Air-Hardening Die-Forged Con-Rods—Achievable Mechanical Properties of Bainitic and Martensitic Concepts

Three air-hardening forging steels are presented, concerning their microstructure and their mechanical properties. The materials have been produced industrially and achieve either bainitic or martensitic microstructures by air-cooling directly from the forging heat. The bainitic steels are rather conservative steel concepts with an overall alloy concentration of approximately 3 wt.%, while the martensitic concept is alloyed with 4 wt.% manganese (and additional elements), and therefore belongs to the recently developed steel class of medium manganese steels. The presented materials achieve high strengths (YS: 720 MPa to 850 MPa, UTS: 1055 MPa to 1350 MPa), good elongations (Au: 4.0 MPa to 5.9 MPa, At: 12.3 MPa to 14.9 MPa), and impact toughnesses (up to 37 J) in the air-hardened condition. It is shown that air-hardened steels achieve properties close to standard Q + T steels, while being produced with a significantly reduced heat treatment.

Hydrogen Absorption during Case Hardening of Steels EN20MnCr5 (SAE5120) and EN18CrNiMo7-6 (SAE4820)

Damages to case-hardened components are often associated with the phenomenon of hydrogen embrittlement due to their specific fracture pattern. In the present work, the effects of the case hardening process on the hydrogen content in the material were investigated and the effects of hydrogen on the mechanical properties were examined. In order to determine not only the influence of the heat treatment process but also the influence of the material, the case-hardening steels EN20MnCr5 (SAE5120) and EN18CrNiMo7-6 (SAE4820) with different degrees of purity were investigated. From the results it can be deduced that the sulphidic and oxidic inclusions have no significant influence on the hydrogen content. When checking the mechanical properties, it was shown in the incremental step loading technique according to ASTM F1624 that a purely case-hardened condition only has a slight tendency to hydrogen embrittlement. However, if the material is additionally loaded with hydrogen, the material fails significantly below the maximum expected load in the incremental step loading test, which is to be interpreted as a clear indication of failure due to hydrogen embrittlement. However, the fracture patterns of these two states do not show any significant differences. Therefore, it does not seem possible to attribute damage to a case-hardened component to hydrogen embrittlement on the basis of the fracture pattern alone.

CARTECH MP35N

CarTech MP35N is a wrought Co-Ni-Cr-Mo alloy that possesses a unique combination of ultra-high tensile strength (up to 2070 MPa, or 300 ksi), good ductility and toughness, and excellent corrosion resistance. The unique properties of CarTech MP35N are developed through work hardening, phase transformation, and aging. If the alloy is used in the fully work hardened condition, service temperatures up to 400 °C (750 °F) are suggested. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Co-134. Producer or source: Carpenter Technology Corporation.

Citric Acid Effect in High early Type Portland Cement Pastes and Mortars

The influence of citric acid in the properties of high strength Portland cement pastes and mortars, both in fresh and hardened condition, was evaluated. The content of citric acid varied from 0 to 0.8 wt%. Tests were carried out in cement pastes to determine the water required for normal consistency and initial and final setting times. Mortars cements were tested to define bulk density, consistency index, air content in the fresh condition and compressive strength after 7, 14, and 28 days. Analysis by XRD was also performed. The results showed that the use of citric acid as a retardant additive is a viable procedure, because it increased the mechanical strength after 14 days and improved the mortar workability.

WIELAND DURO ELMEDUR

Wieland Duro Elmedur B2 is a heat-treatable copper-beryllium alloy. This alloy exhibits high hardness and good electrical conductivity in the age hardened condition. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on forming, heat treating, and machining. Filing Code: Cu-910. Producer or source: Wieland Duro GmbH.

UDDEHOLM FORMAX

Uddeholm Formax is a high-manganese, low-carbon, non-alloy cold work tool steel that is primarily used in the non-heat-treated condition. For special applications it is used in the case-hardened condition. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on forming, heat treating, and joining. Filing Code: TS-793. Producer or source: Uddeholms AB.

WIELAND DURO ELMEDUR HA

Wieland Duro Elmedur HA is a heat-treatable copper-cobalt-nickel-beryllium alloy. In the age hardened condition, this alloy exhibits high electrical and thermal conductivity along with moderate strength and hardness. This datasheet provides information on composition, physical properties, and hardness. It also includes information on joining. Filing Code: Cu-906. Producer or source: Wieland Duro GmbH.

CARTECH CUSTOM AGE 725

CarTech Custom Age 725 is a precipitation hardenable nickel-chromium-molybdenum-niobium alloy that displays outstanding corrosion resistance, similar to that of alloy 625 and superior to that of alloy 718, along with high strength in the age-hardened condition. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on corrosion resistance as well as forming. Filing Code: Ni-757. Producer or source: Carpenter Technology Corporation.

The influence of iron impurities on the compression behaviour of Al-2.24Mg-2.09Li alloy

As a major impurity element in aluminium-lithium (Al-Li) alloys, iron (Fe) reduces formability, fracture toughness and fatigue resistance by solidifying into Al6Fe and Al3Fe particles. The research was performed in order to estimate the influence of Fe impurities on the compression behaviour of Al-2.24Mg-2.09Li alloy. The investigation was performed on the samples in as cast and solution hardened condition. The solution hardening was applied to improve the mechanical properties by dissolving intermetallic particles and enriching ?Al matrix with Mg. However, the higher strength properties and temperature increase during the compression testing were observed in as cast condition. Microstructural investigation revealed significant differences in microstructure changes between the samples in as cast and solution hardened condition. In as cast sample the barrelling effect led to the unequal deformation and surface texture development. The eutectic Al3Fe particles located in the ?Al interdendritic areas did not significantly impact microstructure changes. Even due the solution hardening led to enrichment of ?Al matrix with Mg and Fe, the Al3Fe particles were not dissolved. The coarse morphology of Al3Fe particles and location at the grain boundaries of ?Al grains contributed to low energy intergranular fracture. The fracture nucleation and propagation across the grain boundaries resulted in lower strength values.

Microstructure and Properties of Advanced Tool Steels

In this work, the microstructure and mechanical properties of four types of high-speed tool steels (Vanadis 30, Vanadis 60, ASP 2052 and S 705) were studied. The steel S 705 was made by conventional ingot metallurgy technology, and other types of steels were manufactured by powder metallurgy technology. All studied steels were examined both in the soft state and further in the hardened condition with subsequent tempering. Microstructure of metallographic samples and fracture areas was studied by electron microscopy. Hardness, tensile properties and notch toughness were determined. Significant differences in the properties of steels in both studied states were documented.