Studies on laser surface melting of Al-11% Si alloy

Abstract

In the present investigation the effect of laser surface melting on wear and corrosion resistance of Al-11 wt.% Si alloy has been investigated. Laser surface melting has been carried out using a 2 kW continuous wave CO₂ laser at an applied power of 2.3 kW and scan speed ranging from 6 to 12 mm/min. Following the laser surface melting, a detailed investigation of the melted zone in terms of microstructure, composition and phases were undertaken. Mechanical properties of the melted zone were evaluated so far as the microhardness and wear resistance were concerned. The corro-sion behaviour of the as-received and the laser surface melted surface was evaluated in 1(M) H₂SO₄, 1(M) HNO₃ and 3.56 wt.% NaCl solutions. The microstructure of the melt zone consists of grain refinedAl andAl-Si eutec-tic colonies which results in an improved microhardness from 87 VHN as compared to 55 VHN of the as-received Al-Si alloy. The wear resistance of the melt surface was improved significantly as compared to the as-received Al-Si alloy. A detailed corrosion study in various environments showed that corrosion resistance was marginally less in the 3.56 wt.% NaCl and 1 M H₂SO₄ solutions, but was better in the 1 M HNO₃ solution.