The former logo of <a href="https://en.wikipedia.org/wiki/Nippon_Steel_%26_Sumitomo_Metal" class="extiw" title="w:Nippon Steel &amp; Sumitomo Metal">Nippon Steel &amp; Sumitomo Metal Corporation</a>
Unknown author<span style="display: none;">Unknown author</span>
Own work  using: <a rel="nofollow" class="external free" href="http://www.nssmc.com/product/catalog_download/pdf/P001en.pdf">http://www.nssmc.com/product/catalog_download/pdf/P001en.pdf</a>