NEWS UPDATE
Thursday, August 13, 2015
Top Headlines for the Day
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
***
Stainless steel scrap prices heading down with further declines
Russia's scrap export tax cut to affect price, not volume
China further devalues yuan on industrial output
Russian aluminum scrap price stable
Russian aluminum sheet price stable
Europe FeMn market seen flat until September
Europe FeCr market flat, eyes Chinese export offers
Indian silicomanganese dealers delaying new orders on stable prices
Demand for silicon metal weakens in India
Indian ferromolybdenum prices marginally up on weak currency
Indian IMT bar prices down
European chrome metal prices quiet
European selenium metal market sees further downtick
High carbon ferromanganese prices in Europe show slight correction amid air of stability
European ferrosilicon market remains frozen
European ferromolybdenum prices slip
European ferroniobium market dips further
Minimal trading activity observed within US high carbon ferrochrome market
US low carbon ferrochrome prices remain stagnant
Japanese ferrosilicon prices down
Copper discounts in China continue to widen
Chinese silicon metal export price continues to decrease
Chinese SiMn 6014 Kept at Low Level
China uncertainty weighs on European metals prices
Chinese ferromolybdenum price under heavily downward pressure
Antimony prices fall on cheaper offers as China devalues currency
Chinese tin ingot prices weak
Chinese ferrovanadium price decreases slightly
Chinese ferrosilicon prices decline
Chinese magnesium alloy offers decrease slightly on weak demand
Chinese ferroboron export prices stable
Japanese ferrosilicon prices down
With weak end-user demand occasioned by near-stoppage activity by Japanese steel plants,
quotations and deals on imported Chinese-origin ferrosilicon 75%min grade material are down by
USD15.0-25.0t and new shipment cargoes routed through Vietnamese ports of Haiphong are
Compiled by: IIF-Foundry Informatics Centre, New Delhi
confirmed to have been concluded USD1,075t CIF Japanese ports. A 500t-ferrosilicon 75%min grade
material was reportedly concluded to a Japanese end-user at USD1,075t CIF Japanese ports with
delivery expected by early September, a new low bids following mainstream deals in the past week.
Demand for silicon metal weakens in India
Chinese silicon metal price kept dropping, and the demand in local market remained weak, and thus,
Indian silicon metal market was in thin trading early this week. Market participants claimed that
RMB depreciated sharply against US dollars on Tuesday and Wednesday and the offer for silicon
metal from China decreased further with that for 5-5-3 getting lower from around USD1,620-1,640t
CIF Nhava Sheva last week to USD1,590-1,610t CIF Nhava Sheva.
Chinese ferrosilicon prices decline
Sources reported that Chinese ferrosilicon market sees weakening demand and sliding prices.
Currently, prices for ferrosilicon 72%min natural blocks drop to RMB4,550-4,650t USD707-722t EXW
DA, down by RMB50t USD7.77t from last week, and those for ferrosilicon 75%min natural blocks
decrease to RMB4,900-5,000t USD761-777t, down by RMB50t USD7.77t from last week.
Chinese SiMn 6014 Kept at Low Level
In recent period, price of silicon manganese 6014 also kept in poor performance given sluggish
demand. In fact, low sale price made shutdown situation of silicon manganese in south area become
worse. In Guangxi and Chongqing, price of 6014 concentrated on RMB4,050-5,150/mt without tax
while RMB4,100-4,200/mt for Hunan and Guizhou. In Henan, price of 6014 dropped to RMB4,1504,200/mt. Given traditional slack season in August, the movement of alloy market would be hard to
show good shape. Despite prices already touched the bottom line, the future market of silicon
manganese would still be not optimistic amid slowing growth of economy in China
Industry hails Haryana's new industrial policy
Industry body CII on Tuesday hailed Haryana's new 'Enterprises Promotion Policy 2015' and
described it as "progressive one". CII Northern Region Chairman and Somany Ceramics CMD
Shreekant Somany said, "The focus of the policy is on enhancing the ease of doing business in
Haryana and make it an investment hub both domestically and globally, with the aim to ensure the
overall socio-economic development of the state." He added, "CII is pleased to note that a lot of its
key recommendations like efforts towards effective single window clearance mechanism focus on
development and support to MSMEs, entrepreneurship, skill building and R&D facilitation,
rationalisation of labour laws and minimal or no Inspection regime, need for online grievance
redressal mechanisms have been considered positively."
