OAO “AVTOVAZ”
Minutes of Meeting No 12034 – 8
Technical & Engineering BU
For Research Works
Laboratory & Trial Tests
Dated from 04.05.2005
Reference Documents:
Without official notes
Manufacturer
OOO “Novyie Technologiye”, Samara, RF
Subject of research
Welded Blanks OOO “Novyie Technologiye”
Laboratory of Tool Steels
2 pcs. made of P18 and 40X steel;
Welded Blanks prepared for welding
OAO “AVTOVAZ” Engineering Center
1 pc. made of P6M5 and 4-X steel
1 pc. made of P18 and 40X steel
Reason for submission to reclamation
Harden blank with reheat temperature for welding
analysis
Method of diffusion welding
Reheat temperature = (0,8 – 0,9) of melting point for steel
Reheat temperature = 1200oC
Drawing requirements
Mark of material
Technology requirements
Hardness
Mark of material
Hardness
Results of Researches
Welded Blanks OOO “Novyie Technologiye”
1. Micro-structure:
1.1.
Steel P18 – austenitic grain 11 (10)
1.2.
Steel 40X – austenitic grain 2-3
1.3.
Decarburization is exposed on the cylindrical surface of a blank made of steel 40X
(near destruction area). The decarburized layer is ~ 80 µm deep (see fig 1).
1.4.
Quality of weld (except the decarburized section near cylindrical surface which
contributes to destruction) is good – pores or incomplete penetration are missing.
2. Hardness of steel P18 (core): 851 HV2 (~63,5 HRC)
3. Distribution of micro-hardness from the weld surface to the core:
Place of measurement
т.1
L, µm
20
26
50
64
74
HK0,1
164
235
380
430
495
Depth of decarburized layer
~ 82 µm
т.2
82
core
535
535
10
20
28
core
880
880
880
880
No lowering of microhardness
Fig 1.
4. Additional researches (after annealing):
4.1.
Micro-structure:
-
P18 – sorbite + carbides;
-
40X – ferrite + lamellar pearlite. Decarburization is exposed from the weld. The
decarburized layer is ~ 400 µm deep. Ring crack (or incomplete penetration) is up to
180µm deep in outside diameter of the weld (see fig. 2)
4.2.
Distribution of micro-hardness from the weld surface to the core:
Place of measurement
L, µm
т.1
т.2
Fig 2
HK0,1
20
74
120
170
220
310
352
400
440
480…
128
126
120
130
130
132
134
170
200
205
20
54
80
365
365
365
Depth of decarburized
layer
~ 440 µm
No
Welded blanks prepared for welding in OAO “AVTOVAZ” Engineering Center
After-welded blanks were subject to additional low-temperature annealing - heating up to 720oC,
time delay 3 hours, cooling with a burner
P6M5 – 40X steel
1.1.
Micro-structure:
-
P6M5 – sorbite + carbides;
-
40X – ferrite + lamellar pearlite. Decarburization is exposed on the cylindrical blank made
of 40X steel. The decarburized layer is ~ 400 µm deep.
1.2.
1.3.
Hardness:
- P6M5
- 609 HV2 (~ 54,5 HRC)
- 40X
- 207 HV2 (~ 18 HRC)
Distribution of micro-hardness from the weld surface to the core:
Place of measurement
L, µm
HK0,1
40X
20
30
54
70
90
104
core
198
205
212
212
230
230
230
10
32
50
core
700
700
700
700
P6M5
Depth of decarburized
layer
~ 90 µm
no
P18-40X steel
2.1. Micro-structure:
-
P18 – sorbite + carbides;
-
40X – ferrite + lamellar pearlite. Decarburization is exposed on the cylindrical blank made
of 40X steel. The decarburized layer is ~ 200 µm deep.
2.2.
Hardness:
- P18
- 659 HV2 (~ 56,5 HRC)
- 40X
- 219 HV2 (~ 20 HRC)
2.3.
Distribution of micro-hardness from the weld surface to the core:
Place of measurement
L, µm
HK0,1
40X
20
40
60
84
100
122
core
210
205
220
220
230
230
230
10
20
32
core
730
730
730
730
P18
Depth of decarburized
layer
~ 100 µm
no
Conclusions:
1. Weld quality is good.
2. To better prepare high-speed steel to further hardening it is necessary to optimize
annealing of blanks after welding.