摘要
采用冲击试验机、硬度仪、光学显微镜及高分辨扫描电镜研究了回火温度对新型盾构刀具用钢SDH55强韧性及组织的影响。结果表明:SDH55钢1030℃油淬硬度为60.5 HRC,组织为针状马氏体及未溶碳化物;SDH55钢在500℃回火时,出现了二次硬化峰值;在540~620℃回火时,由于回火软化使硬度随温度升高而不断降低,但冲击吸收能量却呈现先升高后降低的现象,其主要是由二次碳化物形态从杆状变成短杆或球状,最后再变成长条状分布在晶界所导致;从强韧性配合角度考虑,SDH55钢满足盾构刀具服役要求的回火温度应为(540±10)℃,此时,回火硬度为56.0 HRC,室温冲击吸收能量为264 J。
Effect of tempering temperature on strength,toughness and microstructure of a new type shield tool steel SDH55 was investigated by means of optical microscope,scanning electron microscope,impact toughness tester and hardness tester. The results show that after oiled quenched at 1030 ℃,the hardness is 60. 5 HRC and the microstructure of the SDH55 steel is martensite and undissolved carbides. The secondary hardening peak of the SDH55 steel occurs tempered at 500 ℃. When tempered at 540-620 ℃,the hardness decreases with temperature increasing because of temper softening,while the impact absorbed energy increases first and then decreases. The main reason of which is that the secondary carbides shape change from the rod into a short rod or spherical,and finally become long strips distributed in the grain boundary. Considering as strength and toughness,the optimum tempering temperature meeting the service requirements of shield tool is540 ± 10 ℃,under which the hardness is 56. 0 HRC and impact absorbed energy is 264 J.
出处
《金属热处理》
CAS
CSCD
北大核心
2017年第3期57-61,共5页
Heat Treatment of Metals
基金
国家自然科学基金(51171104)
关键词
盾构刀具SDH55钢
回火温度
强韧性
组织
碳化物
shield tool steel SDH55
tempering temperature
strength and toughness
microstructure
carbides
