Hydrogen Assisted Fracture of 30MnB5 High Strength Steel: A Case Study

When steel components fail in service due to the intervention of hydrogen assisted cracking, discussion of the root cause arises. The failure is frequently blamed on component design, working conditions, the manufacturing process, or the raw material. This work studies the influence of quench and tempering and hot-dip galvanizing on the hydrogen embrittlement behavior of a high strength steel. Slow strain rate tensile testing has been employed to assess this influence. Two sets of specimens have been tested, both in air and immersed in synthetic seawater, at three process steps: in the delivery condition of the raw material, after heat treatment and after heat treatment plus hot-dip galvanizing. One of the specimen sets has been tested without further manipulation and the other set has been tested after applying a hydrogen effusion treatment. The outcome, for this case study, is that fracture risk issues only arise due to hydrogen re-embrittlement in wet service

Antifragile Philosophy in R&D Projects: Applying Q Methodology and the Possibility of Open Innovation

Antifragile philosophy can be the key to improving the management of organizations that base their activity on research and development (R&D) projects. These are types of projects with the greatest uncertainty in all aspects, and the application of antifragile philosophy can result in streamlining their management and development. In this article, the Q methodology is used to investigate whether organizations in R&D environments have antifragile characteristics. To this end, 15 innovation experts from research institutes located in Northern Spain were interviewed about their position regarding project management behaviors that are related to antifragile philosophy. As a result, it was verified that the characteristics of an ideal system of a research institute with antifragile philosophy are multidisciplinary and autonomous teams with a capacity for rapid response and adaptation to the environment

Wear And Friction Evaluation Of Different Tool Steels For Hot Stamping

The aim of this work is to investigate the durability of tool steels for hot stamping by comparing the wear resistance of three hot work tool steels. Friction and wear behaviours of different tool steels sliding against a 22MnB5 uncoated steel at elevated temperatures were investigated using a high-temperature version of the Optimol SRV reciprocating friction and wear tester at temperatures of 40 and 200°C. Our results show that friction decreased with increasing temperature, whereas wear of the tool steel increased with temperature for the second and the third tested tool steels. The slightly better wear behaviour of steel specimen 1 comes from the hardness of the carbides in the martensitic microstructure, which are rich in vanadium.The authors gratefully acknowledge the funding provided by the Department of Research and Universities of the Basque Government under Grant no. IT947-16 and the University of the Basque Country UPV/EHU under Program no. UFI 11/29

Retained Austenite Control for the Soft Machining of High-Hardness Tool Steels

Most high-hardness tool steels comprising forming dies require expensive finish machining operations to compensate for the dimensional distortion and surface oxidation caused by the die heat treatment. Precipitation-hardening (PH) tool steels allow for soft finish machining followed by an aging treatment without major deformation or oxidation in the die, but exhibit poor wear performance owing to the lack of carbides in their structure. This drawback can be overcome by combining laser cladding technology, austenite retention, and cryogenic treatments. Hence, an alternative die manufacturing route based on laser cladding was explored. The forming surface of a modified chemistry tool steel die was subjected to cladding. The martensite finish (M-f) temperature of the steel was tuned to enhance austenite retention at room temperature. The cladded surface was then machined in a reduced-hardness condition resulting from retained austenite formation. Subsequent deep cryogenic treatment of the die favoured the retained-austenite-to-martensite transformation, thereby increasing the die hardness without major distortion or oxidation. This process combined the advantages of high-carbide-bearing tool steels and PH steels, allowing for a die with hardness exceeding 58 HRC to be finish machined at <52 HRC. Controlling the occurrence of retained austenite represents an effective strategy for achieving new manufacturing scenarios.The authors gratefully acknowledge the funding provided by the Department of Research and Universities of the Basque Government under Grant No. IT947-16 and the University of the Basque Country UPV/EHU under Program No. UFI 11/29

