Revision of hen1317-5: Technical improvements. AC&CS-CRM Group

Transcription

1 Revision of hen1317-5: Technical improvements Luca Felappi Franz M. Müller Project Leader Road Safety Consultant AC&CS-CRM Group

2 Technical innovation for safer and sustainable steel safety barriers Present and Future Cristina Rodríguez R&D Manager - Mieres Tubos (Grupo Condesa) Spain AFB 20 (2) Roadside Design Safety Brussels, Belgium April 11, 2013

3 Table of contents 1. Introduction Background & Needs 2. High Strength Steels HSS (micro-alloyed steels) Characteristics and technical advantages Traditional structural steel vs HSS 3. Advanced metallic coatings Characteristics and technical advantages 4. Conclusions 5. References < 3 >

4 Table of contents 1. Introduction Background & Needs 2. High Strength Steels HSS (micro-alloyed steels) Characteristics and technical advantages Traditional structural steel vs HSS 3. Advanced metallic coatings Characteristics and technical advantages 4. Conclusions 5. References < 4 >

5 1. Introduction Background & Needs 2011 Typologies of RRS defined by National Regulations & Standards Imposed design & materials (usually, hot rolled structural steel S235JR and hot dip galvanizing) Marking compulsory for all safety barriers in Europe New materials & designs RRS assessed through Crash Tests, according to EN Containment level H1 Working width 1.4 m W5 RRS defined by performance parameters Dynamic deflexion 1.1 m Impact severity A < 5 >

6 1. Introduction Background & Needs Smart road design CE Marked RRS properly installed on roadsides Advanced materials and design Reduction in CO2 equivalent emissions < 6 >

7 1. Introduction Background & Needs Advanced Metallic Coatings High strength steels (HSS) Steel safety barriers Ligther, safer and more sustainable steel safety barriers < 7 >

8 Table of contents 1. Introduction Background & Needs 2. High Strength Steels HSS (micro-alloyed steels) Characteristics and technical advantages Traditional structural steel vs HSS 3. Advanced metallic coatings Characteristics and technical advantages 4. Conclusions 5. References < 8 >

9 2. High Stregth Steels HSS (micro-alloyed steels) HSS: micro-alloyed steels with a low carbon content and fine grain structure. During its manufacturing process, temperatures are controlled by doing the socalled Thermo Mechanical rolling. Covered by EN standard. The mechanical properties of the HSS are usually by default more controlled than in the steel grade S235JR. It represents an essential factor when it comes to ensure that the performance of the barrier installed will be as demonstrated by the Crash Test. Same barrier after car accident N2W4A barrier after Crash Test < 9 >

10 2. High Stregth Steels HSS (micro-alloyed steels) Innovation has been turned into a growing tendency in the use of micro-alloyed steels as an alternative to structural steels. During the development process of a steel safety barrier, it is possible a significant reduction in the overall weight/m. Examples when the approach aims to Containment level, working width and impact severity N2W4A barrier, -25% (from ~19kg/m to ~14kg/m) Higher containment level and less working width N2W5A to N2W4A barrier, -15% (from ~16kg/m to ~14kg/m) In both cases, by decreasing of the thicknesses or using of less components per meter and yet increase of the robustness of the system thanks to the higher resistance of the main components. < 10 >

11 2. High Stregth Steels HSS (micro-alloyed steels) Thanks to the significant reduction in the overall weight/m, the use of microalloyed steels allows the reduction of CO2-equivalent emissions, therefore it is possible to provide safety to the roads in a more sustainable way. Regarding the previous example of the N2W4A barrier, it is possible to use less steel (-25%), comparing to other safety barriers with the same performance, when a barrier of such performance is required to be installed in the roadsides. The production process of the micro-alloyed steels is more sustainable as every parameter of the process is more controlled. < 11 >

12 2. High Stregth Steels (HSS) S235JR - yield limit variability 500 Re (MPa) ~90% withing a range of 100 MPa 191 MPa High variability to ensure the same performance of the Crash Test Samples analyzed S235JR, Re (min 235MPa) EN10025 Tensile tests carried out on 200 different coils for different steel products < 12 >

13 2. High Stregth Steels HSS (micro-alloyed steels) 500 S235JR - yield limit variability 450 Re (MPa) Samples analyzed Higher working width Breaking of essential components Micro-alloyed steels The same study carried out on micro-alloyed steel coils shows that 100% of them have a yield limit within a range of 80MPa. < 13 >

