Steeltec ETG 88 /100

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1 Steeltec ETG 88/100

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3 3 Steel for more competitiveness Steel has been one of the most impor tant materials going back centuries. We man ufacture it in the grade and quality that allow our customers to succeed in the increasingly tough competitive environment. Steel from Steeltec is employed where precision components need to ful fil the highest requirements, in the millions, safely and reliably over the years. Components that have to be produced efficiently and at low cost. The requirements placed on steel have changed. What hasn t is our passion to continually optimise the way we fulfil them: yester day, today and in the future.

4 4 ETG : High-Strength Special Steels for new challenges Stronger competitors, declining prices, shorter deadlines and higher demands regarding the quality and safety of the components to be manufactured: these are the challenges of the market. Those who aim to meet these demands and make a profit turn to new variations of steel. Steels that enable producers to reshape and restructure their manufacturing processes and techniques. And thus make them safer and more cost-effective. These are steels that feature a high strength as drawn, possess a high fatigue strength and abrasion resistance, have outstanding machining properties and are distinguished by short chipping length during machining, exhibit a high degree of uniformity from heat to heat, have low residual stresses and maintain dimensional stability even with asymmetrical machining guarantee consistent mechanical properties over the entire cross section and dimension range. ETG steels open up undreamt-of possibilities in shaping and structuring the manufacturing processes: elimination of extra operations such as hardening, straightening, grinding and deburring shorter processing times through faster machining longer tool life less machine downtime multi-machine operation possibility of running unmanned shifts The added costs of using a higherquality material are more than made up for with the savings in the manufacturing process. For the production of demanding components, manufacturers can strengthen their competitiveness through the use of High-Strength Special Steels: smaller sizes save on weight shorter process times fewer rejects and improved quality high processability motivated machine operators fewer interfaces and less administration satisfied customers In short: Those who replace stan dard steels with ETG High-Strength Special Steels save on costs, improve their quality and gain added safety. The unique properties of ETG 88 and ETG 100 High-Strength Special Steels revolutionise operational processes and manufacture of components. Comparison of component costs ETG /hardening steels ETG Hardening steels Total ETG Total hardening steels 2 0 Material Turning Drilling Tools Heat treatment

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6 6 ETG steels: A unique combination of properties The properties of ETG steels are the outcome of a combination of know-how and production possibilities. These include: State-of-the-art plants that make it possible to link different manufacturing processes together to form a single production system. Melting, shaping and manufacturing of components can be controlled as a whole. Effective knowledge management allowing data, experiences and acquired know-how to be utilised where they are needed: with the customer, in the distribution organisations, in the factory. Everywhere and at all times. Efficient IT solutions through which processes can be analysed, improved and directed. The stringent checks during production guarantee consistently high quality within very close tolerances. State-of-the-art testing procedures at all stages of processing, such as 100% surface crack testing of all ETG steels. Motivated employees, taking responsibility in their thoughts and actions. A network of external partners. In association with customers and suppliers, universities and research institutes, we put the emphasis on continually pushing the existing boundaries.

7 7 Short chipping length makes for safe production processes Product range ETG steels are available in various categories, finishes and sizes: Steel category Processes Size range mm Tolerance ETG 88 round drawn h9 > h11 > h12 ground IT6 ETG 100 round drawn h11 > h12 ground IT6 ETG 88 hexagonal drawn SW h11 Bar lengths: m Colour coding: ETG 88 white end face, ETG 100 gold end face Bright-turned and bright-turned/ground to special order Other categories to meet special requirements (e.g. mechanical properties) are available to special order. Regular sizes are available from stock.

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10 10 Material properties and fabrication information Complex components and demanding manufacturing processes require the right material. The more complex the compon ents and the more sophisticated the manufacturing process, the more import ant it is to use the right material. The job of our technical support staff is to support customers in choosing the materials. Information of a more general nature regarding the use of our ETG steels: As with all drawn steels, loads should be applied longitudinally wherever possible. With lateral loading, the tensile strength and proof stress are reduced. Wall thicknesses of less than 1 mm are in the critical boundary range. In view of the notch sensitivity, sharpedged changes in cross-section should be avoided, especially if sudden stresses may occur. Particular care should be taken when using this material at temperatures below 0 C. For bolts, screws and gear wheels, the applicable standards should be consulted. ETG is suitable for threaded bolts with clamping nuts. It is not suitable though for screws with heads under stress except in the case of special fabrication solutions. ETG 88 and ETG 100 do not meet the strength required for classes 8.8 and 10.9 according to DIN EN ISO Uniform mechanical properties over the entire cross section and dimension range Proof stress related to diameter Hardness at different points of cross section > > > > > ETG 100 ETG 88 ETG R p0,2 [N/mm 2 ] Conventional steel > Conventional steel Diameter [mm]

