Analisis Kekuatan Arus Terhadap Ketangguhan Dan Ketahanan Sambungan Pada Proses Las Tig

Proses pengelasan TIG bertujuan untuk mengetahui kekuatan tarik, lengkung dan struktur mikro pada daerah logam las dan daerah HAZ pada material stainless steel 304 dengan penggunaan variasi arus sebesar 10 A, 20 A, 30 A. Kekuatan tarik sambungan las tertinggi terjadi pada kelompok spesimen 20 Amper yaitu sebesar 425,22 MPa. Kekuatan tarik dengan beban maksimum las tertinggi terjadi pada kelompok spesimen 20 A 656,36 Kgf. Dan pertambahan luas penampang terbesar terjadi pada kelompok spesimen 30 A yaitu sebesar 38,08 mm. Pada uji struktur mikro tidak ditemukan adanya indikasi cacat las, ini ditandai dengan seimbangnya kandungan struktur mikro ferit dan perlit dimana ferit ditandai dengan daerah putih halus sedangkan perlit dengan warna hitam pekat dikarenakan unsur karbon (C) yang dominan sehingga membuat sifat material menjadi getas.

Characterization of micro hole on super alloy GH4037 and stainless steel 304 by millisecond-pulsed Nd:YAG laser processing

In this study, both super alloy GH4037 and stainless steel 304 were selected as experimental materials to be processed by LASERTEC 80 PowerDrill three-dimensional solid laser machining center. The structure of the micro hole was researched by 3D Laser Scanning Confocal Microscope and Scanning Electron Microscope (SEM). Meanwhile, The holes taper, entrance and exit ends diameter, microcrack, recast layer, orifice deposits and the heat affected zone (HAZ) were also investigated. The single factor experimental method was used to research the influences of defocusing amount, pulse energy, repetition frequency, and pulse duration on quality of micro holes. Experimental results indicated that the holes entrance and exit ends diameter enlarged with increased pulse energy from 3.4 J to 4.2 J. The entrance and exit ends diameter of holes decreased with increased pulse duration from 0.5 ms to 2.5 ms. Besides, the variation of holes diameter and taper were more obvious with repetition frequency changing from 10 Hz to 30 Hz, and variation range for the entrance and exit ends diameters and taper were not obvious with increased defocusing amount from −2 mm to 2 mm. The herein results indicated that pulse energy was one of the most significant influencing elements, and higher pulse energy could bring about lower hole taper within a certain range. Meanwhile, shorter pulse duration reduced splash and debris of holes surface. The recast layer, micro crack and HAZ were existed in the both kinds of experimental materials. Moreover, the microcrack and recast layer on holes wall of GH4037 were less than those of 304, and the HAZ in drilling hole for GH4037 was more than that of 304. The experimental results for the holes size were compared with corresponding simulation results under different defocusing amount respectively, which verified the accuracy of simulation results. Combining the above factors, the quality of micro holes drilling on super alloy GH4037 was better than stainless steel 304.

Multi-Objective Optimization of Processing Parameters in WEDM with Stainless Steel-304 for Die-Angular Cutting

This paper is focusing on the improvement of the accuracy of WEDM process for machining the precision-die angular stainless-steel parts. The controllable parameters are studied and analyzed by using Response Surface Method technique with respect to the responses of dimensional accuracy and surface quality. Then, these models are optimized by using the multi-objective optimization technique to realize optimal processing parameters. These optimal controllable parameters are ready for WEDM operating technicians’ use.