OPTIMIZATION OF FILLER METALS CONSUMPTION IN THE PRODUCTION OF WELDED STEEL STRUCTURES

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1 DOI: /adms K. Pańcikiewicz, L. Tuz, Z. Żuek, Ł. Rakoczy AGH Univesity of Science and Technology in Kakow, Faculty Metals Engineeing and Industial Compute Science, Depatment of Physical Metallugy & Powde Metallugy, Heat Teatment and Welding Laboatoy, Poland OPTIMIZATION OF FILLER METALS CONSUMPTION IN THE PRODUCTION OF WELDED STEEL STRUCTURES ABSTRACT The pape pesents the some aspects of the optimization of fille s consumption in the poduction of welded steel stuctues. Coect choice of beveling method can allow to decease cost of poduction and incease quality. The eview of calculation methods of fille consumption at the design stage was caied out. Moeove, the pactical examples of amount of fille s calculation wee pesented and analyzed. The aticle also contain examples of mobile apps which ae makes it easy to see welding costs in just a few seconds. Apps as well as simple excel speadsheets with coect mathematic equations allows to optimize welding pocess. Keywods: fille, optimization, steel stuctues, beveling, welding app INTRODUCTION In the poduction of steel stuctues, it is possible to make both sepaable and insepaable joints. Among the second type, the most common ae: butt, fillet and lap welds. Manufactuing, depending on the thickness of the wall may equie pepaation of the edges (beveling), usually by means of machining. Aangement of two edges ceates goove. Duing welding, goove is fulfilled by melted fille. Upon welding suitable quantity of heat should be intoduced in ode to melt fille and edges of goove, subsequently cystallization and cooling of weld wee obseved. Fig. 1. Butt weld - scheme of welded joint Download Date 1/1/17 1:18 AM

2 8 ADVANCES IN MATERIALS SCIENCE, Vol. 16, No. 1 (47), Mach 016 Fig.. Butt weld; a) non-alloyed steel, b) stainless steel Intoduced tempeatue gadient can cause micostuctual tansfomation which coesponds with change of mechanical popeties. Above mentioned factos contibute to the chemical inhomogeneities and foming thee chaacteistic aea: weld, heat affected zone (HAZ) and base (Fig.1). Optimization of fille s consumption in fabication of steel stuctues takes place due to costs of poduction and equied mechanical popeties of welds [1-5]. The examples of stuctual steel and austenitic stainless steel weld joints ae pesented in the Fig. a, b. OPTIMIZATION OF CONSUMPTION Fille s consumption depending on the geomety of goove can be calculated in accodance with equations. Requiements connected with beveling wee included in standads PN-EN ISO 969 [5]. In Table 1 examples of beveling with pope equations to detemine coss-section aea, ae shown. Estimation of weld length and density gives infomation about weight of weld which is connected with fille consumption. The coss-section aea of joint shall also included aea of penetation bead thickness and excessive weld that efe to the below equation. whee: F sp coss-section aea of weld (mm ), F coss-section aea of goove (mm ), F n coss-section of excessive weld (mm ), F g aea of penetation bead thickness (mm ). F (1) sp =F +Fn+Fg To obtain infomation about coss-section aea of excessive weld and oot face, equations () and (3) [, 3] ae given by: Fn= sn W () n 3 Fg= sg W (3) g 3 whee: s n s g height of excess weld and penetation bead thickness (mm), W n W g width of excess weld and penetation bead thickness (mm ), F n aea of excess weld (mm ), F g aea of penetation bead thickness (mm ). Download Date 1/1/17 1:18 AM

3 K. Pańcikiewicz, L. Tuz, Z. Żuek, Ł. Rakoczy: Optimization of fille s consumption... 9 Joint edge pepaation Table 1. Selected means of beveling and equations to calculate width of goove (W ) and coss section aea of weld (F ) Width of goove W and coss-section aea of weld F W F = b = sb W = stg + b F = s b + stg s c W = tg + b Joint edge pepaation Width of goove W and coss-section aea of weld F W = ( s c) tg + b F = sb + W = ( s c) s c F = tg + sb W = tg [ s ( + c) ] + + b π F = + sb + + s ( + c) tg s 4 b gap; angle; s thickness of base ; c depth of oot face; adius; a thoat thickness F F W [ ] [ ( + c) ] = sb + ( s c) = tg a = a tg ( s c) tg tg + b tg Table. Geomety equiements fo excess weld and excess penetation. Quality level fo fusion-welded joints in steel, nickel, titanium and thei alloys (beam welding excluded) in accodance with BS ISO 5817 Joint design Thicknes s s, mm Quality level D (low) Quality level C (medium) Quality level B (high) 0.5 s n 1 mm+0.5w n s n 5 mm s n 1 mm+0.15w n s n 1 mm+0.a s n 4 mm s n 1 mm+0.1w n s n 1 mm+0.15a s n 3 mm s 0.5 n 1 mm+0.5w n s n 1 mm+0.15w n s n 1 mm+0.1w n s n 10 mm s n 7 mm s n 5 mm s g 1 mm+0.6w g s g 1 mm+0.3w g s g 1 mm+0.1w g s 3 g 1 mm+1w g s g 1 mm+0.6w g s g 1 mm+0.w g s g 5 mm s g 4 mm s g 3 mm Depending on the welding method and design of joint, fo butt weld width of excessive W n is equal to the width of goove W plus 4 mm [, 3]. Width of oot W g is equal to the gap fo single sided welds and second excess weld fo double sided butt welds. Heights of excess weld ( s n ) and penetation bead thickness ( s g ) ae elated to widths W n and W g and should be evey time elated with established in advance quality level of weld. Example equiements fo welds (steel, nickel, titanium and thei alloys except fo electon beam welded joints) ae included in Table. Size of excess weld does not change Download Date 1/1/17 1:18 AM