11 11 Chemical composition ETG 88/100, analysis by mass in %: Element C Si Mn P S min max The analysis corresponds to SAE1144 and 44SMn28 (1.0762). Piece analysis and melt analysis may vary according to EN 10087, table 2. Mechanical properties (typical values) ETG 88 ETG 100 Static Dimensions Ø mm Proof stress drawn R p0,2 N/mm ground R p0,2 N/mm Tensile strength R m N/mm ,100 Ultimate elongation A 5 % 7 6 Reduction of area Z % ap. 30 ap. 20 Elastic modulus N/mm 2 ap. 200,000 ap. 200,000 Tensile strength (transverse) R m N/mm 2 ap. 600 ap. 720 Hardness HRC ap. 28 ap. 32 HB 30 ap. 280 ap. 320 Lateral shear strength τ s N/mm 2 ap. 510 ap. 590 Torsional shear strength τ t N/mm 2 ap. 440 ap. 540 Notched impact energy Av RT J ap. 25 ap. 10 Dynamic Tension/compression σ w N/mm 2 ap. 345 ap. 390 Pulsating σ sch N/mm 2 ap. 490 ap. 540 Reverse bending σ bw N/mm 2 ap. 390 ap. 440 Torsional reversal τ tw N/mm 2 ap. 195 ap. 225 Torsional pulsating τ sch N/mm 2 ap. 345 ap. 390 Fatigue strength values for gear wheels ETG 88 ETG 100 Tooth root stress for pulsating load as drawn σ FLim N/mm nitrocarburised σ FLim N/mm Tooth root stress for alternating load as drawn σ WLim N/mm nitrocarburised σ WLim N/mm Straigth teethed gears (m = 2 mm, z= 17) Tooth system quality 7 acc. to DIN Standard values acc. to DIN 3990 resp. ISO 6336

12 12 ETG opens up new possibilities in the manufacture of components: Greater safety Higher quality Lower costs The use of ETG helps to optimise production processes: Shorter process cycles Elimination of some individual operations Weight savings > Considerable cost savings throughout the entire process chain Steeltec We bring energy to steel ETG and standard steels: A comparison of the mechanical properties ETG steels can be used instead of a whole range of standard steels. This cuts down on logistics expenditures, reduces the risk of material confusion and lowers complexity costs. At the same time, individual components can be made in smaller size: they become lighter and less expensive.

13 13 Strength values of standard steels compared to ETG Guaranteed proof stress Rp0.2 [N/mm2] according to EN Steel category Size range mm Material number EN reference Process Free-cutting tempering steels S20 +C SPb20 +C+QT QT+C SMn28 +C SMnPb28 +C+QT QT+C SMn28 +C SMnPb28 +C+QT QT+C S20 +C SPb20 +C+QT QT+C S20 +C SPb20 +C+QT Hardening steels / C35/C35Pb +C C35E +C+QT C35R +QT+C / C45/C45Pb +C C45E +C+QT C45R +QT+C C50 +C C50E +C+QT C50R +QT+C / C60/C60Pb +C C60E +C+QT C60R +QT+C Cr4 +C+QT CrS4 +QT+C Cr4 +C+QT CrS4 +QT+C CrMo4 +C+QT CrMoS4 +QT+C CrMo4 +C+QT CrMoS4 +QT+C CrNiMo6 +C+QT QT+C High-Strength Special Steels ETG 88 drawn 685 ETG 100 drawn 865 +C Cold-drawn +C+QT Cold-drawn and tempered +QT+C Tempered and cold-drawn The guaranteed proof stress for all sizes means that ETG can be used for a very wide range of applications. ETG can be used instead of a whole range of stand ard steels. The deciding factor is what it will be used for. Optimised sizes enable significant savings in weight and cost.