A statement from the industry body further said, "CII hopes that the chief minister led Economic
Advisory Council (EAC) would monitor and speed up the implementation of necessary revisions." CII
Haryana state council chairman and Satyam auto components managing director Sameer Munjal
said, "The policy is progressive as it focuses on attracting investments & retaining the existing
Compiled by: IIF-Foundry Informatics Centre, New Delhi
investments by leveraging its strengths through sustained aggressive promotional strategies
complemented by a globally competitive and sustainable business environment." CII Haryana state
council vice chairman and Maruti Suzuki executive director Rajeev Gandhi said, "With the
government playing the role of a facilitator and a catalyst, the policy will provide an eco-system that
encourages the minimum government and maximum governance model of the government."
Chinese Aluminum prices may remain under pressure in medium term
Aluminum prices in China will remain under downward pressure from persistent supply glut in the
medium-to-long term, Shanghai Metals Market foresees. Supply and demand imbalance will worsen
due to record high aluminum production and slowing downstream consumption from economic
downturn, SMM understands. Aluminum stocks on the SHFE have been increasing since March,
hitting 321,177 tons as of August 7, a reflection of poor consumption. The most active aluminum
contract on the SHFE hit a six-year low on August 11, down 11.4% from high level seen on May 6.
Price volatility in Iron Ore returns in July
July recorded some of the largest-ever one day moves in The Steel Index (TSI) benchmark 62% Fe
iron ore index as prices came under renewed pressure. The monthly average of the index was down
over 17% compared with June. The latest Chinese import data showed a 6% increase in the country’s
June imports of the raw material. Within this, Australian iron ore, accounting for two thirds,
increased 8% m-o-m. Chaos in China’s volatile equities markets fed through into the “real economy”
as well as affecting steel markets, largely through the effect market turbulence had on commodities
futures (including those for steel and iron ore). The China manufacturing PMI by Caixin and the
official government both signalled contraction in output again. The iron ore derivatives market saw
another record month of trade, with one day alone seeing more than 15 million tons cleared
through the Singapore Exchange (SGX). The total volume across SGX and the CME Group in July
exceeded 124 million tons, 35.5% higher than last month.
The Benefits of Semi-Solid Casting for Aluminum Alloys
Semi-solid metalcasting (SSM) was developed in the 1970s and became a commercial process for
thixocasting (billet re-heating) in the 1990s, and for rheocasting (generating the semi-solid slurry
directly from the liquid) in the 2000s. However, despite significant technical and economic
advantages, as pointed out recently by Jorstad(1), SSM has never advanced to become the major
metalcasting process anticipated by so many early investigators. Certainly there have been a number
of obstacles to the commercialization of SSM, such as the original thixocasting process being
relatively expensive, early rheocasting processes not being fully competitive, along with
improvements made to already-facilitated competing casting processes (squeeze casting,
conventional diecasting, and high vacuum diecasting.)
We agree with Jorstad and suggest that semi-solid casting still has much to offer. The global
economic downturn in the late 2000s resulted in overcapacity of existing processes and a reluctance
to invest in new processes, but the economic recovery makes it an ideal time to reexamine the
benefits of semi-solid casting. Certainly large-volume buyers of castings, such as automotive
Compiled by: IIF-Foundry Informatics Centre, New Delhi
companies, are under pressure to reduce casting weight to improve fuel economy and reduce CO2
emissions. So, our purpose here is to re-examine semi-solid casting and review the benefits of the
process.
There are a number of advantages to producing castings in uncoated metal molds, including the
production of excellent surface finishes, close dimensional tolerances, and probably most important,
fine-scale microstructures (due to rapid heat extraction.) However, the high cooling rates
experienced in metal molds also present processing difficulties, as the liquid metal needs to fill the
cavity quickly before the onset of solidification. To produce high-quality castings, Campbell(2) has
suggested that cavity-filling speeds should not be greater than 0.5 m/sec, thereby establishing a limit
on the minimum wall thickness and the maximum casting size that can be produced by gravity
pouring or low-pressure processes.
In contrast, high-pressure diecasting ignores Campbell’s rule on the maximum cavity-filling speed
and sprays the liquid metal into the die at extremely high rates (30-50 m/sec.) While this allows the
diecasting process to produce extremely thin-walled castings (as thin as 1-2 mm), the turbulent diefilling process tends to trap large quantities of air, resulting in high levels of detrimental residual
porosity in the castings.
