QSTE... hot-rolled high strength cold forming sheet steel as per EN

Transcription

1 QSTE... hot-rolled high strength cold forming sheet steel as per

2 QStE hot-rolled high strength cold forming sheet steel Steels labelled QStE are a class of fine grain micro-alloyed thermo-mechanically rolled (TM) steels. They are suitable for cold forming due to their high strength. The labelling of these steels can differ with different producers (Table 1). They can be labelled as ALFORM355M to ALFORM650M, S355MC to S700MC, RAEX355MC OPTIM to RAEX 700MC OPTIM, DOMEX355MC to D O M E X M C, Y M P R E S S E t o YMPRESSE690, KODUR355 to KODUR550, etc. Each are labelled respective to Re yield strengths. All manufactured steel sheets have to meet the parameters given as per the - standard. QStE class steels (hot-rolled) are manufactured from the thickness of mm to 1mm in the form of slid strips or cut-to-length sheets. Utilisation There are various applications of QStE class steels. They have been used for: outrigger crane arms jib arms chassis constructions containers agriculture machinery etc. s of QStE class steels are labelled with three digits, expressing the value of the minimal yield strength (Re) measured perpendicularly to the direction of rolling. These range from 380MPa to 690MPa according to the - standard. See Table. All the mechanical characteristics which result in QStE class steels as better and higher quality when compared with common grade steels, are generated due to thermomechanical rolling, the addition of micro-alloying elements (Nb, V, Ti), and a very precise setting of rolling parameters. See Chemical composition table (Table 3). The advantage of QStE steels is very little use of alloying elements in the manufacturing process (especially S and F), and this has a positive effect on: - a significantly lower carbon equivalent (C EV>0,39), resulting in the improvement of steel weldability - excellent formability, even when it has to be bent to tight radii and high steel strength - high KV impact strength in low temperatures - suitable for laser cutting Advantages of usage - less weight - easier weldability - simplified manufacturing - robust design - less environmental burden - competitive edge - economical efficiency

3 Benefits When using higher or the highest grade of QStE steels, specifically QStE690TM, the following benefits can be attained in comparison with QStE380TM steel sheets: with the same thickness of material, the new design can be as much a s x stronger; i.e. it can bear x t h e weight, or it can endure x the load, etc. while preserving the same construction strength, a thinner steel sheet can be used, resulting in a decrease of the w e i g h t o f the construction by 5%, and resulting in many positive changes in the designing of new steel constructions for QStE steels, excellent cold forming is typical, even when bent to tight radii, and this can be a decisive feature for the design applications of materials a i m i n g a t economical efficiency, demanding labour input, and static characteristics of the product. Bending QStE steels c o m b i n e h i g h strength with good bendability. Due to lower carbon and sulphur contents the sheet can be bent to tight radii without cracking, regardless of the direction of rolling (Table 4). Shearing QStE steels are well suited to cutting. There is a rule that the highest tensile strength is, the higher the power needed for cutting the material. N a t u r a l l y, w i t h increasing tensile strength, tool wear increases. Cutters should be robust and sharp, blades should be slightly curved for cutting, and there are important parameters shear gap l and the angle of the tool face. See Table 5. Cutting Laser cutting is a well suited cutting technique for QStE steels and due t o t h e i r c h e m i c a l composition no special parameters are required. Plasma cutting can be u s e d w i t h o u t a n y limitations. Machining QSTE steels are, thanks to their chemical composition, with some alloying elements workable at all grades. In the lower grades s p e c i f i c a l l y, Q S t E T M, m a c h i n i n g c h a r a c t e r i s t i c s / a r e identical to S35 and S355 common steel grades. In the highest QStE690TM grades, high speed cutting tools (HSS) must be used for a smooth penetration run of the tool into the material. Specifically during drilling, threading, milling, etc., it is not necessary to adjust the speed of revolutions or advancement. They can be machined as any common material.