14 14 Changes of the mechanical properties in relation to temperature Longitudinal strength in relation to stress-relieving temperature Typical values, stress-relieving time approx. 2 h Elongation A 5 [%] Tensile strength R m Proof stress R p0,2 [N/mm 2 ] 1,200 1,100 1, Rm ETG 100 Rp ETG 100 Rm ETG 88 Rp ETG 88 ETG 88 ETG Stress-relieving temperature [ C] High-temperature longitudinal strength for ETG 100 in relation to hardening temperature Typical values Tensile strength R m Proof stress R p0,2 [N/mm 2 ] 1,100 1, Rm Rp0, Testing temperature [ C]

15 15 In contrast with cold-drawn steel bars, ETG 100 has low internal stress. However, this stress can cause distortion in situations such as: asymmetrical machining long, narrow components thin-walled components We recommend stress-relieving the material for workpieces of this nature. The stress-relieving temperature should be at least 300 C. Stress-relieving is not usually necessary with ETG 88, as its internal stress levels are so low. For high-precision threaded spindles (i.e. lead screws), ETG 100 should only be used in stress-relieved form (approx C, min. 2 h).

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18 18 Processing information The special manufacturing processes used for ETG steels result in a unique combination of high strength combined with outstanding machining properties. Orientation values for various machining processes Machining guidelines Vc [m/min] and f [mm/rev] ETG 88 ETG 100 Multi-spindle CNC turning Vc roughing (Carbide tooling, coated) f Vc finishing f Vc plunging/parting-off f Multi-spindle CAM turning Vc roughing (carbide tooling, coated) f Vc finishing f Vc plunging/parting-off f Short-bed turning CNC Vc roughing (Carbide tooling, coated) f Vc finishing f Vc plunging/parting-off f Plain turning CNC Vc roughing (Carbide tooling, coated) f Vc finishing f Vc plunging/parting-off f Drilling Vc (Solid carb. drill) f Drilling Vc (HSS, coated) f Reaming Vc (HSS, coated) f External/internal threading Vc (Chase threading, carbide/hss, coated) Internal threading Vc (Cutting, carbide tooling, coated) Internal threading Vc (Forming, carbide tooling, coated) Values as a function of machine and machining parameters

19 19 Surface finish The surface finish of ETG 88/100 corresponds to the specifications in EN ETG 88/100 are tested for cracks as standard. We guarantee a surface finish of 3 for round bars and a surface finish of 2 for hexagonal bars. Please note that for a standard bar, the ends of the bar (up to 50 mm) cannot be tested. If surface imperfections might cause problems (e.g. notch-stress concentration effect with surface hardening), the surface of the material must be removed to at least the allowable depth of imperfection. Non-cutting forming, thread rolling Threads can be rolled on ETG. However, worms, trapezoidal threads, etc., should be cut, not rolled. Other non-cutting processes Punching, bending, swaging, forging, etc., should not be carried out on ETG 88 and ETG 100. Welding ETG 88/100 have a limited weldability. Austenitic electrodes should be used and it should be noted that the strength will decrease significantly. The fracture strength depends on the strength of the weld metal. In order to avoid failures, we recommend carrying out tests before welding the part itself. Best results are achieved using tungsten inert gas (TIG) welding. Welding procedure: tungsten inert gas Welding consumable: X15CrNiMn 18-8 (1.4370) Preheat: 300 C Tensile strength of the welded joint: N/mm 2 ETG is not suitable for laser welding. Brazing ETG can also be brazed, but with consequent loss of strength. It must be allowed to cool slowly, as there is a danger of stress cracks. Surface finishing Most surface finishes can be applied to ETG 88/100. For example, they can be hot-galvanised, chromated, chromiumplated, nickel-plated or alkaline-black - ened without difficulty. Due to the manganese sulphide in the steel, special care must be taken when pickling and neutralising. The temperature at which surface finishing is carried out should not exceed 500 C. Ground material is recommended. For changes in mechanical properties, see diagram of strength values on page 14.

