摘要
研究了五种含１—２的Ｎｉ和Ｓｉ的试验钢淬火回火后的微观结构及力学性能，结果表明：少量Ｎｉ和Ｓｉ分别增加残余奥氏体的（γ″）数量和稳定性，含ＩＮｉ和ＩＳｉ的ＧＤ钢２５０℃回火后可得到大于１０％的较稳定的残余奥氏体；Ｎｉ和Ｓｉ共存使淬火个溶碳化物细化：使回火过程中ε－碳化物溶解和渗碳体析出的温度提高到３５０℃左右；１Ｎｉ＋１Ｓｉ可综合发挥Ｎｉ改善冲击韧性和断裂韧性。
Five experimental steels with separate or combined 1-2% Ni and Si additions on the basis ofcomposition of GD steel were made. The tests of hardness,compression, impact and fracture toughness forfive steels oil--quenched at 900℃ followed by tempering in the range of 170-500℃ were conducted. TheTEM observations of microstructure were performed. The volume fractions of retained austenite in specimens undeformed and at 0.2% compressive strain were measured by using X-ray diffraction technique. Theresults indicate that the features of martensite as matrix in five steels have not obvious change. A smallamount of Ni and Si can contribute to increasing the amount and stability of retainedan stem ie, respectively,and a combined addition of 1 % Ni and 1 % Si can make the retained an stenite morethan 10%,and more stable in GD steel tempered at temperature below 250℃. The co--presence of Ni and Sipromotes decreasing the size of primary carbide undissolved during quenching,and raises the temperatures ofcomplete dissolution of carbide and strong precipitation of cementite during tempering up to 350℃. 1-2% Si addition significantly increases compressive yield strength and temper stability,and 1-2% Ni additionis benificial to improving both impact and fracture toughness.2% Si can make a remarkable increase of ak,but it is harmful to K(1c). A combination of 1% Ni and 1% St can produce a comprehensive advantage intemper stability,Strength and toughness. So GD steel can gain high strength and high toughness after tempering in the range of 200-300℃,and the temperature of tempered martensite embrittlement is about350t,corresponding to that of strong precipitation of cementite.
出处
《材料研究学报》
EI
CAS
CSCD
1994年第2期134-141,共8页
Chinese Journal of Materials Research
基金
国家自然科学基金
关键词
模具钢
合金化
显微组织
力学性质
cold-working die steel
alloying
microstructure
mechanical property
