Yonke impahla embonini inomlando omude, kodwa namuhla sikhuluma ngokuyinhloko ngokuthuthukiswa komlandoi-alloy steel forgings.
Kusukela ngempi yezwe yesibili kuya ko-1960,i-alloy steel forgingsikakhulukazi kwakuyinkathi yokuthuthukiswa kwensimbi enamandla amakhulu kanye nensimbi enamandla kakhulu. Ngenxa yezidingo zemboni yezokundiza nokuthuthukiswa kobuchwepheshe be-rocket, izinsimbi eziningi ezintsha ezinamandla aphezulu nezinsimbi ezinamandla aphezulu kakhulu zavela Amamaki ensimbi, njengemvula eyenza lukhuni insimbi engagqwali enamandla amakhulu nezinsimbi ezihlukahlukene ezinealloyi ephezulu enamandla, amamaki ensimbi amele wona.Ngemva kweminyaka yawo-1960, kuningi ubuchwepheshe obusha bensimbi, ikakhulukazi ubuchwepheshe bokucwenga ngaphandle kwesithando somlilo, bamukelwa kabanzi. Insimbi ye-alloy yaqala ukukhula ibheke ekuhlanzekeni okuphezulu, ukunemba okuphezulu kanye ne-ultra-low carbon. Insimbi egudlayo kanye ne-ultra-pure ferrite yavela futhi.Amabanga amasha ensimbi njengensimbi engagqwali.