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Cui H.-Z.,Shandong University of Science and Technology | Li Y.-F.,Shandong University of Science and Technology | Sun J.-Q.,Shandong University of Science and Technology | Li B.-M.,Shandong Best Precision Co Ltd | And 2 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2013

Induction quenching for GCr15 steel ball screw with magnetic flux leakage controlling by coating magnetizer was investigated. Microstructure, hardness, depth and wear resistance of surface induction-hardened layer were analyzed, respectively. The results indicate that the quenched layer microstructure consists of martensite and retained austenite. By coating magnetizer, the density of magnetic lines on the surface of ball screw and the temperature of induction heating are increased. And also the depth of hardening layer is increased and the gradient of hardness curve is decreased. Therefore, the wear resistance of the samples with magnetizer is improved significantly, and is increased by 2.5 to 4 times comparing with that of the unquenched sample. Abrasive wear and stripping layer wear are the main wear mechanisms for the induction-hardened sample. The abrasive debrises are thick and with rough fracture surface for the samples by conventional induction quenching, however, by coating magnetizer, the abrasive debrises of the samples are thin and with smooth fracture surface, which indicates good abrasive resistance. Source


Wang W.,Shandong University of Science and Technology | Cui H.-Z.,Shandong University of Science and Technology | Wang Z.-N.,Shandong University of Science and Technology | Sun J.-Q.,Shandong University of Science and Technology | Li B.-M.,Shandong Best Precision Co Ltd
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2015

The surface of 50CrMo4 (German) steel ball screw was induction quenched, and then tempered at low temperature. The phase constitution, microstructure, microhardness, residual austenite content in quenched layer of the steel were analyzed. Moreover, the wear characteristics of quenched layer under dry friction condition and different loads were investigated. Results reveal that the microhardness of the quenched layer increases from 250 HV to 700 HV and the microstructure is mainly composed of fine tempered martensite. The fracture morphology from the surface to matrix is intergranular fracture, dimple and transgranular fracture, and dimple fracture respectively. Furthermore, the friction coefficient decreases with increasing friction load. At the low load the grooves are observed in the wear surface and the wear mechanism is abrasive wear. With the increasing of friction load some pits begin to appear on the wear surface, and the number of it is increasing. However, at the high load, deep grooves and large flakes are observed, the wear mechanism is the mixture of serious abrasion and delamination. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved. Source


Ding X.,Shandong University | Yan Y.,Shandong University | Wang Q.,Shandong University | Li B.,Shandong Best Precision Co Ltd | Li M.,Shandong University
Advanced Materials Research | Year: 2013

The band microstructure has an adverse effect on the comprehensive mechanics performance of Cr-Mo steel used for ball screw. This paper dealt with the different annealing processes combined with the forming mechanism of the banded structure. It shows that the annealing with long time can basically eliminate the band microstructure. © (2013) Trans Tech Publications, Switzerland. Source


Wang Q.,Shandong University | Tian J.,Shandong University | Ding X.,Shandong University | Li B.,Shandong Best Precision Co Ltd | And 2 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2013

The over distortion of 45 steel mainshaft quenched as well as quenched and tempered was analyzed through microstructure and hardness test. It is found that the microstructure is uneven with ferrite network due to the non-uniform cooling in different positions of the mainshaft during heat treatment process. Accordingly, the countermeasures such as eliminating ferrite network by normalizing and adopting subcritical hardening were proposed. Source


Gai Y.-H.,Shandong University | Yan Y.,Shandong University | Li C.-N.,Shandong University | Li B.-M.,Shandong Best Precision Co Ltd | And 2 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2015

The fatigue test and failure analysis of φ80 mm CrMo steel ball screw pair were studied. The GD8020×1100, NSK8020×1100 and FDI8020×1100 CrMo steel ball screw pairs of the same specification were used to conduct fatigue test. Their failure samples were comparatively analyzed by means of chemical composition testing, field emission scanning electron microscopy and metallographic observation, and microhardness gradient detection on the surface-induction heating hardened layers, etc. The results indicate that the running time of the mainland CrMo steel ball screw pair is the longest under the same fatigue test condition, and its failure reasons are mainly due to the damage of GCr15 steel balls. Furthermore, the running time for the Japan and the China-Taiwan ball screw pairs decreases successively and their main failure causes are the obvious indentation on the nut raceway and the severe peeling on the nut raceway, respectively. Therefore, the comprehensive quality of the φ80 mm mainland CrMo steel ball screw pair reaches or exceeds that of the Japan and the China-Taiwan products. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved. Source

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