# Nanosecond Laser Ablation of Ti-6 Al-4V under Di erent Temperature  
[PERSON]  
1 School of Mechanical Engineering and Mechanics, Ningbo University, Ningbo 315211, China; [EMAIL_ADDRESS] (J.Z.); [EMAIL_ADDRESS] (Z.Z.); [EMAIL_ADDRESS] (Y.X.); [EMAIL_ADDRESS] (X.S.); [EMAIL_ADDRESS] (Y.W.); [EMAIL_ADDRESS] (H.P.); [EMAIL_ADDRESS] (Y.W.); [EMAIL_ADDRESS] (J.Z.); [EMAIL_ADDRESS] (X.S.)  
[PERSON]  
1 School of Mechanical Engineering and Mechanics, Ningbo University, Ningbo 315211, China; [EMAIL_ADDRESS] (J.Z.); [EMAIL_ADDRESS] (Z.Z.); [EMAIL_ADDRESS] (Y.X.); [EMAIL_ADDRESS] (X.S.); [EMAIL_ADDRESS] (Y.W.); [EMAIL_ADDRESS] (H.P.); [EMAIL_ADDRESS] (Y.W.); [EMAIL_ADDRESS] (J.Z.); [EMAIL_ADDRESS] (X.S.)  
[PERSON]  
1 School of Mechanical Engineering and Mechanics, Ningbo University, Ningbo 315211, China; [EMAIL_ADDRESS] (J.Z.); [EMAIL_ADDRESS] (Z.Z.); [EMAIL_ADDRESS] (Y.X.); [EMAIL_ADDRESS] (X.S.); [EMAIL_ADDRESS] (Y.W.); [EMAIL_ADDRESS] (H.P.); [EMAIL_ADDRESS] (Y.W.); [EMAIL_ADDRESS] (J.Z.); [EMAIL_ADDRESS] (X.S.)  
[PERSON]  
1 School of Mechanical Engineering and Mechanics, Ningbo University, Ningbo 315211, China; [EMAIL_ADDRESS] (J.Z.); [EMAIL_ADDRESS] (Z.Z.); [EMAIL_ADDRESS] (Y.X.); [EMAIL_ADDRESS] (X.S.); [EMAIL_ADDRESS] (Y.W.); [EMAIL_ADDRESS] (H.P.); [EMAIL_ADDRESS] (Y.W.); [EMAIL_ADDRESS] (J.Z.); [EMAIL_ADDRESS] (X.S.)  
Zhejiang Key Laboratory of Part Rolling Technology, Ningbo University, Ningbo 315211, China  
Zhejiang Key Laboratory of Part Rolling Technology, Ningbo University, Ningbo University, Ningbo 315211, China
However, most research has focused on PLD and laser etching. Few have focused on laser ultrasonic testing. Aiming to study its ablation characteristics and provide reference for the selection of laser pulse in laser ultrasonic testing, we selected the laser pulse parameters commonly used in laser ultrasonic testing to carry out multi-pulse ablation experiments. In addition, the laser energy selected in our experiment was very high, and the laser fluence was far beyond the threshold value.  
Titanium alloy--as a kind of material with high strength, corrosion resistance and high temperature resistance--has been widely used in the fields of biologic materials [17], aerospace [18], marine engineering [19]. Of all titanium alloys, Ti-6 Al-4V titanium alloy is the most widely used; a number of titanium alloys are improved based on Ti-6 Al-4V [20]. Laser ultrasonic testing is an effective way to detect titanium alloy [21]. Therefore, the study of nanosecond laser ablation characteristics of Ti-6 Al-4V titanium alloys has a certain reference value for the laser ultrasonic testing of titanium alloys.  
In this investigation, two groups of experiments were carried out. Experiment A aimed to study the effect of substrate temperature on Ti-6 Al-4V multi-pulse nanosecond laser ablation process generally, In Experiment B, the universality of the phenomenon of Experiment A under different laser fluence and pulse number was further studied, and the relationship among pulse number, substrate temperature and ablation characteristics was also studied.  
Based on the observation of Ti-6 Al-4V multi-pulse nanosecond laser ablation characteristics, the relationship between substrate temperature and ablation characteristics was studied. Ablation efficiency \(\omega\) was proposed to analysis the ablation process. The phase explosion model and energy accumulation effect were considered to explain the experimental phenomena.