He ʻano mea hao hao ikaika i kūkulu ʻia i nā makahiki 1950.ʻO kāna hana piha kokoke i ke kila.Hoʻokumu ʻia ia ma kāna hana maikaʻi loa i hoʻohana maikaʻi ʻia no ka hoʻolei ʻana i kekahi mau ʻāpana me ka ikaika paʻakikī, ikaika kiʻekiʻe, paʻakikī a me ke kūpaʻa ʻana.Ua ulu koke ka hao i hoʻohana nui ʻia ma mua o ka hao hina hina.ʻO ka mea i kapa ʻia ʻo "steel ma kahi o ke kila", pili nui i ka hao ductile.

ʻO ka hao Ducular ka graphite spherical ma o ka spherulation a me ka mālama ʻana i ka maʻi, e hoʻomaikaʻi maikaʻi i nā waiwai mechanical o ka hao hao, ʻoi aku ka paʻakikī a me ka paʻakikī, i loaʻa ai ka ikaika kiʻekiʻe ma mua o ke kila kalapona.

ʻO ka hao hao he kalapona maʻiʻo ma mua o 2.11% o ka hao kalapona hao, e ka hao puaʻa ʻoihana, ke kila ʻōpala a me kāna mau mea hoʻoheheʻe ma hope o ka hoʻoheheʻe ʻana o ka wela kiʻekiʻe a me ka hoʻoheheʻe ʻana, me ka Fe, kalapona a me nā hao hao ʻē aʻe i ke ʻano graphite, inā. ʻO ka ua o ka graphite kaula hao i kapa ʻia ʻo ka hao hina a i ʻole ka hao hina, ʻo ka ilo hoʻolei ʻia i kapa ʻia ʻo worm ink iron, kahi hui o ka hao i kapa ʻia ka hao keʻokeʻo a i ʻole ka hao code, a ua kapa ʻia ka hao spherical i hoʻolei ʻia.

ʻO ka hana kemika o ka hao ductile koe wale nō ka hao: ʻo ke kalapona maʻiʻo 3.0 ~ 4.0%, ʻike silika 1.8 ~ 3.2%, manganese, phosphorus, sulfur ka nui ʻaʻole iʻoi aku ma mua o 3.0% a me ka nui kūpono o ka honua laʻa, magnesium a me nā mea globtized ʻē aʻe.