Quench aging

Al-Mg-Si alloys are strengthened by precipitation hardening in which MgjSi is formed. They are not very susceptible to stress-corrosion cracking which only occurs in specimens subjected to a high solution-treatment temperature followed by a slow quench Ageing such material eliminates susceptibility . 

Hi-Tech Scientific Limited (Salisbury, England) recently introduced a stopped-flow (SF-51) instrument with conductivity detection that uses a five-mixer aging block that gives preparative quench aging times in the range of 1.0 ms to >10 s (Fig. 4.16). Preparative quench and stopped-flow experiments can be performed under total thermostatted, anaerobic, and chemically inert conditions. The entire stopped-flow package consists of the sample handling unit, a spectrophotometer, and a data processor based on the Apple lie. 

Figure 3c. Loss modulus (E") vs. temperature at different frequencies for the poly(amide-imide) dried at 190 C-quenched-aged 15 days at 20 C.

STAcondition 1 h at 870 °C(1600 °F), water quench, age 8 hat 595 °C (1100 °F) and air cool. DA(duplex annealed) condition 15minat 870 C, air cool, then 8 h at540 °C (1000 F) and air cool. All fatigue tests conducted at a stress ratio of f =0.1. Open symbols indicate fatigue tests solid symbols, tension tests. 

F Solution treated, quench, age Solution treated, air cool, age LI Age only... 

Effect of solution heat treatment temperature on tensile properties and fracture toughness of 25 mm (1.0 in.) Transage 129 plate. The solution heat treatments were followed by a water quench. Aged at 510 C for 24 h, AC. 

Severe loss of ductility of a metal (or alloy) loss of load carrying capacity of a metal or alloy the severe loss of ductility or toughness or both, of a material, usually a metal or alloy. Many forms of embrittlement can lead to brittle fracture and many can occur during thermal treatment or elevated-temperature service (thermally induced embrittlement). Some of these forms of embrittlement, which affect steels, include blue brittleness, 885 °F (475 °C) embrittlement, quench-age embrittlement, sigma-phase embrittlement, strain-age embrittlement, temper embrittlement, tempered martensite embrittlement, and thermal embrittlement. In addition, steels and other metals and alloys can be embrittled by environmental conditions (environmentally assisted embrittlement). Forms of environmental embrittlement include acid embrittlement, caustic embrittlement, corrosion embrittlement, creep-rupture embrittlement, hydrogen embrittlement, bquid metal embrittlement, neutron embrittlement, solder embrittlement, sobd metal embrittlement, and stress-corrosion cracking. 

Embrittlement of low-carbon steels resulting from precipitation of solute carbon of existing dislocations and from precipitation hardening of the steel caused by differences in the solid solubility of carbon in ferrite at different temperatures. Quench age embrittlement is usually caused by rapid cooling of the steel from a temperature shghtly below ACl (the temperature at which austenite begins to form), and can be minimized by quenching from lower temperatures. 

Peak-hardened Solution treated and quenched aged at 220 °C (430 >IOfor4 /2h... 

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