The effects of process variables on pulsed Nd:YAG laser spot welds; Part 1: AISI 409 stainless steel
- Univ. of Waterloo, Ontario (Canada). Dept. of Mechanical Engineering
The weldabilities of AA 1,100 aluminum and AISI 409 stainless steel by the pulsed Nd:YAG laser welding process have been examined experimentally and compared. The effects of Nd:YAG laser welding parameters, including laser pulse time and power intensity, and material-dependent variables, such as absorptivity and thermophysical properties, on laser spot-weld characteristics, such as weld diameter, penetration, melt area, melting ratio, porosity, and surface cratering, have been studied experimentally. When welding AISI 409 stainless steel, weld pool shapes were found to be influenced most by the power intensity of the laser beam and to a lesser extent by the pulse duration. Conduction mode welding, keyhole mode welding, and drilling were observed. Conduction mode welds were produced when power intensities between 0.7 and 4 GW/m{sup 2} were used. The initial transient in weld pool development occurred in the first 4 ms of the laser pulse. The initial transient in weld pool development occurred in the first 4 ms of the laser pulse. Following this, steady-state conditions existed and conduction mode welds with aspect ratios (depth/width) of about 0.4 were produced. Keyhole mode welds were observed at power intensities greater than 4 GW/m{sup 2}. Penetration of these keyhole mode welds increased with increases in both power intensity and pulse time. The major weld defects observed in the stainless steel spot welds were cratering and large-occluded gas pores. Significant metal loss due to spatter was measured during the initial 2 ms of keyhole mode welds. With increasing power intensity, there was an increased propensity for occluded gas pores near the bottom of the keyhole mode welds.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 142341
- Journal Information:
- Metallurgical Transactions, B, Vol. 24B, Issue 6; Other Information: PBD: Dec 1993
- Country of Publication:
- United States
- Language:
- English
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