Hot Rolled Low Pearlite Fine-Grain Steels The spectrum of the design success A business unit of ThyssenKrupp Steel Hoesch Hohenlimburg tk
Microalloyed fine-grain steels - made with flexibility for the market Solutions from Hohenlimburg narrow strip: performance parts for mobile thinking Each new vehicle generation sets new challenges. Partners in the automobile industry take the broad view if their structural components are to meet these demands. These days the demands of the automobile industry and component suppliers are equally as multi-featured as particular. Sometimes weight saving is the decisive factor other times requirements for yield and tensile strength. And that is without mentioning the possibilities for economic further processing which are always at the top of the list with practical decision-making. With their particular properties, microalloyed fine-grain steels from Hoesch Hohenlimburg are a basis for maximum application related suitabillty and reliability with the most varied subassemblies. Core competence of Hoesch Hohenlimburg is practical application dialogue. Precisely for this reason narrow strip from Hoesch Hohenlimburg presents an outstanding basis as input stock: in widths up to 700 mm and thicknesses from 1.5 to 16 mm with mill edges optionally split to smaller widths or with trimmed edges with uniquely thickness tolerances for hot rolled narrow band in best surface quality with uniform material properties 2
Pages 4-5 Subassembly Restraining systems Weight reduction through high tensile materials Pages 6-7 Subassembly Seats Outstanding mechanical properties The following applies in particular for fine-grain steels: high yield point values with outstanding cold formability. From practical experience and through stepped up customer wishes for example in the fields of higher strengths and thinner strip gauges Hoesch Hohenlimburg has expanded the range of designations. Pages 8-9 Subassembly Engine / gearbox First class ductility A set of special designations has been developed for the application-oriented solution of problems. The in-house HSM designations (Hoesch Special Steels Microalloyed) in their properties and strength values exceed the normal products from S315 MC to S 700 MC. Continuous process-automated production and optimum setting of required parameters favour Pages 10-11 Subassembly Axles Optimum thickness ranges Pages 12-13 Subassembly Brakes Tight tolerances microalloyed fine-grain steels from narrow strip precisely for the demands of direct processing: for example increase safety of passive and active restraint systems, seat components or in drive trains. Pages 14-15 Further processing Fine blanking/ welding Customer-service Selection and further development of materials, optimisation of production, laboratory investigations 3
Easily resistant to tensile forces with lightness Microalloyed fine-grain steels, in the high strength range, contribute to weight reduction of the end products particularly important for applications in the automotive field. Maximum values for ultimate strength achieve the desired weight reduction and go hand in hand with the necessary aspects of safety and quality. Light and yet robust this is what counts with restraining system components. Cooling line of the narrow strip mill Subassembly: restraining systems Seat belt fitting Belt coiling frame Airbag components 4
Strong restraint gives security in all situations. Matched material qualities create the necessary prerequisites. Fine-grain steels from Hoesch Hohenlimburg, together with modern manufacturing techniques, make the substitution of heavy cast or forged parts possible and thus save weight, machining processes and energy. Thus material qualities play an important role, as well as the fact that costs need to be restrained in view of international competition. Hoesch designation HSM 260 HSM 300 HSM 340 - HSM 380 HSM 420 HSM 460 HSM 500 HSM 550 HSM 600 HSM 650 HSM 700 HSM 760 Material No.: Designation i.a.w. [Steel - Iron Material List] 1.0970* (Q St E 260 TM*) 1.0972* (Q St E 300 TM*) 1.0974 Q St E 340 TM 1.0976-1.0978 Q St E 380 TM 1.0980 Q St E 420 TM 1.0982 Q St E 460 TM 1.0984 Q St E 500 TM 1.0986 Q St E 550 TM 1.8969 (Q St E 600 TM*) 1.8976 (Q St E 650 TM*) 1.8974 (Q St E 690 TM*) Hoesch special product * In accordance with the Stahl-Eisen-Liste [(German) Steel - Iron List], 1990 Edition Designation i.a.w. DIN EN 10149-2, 1995 - S 315 M - S 355 MC - S 420 MC S 460 MC S 500 MC S 550 MC S 600 MC S 650 MC S 700 MC Seat belt height adjuster 5
Top mechanical properties: a status above the standard Optimum possibilities for adjustment and solid anchoring are important safety factors. Further minimisation of risk through consequent design, which promotes concentration during driving and prevents premature fatigue therefore always remains a complex development task. Here the choice of material is an important design factor. Cooling line control stand Highly developed fine-grain steel products from Hoesch Hohenlimburg offer, for numerous applications including car seats, outstanding mechanical properties overall better optimised than DIN EN 10149-2 demands and also above the uppermost limit of this valid standard specification. Subassembly: seats Car seat - side component Car seat - fixing device Seat rail 6
The way one sits is the way one drives. The input stock must also sit precisely. The table shows as an example the possible narrow spread of the technological parameters of the Hoesch Hohenlimburg narrow strip. Hoesch designation Yield point N/mm 2 min. Ultimate strength N/mm 2 from up to Elongation at fracture % Lo = 5do* HSM 300 HSM 340 HSM 380 HSM 420 HSM 460 HSM 500 HSM 550 HSM 600 HSM 650 HSM 700 HSM 760** 300 340 380 420 460 500 550 600 650 700 760 400-480 420-500 450-530 480-580 520-620 550-650 620-720 650-750 700-800 750-900 850-1000 * Strip thickness > 3.0 mm ** Hoesch Special Product (up to strip thickness of 13.0 mm) 27 25 23 21 19 19 17 17 17 15 15 Car seat fixture 7
Performance impulse for ideal direct processing It is precisely in metal forming technology that the input material used is of decisive significance. And that is what is delivered by Hoesch Hohenlimburg. The special advantage of microalloyed fine-grain steels: strength in combination with the best prerequisites for processing. Incidentally: HSM steels can be bent with tight radii, rollformed to shape and easily shaped. Reversing stand Subassembly: engine/gearbox Hub ring gear Gearshift fork Carrier plate 8