14 Table of contents 1. Introduction Background & Needs 2. High Strength Steels HSS (micro-alloyed steels) Characteristics and technical advantages Traditional structural steel vs HSS 3. Advanced metallic coatings Characteristics and technical advantages 4. Conclusions 5. References < 14 >

15 3. Advanced metallic coatings The batch galvanization have shown along history its capability to ensure a corrosion protection during the service life of the barriers. In the last 20 years, the development of continuous metallic coatings has come on in leaps and bounds. Batch galvanization Profiling (black coils) Profiling (coated coils) < 15 >

16 3. Advanced metallic coatings Batch galvanization Coated coils Galvanizing done on profiled components Zinc inmersion times of several minutes to allow significant iron-zinc alloys to form Coating comprised of free zinc and remainder iron-zinc alloys Zinc thickness controlled primarily by inmersion time and rate of withdrawal Galvanized done on flat steel in coils (before profiling) Inmersion times in zinc only a few seconds: alloy formation limited Coating is essentially all free zinc Coating weight controlled by high technology air knives < 16 >

17 3. Advanced metallic coatings Continuous metallic coatings Such coatings do not change the chemical composition of the most used steel grades nor the mechanical properties (indeed, the inmersion time of the steel in the zinc-bath is lower than in any batch galvanization process). The thickness of the layer are thinner comparing to batch galvanization, therefore a lighter but durable finished components are obtained. It represents a reduction in CO2-equivalent emissions as it is required lower total energy units per ton of product galvanized compared with the batch method. The EN10346 standard covers some of the different typologies of advanced metallic coatings that are already present on the market. Increasingly present on the roads due to the approvals by several Road Authorities. < 17 >

18 3. Advanced metallic coatings Typologies of advanced metallic coatings Z (zinc alloy) ZF (zinc-iron alloy) ZA (zinc-alluminium alloy) ZM (zinc-aluminium magnesium alloy) uncovered edges may be self-repaired by the cathodic protection phenomena when magnesium is added in adequate quantities. 1 week of exposure 5 months of exposure 20 months of exposure < 18 >

19 3. Advanced metallic coatings 1 week of exposure 20 months of exposure ZM coating (25µm) < 19 >

20 Table of contents 1. Introduction Background & Needs 2. High Strength Steels (HSS) Characteristics and technical advantages Traditional structural steel vs HSS 3. Advanced metallic coatings Characteristics and technical advantages 4. Conclusions 5. References < 20 >

21 4. Conclusions EN 1317 standard and CE Marking have paved the way for innovation in the development of safety barriers. The combination of smart road design, CE marked RRS properly installed on roadsides and advanced materials (micro-alloyed steels, metallic coatings ), fulfill the current needs for road safety: safer roads + sustainability. The mechanical properties of the micro-alloyed steels are usually more controlled than in the steel grade S235JR, representing an essential factor when it comes to ensure the rigth perfomance of the barrier. A study carried out with 200 coils shows that the variability in the yield limit of S235JR may be roughly 190MPa, whereas in the case of micro-alloyed steels, 80MPa. Micro-alloyed steels allow a significant reduction in terms of overal weight per meter of the safety barrier (were shown examples up to 25%). Continuous metallic coatings has come on in leaps and bounds in the last 20 years. Characteristics and technical advantages were presented, including typologies present in the market. Uncovered edges may be self-repaired by the cathodic protection phenomena when magnesium is added in adequate quantities, as shows a study of exposure carried out with barriers coated with ZM. < 21 >

22 5. References 51 Boletin Vigilancia Tecnológica Sector Metal-Mecánico, Eficiencia en la producción de acero, 2012, OPTI (Observatorio de Prosprectiva Tecnológica Industrial). EN Road Restraint Systems. Performance classes, impact test acceptance criteria and test methods for safety barriers including vehicle parapets EN Road Restraint Systems. Performance classes, impact test acceptance criteria and test methods for safety barriers including vehicle parapets EN Hot rolled products of structural steels. Technical delivery conditions for non-alloy structural steels EN Specification for hot-rolled flat products made of high yield strength steels for cold forming. Delivery conditions for thermomechanically rolled steels EN Continuously hot-dip coated steel flat products. Technical delivery conditions. Strip-Galvanized Guardrail Beams, Bridges and Structural Engineering, Issue B59, 2008, Berichte der Bundesanstalt für Strassenwesen (bast) The Galvanizing Standard, Performance & Durability in Guardrail Technology, 2009, Gregory Industries, Inc < 22 >

23 THANK YOU FOR YOUR ATTENTION

24 Revision of hen1317-5: Technical improvements Luca Felappi Franz M. Müller Project Leader Road Safety Consultant AC&CS-CRM Group