4 30 ADVANCES IN MATERIALS SCIENCE, Vol. 16, No. 1 (47), Mach 016 stength and shall be educed in accodance with the equiements of poject in ode to educe manufactuing costs [1-4]. Calculation of fille consumption shall also include the mateial losses. Depending on the applied welding technology, some pats of fille can evapoated eg. MMAW o ceated spatte eg. MMAW and GMAW. Moden modification of taditional welding technologies poviding contolled tansfe of doplets fom the wie to the weld pool, limiting spatte and thus mateial losses. Each of the fille s ae also chaacteized by a deposition efficiency ie. elationship of weld deposited to the weight of the electode. In the case of gas welding o gas tungsten ac welding deposition efficiency is 100%, wheeas fo the gas ac welding o submeged ac welding values 97% to 100% ae obseved. The widest ange of efficiency can be obseved duing welding with coveed electodes. Thincoated electodes without feo-alloys in coveing achieve only 60% due to bun off. On the othe hand electodes with high quantity of alloying element in coveing eached even 160% [1-4]. Main featues of welding method have influence on the unused electode stub that is discaded, which geneates losses. Electode stub of coveed electode is mm, howeve stub of wie that is used in gas tungsten ac welding and gas welding is about 150 mm. Gas ac welding and submeged ac welding ae methods in which a continuous and consumable wie electode is fed though a toch but if the pocess will be stopped, welde o welding opeato should cut off appoximately 30 mm of wie befoe the next stike of ac. Example 1 Designe poposed in the daft 50 mm of single side T-joint with fillet weld thickness a=3 mm. Welde fo incease potection made a weld thickness of 4 mm with coect excessive weld that is fulfill the equiements of quality level B in accodance with PN- EN ISO 5817 [6]. Density of weld is ρ=7,85 g/cm 3 (theoetical value). Excessive convexity assumed as a maximum allowable fo quality level B. Results of calculation wee shown in Table 3. Design Thickness a, mm Table 3. Results of calculation fo 1 st example Aea of goove F, mm Weld width W n, mm Weld excess height S n, mm Aea of excess weld F n, mm Aea of weld F sp, mm Fille consumption Z s, kg/m ,6 6,4 15,4 0, ,8 9,6 5,6 0,01 If the joint will be made popely weld consumption will be at 6.04 kg, As a esult of the 4 mm thickness of the weld, additive mateial consumption has inceased almost twice (10.05 kg). Example Single side butt welds of diffeent thickness ae pefomed using by gas ac welding. In ode to optimize fille consumption, the most popula mannes of beveling included in PN-EN ISO wee analyzed [5]. Heights of excessive weld wee chosen as the maximum fo quality level B accoding to PN-EN ISO 5817 [6]. Density of Download Date 1/1/17 1:18 AM

5 K. Pańcikiewicz, L. Tuz, Z. Żuek, Ł. Rakoczy: Optimization of fille s consumption weld ρ=7.85 g/cm 3. Calculations wee caied out on 1 m weld and esults ae pesented in Table 4. Welding position accoding to ISO Type of beveling Thickness of base, mm Table 4. Results of calculation fo nd example Fille consumption Z s kg/1 m of weld Optimal consumption of fille fo diffeent thickness has been maked using the fames and shaded. Additional shaded cells epesents the ange of thickness suggested by PN-EN ISO fo the type of bevel [5]. It is clealy shown that welding of 1 and 14 mm thickness elements is most cost-effective with beveling accoding to item 1.4, although the standad does not indicate this solution as optimal. An impotant limitation of this type of beveling is the necessity to use weld backing system that suppots the molten. Thee ae two ways, the fist employs tempoay backing eg. non-fusible coppe backing which is emoved afte the weld is completed and the second backing becomes a pat of weld. These solutions must be taken into account in the daft. Example 3 The daft assumed 40 m of 8 mm butt weld that will be made using by MMAW. Goove was pepaed in accodance with PN-EN ISO item 1.3 [5]. Fo welding the fist laye electodes mm diamete and 300 mm length ae ecommended, but fo the fill passes electodes 4 mm diamete and 450 mm length. Efficiency of both coveed electodes is estimated at 80%. Requied quality level B accoding to PN-EN ISO 5817 [6]. Welding with coated electodes is connected with fille losses due to stubs estimated as 40 mm. Coect welding technology should ensued depth of fusion not less than 3 mm and minimizing excessive spatte up to % of weight of fulfilled layes. Spatte can cause many poblems in manufactuing pocess, the most common except fo losses of mateial ae Download Date 1/1/17 1:18 AM

