Very Short and Very Long Heat Treatments in the Processing of Steel

Abstract

It is conventionally assumed in the mass production of steels that the processing time must be reasonable and that the material must have uniform properties. The consequence is that short heat-treatments cannot be tolerated since the scale of engineered products may be so large that uniform temperatures cannot be achieved. Similarly, thermal treatments requiring several days or weeks are not considered practical because of productivity concerns.In this paper I will show that these conservative ideas are a huge disadvantage to the creation of radically different steels whose manufacture could lead to an improvement in the quality of life. Indeed, such steels are capable of wiping out the competition from newcomers in the field of structural materials, such as the infamous carbon nanotubes and metal-matrix composites.

Microstructural and Mechanical Properties of the Intercritically Reheated Coarse Grained Heat Affected Zone (ICCGHAZ) of an API 5L X80 Pipeline Steel

“…The reversion into the austenitic condition from low temperature ferrite during heating, due to high temperatures gradient imposed by welding, results in a superheated ferritic microstructure increasing the diffusivity and driving force for austenite formation. [9]. The initial coarse grained microstructure reheated into the dual phase field allows preferential nucleation and growth of austenite along the prior austenite grain boundaries.…”

Metallographic Analysis of Kinetically Activated Bainite (KAB) Welds

“…The bainite reaction is thought to be of a displacive character, therefore the rate limiting factor is the formation of bainite nuclei [6,7]. Since the latter involves the paraequilibrium partitioning of carbon [8], the transformation kinetics are slowed down exponentially as the temperatures decrease [9]. To ensure low transformation temperatures and a carbide-free bainitic microstructure, these alloys contain high concentrations of carbon close to 0.8% and silicon contents of about 1.5% [10].…”

Study on Downhill Welding Mild Steel Using Laser-MAG Hybrid Welding

“…At present, the investigations on low power density laser-arc hybrid welding are mainly focused on laser-TIG welding technology, the interaction between laser and MIG=MAG arc is still focused on high power density laser [13,14]. Besides, lots of articles involve the manufacturing process of steel [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31].…”