4 Tolerances All grades of QStE steels are manufactured in accordance with EN , which specifies the tolerances on material thickness, dimensions and flatness. All materials are supplied with a certificate of the trials of the material mechanical parameters as per EN 10 04, 3.1B. Welding The weldability of QStE steels is excellent even in the highest grades (QStE690 TM) due to their chemical composition, and all methods of welding can be used. Due to their low content of alloying elements, the steels are not susceptible to hot or cold cracking and therefore no preheating of the steel is necessary. Matching filler metals result in producing a weld that is as strong as the steel itself. Under-matched filler metals can be used as well e.g. when welding in lightly stressed areas or when welding high strength steel to mild steel. For m o r e p r e c i s e i n f o r m a t i o n o n matching filler metals see the Table below. Weld metal R P [MPa] Filler metals (AWS classes) MMA Manual arc welding SAW Flux core wire welding MIG/MAG Protective atmosphere wire welding FCAW Special wire welding AWS A5.3 F11AXEX AWS A5.8 ER 110S AWS A5.9 E 11XT AWS A5.5 E AWS A5.5 E AWS A5.3 F10AXEX AWS A5.8 ER 100S AWS A5.9 E10XT AWS A5.5 E 9018 AWS A5.3 F9AXEX AWS A5.8 ER 90S AWS A5.9 E9XT AWS A5.5 E 8018 AWS A5.3 F8AXEX AWS A5.8 ER 80S AWS A5.9 E 8XT AWS A5.5 E 8016 AWS A5.3 F7AXEX AWS A5.5 E 708 AWS A5.17 F7AXEX AWS A5.18 ER 70S AWS A5.0 E 7XT AWS A5.5 E 7018 AWS A5.1 E 7016 AWS A5.17 F7AXEX AWS A5.18 ER 70S AWS A5.0 E 7XT AWS A5.1 QStE380TM QSTE460TM QStE500TM QStE550TM QStE690TM Recommended strength of weld metal for abutting joint in cases where high weight-carrying capacity crosswise to the weld joint is required Strength of weld metal for other welded joints

5 Table 1 Comparison of steel labelling Comparison of steel labelling by different manufacturers SEW 09 1 QStE 380 TM ALFORM 355M S355MC RAEX 355 MC OPTIM DOMEX 355 MC - QStE 460 TM ALFORM 460M S460MC RAEX 460 MC OPTIM DOMEX 460 MC - QStE 500 TM ALFORM 500M S500MC RAEX 500 MC OPTIM DOMEX 500 MC CORUS RQT 501 QStE 550 TM ALFORM 550M S550MC RAEX 550 MC OPTIM DOMEX 550 MC CORUS RQT 601 QStE 690 TM ALFORM 700M S700MC RAEX 700 MC OPTIM DOMEX 700 MC CORUS RQT 701 1) Re is measured crosswise to rolling direction. ) Re is measured length-wise to rolling direction. Table Selected values of typical mechanical properties as per - Table 3 Typical values of chemical composition as per - Table 4 Bending as per - Mechanical properties Re Rm A5 KV [MPa] [MPa] [%] [ C] [ J ] QStE 380 TM QStE 460 TM QStE 500 TM QStE 550 TM QStE 690 TM Chemical composition C Mn Si P S Al Nb V Ti Mo B [%] [%] [%] [%] [%] [%] [%] [%] [%] [%] [%] QStE 380 TM 0,1 1,5 0,5 0,05 0,0 0,015 0,09 0, 0, QStE 460 TM 0,1 1,6 0,5 0,05 0,015 0,015 0,09 0, 0, QStE 500 TM 0,1 1,7 0,5 0,05 0,015 0,015 0,09 0, 0, QStE 550 TM 0,1 1,8 0,5 0,05 0,015 0,015 0,09 0, 0, QStE 690 TM 0,1,1 0,6 0,05 0,015 0,015 0,09 0, 0, 0,5 0,005 Material bending min. R of the bend h < 3mm h = 3 6mm h > 6mm QStE 380 TM 0,5 x h 0,5 x h 1,0 x h QStE 460 TM 0,5 x h 1,0 x h 1,5 x h QStE 500 TM 1,0 x h 1,5 x h,0 x h QStE 550 TM 1,0 x h 1,5 x h,0 x h QStE 690 TM 1,5 x h,0 x h,5 x h * some materials have min. radius of the bend by 50% smaller Table 5 Shearing parameters Shearing parameters shear gap l the angle of the tool face [%t] [ ] QStE 380 TM QStE 460 TM QStE 500 TM QStE 550 TM QStE 690 TM

6 Senica Trstín Hlohovec Bratislava Senec Bratislava Žilina Nitra WINFA, s.r.o. Skladová /A TRNAVA Slovak Republic Trstínska cesta TRNAVA tel: / fax: / web: winfa@winfa.sk