Improving Global Quality of Life
Improving Global Quality of Life
Improving Global Quality of Life
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
9 Needs and challenges <strong>of</strong> major industry sectors for future applications<br />
above however, the retained austenite reduces the mechanical strength, and so an optimum microstructure<br />
control is necessary to obtain a weld metal with required mechanical properties and resistance to hydrogeninduced<br />
cracking.<br />
As mentioned above, the MIG welding is suitable for producing the weld metal for the HSLA steel <strong>of</strong> more<br />
than 780 MPa classes, in which the contents <strong>of</strong> both oxide inclusion and hydrogen must be low. The heat<br />
input <strong>of</strong> the MIG welding, however, controlling the productivity, is practically limited to a significantly lower<br />
level than most <strong>of</strong> other conventional welding processes, and this is an obstacle to its wider application.<br />
It was believed that the practical heat input was limited by the instability <strong>of</strong> the arc plasma due to the<br />
scattering <strong>of</strong> the cathode spot in the weld pool. Hiraoka et al., however, showed that the arc instability could<br />
be resolved by stabilising the wire electrode rather than the cathode spot. Therefore, it can be expected that<br />
the MIG welding can be carried out at much higher heat input by stabilising the wire cathode and thus the<br />
obstacle to the wider use <strong>of</strong> the MIG welding to the advanced steel can be removed.<br />
In Japan, a national project on the innovation <strong>of</strong> welding for advanced steels has been undertaken with the<br />
cooperation <strong>of</strong> universities, governmental research institutes, and industries. As exemplified by the HSLA<br />
steel <strong>of</strong> more than 780 MPa classes, the desired microstructure <strong>of</strong> the weld metal is different from those <strong>of</strong><br />
lower strength steels, and the weldability, a measure <strong>of</strong> hydrogen embrittlement susceptibility <strong>of</strong> weldment,<br />
depends on factors other than the carbon equivalent <strong>of</strong> the base metal. Thus, one needs to establish a new<br />
paradigm <strong>of</strong> the weldability for advanced steels like HSLA steel <strong>of</strong> 780 MPa class. It is also required to develop<br />
a welding process that enables one to produce a weld metal with low oxygen content at high productivity. A<br />
comprehensive approach based on the microstructural design and control <strong>of</strong> the weld metal, development <strong>of</strong><br />
the welding process involving high energy density beam welding, and the control <strong>of</strong> residual stress and strain<br />
will contribute to solving these problems and eventually to the improvement <strong>of</strong> the quality <strong>of</strong> global life.<br />
9.13.4 Hot topics<br />
Research and development <strong>of</strong> welding processes and technologies for the joining <strong>of</strong> advanced steels<br />
e.g. high strength low alloy.<br />
Research in the metallurgy, preheat and residual stress <strong>of</strong> advanced steels.<br />
9.14 Electronics sector<br />
(Images in Section 9.14, 9.15 and 9.16 reproduced courtesy <strong>of</strong> TWI Ltd).<br />
High density electronic<br />
package<br />
Electronics, combined with sensing technology, form the fundamental operating<br />
systems for nearly all modern industrial products and systems from mobile phones<br />
to power stations. As electronics becomes more sophisticated its integration<br />
into products is increasing, to a point where many systems (e.g. automotive,<br />
aerospace, assembly equipment, welding power supplies) cannot be operated<br />
without electronic/computer/sensor assistance.<br />
The electronics sector is also a key influencing factor<br />
in environmental issues. On one side it can be used<br />
to significantly save energy through intelligent system management (e.g. motor<br />
controls, consumer product energy usage) and renewable energy controls (e.g.<br />
solar, wind and tidal). Conversely, it is the major contributor to the growth in landfill<br />
waste (e.g. consumer products - mobile phones, TVs, games machines etc.). Future<br />
developments in terms <strong>of</strong> materials and assembly processes will influence the overall<br />
balance <strong>of</strong> electronics’ environmental sustainability.<br />
Electronics for landfill waste<br />
Through Optimum Use and Innovation <strong>of</strong> Welding and Joining Technologies<br />
<strong>Improving</strong> <strong>Global</strong> <strong>Quality</strong> <strong>of</strong> <strong>Life</strong><br />
139