Pulse laser welding of high carbon alloy steel: assessment of melt pool geometry and mechanical performance

Sadhana ◽  
2021 ◽  
Vol 46 (1) ◽  
Author(s):  
Chinmaya Kumar Sahoo ◽  
Sidharth Mallick ◽  
Kamlesh Kumar ◽  
Manoj Masanta
Alloy Digest ◽  
1969 ◽  
Vol 18 (12) ◽  

Abstract AISI C1060 is a high-carbon water or oil hardening tool and spring steel recommended for heavy machinery parts, shafts, springs and miscellaneous tools requiring strength and wear resistance. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as heat treating, machining, and joining. Filing Code: CS-32. Producer or source: Carbon and alloy steel mills.


Alloy Digest ◽  
1965 ◽  
Vol 14 (6) ◽  

Abstract AISI 8660 is a high carbon, chromium-nickel-molybdenum alloy steel having high hardness and strength, suitable for springs and axle shafts. This datasheet provides information on composition, hardness, and tensile properties. It also includes information on forming, heat treating, machining, and joining. Filing Code: SA-178. Producer or source: Alloy steel mills and foundries.


2021 ◽  
Vol 11 (10) ◽  
pp. 4522
Author(s):  
Tianzhu Sun ◽  
Pasquale Franciosa ◽  
Conghui Liu ◽  
Fabio Pierro ◽  
Darek Ceglarek

Remote laser welding (RLW) has shown a number of benefits of joining 6xxx aluminium alloys such as high processing speed and process flexibility. However, the crack susceptibility of 6xxx aluminium alloys during RLW process is still an open problem. This paper experimentally assesses the impact of transverse micro cracks on joint strength and fatigue durability in remote laser welding of AA6063-T6 fillet lap joints. Distribution and morphology of transverse micro cracks were acquired by scanning electron microscope (SEM) on cross-sections. Grain morphology in the weld zone was determined by electron backscatter diffraction (EBSD) while static tensile and dynamic fatigue tests were carried out to evaluate weld mechanical performance. Results revealed that increasing welding speed from 2 m/min to 6 m/min did not introduce additional transverse micro cracks. Additionally, welding at 2 m/min resulted in tensile strength improvement by 30% compared to 6 m/min due to the expansion of fusion zone, measured by the throat thickness, and refinement of columnar grains near fusion lines. Furthermore, the weld fatigue durability is significantly higher when fracture occurs in weld root instead of fusion zone. This can be achieved by increasing weld root angle with optimum weld fatigue durability at around 55°.


Author(s):  
Yan Zhang ◽  
DeShui Yu ◽  
JianPing Zhou ◽  
DaQian Sun ◽  
HongMei Li

Abstract To avoid the formation of Ti-Ni intermetallics in a joint, three laser welding processes for Ti alloy–NiTi alloy joints were introduced. Sample A was formed while a laser acted at the Ti alloy–NiTi alloy interface, and the joint fractured along the weld centre line immediately after welding without filler metal. Sample B was formed while the laser acted on a Cu interlayer. The average tensile strength of sample B was 216 MPa. Sample C was formed while the laser acted 1.2 mm on the Ti alloy side. The one-pass welding process involved the creation of a joint with one fusion weld and one diffusion weld separated by the remaining unmelted Ti alloy. The mechanical performance of sample C was determined by the diffusion weld formed at the Ti alloy–NiTi alloy interface with a tensile strength of 256 MPa.


Author(s):  
Renangi Sandeep ◽  
Arivazhagan Natarajan

In the twenty-first century, the application of carbon fiber reinforced polymer (CFRP) materials in the vehicle industry are growing rapidly due to lightweight, high specific strength, and elasticity. In the automobile and aerospace industries, CFRP needs to be joined with metals to build complete structures. The demand for hybrid structures has prompted research into the combination of CFRP and metals in manufacturing. Aluminium and CFRP structures combine the mechanical properties of aluminium with the superior physical and chemical properties of CFRP. However, joining dissimilar materials is often challenging to achieve. Various joining technologies are developed to produce hybrid joints of CFRP, and aluminium alloys include conventional adhesives, mechanical and thermal joining technologies. In this review article, an extensive review was carried out on the thermal joining technologies include laser welding, friction-based welding technologies, ultrasonic welding, and induction welding processes. The article primarily focused on the current knowledge and process development of these technologies in fabricating dissimilar aluminium and CFRP structures. Besides, according to Industry 4.0 requirements, additive manufacturing-based techniques to fabricate hybrid structures are presented. Finally, this article also addressed the various improvements for the future development of these joining technologies. Ultrasonic welding yields the maximum shear strength among the various hybrid joining technologies due to lower heat input. On the other hand, laser welding produces higher heat input, which deteriorates the mechanical performance of the hybrid joints. Surface pretreatments on material surfaces prior to joining showed a significant effect on joint shear strength. Surface modification using anodizing is considered an optimal method to improve wettability, increasing mechanical interlocking phenomena.


Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 792 ◽  
Author(s):  
Panos Efthymiadis ◽  
Khalid Nor

Laser welding of dissimilar high-strength steels was performed in this study for two different geometries, flat and circular samples with material thicknesses of 5 and 8 mm. The material combinations were a low carbon to a medium or high carbon steel. Three different welding systems were employed: a Nd:YAG, a CO2 and a fiber laser. The process stability was evaluated for all the experiments. The resulting full penetration welds were inspected for their surface quality at the top and bottom of the specimens. Cross sections were taken to investigate the resulting microstructures and the metallurgical defects of the welds, such as cracks and pores. Significant hardening occurred in the weld region and the highest hardness values occurred in the Heat Affected Zone (HAZ) of the high carbon steel. The occurrence of weld defects depends strongly on the component geometry. The resulting microstructures within the weld were also predicted using neural network-simulated Continuous Cooling Transformation (CCT) diagrams and predicted the occurrence of a mixture of microstructures, such as bainite, martensite and pearlite, depending on the material chemistry. The thermal fields were measured with thermocouples and revealed the strong influence of component geometry on the cooling rate which in term defines the microstructures forming in the weld and the occurring hardness.


1987 ◽  
Vol 5 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Fukuhisa Matsuda ◽  
Hiroji Nakagawa ◽  
Hwa Soon Park ◽  
Toshihiro Murakawa ◽  
Michio Yamaguchi

Author(s):  
Angshuman Chattopadhyay ◽  
Gopinath Muvvala ◽  
Vikranth Racherla ◽  
Ashish Kumar Nath

Joining of dissimilar metals and alloys has been envisioned since a long time with specific high end applications in various fields. One such combination is austenitic stainless steel grade SS304 and commercial grade titanium, which is very difficult to join under conventional fusion process due to extensive cracking and failure caused by mismatch in structural and thermal properties as well as formation of the extremely brittle and hard intermetallic compounds. One of the methods proposed in literature to control the formation of intermetallics is by fast cooling fusion process like laser beam welding. The present study has been done on laser welding of titanium and stainless steel AISI 304 to understand the interaction of these materials during laser welding at different laser power and welding speed which could yield different cooling rates. Two types of cracks were observed in the weld joint, namely longitudinal cracks and transverse cracks with respect to the weld direction. Longitudinal cracks could be completely eliminated at faster welding speeds, but transverse cracks were found little influenced by the welding speed. The thermal history, i.e. melt pool lifetime and cooling rate of the molten pool during laser welding was monitored and a relation between thermo-cycle with occurrence of cracks was established. It is inferred that the longitudinal cracks are mainly due to the formation of various brittle intermetallic phases of Fe and Ti, which could be minimized by providing relatively less melt pool lifetime at high welding speeds. The reason of the transverse cracks could be the generation of longitudinal stress in weld joint due to the large difference in the thermal expansion coefficient of steel and titanium. In order to mitigate the longitudinal stress laser welding was carried out with a novel experimental arrangement which ensured different cooling rates of these two metals during laser welding. With this the tendency of transverse cracks also could be minimized significantly.


Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5316
Author(s):  
Zhenlong Zhu ◽  
Yilong Liang ◽  
Jianghe Zou

Accurately improving the mechanical properties of low-alloy steel by changing the alloying elements and heat treatment processes is of interest. There is a mutual relationship between the mechanical properties and process components, and the mechanism for this relationship is complicated. The forward selection-deep neural network and genetic algorithm (FS-DNN&GA) composition design model constructed in this paper is a combination of a neural network and genetic algorithm, where the model trained by the neural network is transferred to the genetic algorithm. The FS-DNN&GA model is trained with the American Society of Metals (ASM) Alloy Center Database to design the composition and heat treatment process of alloy steel. First, with the forward selection (FS) method, influencing factors—C, Si, Mn, Cr, quenching temperature, and tempering temperature—are screened and recombined to be the input of different mechanical performance prediction models. Second, the forward selection-deep neural network (FS-DNN) mechanical prediction model is constructed to analyze the FS-DNN model through experimental data to best predict the mechanical performance. Finally, the FS-DNN trained model is brought into the genetic algorithm to construct the FS-DNN&GA model, and the FS-DNN&GA model outputs the corresponding chemical composition and process when the mechanical performance increases or decreases. The experimental results show that the FS-DNN model has high accuracy in predicting the mechanical properties of 50 furnaces of low-alloy steel. The tensile strength mean absolute error (MAE) is 11.7 MPa, and the yield strength MAE is 13.46 MPa. According to the chemical composition and heat treatment process designed by the FS-DNN&GA model, five furnaces of Alloy1–Alloy5 low-alloy steel were smelted, and tensile tests were performed on these five low-alloy steels. The results show that the mechanical properties of the designed alloy steel are completely within the design range, providing useful guidance for the future development of new alloy steel.


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