Study on Yield Strength Prediction after Bake Hardening of 6000 Series Aluminum Alloys Using Machine Learning

Junya Nagai･Kentarou Aono･Ryousuke Negawa･Hiroki Takami (SUBARU)

The 6000 series aluminum alloys used in automobile panels undergo hardening namely Bake Hardening (BH) after forming strain and/or paint baking. Combinations of such conditions affect the yield strengths; therefore, identifying the relationship of those combinations and yield strengths requires a large number of tension tests. This study aims to establish a prediction method for the yield strength after BH under arbitrary combinations of conditions without significantly increasing the number of tensile test data volume by applying machine learning.

Strength Properties of Steel/Aluminum Dissimilar Spot Welded Joint (First Report)
-Investigation of Tensile Shear and Peel Strength-

Ayaka Kagami･Eisuke Umeno･Naoki Horita･Tetsuya Fujisaki (Toyota Motor)･Hideaki Matsuoka･Tatsuyuki Amago (Toyota Central R&D Labs.)

In spot welding between steel plate and an aluminum alloy, it is well known that the intermetallic compound formed at the joint interface is closely related to the joint strength. In this study, we fabricated welded joints with protrusion-like structures to overcome the brittleness of intermetallic compounds in spot welding between steel plates and aluminum alloy sheet. We investigate the tensile shear strength and L-shaped peel strength and present the relationship with the nugget diameter.

Development of heat-radiative aluminum coating material for automotive component housings

Hironori Watanabe･Osamu Katou･Yoshihiko Kyo (UACJ Corporation)

The heat-radiative aluminum coating material can be used as housings for electronic devices and automotive components, and are thought to contribute to thermal control by increasing the heat radiation from the coating, which promotes heat radiation. In this report, we present the results of an investigation into the relationship between the contained particles and coating performance by adjusting the particle size and concentration of silica contained in epoxy resin-based paints.

Nitriding Behavior of Stainless Steel in Ammonia Combustion Atmosphere

Yoshitomo Fujimura･Atsutaka Hayashi･Naoki Hirakawa･Jun-ichi Hamada (Nipponsteel)

Assuming ammonia combustion, the nitriding behavior of stainless steels at 600℃ for 50 hours in NH3-H2O-N2 atmospheres were investigated. The nitride layer formed on the surface of austenitic stainless steels is thinner than that of ferritic stainless steels. Even in ferritic stainless steel, nitriding tended to be restrained in a low NH3 atmosphere.

Bending fatigue behaviors of T-shaped Ni alloy brazed joints

Gyoko Oh･Atsushi Umezawa (Tokyo Roki)

Tests and numerical stress analyzes were conducted on the relationship between fatigue strength, fracture behavior, metallographic structure, and stress concentration of Ni alloy brazed joints of ferritic stainless steel. It was clarified that the surface layer of the brazing alloy was enriched with P and Cr, forming a solidified structure of Ni-Cr-Fe-Si-P, that the radius of curvature of the fillet had an effect on stress concentration, and that these factors were quantitatively related to fatigue limits.

Material Development for Cold Spray Valve Seat

Yoshinori Izawa･Junichi Arai･Hayato Hirayama･Shotaro Takahashi (Nissan Motor)

In order to form straight ports important for tumble flow reinforcement, materials for Cold Spray Valve Seat were developed. Cu-based material powder which satisfies contradictory requirements of ductility　necessary for coating and hardness necessary for wear resistance and Fe-based hard particle with the same lubricity as Co-base hard particle were designed. Finally, we achieved high wear resistance by combined coating layer.

Development of Steel for Carbo-Nitriding with Superior Pitting Fatigue/Bending Fatigue Strength

Arisa Ito･Tomoya Tamai･Ryosuke Ohashi･Ayumi Yamazaki (Daido Steel)

Gears for Reduction gear used in e-Axle, which are attracting attention as the drive unit for electric vehicles, require high strength in both tooth flank and tooth root properties. Carbo-nitriding process is a treatment that improves strength properties by increasing surface hardness and softening resistance. In this study, a steel with superior pitting fatigue strength and bending fatigue strength was developed by carbo-nitriding.