Failure caused by defects in machining

Defects caused by machining include cutting streaks and cutting heat. Streaks and scratches on the surface of the part act as a notch surface, and stress concentration occurs at the notch during use. Especially in the case of impact loads and alternating loads, the parts quickly break down. Rough grinding, when the pressure of the grinding wheel is too high, the ground surface is heated, causing the material to anneal, phase change, and even begin to melt. Pay attention to this problem when grinding hardened parts. The stress generated during the grinding process is the main cause of the grinding crack. The grinding crack is perpendicular to the grinding direction or has a mesh shape with a depth of up to 1 mm. When steel having a high carbon content and a carburized layer having a network of cementite are ground, cracks are particularly likely to occur. The spinning wheel crack analyzed below is an example.
The spinning wheel material is GCrl5, and the processing technology is blanking-forging type-destressing annealing-roughing-normalizing-spheroidizing annealing-finishing-quenching-tempering-grinding. After the forming, it was found that the rim of the rim had a crack from the top to the bottom in the longitudinal direction.
Observe the crack under a metallographic microscope and see several bright areas along the rim of the rim as shown in Figure 10-15. The crack originates from a white bright layer, see Figure 10-16. It was observed that the material had more severe banded carbide segregation.


Figure 10-15 White rim of the rim of the rim × 200


Figure 10-16 Crack originating from white bright layer

Hardness
The microhardness was measured from the surface white bright layer area to the test piece, and the hardness distribution is shown on the right side of Fig. 10-15.
Composition analysis was performed under a scanning electron microscope equipped with an energy spectrometer. The white bright layer contains 2.33% Cr, and only the white bright layer contains 1.48% Cr, and the internal banded carbide segregation contains 2.5% Cr.
2. Analysis Conclusion There is banded carbide segregation in the material. The large amount of carbides dissolved in the austenite at the segregation during quenching heating causes the martensite point to decrease in the amount of retained austenite. The presence of more carbides and retained austenite in the steel will seriously affect the conduction of grinding heat, and the residual tensile stress after grinding will also increase. The grinding surface is instantaneously heated rapidly, and the instantaneous temperature of the surface layer is higher than the critical temperature of the phase transformation and is cooled at a speed of 800-1000 ° C / s. The surface layer is quenched to produce a white bright layer. In addition, the surface layer during the rapid heating and cooling process, especially at the flange of the large plastic deformation, generates a large residual tensile stress.
The white bright layer has a hardness as high as HV1029. The softening layer hardness HV775 appears only in the white bright layer where the heated temperature is lower than the phase transition point. In order to confirm that the white bright layer is a quenched structure, the sample is tempered at 500 ° C, and after tempering, the self-bright layer becomes dark, and a tempered structure appears.
The conclusion is the segregation of the banded carbides of the raw materials. Thermal stress, tissue stress and secondary quenching of the surface during the grinding process result in longitudinal cracks at the flange.

Cement-based non-shrinking self-leveling Grouting Material
KS series of grout is a high-tech one-component grouting material using Portland cement, pre-grade filler and additives that control the expansion in the plastic and can reduce water consumption.
Application of grouting Material:
Widely used in free-flowing precision grouting construction, including heavy machinery floor support, crane tracks and pillars foundation, but also can be used as mast, anchor bolt of the excellent reinforcement of grouting material; also is a good material for concrete repair works; design Beneath bridge supports, posts and flanged lamp posts, heavy pillar bases, and machine bases with dynamic loads. Such as thermal power plants, large paper mills, steel plant, steel mills, large machinery and equipment plants, cement plants.
Product advantages:
1, compensation shrinkage ---- gas expansion system, to compensate for shrinkage and settlement in the plastic slurry, to ensure that the grout material and the foundation in close contact
2, no chloride ---- The formula does not use chloride, thus avoiding the chloride hazards
3, high early strength ---- make the factory equipment faster to install and early use
4, non-ferrous ---- will not be rusty and stains or cracks due to rust expansion
5, reliability ---- factory pre-packaging materials, to eliminate the site produced by the error mixing


According to the standard:

KS series grouting material is based on the following part of the relevant standard test:
ASTMC-1107-97(Type)CRD-C621-82A
YB/T9261-1998       MS 522:part2:1989
ASTM C940-87        BS 4551:1980
JC/T986-2005

Expansion performance:

According to the American Standard ASTMC827 plasticizing stage test expansion rate of 0.5% or more, the long-term expansion of the curing stage to meet the requirements of the relevant standards.