20 20 Information for heat-treating ETG steels The high strength of ETG steels lies in the range of tempered steels, which means that in most cases no additional heat treatment is necessary. If greater abrasion resistance or fatigue strength is needed, various surface hardening processes can be used. The high basic strength guarantees a good underlying structure and ideally fulfils the prerequisites for the following heat treatment processes: Induction hardening (high frequency) Nitrocarburising Salt bath nitrocarburising Gas nitrocarburising Plasma nitrocarburising Induction hardening (HF) Hardness pattern Induction hardening (HF) Treatment temperature: C Quenching media: oil, polymer Achievable hardness: HRC The depth of hardening should be kept to a minimum, generally not more than 1 mm. For complicated parts, an initial stress-relieving at C is recommended. Using water as a quench medium results in higher hardness, however there is a danger that quench cracking will occur. Microhardness HV 0, Distance from surface [mm]

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22 22 Nitrocarburising Hardness pattern Microhardness HV Distance from surface [mm] The hardness of the white layer cannot be measured for technical reasons. According to the literature, the hardness is approx. 1,000 HV.

23 23 Salt bath nitrocarburising Treatment temperature: 570 C Treatment duration: min The treatment time affects the thickness of the hard compound layer. The usual treatment time is 90 min. Thickness of compound layer: µm; the quenching medium must be appropriate for the workpiece: water (warm) for ø <15 mm, oil for larger workpieces. The bath nitrocarburising process creates an abrasion-resistant surface. It also reduces notch sensitivity and increases fatigue strength for reverse bending. Salt bath nitrocarburising results in a loss of substrate strength amounting to approx. 10%. After bath nitrocarburising, no more machining can be carried out. For this reason, if high dimensional accuracy is required, the work piece must be stressrelieved at C before final machining. After bath nitrocarburising, it is advantageous to remove salt residues from workpiece surfaces by brushing. Gas nitrocarburising Treatment temperature: 570 C Treatment duration: 1 3 h Thickness of compound layer: approx. 15 µm Quench medium: water, oil, gas Pretreatment is the same as for bath nitrocarburising. A similarly abrasionresistant surface is created. The process results in a loss of substrate strength amounting to approx. 10%. Plasma nitrocarburising Treatment temperature: C Treatment duration: h Thickness of compound layer: approx. 10 µm This process glow-discharge nitrocarburising in a vacuum has produced good re sults with ETG. Due to the lower treatment temperature, there is less reduc tion in the core strength than with salt bath or gas nitrocarburising. Recommendations Avoid hardening over sharp edges, keyways or lateral holes. Do not harden thin-walled components through the full thickness of the wall. End faces or spherically shaped areas should be stress-relieved at C before hardening. With induction hardening, avoid hardening to a depth greater than 1 mm. Like all rolled-and-drawn material, ETG has a slightly decarburised boundary zone, which means that the hardening effect in this zone is reduced. When hardening gear wheels, the tooth root should also be hardened to a depth of 0.2 mm. Hardening of the drawn surfaces should be avoided due to the possible pres ence of surface imperfections. Due to the notch effect, hardening stresses at the imperfections can cause cracks. To avoid the occurrence of hardening cracks due to hardening stresses, the hardened components should be tempered (200 C, 1 h). There is less danger of hardness cracks occurring in ETG 88 than in ETG 100 due to its lower residual stress. Depending on the nitrocarburising pro c- ess employed, tempering at 350 C for at least 2 h may be necessary to remove the hydrogen that has been introduced. Depth of decarburised zone (experimental values) Dimension Ø 20 mm Ø >20 mm Decarburisation max mm max mm The technical information contained in this document reflects current results obtained using generally accepted testing procedures on production quantities. They do not give a guarantee of the suitability for any particular application. The responsibility lies with the user. Steeltec AG, 07.07

24 Steeltec AG Postfach, CH-6021 Emmenbrücke Telephone , fax Group Companies Steeltec AG Salen, Postfach, CH-9536 Schwarzenbach SG Telephone , fax Steeltec Praezisa GmbH Postfach 6, D Niedereschach Telephone , fax or 1781 Steeltec Fournitures Industrielles Clusiennes S.A.R.L. Boîte postale 81, F Cluses Cedex Telephone , fax Steeltec Toselli S.r.l. Via R. Sanzio 52, I Cassina Nuova di Bollate (MI) Telephone , fax