Effect of Preheating Temperature on Microstructure and Properties of 42CrMo4/38MnVS6 Heterogeneous Laser Welded Joint

Abstract

Laser-welded forged steel pistons can meet the needs of the new era of heavy truck engines. 42CrMo4 and 38MnVS6 are widely used as piston materials due to the good mechanical properties. This study investigates the influence of preheating on microstructure and mechanical properties of 42CrMo4/38MnVS6 laser welding joint. The experimental results show preheating increases the laser absorption capacity of the metal, which can lead to an increase in weld width. The microstructure of weld is the high-hardness and poor toughness twin martensite without preheating. As the temperature of preheating increases, the twin martensite in the weld begins to transform into lath martensite and regenerates ferrite and bainite. As the preheating temperature increases, the plane fracture toughness (K1C) of the weld increases and then decreases, reaching the highest value of 2322.94 MPa·mm −1/2 at 150 • C. Compared with no preheating conditions, the tensile strength of the welded joint after preheating is improved. The fracture mode of welded joints changes from brittle fracture to ductile fracture. When the preheating temperature is 100-200 • C, the tensile strength of the welded joint reaches 1018.1-1032.5 MPa; when the preheating temperature is 250 • C-300 • C, the tensile strength decreases. the heat input is in the range of 275 J/mm 0.5 ·s 0.5 to 435 J/mm 0.5 ·s 0.5 , and there was no defect in the weld [12]. Kuryntsev et al. studied the effect of heat treatment on laser welded joints of 0.349C-1Cr-1Si steel. The results showed that the laser welded joint had the characteristics of high hardness and low elongation. After heat treatment, the elongation and ductility of the welded joint are improved [13]. Laser welding has a high energy density, and the base metal is not easy to deform after welding. It can optimize the piston structure and is conducive to the full combustion of fuel. Therefore, the development of laser welding forged steel piston has become one of the development directions of piston structure [14][15][16][17]. Preheating before welding can increase the laser absorption rate of the metal and reduce the cooling rate of the weld, adjust the stress distribution of the welded joint, avoid the generation of hardened structure in the weld, and is one of the welding methods to effectively improve the mechanical properties of the welded joint [18,19].At present, there are more studies on laser welding of aluminum alloy and low carbon steel with preheating, but less on medium carbon steel [20][21][22]. In this paper, the effect of preheating on the weld structure of 42CrMo4/38MnVS6 laser welding is studied, and the mechanical properties of welded joints under different preheating temperature are compared and analyzed, which provides the basis of experimental and theoretical for the application of laser welding technology in a forged steel piston. Materials and Methods Materials

Inconel 625/AISI 413 Stainless Steel Functionally Graded Material Produced by Direct Laser Deposition

“…In this study, the substrate used for deposition was 42CrMo4 steel, machined plates in 100 × 120 × 15 mm, supplied in quenched and tempered condition. This steel is widely used for manufacturing industrial components, such as gears, automotive components, and drilling joints [ 20 , 21 , 22 ]. In the current study, the production of FGM was performed on two substrates: (1) one substrate in room temperature and (2) another one preheated to 300 °C by a manual gas system.…”

Pengaruh Tebal Deposit Lasan Terhadap Properti Lapisan Menggunakan Elektroda HV 450

“…Ukuran butir pada produk las dipengaruhi oleh panas yang terlibat baik sebelum maupun setelah proses pengelasan. Ketika material logam diberikan heat input atau pre heating akan memiliki ukuran butir yang lebih besar dibandingkan dengan material logam tanpa melibatkan pemanasan sebelum pengelasan (Su dkk., 2019). Penelitian yang dilakukan oleh Sopiyan dkk., menemukan semakin tinggi arus yang digunakan, maka akan semakin tinggi kekerasan lapisan yang terbentuk (Sopiyan, Susetyo dan Syamsuir, 2018).…”

improving the process of achieving required microstructure and mechanical properties of 38mnvs6 steel

“…The micro-alloy steel 38MnVS6 (38MnSiVS5, before called 38MnVS5) [5,6] is medium-carbon-manganese steel 38MnVS6 [8,10], which is one of main of unhardened steels [7] about destiny for controlled cooling from forging temperature. One of the benefits using micro-alloy steel 38MnVS6 is the content of micro alloys, for example V (Table 1), which allows on the growth of steel strength without necessarily hardened and tempered, which in turn off allows reducing the production costs [7,14].…”

“…These actions are referred in particular to the minimization of the costs of logistic actions, thermal treatment and realization production process time [4]. As part of these activities particularly important, mainly in the automotive industry [4], is using the micro-alloy steel, for example, 38MnVS6 (38MnSiVS5, previously marked 38MnVS5) [5,6], so the medium-carbon-manganese steel [7,8], about an application to controlled cooling from forging temperature. It results among others from content for example Al, Ti or V, which allows the growth of steel strength, without hardening and tempering.…”