Semi-solid metalcasting maintains all the advantages of diecasting, while eliminating all (or most) of
the residual porosity, thereby producing high-quality, thin-walled castings with excellent mechanical
properties. Instead of using a fully liquid metal to produce the castings, semi-solid casting uses a
high-viscosity feed material that is about 50% solid and 50% liquid. The fluid behavior of semi-solid
materials is displayed in Figure 1, which shows the impact of solid content on apparent viscosity.
While low solid contents have only a small impact on viscosity, increasing the solid content above
40% or so significantly increases viscosity.
This difference in flow behavior is demonstrated by the partially filled plate castings shown in Figure
2. The casting on the left was partially filled at high speed with fully liquid aluminum, and the
turbulent filling behavior is evident. However, when the plate cavity was filled at the identical
injection speed with semi-solid metal, the filling behavior became laminar. The difference is due to
the high viscosity of the semi-solid alloy, and this controlled die-filling behavior allows SSM to
produce thin-walled, complex-shaped castings with excellent mechanical and functional
performance.
Research(4) has confirmed that the high viscosity of semi-solid alloys can indeed minimize the
number of defects in castings. Figure 3 shows the impact of solid fraction and filling speed on defect
formation in castings (the defects being identified by x-ray.) The researchers found that defect-free
castings could be produced only with fully liquid aluminum (solid fraction of 0%) when the cavity
injection speed was 0.5 m/sec; defects were formed at higher filling speeds. Note that this is in
agreement with the maximum die-filling speed suggested by Campbell(2.)
However, as the solid fraction of the feed material was increased, the maximum die-filling speed at
which defects were avoided also increased. For example, at a solid content of 30%, the maximum
die-filling speed to avoid defects increased to 1.5 m/sec. Of most importance commercially is the
alloy containing 50% solid, and the researchers showed that defect-free castings could be produced
at an injection speed of 3.5 m/sec (seven times faster than for fully liquid aluminum.)
This ability to fill thin sections while avoiding defects is significant, as thin-walled castings are
obviously of great commercial interest. Similar to conventional diecasting, semi-solid casting is
capable of producing ultra-thin walled castings in the range of 1-2 mm. While such sections require
very high filling velocities, well above those generally considered stable, such velocities appear to be
Compiled by: IIF-Foundry Informatics Centre, New Delhi
easily tolerated by semi-solid slurries, allowing such ultra-thin walled castings to be filled without
defects.(1.) For example, researchers(5) reported on the production of such a casting about 125X200
mm in size, with a wall thickness of 1 mm (Figure 4.) However, it’s worth noting that such ultra-thin
walled castings are not typical, and most commercial semi-solid castings have wall thickness in the
range of 2-5 mm.
Superior Soundness, Longer Die Life. The combination of controlled die filling by a highly viscous
semi-solid material, together with the high intensification pressures used to feed solidification
shrinkage, allows the semi-solid process to produce castings of exceptionally high quality, having
very low levels of porosity. While conventional high-pressure diecastings typically have porosity
levels measurable in whole percentages, and the porosity content of squeeze castings are typically
measurable in tenths of a percent, porosity levels in semi-solid castings are typically as low as
hundredths of a percent.(1.) Such low porosity levels produce castings with excellent mechanical
properties, certainly equal or better in quality and cost than achievable by low-pressure permanent
mold or squeeze casting (Table 1.) Therefore, properties that are influenced by porosity and defects,
such as elongation(6) and fatigue(7), tend to be much better for SSM than for castings produced by
competing processes. In addition, due to the lack of residual porosity, semi-solid castings are fully
weldable. Another significant advantage of semi-solid casting is the considerable extension in tool
life versus conventional diecasting, and especially compared to squeeze casting. As pointed out by
Jorstad(1) for metal-mold casting processes, the number of castings that can be produced before the
onset of heat checking (thermal fatigue) and eventual tool failure is a function of two factors:
(1) the total heat load placed on the die; and, (2) the temperature difference (∆T) between the tool
and the incoming metal. Each of these are discussed below.
The heat load imposed on the die occurs as the tool absorbs heat from the solidifying aluminum. The
magnitude of the heat load is a function of three factors: the superheat of the liquid, the latent heat
of solidification, and the specific heat required to cool the solid casting to its ejection temperature.
