ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
High strength steels containing significant fractions of retained austenite have beendeveloped in recent years, and are the subject of growing commercial interest when associated withthe TRIP phenomenon during deformation. A new process concept “quenching and partitioning”(Q&P) has been proposed by CSM/USA, and the results show the potential to create a new kind ofsteel microstructure with controlled amounts of retained austenite, enriched by carbon partitioning.Four steels containing C, Si, Mn, Ni, Cr and Mo, were designed with variation in the Ni and Ccontent, aiming to decrease Bs temperature and to suppress carbide formation during thepartitioning treatment. Several heat-treatment procedures were performed in specimens previouslymachined for tensile testing, while x-ray diffraction was used to determine the fraction of retainedaustenite. The tensile test results showed that except for the high C high Ni alloy, most of theprocessing conditions resulted in strengths superior to those of advanced high strength steels(AHSS), although it is importantly recognized that higher alloy additions were used in this study, incomparison with conventional AHSS grades.. A variety of strength and ductility combinations wereobserved, confirming the potential of the Q&P process and illustrating the strong influence of thefinal microstructure on the mechanical properties. Experimental results for samples partitioned at400 °C indicate that higher ultimate tensile strength is associated with higher fraction of retainedaustenite for multiple heat treatments of each alloy investigated. The amount of retained austeniteobtained was generally lower than that predicted by the model. Further studies are in progress tounderstand the influence of alloying and processing parameters (time/temperature) on thepartitioning of carbon and precipitation of transition carbides
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/15/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.4476.pdf
Permalink