Material properties:

project

model

KS-40

KS-60

KS-801

40

401

60

601

(mpa)

compression strength(mpa)

1 day

20

22

25

30

45

28 day

40

50

60

70

85

(mpa)

Flexural strength(mpa)

28 day

9

10

12

12

12


Setting time


Initial setting

6.5h

6.5h

6h

6h

6h


Final condensate

 

8h

8h

7.5h

7.5h

7.5h


Expansion time



Plastic stage


Start 10min to initial setting


Start 10min to initial setting


Start 15min to initial setting


Start 15min to initial setting


Start 15min to initial setting



Curing stage


The final setting to cure more than 28 days


The final setting to cure more than 28 days

 

The final setting to cure more than 28 days             


The final setting to cure more than 28 days


The final setting to cure more than 28 days


Liquid density

(kg/m³)

2150

2150

2200

2200

2250


Water consumption

Ks/dag

3.8~4.0

3.8~4.0

3.8~4.0

3.8~4.0

3.6~3.8

Construction Instructions:


 1. floor grouting:

The flow distance should be determined based on the slit width and the liquid flow indenter to ensure that the grout flows from the gap to the front exit and the gap must not exceed 200 mm. If you guarantee a pressure head of 250mm, the maximum flow distance of up to 3 meters.

Note: The base surface must be constructed with oil-free and non-adherent loose material. If the surface of the concrete defects or slurry is cut intact before construction, the screw holes or solidified hole dust or sand blown net.

2. Floor:

Clean, no oil and other impurities must be removed to provide relief holes to ensure that all isolated areas are ventilated.

Pre-soaked: A few hours before grouting, the cleaned foundation must be submerged in water. Remove water from the free water and the hole just before pouring.

3.  Stir:

To achieve the desired consistency, the amount of water must be accurate, the selected amount of water after slowly pouring it into the mixing vessel, while stirring feed, add complete package and continue stirring for 3-4 minutes until evenly dispersed, no knot Block phenomenon so far.

4.  Grout:

The well-mixed material is poured over a period of 10 minutes to fully benefit from the expansion process. Each single perfusion thickness up to 200mm, the minimum width of the seam is 10mm.

5. Specific construction of large volume grouting:


Such as the thickness of more than 200mm. Aggregate grading (stones up to 10 mm in diameter) shall be added to the slurry to reduce the heat of hydration. The amount of aggregate used shall not exceed 1 part by weight of 1 part of KS series grout.

6.Low temperature construction:
When the temperature drops below 2 ° C, warm water (30-40 ° C) may be used to accelerate the strength increase and the cementitious material should be handled in winter.
High-temperature construction:
When the temperature exceeds 35 ℃, grouting material should be stored in a cool place, and cold water mixing.
Conservation:After grouting is complete, all exposed parts should be cured with Cask Cares or wet sacks.
Countermeasure :
KS series grout contains cement powder, which when mixed with gypsum or when wet, releases alkali that is harmful to the skin. Avoid inhaling dust and avoid touching the skin or eyes.
Estimation:pack
KS series grouting material) 25KG/bag
Under free flow the volume is about 13.0L
CONSTRUCTION schematic:

grouting material


KS series grouting material

grouting material

grouting material CONSTRUCTION schematic:

Storage:
KS series grouting material intact material in dry place storage period of 12 months, if stored in high temperature and high temperature storage area will be shortened.
Kasler Building Materials Co., Ltd. guarantees the quality of its products manufactured and sold, and sells it according to the agreed sales terms. Casper pledges to make every effort to advise clients on the construction of the project, recommending the use of solutions and materials. However, as we are unable to exercise direct and continuous control over the use of our products for sale, CASLUS BUILD MATERIALS CO., LTD can not afford to use whatever advice our customers ultimately end up using and recommending solutions and materials The use of the product caused by a variety of direct or indirect responsibility.


Grouting Material

Grouting Material,Cement Grouting Material,High Strength Grouting Material,Non-Shrinkage Grouting Material

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