آلیاژهای Ti-25Nb-xSn ریختگی برای کاربردهای بیوپزشکی

The structure and mechanical properties of

as-cast Ti–25Nb–xSn alloys for biomedical applications

ساختار و خواص مکانیکی آلیاژهای Ti-25Nb-xSn ریختگی برای کاربردهای پزشکی زیستی

ABSTRACT

The effects of tin on the structure and mechanical properties of a Ti–25Nb-based system were studied with an emphasis on improving the strength/modulus ratio. Commercially pure titanium (c.p. Ti) was used as a control. As-cast Ti–25Nb and a series of Ti–25Nb–xSn (x=1, 3, 5, 7, 8, 9, 10, 11, 13, and 15 wt%) alloys prepared using a commercial arc-melting vacuum pressure casting system were investigated. The experimental results showed that the as-cast Ti–25Nb has an α″ phase, and when 1–5 wt% Sn was introduced into the Ti–25Nb alloy, the structure remained essentially unchanged. However, with 7–15 wt% Sn, retention of the metastable β phase began. Among the developed Ti–25Nb–xSn alloys, all the alloys had good ductility, and Ti–25Nb–8Sn and Ti–25Nb–9Sn alloys had lower bending moduli (52 and 53 GPa, respectively) than c.p. Ti (99 GPa) and the other Ti–25Nb-based alloys (61–133 GPa). Moreover, Ti–25Nb–9Sn and Ti–25Nb–11Sn alloys exhibited higher bending strength/modulus ratios, as large as 20.5 and 20.6, respectively, higher than those of c.p. Ti (8.5) and the Ti–25Nb alloys (19.8). The Ti–25Nb–10Sn (41°) and Ti–25Nb–11Sn (46°) alloys had superior elastically recoverable angles, about 17.0 and 15.2 times greater than that of c.p. Ti, respectively. In the current search for a better implant material, β-phase Ti–25Nb-(8–11)Sn alloys show considerable promise due to their low moduli, ductile properties, excellent elastic recovery capability, reasonably high strength (or high strength/modulus ratio), and better shape memory effect

 

اثر پارامترهای جوشکاری ترمیمی بر عمر مفید قالب های دایکست

Effect of repair-welding parameters on life time of

die casting moulds

اثر پارامترهای جوشکاری ترمیمی بر عمر مفید قالب های دایکست

ABSTRACT

In die casting, H13 hot working tool steels are exposed to heat shocking and cracking due to the thermal fatigue which is exerted by die casting process. The gradual destruction of mould surfaces during the service, decreases casting piece quality and limits the mould life time. These moulds are expensive and replacing of them is the main problem of the die casting industries therefore repair-welding of die casting moulds can be helpful. H13 steel has low weldability because of the significant hardening resulted from large amounts of alloying elements. Within this study, results were obtained on the performance of repair welded parts that were welded by three types of filler metals on the thermal fatigue test. The filler metals that are used in this study are H13 tool steel, maraging steel and Co-base alloy. Maximum and minimum life time of the repair welded parts of die casting mould in the thermal fatigue test were obtained from Co-base alloy and H13 hot work steel filler metals, respectively. Repair-welding by maraging filler metal shows the intermediate life time. It seems that repair-welding of H13 moulds by maraging filler metals is more economic because of its lower price in comparison with the Co-base filler metal.

 

مشخصه‎های ضخامت پوسته در ورق تولید شده به روش ریخته‎گری مداوم

Characteristics of shell thickness in a slab continuous casting mold

مشخصه‎های ضخامت پوسته در ورق تولید شده به روش ریخته‎گری مداوم 

ABSTRACT

It is of great importance to form a thick and sufficiently uniform solidifying shell in the mold to prevent breakout in the continuous casting process. Breakout starts to take place at the thinnest point commonly, and therefore, it is significant to investigate the slab thickness distribution in longitudinal and transverse directions to determine this point. Experimental and numerical simulations are the two ways for  measurement of shell thickness in the mold. The former such as adding sulfur into the mold [1], disturbs the normal production and obtains some useful data, which cannot characterize the shell thickness profiles thoroughly. On the other hand, several scholars have researched the flow, heat transfer, and solidification in the mold by numerical simulation . However, some profound researches on the characteristics of the shell thickness have been done.

  

درصد گاز در ریخته­ گری دایکاست فشار بالا

Gas content in high pressure die castings

درصد گاز در ریخته­ گری دایکاست فشار بالا

ABSTRACT

This paper presents the results of a quantitative study of the gas level in various types of castings from the high pressure die casting (HPDC) process using a vacuum fusion method. It was found that the major part of the gas was from the air entrapment during cavity filling. Other sources such as air entrapment during ladling, residual die lubricant and quenching water were also noticeable. Measurements of a large casting and castings from a multi-cavity die showed that the gas content was unevenly distributed. The modified vacuum fusion method has been proved to be a valuable tool for evaluating and quantifying the level of gas in castings as well as for an assessment of the influence of different process parameters on gas evolution in castings.

مقدمه ای بر ریخته گری تحت فشار و عیوب رایج در آن

Introduction Of High Pressure Die-Casting

And Common Defects In Die-Casting

مقدمه ای بر ریخته گری تحت فشار و عیوب رایج در آن

ABSTRACT

Die casting is a manufacturing process that can produce geometrically complex metal parts through the use of reusable molds, called dies. The die casting process involves the use of a furnace, metal, die casting machine, and die. The metal, typically a non-ferrous alloy such as aluminum or zinc, is melted in the furnace and then injected into the dies in the die casting machine. There are two main types of die casting machines - hot chamber machines (used for alloys with low melting temperatures, such as zinc) and cold chamber machines (used for alloys with high melting temperatures, such as aluminum). The differences between these machines will be detailed in the sections on equipment and tooling. However, in both machines, after the molten metal is injected into the dies, it rapidly cools and solidifies into the final part, called the casting. The steps in this process are described in greater detail in the next section.