RM Testing training- HHML.ppt

METALLURGICAL
TESTING OF
RAW MATERIAL
(BAR STOCK)

METALLURGY
• METALLURGY IS RELATED TO THE
STUDY OF MATERIAL PROPERTIES &
THE VARIOUS MANUFACTURING
PROCESS
(FORGING,CASTING,ROLLING ETC.) &
THE PROCESS WHICH CHANGE THE
MATL. PROPERTY.

TYPE OF METALS
• WE CAN BROADLY CLASSIFY THE
METALS IN TWO GROUPS.
• 1.FERROUS METALS
• 2.NON FERROUS METALS
• IN AUTOMOBILE WE ARE MAINLY
CONCERNED WITH FERROUS
METALS.

FERROUS METALS
STEEL (CARBON UP TO 2.0 %) CAST IRON (CARBON MORE THAN 2.0 % )
CARBON STEEL ALLOY STEEL TOOL STEEL
MALLEABLE IRON
GREY CAST IRON

PLAIN CARBON STEEL
LOW CARBON STEEL MEDIUM CARBON STEEL HIGH CARBON STEEL
CARBON UP TO 0.3 % CARBON 0.3-0.6 % CARBON MORE THAN0.6 %

• PLAIN CARBON STEEL
• CARBON IS THE MAIN ELEMENT WHICH GOVERNS THE PROPERTY OF
STEEL.
• OTHER ELEMENTS ARE KEPT BELOW A CERTAIN LIMIT SO THAT THEY
DO NOT INFLUENCE THE PROPERTIES OF STEEL.
• LOW CARBON STEEL
• EASILY WELDABLE
• HAS GOOD WORKABILITY
• SHOW POOR RESPONSE TO HEAT TREATMENT
• IT IS MAINLY USED FOR SHEETS,STRIPS,ETC.
• MEDIUM CARBON STEEL
• HAS GOOD STRENGTH
• TOUGHNESS
• ITS RESPONSE TO HEAT TREATMENT IS ALSO GOOD.
• HIGH CARBON STEEL
• HAS GOOD STRENGTH
• USED AS TOOL STEEL.

DISADVANTAGE OF PLAIN CARBON STEEL
• 1.LOW HARDENABILITY
• 2.MAJOR LOSS OF HARDNESS ON
TEMPERING
• 3.LOW STRENGTH AT ELEVATED TEMP.
• 4.LOW CORROSION & OXIDATION
RESISTANCE.
• THE MOST COMMON METHOD TO
OVERCOME THE DISADVANTAGES OF
PLAIN CARBON STEEL IS TO USE ALLOY
STEEL.

ALLOY STEELS
• ALLOY STEELS ARE THOSE IN WHICH
ONE OR MORE ELEMENTS ARE
ADDED TO STEEL FOR ENCHANCING
FURTHER THE PROMINENT
CHARACTERISTICS OF THE PLAIN
CARBON STEELS OR TO ENSURE
SPECIFIC PROPERTIES.THE ADDED
ELEMENTS ARE KNOWN AS
ALLOYING ELEMENTS.

CLASSIFICATION OF ALLOY STEELS
LOW ALLOY STEELS MEDIUM ALLOY STEELS HIGH ALLOY STEELS
TOTAL ALLOYING
CONTENT IS LESS
THAN 5 %
TOTAL ALLOYING
CONTENT IS 5-10 %
TOTAL ALLOYING
CONTENT IS MORE
THAN 10 %

CLASSIFICATION OF ALLOY STEEL ON THE
BASIS OF ALLOYING ELEMENTS
Cr STEEL Cr--Mo STEEL
SCr 415 H
SCr 420 H
SCM 415 H
SCM 420 H

ADVANTAGES OF ALLOY STEELS
• ALLOYING ELEMENTS ARE ADDED TO
IMPART A NUMBER OF DESIRABLE
PROPERTIES IN STEELS.
• 1.THEY ARE ADDED TO
• INCREASE THE HARDENABILITY
• INCREASE RESISTANCE TO SOFTENING ON
TEMPERING,
• INCREASE RESISTANCE TO CORROSION &
ABRASION.
• IMPROVE THE HIGH TEMP. PROPERTIES.

BASIC METALLURGICAL REQUIREMENTS
OF BASIC STEELS (BAR STOCK)
• THE STEELS ARE PRODUCED THROUGH HOT ROLLING OR HOT
FORGING USUALLY FOLLOWED BY FORGING,CUTTING OR OTHER
MACHINING & HEAT TREATMENT BEFORE IT IS PUT TO USE.
• VARIOUS PROPERTIES TO BE CHECKED IN STEEL BEFORE USE
(OR IN AS RECD. CONDITION FROM STEEL SUPPLIER)
• 1.STEEL MAKING METHOD
• 2.CHEMICAL COMPOSITION
• 3.SUPPLY CONDITION (HARDNESS)
• 4.MICRO STRUCTURE
• 5.HARDENABILITY
• 6.GRAIN SIZE
• 7. INCLUSION RATING
• 8. DECARBURISATION
• 9.STREAK FLAW
• 10.MACRO STRUCTURE.

