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A novel low-density steel with high aluminium content was, for the first time, manufactured as coils by the conventional industry process consisting of continuous casting followed by hot-rolling and cold-rolling. The duplex δ-TRIP microstructure, comprising a mixture of blocky retained austenite and both δ- and α-ferrite, was then produced by laboratory-scale heat treatments. The microstructure generation was achieved by an intercritical annealing followed by direct quenching, which was the same process as that for producing conventional dual-phase steels. The alloy exhibits quite interesting mechanical properties with a combination of 930 MPa tensile strength and of 21% total elongation, both in rolling and transverse directions. The formability of this novel alloy was assessed and discussed.

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Two ferritic interstitial-free steels with approximately the same amount of solid solution strengthening by addition of 2 wt-% silicon and 4 wt-% aluminium are investigated using quasi-static tensile and dynamic impact tests. The addition of 2 wt-% silicon (2Si) results in brittle fracture in V-notched Charpy impact tests at ambient temperature, whilst the 4 wt-% aluminium-containing (4Al) steel has high absorbed energy of 320 ± 12 J cm−2. In addition, the 4Al steel has a ductile-to-brittle-transition temperature (DBTT) ∼60°C lower than the 2Si steel. It is proposed that the addition of silicon suppresses dislocation cross-slip at high strain rate and is responsible for the observed cleavage fracture and high DBTT in the 2Si steel. The ease of dislocation slip in the 4Al steel increases the impact toughness.

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The development of the cotton fiber is very sensitive to temperature variation, and high temperature stress often causes reduced fiber yield and fiber quality. Short term high temperature stress often occurs during cotton production, but little is known about the specific timing and duration of stress that affects fiber development. To make this clear, pot experiments were carried in 2014 and 2015 in a climate chamber using cotton cultivars HY370WR (less sensitive variety) and Sumian 15 (heat sensitive variety), which present different temperature sensitivities. Changes of the most important fiber quality indices (i.e., fiber length, fiber strength and marcironaire) and three very important fiber development components (i.e., cellulose, sucrose and callose) were analyzed to define the time window and critical duration to the high temperature stress at 34°C (max38°C/min30°C). When developing bolls were subjected to 5 days of high temperature stress at different days post anthesis (DPA), the changes (Δ%) of fiber length, strength and micronire, as a function of imposed time followed square polynomial eq. as y=a+bx+cx 2 , and the time around 15 DPA was the most sensitive period for fiber quality development in response to heat stress. When 15 DPA bolls were heat-stressed for different durations (2, 3, 4, 5, 6, 7 days), the changes (Δ%) of fiber length, strength and micronire, as a function of stress duration followed logistic equations y= A 1 −A 2 1+(x/x 0) p +A 2. Referred to that 5, 10 and 15% are usually used as criteria to decide whether techniques are effective or changes are significant in crop culture practice and reguard to the fiber quality indices change range, we suggested that 5% changes of the major fiber quality indices (fiber length, fiber strength and micronaire) and 10% changes of fiber development components (cellulose, sucrose and callose) could be taken as criteria to judge whether fiber development and fiber quality have been significantly affected by high temperature stress. The key time window for cotton fiber development in response to the high temperature stress was 13-19 DPA, and the critical duration was about 5 days.

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