退火温度对H13钢等离子堆焊Ni60/WC覆层组织和硬度的影响
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摘要
采用等离子堆焊技术在H13钢基体表面上制备了Ni60/WC复合覆层。研究了退火温度对基体、热影响区和Ni60/WC复合覆层组织、硬度的影响。结果表明:经退火处理后消除了覆层裂纹敏感性,WC分布得到改善。800℃退火后花瓣状枝晶得到细化,组织更为均匀。焊态下覆层热影响区组织主要由粗大片状马氏体和板条马氏体以及残留奥氏体组成,600℃退火后热影响区组织主要由板条状铁素体、针状铁素体和颗粒状渗碳体组成,800℃退火后热影响区组织主要由等轴状铁素体和粒状渗碳体组成,退火处理后热影响区组织得到明显改善。经过600℃退火后覆层硬度略微下降,淬硬区得到缓和; 800℃退火后覆层硬度分布均匀,淬硬区消失,基体到覆层过渡处的硬度呈梯度上升,进而改善了基体与覆层之间的结合,提高了覆层的力学性能。
Ni60/WC composite coatings were prepared on the surface of H13 steel substrate by plasma transfer arc welding technology. The effects of annealing temperature on the microstructure and hardness of the substrate,heat affected zone and Ni60/WC composite coatings were studied. The results show that the crack sensitivity of the coatings is eliminated after annealing,and the WC distribution is improved. After annealing at 800 ℃,the dendritic petal dendrites are refined and the microstructures are more uniform. The heat affected zone of unannealed coatings mainly consists of coarse lamellar martensite,lath martensite and retained austenite. After annealing at 600 ℃,the microstructure in the heat affected zone is mainly composed of lath ferrite,acicular ferrite and granular cementite. After annealing at 800 ℃,the heataffected zone is mainly composed of equiaxed ferrite and cementite,and the microstructure of the heat affected zone is improved. After annealing at 600 ℃,the hardness of the coatings decreases slightly and the hardened area is relaxed. After annealing at 800 ℃,the hardness of the coatings is uniform and the hardened zone disappears,the hardness from the substrate to the coatings increases gradually,thus improving the bonding between the substrate and the coatings and the mechanical properties of the coatings.
Ni60/WC composite coatings were prepared on the surface of H13 steel substrate by plasma transfer arc welding technology. The effects of annealing temperature on the microstructure and hardness of the substrate,heat affected zone and Ni60/WC composite coatings were studied. The results show that the crack sensitivity of the coatings is eliminated after annealing,and the WC distribution is improved. After annealing at 800 ℃,the dendritic petal dendrites are refined and the microstructures are more uniform. The heat affected zone of unannealed coatings mainly consists of coarse lamellar martensite,lath martensite and retained austenite. After annealing at 600 ℃,the microstructure in the heat affected zone is mainly composed of lath ferrite,acicular ferrite and granular cementite. After annealing at 800 ℃,the heataffected zone is mainly composed of equiaxed ferrite and cementite,and the microstructure of the heat affected zone is improved. After annealing at 600 ℃,the hardness of the coatings decreases slightly and the hardened area is relaxed. After annealing at 800 ℃,the hardness of the coatings is uniform and the hardened zone disappears,the hardness from the substrate to the coatings increases gradually,thus improving the bonding between the substrate and the coatings and the mechanical properties of the coatings.
引文
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[2]Wang H J,Wu Y Z,Wang H C,et al. Design method and verification for long life hot forging die[J]. Materials Research Innovations,2011,15(1):s377-s380.
[3]Behrens B A,Bruer G,Paschke H,et al. Reduction of wear at hot forging dies by using coating systems containing boron[J]. Production Engineering,2011,5(5):497-506.
[4]葛言柳,邓德伟,田鑫,等.焊接参数对Ni60合金等离子堆焊层组织结构和显微硬度的影响[J].中国表面工程,2011,24(5):26-31.Ge Yanliu,Deng Dewei,Tian Xin,et al. Influence of parameters on microstructure and microhardness of Ni60 alloy plasma transfer arc welding[J]. China Surface Engineering,2011,24(5):26-31.
[5]Gurumoorthy K,Kamaraj M,Rao K P,et al. Microstructural aspects of plasma transferred arc surfaced Ni-based hardfacing alloy[J]. Materials Science&Engineering A,2007,456(1/2):11-19.
[6]张野,王文权,徐红勇. Mo对等离子喷焊Ni60A涂层组织与性能的影响[J].材料热处理学报,2016,37(7):185-190.Zhang Ye,Wang Wenquan,Xu Hongyong. Effect of molybdenum on microstructure and properties of Ni60A coatings produced by plasma spaying welding[J]. Transactions of Materials and Heat Treatment,2016,37(7):185-190.
[7]邓德伟,葛言柳,田鑫,等.等离子堆焊球形碳化钨颗粒增强镍基合金堆焊层的组织与性能[J].金属热处理,2012,37(11):69-73.Deng Dewei, Ge Yanliu, Tian Xin, et al. Microstructure and mechanical properties of nickel-based hardfaced coating reinforced by spherical tungsten carbides by PTAW[J]. Heat Treatment of Metals,2012,37(11):69-73.
[8]Celik O N. Microstructure and wear properties of WC particle reinforced composite coating on Ti6Al4V alloy produced by the plasma transferred arc method[J]. Applied Surface Science,2013,274(274):334-340.
[9]Liyanage T,Fisher G,Gerlich A P. Microstructures and abrasive wear performance of PTAW deposited Ni-WC overlays using different Ni-alloy chemistries[J]. Wear,2012,s274-275(3):345-354.
[10]Ma Q S,Li Y,Wang J,et al. Investigation on cored-eutectic structure in Ni60/WC composite coatings fabricated by wide-band laser cladding[J]. Journal of Alloys and Compounds,2015,645:151-157.
[11]李朋洋,余新泉,黄怡,等.火焰喷焊和等离子堆焊制备Ni60及Ni60-WC涂层的组织与性能[J].机械工程材料,2017,41(10):38-43.Li Pengyang,Yu Xingquan,Huang Yi,et al. Microstructure and properties of Ni60 and Ni60-WC coatings by flame sprayings and plasma arc surfacing[J]. Materials for Mechanical Engineering,2017,41(10):38-43.