Hydrogen Assisted Fracture of 30MnB5 High Strength Steel: A Case Study

When steel components fail in service due to the intervention of hydrogen assisted cracking, discussion of the root cause arises. The failure is frequently blamed on component design, working conditions, the manufacturing process, or the raw material. This work studies the influence of quench and tempering and hot-dip galvanizing on the hydrogen embrittlement behavior of a high strength steel. Slow strain rate tensile testing has been employed to assess this influence. Two sets of specimens have been tested, both in air and immersed in synthetic seawater, at three process steps: in the delivery condition of the raw material, after heat treatment and after heat treatment plus hot-dip galvanizing. One of the specimen sets has been tested without further manipulation and the other set has been tested after applying a hydrogen effusion treatment. The outcome, for this case study, is that fracture risk issues only arise due to hydrogen re-embrittlement in wet service

Susceptibilidad a la fragilización por hidrógeno de aceros de alta resistencia: comportamiento en ambientes marinos y modelización de patrones de agrietamiento

The use of high strength steels is increasing steadily due to the cost, weight and performance advantages they offer. As a drawback, these materials are sensitive to environmental hydrogen embrittlement processes that reduce drastically the working loads they can resist, what limits their spreading to many applications. Since this embrittlement is catalyzed by corrosion prevention strategies involving cathodic protection, seawater exposed structures are specially concerned for the attack of hydrogen. Thus, high strength steel use for wet applications must be carefully assessed. In this context, this thesis deals with the study of the hydrogen embrittlement susceptibility of industrial high strength steels for immersed service in mooring chains and bolted joints. Based on the slow strain rate tensile testing method, the influence of cathodic protection and water temperature has been studied for submerged mooring chain steel grades R4, R5 and bolt steel class 10.9. A finite difference modeling strategy for predicting the cracking pattern observed during the experimental work is proposed.El empleo de aceros de alta resistencia está en constante aumento debido a las ventajas que ofrecen en coste, peso y rendimiento. Como contrapartida, estos materiales son sensibles a procesos de fragilización ambiental por hidrógeno que reducen de forma drástica las cargas que pueden resistir en servicio, lo que limita su extensión a muchas aplicaciones. Teniendo en cuenta que esta fragilización se cataliza en presencia de estrategias de protección catódica contra la corrosión, las estructuras en contacto con agua marina están especialmente expuestas al ataque por hidrógeno. En consecuencia, el uso de aceros de alta resistencia en contacto con agua debe ser analizado con cautela. En este contexto, esta tesis estudia la susceptibilidad a la fragilización por hidrógeno de aceros de alta resistencia de uso industrial para cadenas de fondeo y uniones atornilladas sumergidas. Se ha estudiado la influencia del tipo de protección catódica y la temperatura del agua en aceros para cadena de grados R4, R5 y acero de tornillería de clase 10.9, aplicando el método de ensayo de tracción a baja velocidad de deformación. Los patrones de agrietamiento observados en el trabajo experimental se han modelizado mediante una estrategia de cálculo por diferencias finitas

Susceptibilidad a la fragilización por hidrógeno de aceros de alta resistencia: comportamiento en ambientes marinos y modelización de patrones de agrietamiento

