AL6061 ek popular aluminium alloy hai, jo magnesium aur silicon ke mix se banta hai. Ye lightweight, strong, aur corrosion-resistant hota hai, isliye aeroplanes, bikes, aur automotive parts mein use hota hai. T651 ka matlab hai ki yeh alloy age-hardened aur stress-relieved hai. Ab iska age hardening process samajhte hain:
Age Hardening in AL6061-T651
Age hardening (ya precipitation hardening) se AL6061 ki strength badhti hai. Ye process teen steps mein hota hai:
- Solution Heat Treatment:
- Alloy ko ~530°C tak garam kiya jata hai.
- Isse magnesium aur silicon ke particles aluminium matrix mein dissolve ho jate hain, jaise sugar pani mein ghulta hai.
- Ye ek uniform “solid solution” banata hai.
- Quenching:
- Garam alloy ko jaldi se thanda kiya jata hai (usually pani mein).
- Isse dissolved particles “freeze” ho jate hain aur ek supersaturated solid solution ban jata hai.
- Thandapan itna fast hota hai ki particles ko precipitate banne ka time nahi milta.
- Aging (Artificial Aging for T651):
- Thanda alloy ko fir se ek lower temperature (~175°C) pe rakha jata hai kuch hours ke liye.
- Is stage pe chhote-chhote precipitates (jaise Mg₂Si) bante hain, jo alloy ke andar spread hote hain.
- Ye precipitates dislocations (metal ke internal defects) ko block karte hain, jisse alloy hard aur strong ho jata hai. T651 mein, aging ke baad alloy ko stretching karke stress-relieve bhi kiya jata hai (1-3% strain). Isse internal stresses kam hote hain, aur material ka warping ya cracking ka risk ghat jata hai.
AL6061-T651 ki Properties
- Strength: T651 temper mein AL6061 ki tensile strength ~310 MPa hoti hai, jo T6 se thodi better hai stress-relieving ki wajah se.
- Hardness: Ye kaafi hard hota hai, lekin brittle nahi.
- Uses: Aircraft structures, yacht frames, automotive chassis, ya high-stress parts.
Key Points
- T651 ka aging artificial hai, matlab controlled temperature pe kiya jata hai, natural aging (room temp pe) se different.
- Age hardening se AL6061 ki microstructure mein precipitates bante hain, jo iski strength 2-3 times badha dete hain raw aluminium ke comparison mein.
- Agar zyada aging ho jaye (over-aging), toh precipitates bade ho sakte hain, aur alloy thoda soft ho sakta hai.