d,＝,3a,d,＝,4a,HRB400,6,～,25,28,～,50,400,570,14,d,＝,4a,d,＝,5a,HRB500,6,～,25,28,～,50,500,630,12,d,＝,6a,d,＝,7a,应 用,HRB335,和,HRB400,主要用于非,预,预应力和预,应,应力混凝土,。
HRB500,主要用于预,应,应力混凝土,Back,冷轧带肋钢,筋,筋,冷轧带肋钢,筋,筋主要力学,性,性能和工艺,性,性能如表,7.5.8,所示Back,级别代号,抗拉强度,σ,b,(MPa),不小于,伸长率不小于,(%),,冷弯,180°,D,－弯心直径,d,－钢筋公称直径,应力松驰,σ,com,=0.7σ,b,,,反复弯曲次数,,,δ,10,,δ,100,,,,,,,,,,1000h,≮(%),10h,≮(%),,CRB550,CRB650,CRB800,CRB970,CRB1270,,550,650,800,970,1170,8,－,－,－,－,－,4,4,4,4,D=3d,D=3d,D=3d,D=3d,D=3d,－,8,8,8,8,－,5,5,5,5,－,3,3,3,3,表,7.5.8,冷轧带肋钢,筋,筋主要力学,性,性能和工艺,性,性能,级别代号,抗拉强度,σ,b,(MPa),不小于,伸长率不小于,(%),,冷弯,180°,D,－弯心直径,d,－钢筋公称直径,应力松驰,σ,com,=0.7σ,b,,,反复弯曲次数,,,δ,10,,δ,100,,,,,,,,,,1000h,≮(%),10h,≮(%),,CRB550,CRB650,CRB800,CRB970,CRB1270,,550,650,800,970,1170,8,－,－,－,－,－,4,4,4,4,D=3d,D=3d,D=3d,D=3d,D=3d,－,8,8,8,8,－,5,5,5,5,－,3,3,3,3,表,7.5.8,冷轧带肋钢,筋,筋主要力学,性,性能和工艺,性,性能,Back,这是一类冷,加,加工钢筋。
将直径为,6.5-8,㎜,㎜,的碳素结构,钢,钢的,Q235,或,Q215,盘条，通过,拔,拔丝机进行,多,多次冷拔而,成,成冷拔低碳钢,丝,丝分为甲、,乙,乙两级甲级冷拔钢,丝,丝主要用作,预,预应力筋；,乙,乙级冷拔钢,丝,丝可用作普,通,通钢筋（非,预,预应力筋）,，,，也可用于,焊,焊接网、焊,接,接骨架、箍,筋,筋和构造钢,筋,筋等冷拔,低,低碳钢丝的,力,力学性能要,求,求见下表,7.5.9,冷拔低碳钢,丝,丝,Back,Tab.7.5.9,冷拔低碳钢,丝,丝的力学性,能,能,(GBJ204-83),钢丝级别,,直径,mm,抗拉强度,N/mm,2,（,Kgf/cm,2,）,,,伸长率,（,标距,100,mm,）,,（,%,）,,反复弯曲,(,180,°),,应用,,,,Ⅰ,Ⅱ,,,,,,,,≥,,,,,,,,甲级,5,4,650,（,65,）,,700,（,70,）,,,600,（,60,）,,650,（,65,）,,3,2.5,4,,预应力筋,乙级,3,～,5,550,（,55,）,,,,2,4,,非预应力筋,Chapter 7,THE END,。