Not until there is smooth interplay between engine and gearbox is power applied to the road. All components in their turn must fulfil their function reliably even under continuous maximum loading. R eh (N/mm 2 ) 900 800 700 600 500 400 300 200 300 400 500 600 700 800 900 60 Dependence of upper yield strength R eh on tensile strength R m 1,0 R m 2 0,8 R m Dependence of the elongation at fracture and the uniform elongation on the ultimate strength R eh Fine-grain steels for cold forming The various products are extremely suitable for direct processing with high demands on cold formability and can thus replace normal heat-treatable steels. Therefore, an expensive hot forming and/or heat treatment of components can be dispensed with. The cold formability is improved through the chemical combination of special alloying concepts. With thermomechanical rolling of fine-grain steels, yield point, elongation at fracture and uniform elongation are closely associated with ultimate strength (see tables). 50 40 A 5 A 5, A g (%) 30 20 A g 10 0 300 400 500 600 700 800 900 Gearbox component 9
Optimum dimensioning. Even for larger material thicknesses Employed as axle or axle suspension the material certainly has to put up with a lot loads from vehicle mass and dynamic forces from road interaction. In the dialogue with customer design and development staff Hoesch Hohenlimburg will propose suitable steel grades in a broad spectrum of thickness for maximum service life. Overall view pickling plant The coise of fine-grain steels covers the complete range up to max. 700 mm width and max. 16 mm thickness in coils and cut lengths. This represents an unusual range of dimensions for microalloyed fine-grain steels in the shape of hot rolled narrow strip. Subassembly: Axles Rear axle Axle end seating 10
Everything depends on the axle design. An accurate layout influences the chassis-specific characteristics of a given vehicle design. One needs to find the right measure to insure stable driving conditions. The complete spectrum of thickness can be rolled and further processed in Hohenlimburg: slitting, cutting to length, pickling with thickness tolerances entirely as desired over the complete width and length. Slitting line The fine-grain crystalline structure of HSM steel can also be achieved through the deliberate setting of the rolling temperatures and the degree of deformation. Transverse control arm 11
Impressive safety for individual design requirements All components and systems of the brake assembly must be able to withstand the tough loads at any second. Microalloyed fine-grain steels offer quite narrow spreads of tensile values completely in line with the design requirements. Hoesch Hohenlimburg restricts the relatively generous range for yield and tensile strength values allowed by DIN EN 10149-2. Finishing train Subassembly: Brakes Brake pedal Ball pressure accumulator 12
Precision brake systems recognise no compromises as, in critical situations, it all depends on correct functioning. Every bit of safety reserve counts. And naturally material quality also belongs to this. HSM designations set their own standards and offer better alternatives over and above just meeting standard specifications. Due to tight dimensional tolerances Hohenlimburg narrow strip puts you always on the safe side of your design for the safety of both the product and the end user, the driver. Impulse wheel 13
Easy subsequent processing - support along the complete line Fineblanking: HSM steels easily meet the requirements for fineblanking through the fine-grain microstructure and low pearlite content. Welding: HSM steels can be easily welded in line with all known methods. Welding fillers should be matched to the level of strength and the good ductility of the basic material. Lower carbon and manganese as well as microalloying contents determine a low carbon equivalent and therefore guarantee good welding properties. With the types of steel up to HSM 500 no fundamental excessive hardening or work softening occurs. With the other types of steel one has to reckon with slight weld hardening only. They remain, however, below the corresponding values of S 355 engineering steel. Information on heat treatment: Our microalloyed fine-grain designations, due to the thermomechanical treatment, are fundamentally unsuitable for heat treatment. Heat treatment above 580 Celsius, in particular with long holding times, is associated with a lowering of the yield point and ultimate strength values. General engineering steels Microalloyed fine-grain steels 0,3 0,25 C Äq (%) 0,2 0,15 0,1 0,05 0 S 235 S 275 S 355 HSM 300 HSM 380 HSM 460 HSM 500 HSM 600 HSM 700 HSM 760 Comparison carbon equivalents with general engineering steels and microalloyed fine-grain steels 14
Diverse properties of further processing influence the total cost calculation to a high degree. Here also there is a great deal to say for microalloyed fine-grain steels. Individual support: we are happy to discuss your applications You yourself determine at what time and to what extent you want to make use of our comprehensive services. Our services cover, for example: advice with the selection of material further developments of existing materials according to your requirements support with your manufacturing optimisation laboratory investigations. We can advise you already in the planning phase on choice of material and, together with you, determine precisely the suitable product. Our application engineers are often in close dialogue with customers for new designs and further developments. They can contribute to the optimisation of manufacture processes on given production facilities. In addition, we can also carry out numerous tests on quality assurance for you in our own laboratories. A telephone call suffices and our technical customer service will help you further. 15
Hoesch Hohenlimburg GmbH Narrow Strip Division Oeger Strasse 120 D-58119 Hagen Tel.: ++49-23 34/91-2391 or 91-0 Fax: ++49-23 34/91-3369 Technical Customer Service: Tel.: ++49-23 34/91-3245 -2271-2295 Fax: ++49-23 34/91-3358 E-mail: mittelband@tks-hho.thyssenkrupp.com Internet: www.hoesch-hohenlimburg.de A.F.C./08/2003 With reservation engineering prozess variation.