The use of high strength steels is increasing steadily due to the cost, weight and performance advantages they offer. As a drawback, these materials are sensitive to environmental hydrogen embrittlement processes that reduce drastically the working loads they can resist, what limits their spreading to many applications. Since this embrittlement is catalyzed by corrosion prevention strategies involving cathodic protection, seawater exposed structures are specially concerned for the attack of hydrogen. Thus, high strength steel use for wet applications must be carefully assessed. In this context, this thesis deals with the study of the hydrogen embrittlement susceptibility of industrial high strength steels for immersed service in mooring chains and bolted joints. Based on the slow strain rate tensile testing method, the influence of cathodic protection and water temperature has been studied for submerged mooring chain steel grades R4, R5 and bolt steel class 10.9. A finite difference modeling strategy for predicting the cracking pattern observed during the experimental work is proposed.El empleo de aceros de alta resistencia está en constante aumento debido a las ventajas que ofrecen en coste, peso y rendimiento. Como contrapartida, estos materiales son sensibles a procesos de fragilización ambiental por hidrógeno que reducen de forma drástica las cargas que pueden resistir en servicio, lo que limita su extensión a muchas aplicaciones. Teniendo en cuenta que esta fragilización se cataliza en presencia de estrategias de protección catódica contra la corrosión, las estructuras en contacto con agua marina están especialmente expuestas al ataque por hidrógeno. En consecuencia, el uso de aceros de alta resistencia en contacto con agua debe ser analizado con cautela. En este contexto, esta tesis estudia la susceptibilidad a la fragilización por hidrógeno de aceros de alta resistencia de uso industrial para cadenas de fondeo y uniones atornilladas sumergidas. Se ha estudiado la influencia del tipo de protección catódica y la temperatura del agua en aceros para cadena de grados R4, R5 y acero de tornillería de clase 10.9, aplicando el método de ensayo de tracción a baja velocidad de deformación. Los patrones de agrietamiento observados en el trabajo experimental se han modelizado mediante una estrategia de cálculo por diferencias finitas

Hydrogen embrittlement susceptibility of R4 and R5 high-strength mooring steels in cold and warm seawater

Hydrogen embrittlement susceptibility ratios calculated from slow strain rate tensile tests have been employed to study the response of three high-strength mooring steels in cold and warm synthetic seawater. The selected nominal testing temperatures have been 3 ◦C and 23 ◦C in order to resemble sea sites of offshore platform installation interest, such as the North Sea and the Gulf of Mexico, respectively. Three scenarios have been studied for each temperature: free corrosion, cathodic protection and overprotection. An improvement on the hydrogen embrittlement tendency of the steels has been observed when working in cold conditions. This provides a new insight on the relevance of the seawater temperature as a characteristic to be taken into account for mooring line design in terms of hydrogen embrittlement assessment

Influence of the laser deposited 316L single layers on corrosion in physiological media

A multilayer laser-deposited lining of AISI 316L stainless steel makes a regular structural steel surface corrosion resistant in physiological media. Despite the application of single-layer stainless-steel linings being economically beneficial and allowing thinner surface modifications, dilution effects that modify the pitting resistance of the coating must be accounted for. In order to study the feasibility of employing single-layer coatings instead of multilayer coatings for corrosion protection in physiological media, a polarization testing back-to-back comparison was performed between laser-deposited AISI 316L monolayers on 42CrMo4 quenched and tempered steel and cold-rolled AISI 316L sheet in Dulbecco's Phosphate Buffer Solution at 36 degrees C. A higher dispersion in pitting resistance, ranging from 800 mV to 1200 mV, was found on the coated samples, whereas the cold-rolled material was more stable in the 1200 mV range. The resulting differences in corrosion rates and pitting potentials open the discussion on whether the chemical composition deviations on AISI 316L dilution layers are acceptable in terms of surface functionality in medical devices

Influence of the laser deposited 316L single layers on corrosion in physiological media

A multilayer laser-deposited lining of AISI 316L stainless steel makes a regular structural steel surface corrosion resistant in physiological media. Despite the application of single-layer stainless-steel linings being economically beneficial and allowing thinner surface modifications, dilution effects that modify the pitting resistance of the coating must be accounted for. In order to study the feasibility of employing single-layer coatings instead of multilayer coatings for corrosion protection in physiological media, a polarization testing back-to-back comparison was performed between laser-deposited AISI 316L monolayers on 42CrMo4 quenched and tempered steel and cold-rolled AISI 316L sheet in Dulbecco's Phosphate Buffer Solution at 36 degrees C. A higher dispersion in pitting resistance, ranging from 800 mV to 1200 mV, was found on the coated samples, whereas the cold-rolled material was more stable in the 1200 mV range. The resulting differences in corrosion rates and pitting potentials open the discussion on whether the chemical composition deviations on AISI 316L dilution layers are acceptable in terms of surface functionality in medical devices