Due to its well-known superior strength to weight ratios, titanium has become a more and more critical material choice in aerospace applications which require heavy loading.
Due to titanium’s high chemical activity welding can be a real challenge but to overcome this, new technologies are being developed which uses the slag pool and argon to shield the weld site from interstitial element contamination. Continue reading
Category Archives: High Strength Steels
CMnAlSi TRIP Steels: Part Two
Key characteristics of TRIP steels include good strength and high ductility levels and specifically, an increase of the work hardening rate at higher strain rates which is critical for stamping and forming applications.
Studying the microstructural changes in relation to the chemical composition and applied heat treatments gives excellent potential for material development and opens opportunities to further improve performance in a crash situation.
CMnAlSi TRIP Steels: Part One
Continued material development in the automotive has given rise to a new generation of HSLA grades which are characterized by excellent strength and high ductility levels.
Studies of microstructure changes in high strength CMnAlSi steel after austenitization show that it is not possible to obtain a fully austenitic region with the addition of Al or Si higher than about 1.5% and actually these two elements strongly stabilize ferrite.
Application of Microalloyed HSLA Steel: Part Two
For many steel grades microalloying with niobium is the key to achieve their characteristic property profile.
Microalloyed HSLA steels were among the first high strength steel grades used in vehicle construction. In some recent passenger cars they account for up to 40% of the body mass.
Application of Microalloyed HSLA Steel: Part One
Microalloy (MA) or High Strength Low Alloy (HSLA) steels constitute an important category of steels estimated to be around 12% of total world steel production.
HSLA steel typically contains 0.07 to 0.12% carbon, up to 2% manganese and small additions of niobium, vanadium and titanium (usually max. 0.1%) in various combinations.
Copper Bearing HSLA Steel: Part Two
The addition of copper in HSLA steels has been found to greatly benefit the strength levels of steels used for among other applications, offshore structures, pipelines and ship hulls.
In combination with copper additions, low carbon content is also essential for attaining the desired effects and during the last three decades, research has also extended to comparing the benefits of hot rolling versus quenching and tempering to make further gains in quality of the material properties.
High Carbon Steels
Generally, the high carbon steels contain from 0.60 to 1.00% C with manganese contents ranging from 0.30 to 0.90%.
The pearlite has a very fine structure, which makes the steel very hard. Unfortunately this also makes the steel quite brittle and much less ductile than mild steel.
Multi Phase Twinning-Induced Plasticity (TWIP) Steel
The iron-manganese TWIP steels, which contain 17-20% of manganese, derive their exceptional properties from a specific strengthening mechanism: twinning. The steels are fully austenitic and nonmagnetic, with no phase transformation. The formation of mechanical twins during deformation generates high strain hardening, preventing necking and thus maintaining a very high strain capacity.
High Strengths Steels: TRIP Steels
TRIP-aided multiphase steels are a new generation of low-alloy steels that exhibit an enhanced combination of strength and ductility, thus satisfying the requirements of automotive industry for good formable high-strength steels.
After the thermal treatment of TRIP steels, a triple-phase microstructure is obtained, consisting of ferrite, bainite and retained austenite. TRIP steels are essentially composite materials with evolving volume fractions of the individual phases.