Process parameters (laser power and scanning speed) for H13 steel specimens produced by selective laser melting (SLM) are optimized, and microstructural characteristics and mechanical properties are investigated. The optimum process parameters are a laser power of 170 W and a scanning speed of 400 mm/s according to the maximum relative density of 99.2%. The microstructure consists of cellular grains and columnar crystal, which are composed of lath martensite and retained austenite, and there are no carbides or other second-phase particles present. The size of cellular grains is 1 μm. Compared with the common processed (forged and heat-treated) H13, SLM H13 has similar microhardness (561 HV) and tensile strength (1909 MPa) values. However, the elongation (12.4%) is a factor of ∼3 times higher and the impact energy (14.4 J) of the SLM specimen is somewhat lower. The relationship between the microstructure and mechanical properties is discussed. Fine grains and no second-phase precipitation determine the strength and plasticity of SLM samples.

I first heard of the term ‘Chinglish’ when I was at Baiduizi (白堆子) Beijing Foreign Languages School in the 1970s, through Janet Adams’ book, From Chinglish to English. The book contained 60 short dialogues in simple American English. It was meant to be teaching us colloquial English, compared to, I suppose, the textbook English written by Chinese teachers. I found the term Chinglish rather odd, and it was an odd thing for us pupils at that particular school to be made aware of, because the school was, quite literally, the only school in China at the time where foreigners were directly teaching Chinese children foreign languages and cultures. Few of these foreign teachers had formal teaching qualifications, and they were not using any textbooks written by Chinese teachers, but in their own ways using material the school compiled specially for the pupils. It was a form of audio-lingual and direct method. The language we were taught was pretty colloquial and we did not, as far as I could tell, speak Chinglish that the examples in Adams’ book illustrated.

In this paper many studies have been carried out to ascertain the phenomenon of strain-induced precipitation and coarsening of carbides in AISI H13 hot-work die steel during the tests at 700 °C. The microstructure of H13 with various loadings was studied to identify the effects of mechanical strain on the evolutionary behavior of carbides. SEM and TEM were used to observe the size and distribution of the carbides of each sample. It was found that the coagulation of carbides is more obvious in mechanical strained samples than that in mechanical strain-free sample which means mechanical strain promotes the precipitation and coarsening of carbides, and these processes are affected by the mechanical strain amplitude. Precipitation is increased by the strain enhanced because of more nucleation sites produced and accelerate the diffusion of solute atoms. Moreover, the results are shown that lower strain rates are more beneficial for precipitation and coarsening of carbides under the same strain because they provide a longer time to nucleate and grow into nuclei.

The aim of this research was to investigate the influence of substrate roughness on the adhesion and tribological performance of thin TiN coatings obtained by physical vapor deposition. For that purpose, substrates of AISI H13 steel with surface finishes of 0.06, 0.28 and 0.90 μm in Ra were coated with TiN under the same coating conditions. The chemical composition of the steel, as well as that of the TiN coating, were obtained using EDS analysis. Adhesion tests were carried out following the procedure of BSi 1071-8 standard while hardness was evaluated by ASTM C 1327-03. On the other hand, dry sliding friction tests were conducted with a pin-on-disk tribometer, according to the ASTM G 99-05 standard. This study showed that the roughness of the coating increases as the substrate roughness increases. Regarding adhesion and hardness, all the samples showed an adhesion class 1 according to the standard and a hardness value of 14.51 GPa. Nevertheless, the highest substrate roughness produced the best adhesion. On the other hand, the lowest values for the friction coefficient and wear behavior were obtained by the sample with the lowest substrate roughness of 0.06 µm. In addition, it was found that friction and wear increase when the substrate roughness increases.

TiC/H13 nanocomposite parts were processed by selective laser melting using various energy densities; one part also underwent hot isostatic pressing (HIP). The effect of energy density and HIPing on densification, microstructure, and hardness were evaluated. It was found that the densification was not largely affected by the energy density, but the HIP-treated sample displayed a large improvement in relative density. With increasing energy density, the microstructures showed high levels of dispersion of nanoparticles, while HIP treatment coarsened the microstructure and induced agglomeration. Both HIP treatment and increased energy density lowered hardness markedly; this was likely due to annealing effects.

H13 tool steel was deposited using the additive manufacturing technique Direct Metal Deposition to produce a part having a wedge geometry. The wedge was characterized both in terms of microstructure and residual stress. It was found that phase transformations were significantly influencing the microstructure, which was then linked to the residual stress distribution as seen in Fig. 8. The residual stress distribution was found to be opposite to that reported in the literature. This was attributed to the low temperature martensitic phase transformation of the H13 tool steel and the subsequent tempering of the microstructure with an increasing number of layers of deposited material. The high hardness and compressive residual stress of the top 4 mm of the wedge are ideal in die casting and forging dies, as it will resist thermal fatigue. It also has a hardness higher than that produced by typical heat treatment processes.

The tribological properties for pulsed W+C and Mo+C dual implanted H13 steel are given in this paper. The pulsed ion of W, Mo and C were implanted at 40KV to dose of (3~12)×1017/cm2 with ion flux from 25 to 100µA/cm2 using MEVVA implanter. The results show that the wear resistance life and hardness of the dual implanted H13 steel increase 2~3 times. The comparison of dual implantation with single implantation shows that the dual implantation is better. The tribological properties of W+C dual implanted H13 steel is better than Mo+C dual implanted H13 steel. The TEM and X-ray diffraction analysis show that the super high hardening dispersed phases of MoC, MoCx, WC and W2C were formed during ion implanting. The iron compounds of tungsten and molybdenum and iron carbides were obtained also. That is, the strengthening effect in H13 steel of phases MoC and WC is better than FeMo, Fe3Mo2, Fe2W and Fe7W6.

This article is a case study on the Yunnanese scholar Li Yuanyang under the background of the Ming's incorporating and sinicizing Yunnan, exploring how he views the Ming's actions and writes Yunnan's becoming a part of China. First, it retells Li's life experiences and examines the Yunnan native things and Chinese traditions in his writings. Then, after noting his emphasis of Yunnan's belonging to China, it concentrates on his comments on the Ming's military campaigns. As it analyzes, on the one hand, he justifies these campaigns against indigenous rebellions, on the other hand, he also criticizes unnecessary wars and some imperial officials' selfish deeds. Besides, he considers the constructing and reconstructing projects as a symbol of the central state's righteous governance, which should also bring benefit and benevolence to the indigenes. In a word, Li's case reflects the deep impact of the Ming's invasion on the local elites, as well as how they react to this.

The chemical change in the surface of H13 steel or aluminum is produced by implanting a reactive elements, such as Ti, Mo and W. The X-ray diffraction pattern shows that implanted Ti at 400 C has reacted with carbon(0.35 in wt.%) forming a second phase TiC. Auger analysis shows that the carbon atoms have been condensed in the Ti implanted region. Carbon peak concentration of 30 At.% is greater than Ti atom peak concentration of 12 At.%.

Several second phases are formed during pulsed Mo ion implantation 2 into aluminum with high ion flux of 50˜80µA/cm2 which raises the target temperature from 400°C to 600°C.

More second phases are formed by dual Mo+C implantation with high dose of 3˜5×10 17/cm2 and high flux of 50˜75µA/cm2 . And the target temperature is raised from 400 to 600°C. The FeMo Fe3Mo2, Fe2MoC, Mo2C, MoC, MoCx, phases and iron carbides are identified by X-ray diffraction technique.