• STEEL MAKING METHOD
• BASIC STEEL TO BE USED SHALL BE MANUFACTURED
BY
• 1.VACUUM DEGASSING PROCESS
• 2. AL KILLED STEEL
• THIS CAN BE CONFIRMED BY STEEL SUPPLIER
CERTIFICATE.
• STEEL SUPPLIER SHOULD BE SUGGESTED TO
INDICATED THE STEEL MFG. ROUTE ON THE
CERTIFICATE.

BASIC METALLURGICAL REQUIREMENTS OF
BASIC STEELS (BAR STOCK)
• CHEMICAL COMPOSITION
• CHEMICAL COMPOSITION OF STEEL SHALL BE AS PER STANDARD.
• PERMISSIBLE VARIATIONS IN CHEMICAL COMPOSITIONS ARE AS
BELOW
ELEMENT SPECIFICATION
OF MAX.
CHEMICAL
CONTENT
LOWER LIMIT UPPER LIMIT
CARBON 0.30 AND
UNDER
0.01 0.01
0.30 TO
0.75
0.02 0.02

ELEMENT SPECIFICA
TION
OF MAX.
CHEMICAL
CONTENT
LOWER
LIMIT
UPPER
LIMIT
SILICON 0.35 AND
UNDER
0.02 0.02

ELEMENT SPECIFICAT
ION
OF MAX.
CHEMICAL
CONTENT
LOWER
LIMIT
UPPER
LIMIT
MANGANESE 0.90 AND
UNDER
0.03 0.03
0.90 TO
2.10
0.04 0.04

ELEMENT SPECIFICAT
ION
OF MAX.
CHEMICAL
CONTENT
LOWER
LIMIT
UPPER
LIMIT
PHOSPHORUS 0.50 AND
UNDER
- 0.005

ELEMENT SPECIFICAT
ION
OF MAX.
CHEMICAL
CONTENT
LOWER
LIMIT
UPPER
LIMIT
SULPHUR 0.60 AND
UNDER
- 0.005

ELEMENT SPECIFICAT
ION
OF MAX.
CHEMICAL
CONTENT
LOWER
LIMIT
UPPER
LIMIT
CHROMIUM 0.90AND
UNDER
0.03 0.03
0.90 TO
2.10
0.05 0.05

ELEMENT SPECIFICAT
ION
OF MAX.
CHEMICAL
CONTENT
LOWER
LIMIT
UPPER
LIMIT
MOLYBEDNU
M
0.20AND
UNDER
0.01 0.01
0.20 TO
0.40
0.02 0.02

OTHER ALLOYING
ELEMENTS
PERMISSIBLE
LEVEL
COPPER (Cu) 0.30 MAX.
NICKEL (Ni) 0.25 MAX.

EFFECT OF VARIOUS ELEMENTS ON PROPERTIES OF
STEEL
ALUMINIUM:-
1. USED AS DEOXIDISER
2. RESTRICTS GRAIN GROWTH (HELPS IN FINE GRAIN FORMATION)
3. ALLOYING ELEMENT IN NITRIDING STEELS
CARBON:-
1. PRINCIPAL HARDENING ELEMENT
2. INCREASE IN CARBON % INCREASES THE HARDNESS
3. DUCTILITY & WELDABILITY DECREASES AS CARBON INCREASES.

STEEL
CHROMIUM:-
1. INCREASES COROSION AND OXIDATION RESISTANCE.
2. INCREASES HARDENABILITY
3. INCREASES STRENGTH AT HIGH TEMPERATURE.
4. WITH ADDED CARBON RESIST WEAR & ABRASION.
MANGANESE:-
1. COUNTERACTS EFFECT OF BRITTLENESS FROM SULPHER.
2. INCREASES HARDENABILITY.
3. HIGH Mn & HIGH C PRODUCES STEELS RESISTANT TO WEAR &
ABRASION.

STEEL
MOLYBEDNUM:- USED WITH OTHER ELEMENTS & HAS
BENEFICIAL EFFECTS ON STEEL
1. WITH Cr & Mn IT IMPROVES & ADDS TO HARDENABILITY OF
STEEL.
2. USEFUL WHERE CLOSE HARDENABILITY IS REQD.
3. INCREASES CORROSION RESISTANCE.
4. INCREASES HIGH TEMP. STRENGTH.
5. INCREASES TENSILE & CREEP STRENGTH.
NICKEL:-
1. PROVIDES TOUGHNESS AT LOW TEMP.
2. INCREASES CORROSION RESISTANCE WITH Cr.