6 3 ADVANCES IN MATERIALS SCIENCE, Vol. 16, No. 1 (47), Mach 016 excessive clean-up and spatte balls sticking to tools. Density of weld is ρ=7.85 g/cm 3. Calculation esults ae included in Table 5. Thickness s, mm Table 5. Calculation esults fo thid example Aea of goove F, mm Weld width W n, mm Weld excess height S n, mm Aea of excessive weld F n, mm Penetation bead thickness S g, mm Aea of bead thickness F g, mm Aea of butt weld F sp, mm Fille consumption Z s, kg/m 8 Electode size Diamete x Length 3 5 X, mm x300 4x450 Volume of electode V 1, mm Weight of electode m 1, g Volume of weld V, mm Weight of weld m, g Type of pass Numbe of electodes L (geneal calculations) Numbe of electodes L (accuate calculations) ods/m ods/40 m ods/m ods/40 m Root pass Fill pass Assumed conditions and geneal calculations povided infomation that will be necessay to use 17 electodes mm diamete and 10 electodes 4 mm diamete in ode to made 1 mete of weld and so 680 and 400 espectively to caied out 40 m of butt weld. Accuate calculations given quite diffeent esults 665 and 380 electodes thus less 15 thin and 0 thick. Welding pogams The calculations of fille consumption can be significantly impoved by using even office softwae. One way is to pepae seveal excel speadsheets fo each type of beveling and equip them with the appopiate fomulas and functions. Example of such excel speadsheet is shown in Fig. 3. Download Date 1/1/17 1:18 AM

7 K. Pańcikiewicz, L. Tuz, Z. Żuek, Ł. Rakoczy: Optimization of fille s consumption Fig. 3. Calculations pefomed in excel speadsheet Suppoting softwae is often made by fille manufactues fo thei clients. An example is Welding Calculato fom Voestalpine [7], which is accessible though the website o application Weld Wizad fom Fonius [8] also available fo mobile devices with Andoid and ios opeating systems (Fig. 4). Fig. 4. Calculations pefomed in Welding Calculato and Weld Wizad Download Date 1/1/17 1:18 AM

8 34 ADVANCES IN MATERIALS SCIENCE, Vol. 16, No. 1 (47), Mach 016 SUMMARY Estimation of fille consumption is diectly connected with subsequent consumption and cost as well as labo costs and mateials (tools) used to bevel the edges. The optimal shape of weld goove can cause that the cost of making joint can be educed by half o moe. Implementation of above mentioned apps may contibute to incease the competitiveness of contactos, togethe with high quality and mechanical popeties of welded joints. This eseach wok was suppoted by the Polish Ministy of Science and Highe Education, Gant No Appeciation is also expessed to Pof. A.S. Wonski (Univesity of Badfod, UK) fo help in the manuscipt editing. BIBLIOGRAPHY 1. Feenc K. (Ed.), Welding Technology in Pactice (in Polish), Velag Dashofe.. Pilaczyk J. (Ed.) Enginee Guide. Welding (in Polish). Vol. 1, Wydawnictwa Naukowo- Techniczne, Waszawa, Słania J., Welding Plans. Theoy and Pactice (in Polish), Agenda Wydawnicza SIMP, Redakcja Pzeglądu Spawalnictwa, Waszawa, Feenc K., Feenc J., Welded Stuctues. Joints (in Polish), Wydawnictwa Naukowo-Techniczne, Waszawa, PN-EN ISO 969-1: Welding and allied pocesses Recommendations fo joint pepaation Pat 1: Manual -ac welding, gas-shielded -ac welding, gas welding, TIG welding and beam welding of steels 6. PN-EN ISO 5817: Welding -- Fusion-welded joints in steel, nickel, titanium and thei alloys (beam welding excluded) -- Quality levels fo impefections 7. ( ) /hs.xsl/79_34740_eng_html.htm#.vxrxelixhvc ( ) Download Date 1/1/17 1:18 AM