For squeeze casting, where the fully liquid metal is injected into the die at 730-735°C and the solid
casting is ejected around 425-430°C, the magnitude of this heat load is about 900 J/g. The total heat
load from conventional diecastings is only slightly lower, due to diecastings typically being thinner in
nature. In contrast, the heat load during semi-solid casting is much lower (around 500 J/g), due to
the injection temperature for a semi-solid alloy with a solid content of 50% being as low as 575°C.
For the same reason, the ∆T between the tool and incoming metal is much smaller for semi-solid
casting compared to other metal mold processes. For squeeze casting, the magnitude of the
difference is around 480-535°C, for conventional diecasting about 450- 525°C, but it is only 230290°C for semi-solid casting. Because of these differences, the tool life for semi-solid casting is easily
double the tool life of conventional diecasting, and three-to-five times that of squeeze casting.(1.)
This is of great consequence, as tools for all three high-pressure processes are very expensive
(generally ≥$100,000.)
SEED Process. For successful semi-solid casting, it is necessary that the solid phase have a nondendritic, globular microstructure. While a great number of different methods have been proposed
to produce semi-solid castings, if the goal is to produce high-quality castings, it is necessary to use a
process that generates the globular microstructure while treating the liquid metal gently, avoiding
the introduction of defects during turbulent processing (such as rapid stirring or mixing.) While
thixocasting (billet re-heating) has been shown to be capable of producing extremely high-quality
castings(7), commercial competitiveness of thixocasting is hampered the limited number of billet
suppliers, along with the high cost associated with the specially processed feed material and the low
Compiled by: IIF-Foundry Informatics Centre, New Delhi
value of offal. Rheocasting, where the semi-solid slurry is generated directly from the liquid adjacent
to the casting machine, has greatly improved competitiveness, but potential users must take care to
pick a suitable rheocasting process.
With the SEED process (Swirled Enthalpy Equilibration Device), castings are produced with minimal
levels of turbulence.(9,10.) As shown schematically in Figure 5, the liquid alloy is melted and held at
a superheat of about 30°C. A controlled amount of the melt is transferred to a coated crucible, and
the wall thickness of the crucible is chosen so that the melt is chilled to a temperature within the
semi-solid temperature range. Then, the crucible is gently swirled, to distribute the solid phase
uniformly within the crucible (while avoiding turbulent mixing.) Once the slug is at the correct
temperature (and solid fraction), the slug is ejected from the crucible and controlled parameters
used to inject it into the die cavity.
In summary, there are a significant number of benefits to semi-solid casting that should be of
interest to the producers and users of high-quality aluminum castings,(1.) including:
• Castings can be produced without splashing, oxide formation and entrapment of air, as long as the
rheocasting process is carefully chosen.
• The viscous semi-solid alloy flows only when forced, and will not cascade into lower cavities of the
die.
• High pressures (up to 100 MPa) can allow the complete feeding of solidification shrinkage
porosity.
• SSM cast products have exceptional soundness, and therefore have excellent strength, ductility
and fatigue resistance, and are fully weldable.
• The fast cavity-filling time allows semi-solid alloys to fill extremely thin sections (2- 3 mm and
less), minimizing casting weight.
• SSM reduces cycle time, thereby maximizing productivity.
• SSM significantly extends tool life, so a die life of hundreds of thousands of shots is possible.
To succeed commercially, semi-solid casters must take advantage of the cost-saving features
available with the processes, which include the use of low-cost feed materials, reduced metal
content (through the use of thin-walled castings), reduced machining via near-net shape processing,
reduced porosity leading to better mechanical properties (especially elongation and fatigue), the
elimination of impregnation for pressure-tight castings, minimization of scrap, and extended die life.
However, as noted, it’s critical that the producers of semi-solid castings have technically and
economically successful product launches, and so must pick rheocasting processes that minimize
turbulence during the production of the semi-solid slurry and so are capable of producing high
quality castings. The SEED process is such a rheocasting process(9), as it optimizes metal quality
during both the production of the slurry and during the casting process itself. So, in the authors’
opinions, if casters pay attention to the details and follow established quality practices, the age of
semi-solid casting can still be realized.
Compiled by: IIF-Foundry Informatics Centre, New Delhi