STEEL
PHOSPHOROUS:-
1. STRENGTHEN LOW C STEEL.
2. INCREASES CORROSION RESISTANCE.
3. IMPROVES MACHINABILITY IN FREE CUTTING STEEL.
4. INCREASES TENSILE STRENGTH IN LOW CARBON ALLOY STEEL.
SILICON:-
1. USED AS DEOXIDISER..
2. INCREASES TENSILE STRENGTH & ABRASION RESISTANCE.
3. RAISES YIELD POINT.
4. ENHANCES RESISTANCES TO SCALING.
5. STRENGTHEN LOW ALLOY STEEL

STEEL
SULPHUR:-
1. DECREASES DUCTILITY .
2. IMPROVES MACHINABILITY IN FREE CUTTING STEEL.
3. WELDABILITY DECREASES WITH INCERASING S.
4. TENDS TO PROMOTE WELDING CRACKS.

PERMISIBLE RANGE OF GASES
GAS PERMISSIBLE
LEVEL
OXYGEN 15 PPM MAX.
(TARGET 12 PPM)
NITROGEN 60 PPM MAX.
HYDROGEN 2 PPM MAX.

EFFECT OF VARIOUS GASES ON PROPERTIES OF STEEL
HYDROGEN:- HARMFUL TO STEEL.
1. CAUSES EMBRITTLEMENT .
2. DECREASES ELONGATION & REDUCTION IN AREA.
3. DECRASES TENSILE STRENGTH.
4. AT ELEVATED TEMP. ACTS AS DECARBURISING AGENTS.
NITROGEN:-
1. HAS DETERIORATING EFFECT BECAUSE IT IMPAIRS TOUGHNESS.
OXYGEN:- INJURIOUS TO STEEL.
1. WEAKENS MECHANICAL PROPERTIES.

• SUPPLY CONDITION (HARDNESS)
.
SUPPLY CONDITION HARDNESS
AS ROLLED 100 HRB MAX.
COLD FORGING
(SPHERODISED)
83 HRB MAX.
AS NORMALISED 80-95 HRB

• MICRO STRUCTURE
.
SUPPLY
CONDITION
MICRO STRUCTURE
NORMALISED UNIFROMALLY DISTRIBUTED
PEARLITE & FERRITE WITH MAX.
10% BAINITE .SHOULD BE FREE
FROM BANDING
FULL
ANNEALING
PEARLITE LAMELLAR STRUCTURE
OF 60% OR MORE
SPHEROIDIZING SPHERIC RATE IS 80% OR MORE

• HARDENABILITY
• THE HARDENABILITY J-13 (HARDNESS AT
A DISTANCE (J) OF 13 mm. FROM QUENCH
END) SHALL BE AS PER FOLLOWING
TABLE.
.

STEEL GRADE HARDENABILITY
SCr415H -27
SCr420H 25-30
SCM415H 23-28(TARGET:-25-30)
SCM418H 25-30(TARGET:-28-30)
SCM420H 27-32(TARGET:-28-32)
SCr440H 37-54
SCM435H 39-53
HARDENABILITY

• GRAIN SIZE
• THE AUSTENITIC GRAIN SIZE OF THE STEEL CAN BE CHECKED
WITH THE HELP OF MICROSCOPE & IT SHOLD ALSO CONFIRMED
WITH THE HELP OF STEEL SUPPLIER CERTIFICATE.
• THE GRAIN SIZE SHALL CONFIRM TO THE TABLE GIVEN BELOW
.
HEAT TREATMENT AUSTENITIC GRAIN SIZE
FOR CARBURISING AVERAGE GRAIN SIZE
NO. 6.0MIN.
FOR REFINING AVERAGE GRAIN SIZE
NO. 5.0MIN.

• INCLUSION RATING
• THE INCLUSION RATING SHOULD BE CHEKED AS PER
FOLLOWING
SERIES
TYPE
A B C D
THICK 1.5MAX 0.5 MAX 0.5 MAX 1.0 MAX
THIN 2.0 MAX 1.0 MAX 0.5 MAX 1.0 MAX

• DECARBURISATION
• THE DECARBURISATION (TOTAL+PARTIAL) SHALL BE
RESTRICTED AS PER FOLLOWING
DIA DECARB
(TOTAL+PARTIAL)
UP TO 32 mm. 0.15 MAX.
ABOVE 32 mm. 0.20 MAX.

• MACRO STREAK FLAW
• THESTREAK FLAW OF STEEL SHALL CONFIRM TO
FOLLOWING TABLE
CLASSIFICATION STREAK FLAW
INDICATION
FOR CARBURISING 8-12-(-5) MAX.
FOR REFINING 10-15 –(6)MAX.

RM Testing training- HHML.ppt

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