Abstract:
PURPOSE: Non-normalized steel with an ultrafine grained pearlite structure and a preparation method thereof are provided to obtain an ultrafine grained colony and lamella structure by restricting ferrite transformation and continuous cooling pearlite transformation and inducing low-temperature pearlite. CONSTITUTION: A method for preparing non-normalized steel with an ultrafine grained pearlite structure comprises the steps of: compressing a steel material at high temperatures, rapidly cooling the hot-forged body to a low-temperature pearlite transformation range, maintaining the super-cooled hot-forged body at a constant temperature in the low-temperature pearlite transformation range, and air-cooling the hot-forged body.
Abstract:
PURPOSE: A multi-stage control cooling process for manufacture of V-MA pearlite-ferrite hot-forged steel is provided to increase the ferrite fraction by super-cooling a hot-formed structure to low temperatures and maintaining a constant temperature at the transformation temperature of ferrite. CONSTITUTION: A multi-stage control cooling process for manufacture of V-MA pearlite-ferrite hot-forged steel comprises the steps of: rapidly cooling a hot-forged body to a low transformation temperature range of austenite-ferrite, maintaining a constant temperature in the transformation temperature range of austenite-ferrite, and air-cooling the hot-forged body.
Abstract:
강재를 고온압축 변형하는 열간단조단계; 상기 열간단조단계에 의한 열간단조체를 저온의 펄라이트 변태구간으로 급속냉각하는 급속냉각단계; 상기 급속냉각단계에 의해 과냉된 열간단조체를 저온의 펄라이트 변태구간에서 등온으로 유지시키는 등온변태단계; 및 상기 등온변태단계를 거친 열간단조체를 공랭하는 공랭단계;를 포함하는 초미세립 펄라이트 조직을 갖는 비조질강의 제조방법과 그에 의한 비조질강이 소개된다.
Abstract:
PURPOSE: A plaster casting device using vibration and pressurization for producing a prototype of a die-casting process and a method thereof are provided, which can obtain uniform internal density and completely fill even thin walls by injecting molten metal into a plaster mold at low pressure and by directly applying vibration to the molten metal. CONSTITUTION: The method for producing the prototype of the die-casting process is characterized in that: a pressurizing device to directly pressurize molten metal in a plaster mold, which comprises a cylinder(11) injecting the molten metal into the plaster mold at low pressure, a speed controller(12) controlling the speed of the cylinder(11), and a plunger(14) directively pressurizing the molten metal; and a vibrating device to directly vibrate the molten metal, which comprises an excitation part(21) vertically exciting a vibration plate(24) and a vibration controller(23) controlling the amplitude and frequency of the excitation part(21).
Abstract:
석출경화형 고강도, 고연성 및 경량성이 우수한 경량 강재 및 그 제조 방법에 대하여 개시한다. 본 발명에 따른 경량 강재는 중량%로, 망간(Mn) : 10.0~15.0%, 알루미늄(Al) : 6.0~9.0%, 크롬(Cr) : 3.0~5.0%, 탄소(C) : 0.8~1.2% 및 나머지 철(Fe)과 불가피한 불순물로 이루어지고, 주상은 오스테나이트 상이며, 제2상으로 페라이트 상과 나노 κ-카바이드((Fe,Mn) 3 AlC) 입자를 포함하는 복합조직을 갖는 것을 특징으로 한다.