PROPERTIES OF Al 6063 BY USING EQUAL CHANNEL

PROPERTIES OF Al 6063 BY USING EQUAL CHANNEL ANGULAR PRESSING PROCESS Submitted by E. KUMAR B. ANANTHA KUMAR T. ASHOK KUMAR P. KIRAN KUMAR G. SIVA (14 FF 5 A 0302) (13 FF 1 A 0309) (13 FF 1 A 0351) (13 FF 1 A 0333) (13 FF 1 A 0322)

ABSTRACT �Equal Channel Angular Pressing (ECAP) is for modifying microstructure in producing ultra-fine grained materials (UFG). It consists of pressing test samples through a die containing two channels, equal in cross section and intersecting at an angle φ and a corner angle ψ. As a result of pressing, the sample theoretically deforms by simple shear and retains the same cross sectional area to repeat the pressing for several cycles. The 6063 -T 835 aluminium alloy was examined after six pressing operations by route BC in a φ = 90° and ψ = 16° die. Mechanical behaviour of the ECAP processed material was investigated by uniaxial tensile tests. It was found that, the ECAP process increases the mechanical properties. The significant increase in ultimate tensile strength (σUTS), yield strength (σYS) and strength to fracture (σF) after ECAP was observed and discussed by two strengthening mechanisms.

INTRODUCTION • Aluminum 6063 alloys are versatile materials which are widely used in manufacturing several parts in the automobile and aircraft industries. • The aircraft and aerospace industry uses aluminium alloys because it is much lighter than steel and every kilogram of weight reduction results in greater fuel savings and higher payloads. • The equal channel angular pressing is relatively recent method for producing severe plastic deformation in materials subjected to it resulting in refinement of their structure and enhancement of their mechanical characteristics.

PROCESS �The ECAP die is composed of two channels with identical rectangular cross sections connected through the intersection at a specific angle, usually 90°. The cross section can also be circular or square. The work piece is machined to fit within the channel and extruded through two intersecting channels with the same cross section using a plunger. During the ECAP process, adequate lubrication is essential because of frictional influences, tool wear and the loads necessary for plastic deformation. One important advantage of the ECAP process is that it can be repeated several times without changing the dimensions of the work piece, and the applied strain can be increased to any level; these advantages mean that the severe strains that can be applied and a simple shear deformation mode contribute to the strong and unusual properties of the material produced.

ECAP

Materials, Equipment and Experimental Procedures Materials • Al 6063 is an aluminium alloy with magnesium and silicon as the alloying elements. The standard controlling its composition is maintained by The Aluminium Association. It has generally good mechanical properties and is heat treatable and wieldable. It is similar to the British aluminium alloy HE 9 • It allows complex shapes to be formed with very smooth surfaces fit for anodizing and so is popular for visible architectural applications such as window frames, doorframes, roofs, and sign frames. Application requiring higher strength typically use 6062 or 6063

Chemical composition The alloy composition of 6063 is: • Silicon minimum 0. 2%, maximum 0. 6% by weight • Iron no minimum, maximum 0. 35% • Copper no minimum, maximum 0. 10% • Manganese no minimum, maximum 0. 10% • Magnesium minimum 0. 45%, maximum 0. 9% • Chromium no minimum, maximum 0. 10% • Zinc no minimum, maximum 0. 10% • Titanium no minimum, maximum 0. 10% • Other elements no more than 0. 05% each, 0. 15% total • Remainder Aluminium

ECAP PROCESS EQUIPMENT 1. DIE 2. PLUNGER(spring type plunger) 3. BILLET

DIE Design die by manually as per required dimensions. This die consists of angular channel. As per our requirement we design our channel diameter. Avoiding sharp corners in the channel to reduce the fractures. Hardened steel used in die design.

�PLUNGER �The spring must be compressed for insertion and these forces can damage the spring if the technician is not careful. �Spring loaded devices protect the spring within a cylindrical body that holds it in place. A plunger extends from the tip of the plunger to allow activation of the spring inside. Because the spring is held firmly in place, there is no danger of it escaping. During installation, tool forces are directed at the plunger body rather than the spring, reducing the chance of spring damage.

BILLET The billet is Al 6063.

Experimental Procedures Design and manufacturing of the equal channel angular pressing die, ECAP.

MECHANICAL PROPERTIES OF AL 6063 BEFORE ECAP PROCESS Rod and Bar Up to 150 mm Dia. Property Value Proof Stress 190 MPa Tensile Strength 230 MPa Elongation A 50 mm Hardness Brinell Elongation A 5% 80 HB 7%

�AFTER ECAP PROCESS Heat No 203 Tensile Strengh Yield strength Elongation (N/mm 2) (%) 256. 4 221. 3 13. 25

Advantages of ecap process �Very large deformation strain can be obtained after repeated passes without changing the shape of billets. �Good refinement structure and no material reduction. �Improve mechanical properties. �The areas exposed to tensile stresses are limited during deformation.

Grain sizes

�Result and discussion �All of the stress–strain results for all experiments are based on the current configuration of the specimen

Design in CATIA Assembly part

Drafting

Result in ANYSIS

CONCLUSION • In this study, the mechanical behaviour of 6063 -T 835 aluminium alloy subject to the ECAP process was investigated and compared to the material with no ECAP processing. • It was determined that for a number of six passes in an ECAP die with intersecting channels angle φ = 90° and corner angle ψ=16°, an increasing mechanical properties. • Good refinement structure. • No billet material reduction.